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Structure of Cell and its functions in life

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Cell Structure and Cell Structure and Function Function
Chapter Outline Chapter Outline  Cell theory Cell theory  Properties common to all cells Properties common to all cells  Cell size and shape – Cell size and shape – why are cells so small? why are cells so small?  Prokaryotic cells Prokaryotic cells  Eukaryotic cells Eukaryotic cells  Organelles and structure in all eukaryotic cell Organelles and structure in all eukaryotic cell  Organelles in plant cells but not animal Organelles in plant cells but not animal  Cell junctions Cell junctions
History of Cell Theory History of Cell Theory  mid 1600s – Anton van Leeuwenhoek mid 1600s – Anton van Leeuwenhoek  Improved microscope, observed many living cells Improved microscope, observed many living cells  mid 1600s – Robert Hooke mid 1600s – Robert Hooke  Observed many cells including cork cells Observed many cells including cork cells 1850 – Rudolf Virchow 1850 – Rudolf Virchow  Proposed that all cells come from existing Proposed that all cells come from existing cells cells
Cell Theory Cell Theory 1. 1. All organisms consist of 1 or more All organisms consist of 1 or more cells. cells. 2. 2. Cell is the smallest unit of life. Cell is the smallest unit of life. 3. 3. All cells come from pre-existing All cells come from pre-existing cells. cells.
Observing Cells Observing Cells (4.1) (4.1)  Light microscope Light microscope  Can observe living cells in true color Can observe living cells in true color  Magnification of up to ~1000x Magnification of up to ~1000x  Resolution ~ 0.2 microns – 0.5 microns Resolution ~ 0.2 microns – 0.5 microns
Observing Cells Observing Cells (4.1) (4.1)  Electron Microscopes Electron Microscopes  Preparation needed kills the cells Preparation needed kills the cells  Images are black and white – may be Images are black and white – may be colorized colorized  Magnifcation up to ~100,000 Magnifcation up to ~100,000 • Transmission electron microscope (TEM) Transmission electron microscope (TEM)  2-D image 2-D image • Scanning electron microscope (SEM) Scanning electron microscope (SEM)  3-D image 3-D image
SEM TEM
Cell Structure Cell Structure  All Cells have: All Cells have:  an outermost plasma membrane an outermost plasma membrane  genetic material in the form of DNA genetic material in the form of DNA  cytoplasm with ribosomes cytoplasm with ribosomes
1. Plasma Membrane 1. Plasma Membrane • All membranes are phospholipid All membranes are phospholipid bilayers with embedded proteins bilayers with embedded proteins • The outer plasma membrane The outer plasma membrane  isolates cell contents isolates cell contents  controls what gets in and out of the cell controls what gets in and out of the cell  receives signals receives signals
2. Genetic material in the 2. Genetic material in the form of DNA form of DNA  Prokaryotes – no membrane Prokaryotes – no membrane around the DNA around the DNA  Eukaryotes – DNA is within a Eukaryotes – DNA is within a membrane membrane
3. Cytoplasm with ribosomes 3. Cytoplasm with ribosomes  Cytoplasm – fluid area inside outer Cytoplasm – fluid area inside outer plasma membrane and outside plasma membrane and outside DNA region DNA region  Ribosomes – make proteins Ribosomes – make proteins
Cell Structure Cell Structure  All Cells have: All Cells have:  an outermost plasma membrane an outermost plasma membrane  genetic material in the form of DNA genetic material in the form of DNA  cytoplasm with ribosomes cytoplasm with ribosomes
Why Are Cells So Small? Why Are Cells So Small? (4.2) (4.2)  Cells need sufficient surface area to allow Cells need sufficient surface area to allow adequate transport of nutrients in and adequate transport of nutrients in and wastes out. wastes out.  As cell volume increases, so does the As cell volume increases, so does the need for the transporting of nutrients and need for the transporting of nutrients and wastes. wastes.
Why Are Cells So Small? Why Are Cells So Small?  However, as cell volume increases the However, as cell volume increases the surface area of the cell does not expand surface area of the cell does not expand as quickly. as quickly.  If the cell’s volume gets too large it cannot If the cell’s volume gets too large it cannot transport enough wastes out or nutrients in. transport enough wastes out or nutrients in.  Thus, surface area limits cell volume/size. Thus, surface area limits cell volume/size.
Why Are Cells So Small? Why Are Cells So Small?  Strategies for increasing surface Strategies for increasing surface area, so cell can be larger: area, so cell can be larger:  “ “Frilly” edged……. Frilly” edged…….  Long and narrow….. Long and narrow…..  Round cells will always be small. Round cells will always be small.
Prokaryotic Cell Structure Prokaryotic Cell Structure  Prokaryotic Cells are smaller and Prokaryotic Cells are smaller and simpler in structure than eukaryotic simpler in structure than eukaryotic cells. cells.  Typical prokaryotic cell is __________ Typical prokaryotic cell is __________  Prokaryotic cells do NOT have: Prokaryotic cells do NOT have: • Nucleus Nucleus • Membrane bound organelles Membrane bound organelles
Prokaryotic Cell Structure Prokaryotic Cell Structure  Structures Structures  Plasma membrane Plasma membrane  Cell wall Cell wall  Cytoplasm with ribosomes Cytoplasm with ribosomes  Nucleoid Nucleoid  Capsule* Capsule*  Flagella* and pili* Flagella* and pili* *present in some, but not all prokaryotic cells *present in some, but not all prokaryotic cells
Prokaryotic Cell
Structure of Cell and its functions in life
TEM Prokaryotic Cell
Eukaryotic Cells Eukaryotic Cells  Structures in all eukaryotic cells Structures in all eukaryotic cells  Nucleus Nucleus  Ribosomes Ribosomes  Endomembrane System Endomembrane System • Endoplasmic reticulum – smooth and rough Endoplasmic reticulum – smooth and rough • Golgi apparatus Golgi apparatus • Vesicles Vesicles  Mitochondria Mitochondria  Cytoskeleton Cytoskeleton
CYTOSKELETON MITOCHONDRION CENTRIOLES LYSOSOME GOLGI BODY SMOOTH ER ROUGH ER RIBOSOMES NUCLEUS PLASMA MEMBRANE Fig. 4-15b, p.59 VESICLE CYTOPLASM
Nucleus Nucleus (4.5) (4.5)  Function Function – isolates the cell’s genetic – isolates the cell’s genetic material, DNA material, DNA  DNA directs/controls the activities of the cell DNA directs/controls the activities of the cell • DNA determines which types of RNA are made DNA determines which types of RNA are made • The RNA leaves the nucleus and directs the The RNA leaves the nucleus and directs the synthesis of proteins in the cytoplasm at a synthesis of proteins in the cytoplasm at a ______________ ______________
Nucleus Nucleus  Structure Structure  Nuclear envelope Nuclear envelope • Two Phospholipid bilayers with Two Phospholipid bilayers with protein lined pores protein lined pores  Each pore is a ring of 8 proteins with an Each pore is a ring of 8 proteins with an opening in the center of the ring opening in the center of the ring  Nucleoplasm – fluid of the nucleus Nucleoplasm – fluid of the nucleus
Nuclear pore bilayer facing cytoplasm Nuclear envelope bilayer facing nucleoplasm Fig. 4-17, p.61
Nucleus Nucleus  DNA is arranged in chromosomes DNA is arranged in chromosomes  Chromosome – fiber of DNA with Chromosome – fiber of DNA with proteins attached proteins attached  Chromatin – all of the cell’s DNA and Chromatin – all of the cell’s DNA and the associated proteins the associated proteins
Nucleus Nucleus  Structure, Structure, continued continued  Nucleolus Nucleolus • Area of condensed DNA Area of condensed DNA • Where ribosomal subunits are made Where ribosomal subunits are made  Subunits exit the nucleus via nuclear pores Subunits exit the nucleus via nuclear pores
ADD THE LABELS
Endomembrane System Endomembrane System (4.6 – 4.9) (4.6 – 4.9)  Series of organelles responsible for: Series of organelles responsible for:  Modifying protein chains into their final Modifying protein chains into their final form form  Synthesizing of lipids Synthesizing of lipids  Packaging of fully modified proteins and Packaging of fully modified proteins and lipids into vesicles for export or use in lipids into vesicles for export or use in the cell the cell  And more that we will not cover! And more that we will not cover!
Structures of the Structures of the Endomembrane System Endomembrane System  Endoplasmic Reticulum (ER) Endoplasmic Reticulum (ER)  Continuous with the outer membrane of Continuous with the outer membrane of the nuclear envelope the nuclear envelope  Two forms - smooth and rough Two forms - smooth and rough  Transport vesicles Transport vesicles  Golgi apparatus Golgi apparatus
Structure of Cell and its functions in life
Endoplasmic Reticulum (ER) Endoplasmic Reticulum (ER)  The ER is continuous with the outer The ER is continuous with the outer membrane of the nuclear envelope membrane of the nuclear envelope  There are 2 types of ER: There are 2 types of ER: • Rough ER – has ribosomes attached Rough ER – has ribosomes attached • Smooth ER – no ribosomes attached Smooth ER – no ribosomes attached
Endoplasmic Reticulum Endoplasmic Reticulum  Rough Endoplasmic Reticulum (RER) Rough Endoplasmic Reticulum (RER) • Network of flattened membrane sacs create Network of flattened membrane sacs create a “maze” a “maze”  RER contains enzymes that recognize and RER contains enzymes that recognize and modify proteins modify proteins • Ribosomes are attached to the outside of Ribosomes are attached to the outside of the RER and make it appear rough the RER and make it appear rough
Endoplasmic Reticulum Endoplasmic Reticulum  Function RER Function RER • Proteins are modified as they move through Proteins are modified as they move through the RER the RER • Once modified, the proteins are packaged Once modified, the proteins are packaged in transport vesicles for transport to the in transport vesicles for transport to the Golgi body Golgi body
Endomembrane System Endomembrane System  Smooth ER (SER) Smooth ER (SER)  Tubular membrane structure Tubular membrane structure  Continuous with RER Continuous with RER  No ribosomes attached No ribosomes attached  Function SER Function SER  Lipids are made inside the SER Lipids are made inside the SER • fatty acids, phospholipids, sterols.. fatty acids, phospholipids, sterols..  Lipids are packaged in transport vesicles and Lipids are packaged in transport vesicles and sent to the Golgi sent to the Golgi
Golgi Apparatus Golgi Apparatus  Golgi Apparatus Golgi Apparatus  Stack of flattened membrane sacs Stack of flattened membrane sacs  Function Golgi apparatus Function Golgi apparatus  Completes the processing substances Completes the processing substances received from the ER received from the ER  Sorts, tags and packages fully processed Sorts, tags and packages fully processed proteins and lipids in vesicles proteins and lipids in vesicles
Structure of Cell and its functions in life
Golgi Apparatus Golgi Apparatus  Golgi apparatus receives transport Golgi apparatus receives transport vesicles from the ER on one side of the vesicles from the ER on one side of the organelle organelle  Vesicle binds to the first layer of the Golgi and Vesicle binds to the first layer of the Golgi and its contents enter the Golgi its contents enter the Golgi
Golgi Apparatus Golgi Apparatus  The proteins and lipids are modified as they The proteins and lipids are modified as they pass through layers of the Golgi pass through layers of the Golgi  Molecular tags are added to the fully modified Molecular tags are added to the fully modified substances substances • These tags allow the substances to be sorted and These tags allow the substances to be sorted and packaged appropriately. packaged appropriately. • Tags also indicate where the substance is to be Tags also indicate where the substance is to be shipped. shipped.
Golgi Apparatus Golgi Apparatus
Transport Vesicles Transport Vesicles  Transport Vesicles Transport Vesicles  Vesicle = small membrane bound sac Vesicle = small membrane bound sac  Transport modified proteins and lipids from Transport modified proteins and lipids from the ER to the Golgi apparatus (and from Golgi the ER to the Golgi apparatus (and from Golgi to final destination) to final destination)
Endomembrane System Endomembrane System  Putting it all together Putting it all together  DNA directs RNA synthesis DNA directs RNA synthesis   RNA RNA exits nucleus through a nuclear pore exits nucleus through a nuclear pore   ribosome ribosome   protein is made protein is made   proteins proteins with proper code enter RER with proper code enter RER   proteins proteins are modified in RER and lipids are made are modified in RER and lipids are made in SER in SER   vesicles containing the vesicles containing the proteins and lipids bud off from the ER proteins and lipids bud off from the ER
Endomembrane System Endomembrane System  Putting it all together Putting it all together  ER vesicles merge with Golgi body ER vesicles merge with Golgi body   proteins and lipids enter Golgi proteins and lipids enter Golgi   each is each is fully modified as it passes through fully modified as it passes through layers of Golgi layers of Golgi   modified products are modified products are tagged, sorted and bud off in Golgi tagged, sorted and bud off in Golgi vesicles vesicles   … …
Endomembrane System Endomembrane System  Putting it all together  Golgi vesicles either merge with the Golgi vesicles either merge with the plasma membrane and release their plasma membrane and release their contents OR remain in the cell and contents OR remain in the cell and serve a purpose serve a purpose  Another Another animation
Vesicles Vesicles  Vesicles - small membrane bound sacs Vesicles - small membrane bound sacs  Examples Examples • Golgi and ER transport vesicles Golgi and ER transport vesicles • Peroxisome Peroxisome  Where fatty acids are metabolized Where fatty acids are metabolized  Where hydrogen peroxide is detoxified Where hydrogen peroxide is detoxified • Lysosome Lysosome  contains digestive enzymes contains digestive enzymes  Digests unwanted cell parts and other wastes Digests unwanted cell parts and other wastes
Lysosomes Lysosomes (4.10) (4.10)  The lysosome is an example of an The lysosome is an example of an organelle made at the Golgi apparatus. organelle made at the Golgi apparatus.  Golgi packages digestive enzymes in a Golgi packages digestive enzymes in a vesicle. The vesicle remains in the cell and: vesicle. The vesicle remains in the cell and: • Digests unwanted or damaged cell parts Digests unwanted or damaged cell parts • Merges with food vacuoles and digest the contents Merges with food vacuoles and digest the contents • Figure 4.10A Figure 4.10A
Lysosomes Lysosomes (4.11) (4.11)  Tay-Sachs disease occurs when the Tay-Sachs disease occurs when the lysosome is missing the enzyme needed lysosome is missing the enzyme needed to digest a lipid found in nerve cells. to digest a lipid found in nerve cells.  As a result the lipid accumulates and nerve As a result the lipid accumulates and nerve cells are damaged as the lysosome swells cells are damaged as the lysosome swells with undigested lipid. with undigested lipid.
Mitochondria Mitochondria (4.15) (4.15)  Function – synthesis of ATP Function – synthesis of ATP  3 major pathways involved in ATP 3 major pathways involved in ATP production production 1. 1. Glycolysis Glycolysis 2. 2. Krebs Cycle Krebs Cycle 3. 3. Electron transport system (ETS) Electron transport system (ETS)
Mitochondria Mitochondria  Structure: Structure:  ~1-5 microns ~1-5 microns  Two membranes Two membranes • Outer membrane Outer membrane • Inner membrane - Highly folded Inner membrane - Highly folded  Folds called cristae Folds called cristae  Intermembrane space (or outer compartment) Intermembrane space (or outer compartment)  Matrix Matrix • DNA and ribosomes in matrix DNA and ribosomes in matrix
Mitochondria Mitochondria
Mitochondria Mitochondria (4.15) (4.15)  Function – synthesis of ATP Function – synthesis of ATP  3 major pathways involved in ATP 3 major pathways involved in ATP production production 1. 1. Glycolysis - cytoplasm Glycolysis - cytoplasm 2. 2. Krebs Cycle - matrix Krebs Cycle - matrix 3. 3. Electron transport system (ETS) - Electron transport system (ETS) - intermembrane space intermembrane space
Mitochondria Mitochondria TEM TEM
Structure of Cell and its functions in life
Vacuoles Vacuoles (4.12) (4.12)  Vacuoles are membrane sacs that are Vacuoles are membrane sacs that are generally larger than vesicles. generally larger than vesicles.  Examples: Examples: • Food vacuole - formed when protists bring food Food vacuole - formed when protists bring food into the cell by endocytosis into the cell by endocytosis • Contractile vacuole – collect and pump excess Contractile vacuole – collect and pump excess water out of some freshwater protists water out of some freshwater protists • Central vacuole – covered later Central vacuole – covered later
Cytoskeleton Cytoskeleton (4.16, 4.17) (4.16, 4.17)  Function Function  gives cells internal organization, shape, and gives cells internal organization, shape, and ability to move ability to move  Structure Structure  Interconnected system of microtubules, Interconnected system of microtubules, microfilaments, and intermediate filaments microfilaments, and intermediate filaments (animal only) (animal only) • All are proteins All are proteins
Cytoskeleton Cytoskeleton
Microfilaments Microfilaments  Thinnest cytoskeletal elements (rodlike) Thinnest cytoskeletal elements (rodlike)  Composed of the globular protein Composed of the globular protein actin actin  Enable cells to change shape and move Enable cells to change shape and move
Cytoskeleton Cytoskeleton  Intermediate filaments Intermediate filaments  Present only in animal cells of Present only in animal cells of certain tissues certain tissues  Fibrous proteins join to form a Fibrous proteins join to form a rope-like structure rope-like structure • Provide internal structure Provide internal structure • Anchor organelles in place. Anchor organelles in place.
Cytoskeleton Cytoskeleton  Microtubules – long hollow Microtubules – long hollow tubes made of tubulin proteins tubes made of tubulin proteins (globular) (globular)  Anchor organelles and act as Anchor organelles and act as tracks for organelle movement tracks for organelle movement  Move chromosomes around Move chromosomes around during cell division during cell division • Used to make cilia and flagella Used to make cilia and flagella
Cilia Cilia and and flagella flagella (structures for cell motility) (structures for cell motility)  Move whole cells or materials across the cell surface Move whole cells or materials across the cell surface  Microtubules wrapped in an extension of the plasma Microtubules wrapped in an extension of the plasma membrane (9 + 2 arrangement of MT) membrane (9 + 2 arrangement of MT)
Plant Cell Structures Plant Cell Structures  Structures found in plant, but not animal Structures found in plant, but not animal cells cells  Chloroplasts Chloroplasts  Central vacuole Central vacuole  Other plastids/vacuoles – chromoplast, Other plastids/vacuoles – chromoplast, amyloplast amyloplast  Cell wall Cell wall
Chloroplasts Chloroplasts (4.14) (4.14)  Function – site of photosynthesis Function – site of photosynthesis  Structure Structure  2 outer membranes 2 outer membranes  Thylakoid membrane system Thylakoid membrane system • Stacked membrane sacs called granum Stacked membrane sacs called granum  Chlorophyll in granum Chlorophyll in granum  Stroma Stroma • Fluid part of chloroplast Fluid part of chloroplast
Structure of Cell and its functions in life
Plastids/Vacuoles in Plants Plastids/Vacuoles in Plants  Chromoplasts – contain colored pigments Chromoplasts – contain colored pigments • Pigments called carotenoids Pigments called carotenoids  Amyloplasts – store starch Amyloplasts – store starch
Central Vacuole Central Vacuole  Function – storage area for water, sugars, Function – storage area for water, sugars, ions, amino acids, and wastes ions, amino acids, and wastes  Some central vacuoles serve specialized Some central vacuoles serve specialized functions in plant cells. functions in plant cells. • May contain poisons to protect against predators May contain poisons to protect against predators
Central Vacuole Central Vacuole  Structure Structure  Large membrane bound sac Large membrane bound sac  Occupies the majority of the volume of the Occupies the majority of the volume of the plant cell plant cell  Increases cell’s surface area for transport of Increases cell’s surface area for transport of substances substances   cells can be larger cells can be larger
Cell surfaces protect, support, and join cells Cell surfaces protect, support, and join cells  Cells interact with their environments and Cells interact with their environments and each other via their surfaces each other via their surfaces  Many cells are protected by more than the Many cells are protected by more than the plasma membrane plasma membrane
Cell Wall Cell Wall  Function – provides structure and protection Function – provides structure and protection  Never found in animal cells Never found in animal cells  Present in plant, bacterial, fungus, and some protists Present in plant, bacterial, fungus, and some protists  Structure Structure  Wraps around the plasma membrane Wraps around the plasma membrane  Made of cellulose and other polysaccharides Made of cellulose and other polysaccharides  Connect by plasmodesmata Connect by plasmodesmata (channels through the walls) (channels through the walls)
Plant Cell TEM Plant Cell TEM
Typical Plant Cell Typical Plant Cell
Typical Plant Cell –add the labels Typical Plant Cell –add the labels
Origin of Mitochondria and Origin of Mitochondria and Chloroplasts Chloroplasts  Both organelles are believed to have once Both organelles are believed to have once been free-living bacteria that were been free-living bacteria that were engulfed by a larger cell. engulfed by a larger cell.
Proposed Origin of Mitochondria Proposed Origin of Mitochondria and Chloroplasts and Chloroplasts  Evidence: Evidence:  Each have their own DNA Each have their own DNA  Their ribosomes resemble bacterial Their ribosomes resemble bacterial ribosomes ribosomes  Each can divide on its own Each can divide on its own  Mitochondria are same size as bacteria Mitochondria are same size as bacteria  Each have more than one membrane Each have more than one membrane
Cell Junctions Cell Junctions (4.18) (4.18)  Plasma membrane proteins connect Plasma membrane proteins connect neighboring cells - called cell junctions neighboring cells - called cell junctions  Plant cells – plasmodesmata provide Plant cells – plasmodesmata provide channels between cells channels between cells
Cell Junctions Cell Junctions (4.18) (4.18)  3 types of cell junctions in animal cells 3 types of cell junctions in animal cells 1. 1. Tight junctions Tight junctions 2. 2. Anchoring junctions Anchoring junctions 3. 3. Gap junctions Gap junctions
Cell Junctions Cell Junctions 1. 1. Tight junctions – membrane proteins seal Tight junctions – membrane proteins seal neighboring cells so that water soluble neighboring cells so that water soluble substances cannot cross between them substances cannot cross between them • See between stomach cells See between stomach cells
Cell Junctions Cell Junctions 2. 2. Anchoring junctions – cytoskeleton fibers Anchoring junctions – cytoskeleton fibers join cells in tissues that need to stretch join cells in tissues that need to stretch • See between heart, skin, and muscle cells See between heart, skin, and muscle cells 3. 3. Gap junctions – membrane proteins on Gap junctions – membrane proteins on neighboring cells link to form channels neighboring cells link to form channels • This links the cytoplasm of adjoining cells This links the cytoplasm of adjoining cells
Gap junction Anchoring junction Tight junction
Plant Cell Junctions Plant Cell Junctions  Plasmodesmata Plasmodesmata form channels between form channels between neighboring plant cells neighboring plant cells
Vacuole Walls of two adjacent plant cells Plasmodesmata Layers of one plant cell wall Cytoplasm Plasma membrane

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Structure of Cell and its functions in life

  • 1. Cell Structure and Cell Structure and Function Function
  • 2. Chapter Outline Chapter Outline  Cell theory Cell theory  Properties common to all cells Properties common to all cells  Cell size and shape – Cell size and shape – why are cells so small? why are cells so small?  Prokaryotic cells Prokaryotic cells  Eukaryotic cells Eukaryotic cells  Organelles and structure in all eukaryotic cell Organelles and structure in all eukaryotic cell  Organelles in plant cells but not animal Organelles in plant cells but not animal  Cell junctions Cell junctions
  • 3. History of Cell Theory History of Cell Theory  mid 1600s – Anton van Leeuwenhoek mid 1600s – Anton van Leeuwenhoek  Improved microscope, observed many living cells Improved microscope, observed many living cells  mid 1600s – Robert Hooke mid 1600s – Robert Hooke  Observed many cells including cork cells Observed many cells including cork cells 1850 – Rudolf Virchow 1850 – Rudolf Virchow  Proposed that all cells come from existing Proposed that all cells come from existing cells cells
  • 4. Cell Theory Cell Theory 1. 1. All organisms consist of 1 or more All organisms consist of 1 or more cells. cells. 2. 2. Cell is the smallest unit of life. Cell is the smallest unit of life. 3. 3. All cells come from pre-existing All cells come from pre-existing cells. cells.
  • 5. Observing Cells Observing Cells (4.1) (4.1)  Light microscope Light microscope  Can observe living cells in true color Can observe living cells in true color  Magnification of up to ~1000x Magnification of up to ~1000x  Resolution ~ 0.2 microns – 0.5 microns Resolution ~ 0.2 microns – 0.5 microns
  • 6. Observing Cells Observing Cells (4.1) (4.1)  Electron Microscopes Electron Microscopes  Preparation needed kills the cells Preparation needed kills the cells  Images are black and white – may be Images are black and white – may be colorized colorized  Magnifcation up to ~100,000 Magnifcation up to ~100,000 • Transmission electron microscope (TEM) Transmission electron microscope (TEM)  2-D image 2-D image • Scanning electron microscope (SEM) Scanning electron microscope (SEM)  3-D image 3-D image
  • 8. Cell Structure Cell Structure  All Cells have: All Cells have:  an outermost plasma membrane an outermost plasma membrane  genetic material in the form of DNA genetic material in the form of DNA  cytoplasm with ribosomes cytoplasm with ribosomes
  • 9. 1. Plasma Membrane 1. Plasma Membrane • All membranes are phospholipid All membranes are phospholipid bilayers with embedded proteins bilayers with embedded proteins • The outer plasma membrane The outer plasma membrane  isolates cell contents isolates cell contents  controls what gets in and out of the cell controls what gets in and out of the cell  receives signals receives signals
  • 10. 2. Genetic material in the 2. Genetic material in the form of DNA form of DNA  Prokaryotes – no membrane Prokaryotes – no membrane around the DNA around the DNA  Eukaryotes – DNA is within a Eukaryotes – DNA is within a membrane membrane
  • 11. 3. Cytoplasm with ribosomes 3. Cytoplasm with ribosomes  Cytoplasm – fluid area inside outer Cytoplasm – fluid area inside outer plasma membrane and outside plasma membrane and outside DNA region DNA region  Ribosomes – make proteins Ribosomes – make proteins
  • 12. Cell Structure Cell Structure  All Cells have: All Cells have:  an outermost plasma membrane an outermost plasma membrane  genetic material in the form of DNA genetic material in the form of DNA  cytoplasm with ribosomes cytoplasm with ribosomes
  • 13. Why Are Cells So Small? Why Are Cells So Small? (4.2) (4.2)  Cells need sufficient surface area to allow Cells need sufficient surface area to allow adequate transport of nutrients in and adequate transport of nutrients in and wastes out. wastes out.  As cell volume increases, so does the As cell volume increases, so does the need for the transporting of nutrients and need for the transporting of nutrients and wastes. wastes.
  • 14. Why Are Cells So Small? Why Are Cells So Small?  However, as cell volume increases the However, as cell volume increases the surface area of the cell does not expand surface area of the cell does not expand as quickly. as quickly.  If the cell’s volume gets too large it cannot If the cell’s volume gets too large it cannot transport enough wastes out or nutrients in. transport enough wastes out or nutrients in.  Thus, surface area limits cell volume/size. Thus, surface area limits cell volume/size.
  • 15. Why Are Cells So Small? Why Are Cells So Small?  Strategies for increasing surface Strategies for increasing surface area, so cell can be larger: area, so cell can be larger:  “ “Frilly” edged……. Frilly” edged…….  Long and narrow….. Long and narrow…..  Round cells will always be small. Round cells will always be small.
  • 16. Prokaryotic Cell Structure Prokaryotic Cell Structure  Prokaryotic Cells are smaller and Prokaryotic Cells are smaller and simpler in structure than eukaryotic simpler in structure than eukaryotic cells. cells.  Typical prokaryotic cell is __________ Typical prokaryotic cell is __________  Prokaryotic cells do NOT have: Prokaryotic cells do NOT have: • Nucleus Nucleus • Membrane bound organelles Membrane bound organelles
  • 17. Prokaryotic Cell Structure Prokaryotic Cell Structure  Structures Structures  Plasma membrane Plasma membrane  Cell wall Cell wall  Cytoplasm with ribosomes Cytoplasm with ribosomes  Nucleoid Nucleoid  Capsule* Capsule*  Flagella* and pili* Flagella* and pili* *present in some, but not all prokaryotic cells *present in some, but not all prokaryotic cells
  • 21. Eukaryotic Cells Eukaryotic Cells  Structures in all eukaryotic cells Structures in all eukaryotic cells  Nucleus Nucleus  Ribosomes Ribosomes  Endomembrane System Endomembrane System • Endoplasmic reticulum – smooth and rough Endoplasmic reticulum – smooth and rough • Golgi apparatus Golgi apparatus • Vesicles Vesicles  Mitochondria Mitochondria  Cytoskeleton Cytoskeleton
  • 22. CYTOSKELETON MITOCHONDRION CENTRIOLES LYSOSOME GOLGI BODY SMOOTH ER ROUGH ER RIBOSOMES NUCLEUS PLASMA MEMBRANE Fig. 4-15b, p.59 VESICLE CYTOPLASM
  • 23. Nucleus Nucleus (4.5) (4.5)  Function Function – isolates the cell’s genetic – isolates the cell’s genetic material, DNA material, DNA  DNA directs/controls the activities of the cell DNA directs/controls the activities of the cell • DNA determines which types of RNA are made DNA determines which types of RNA are made • The RNA leaves the nucleus and directs the The RNA leaves the nucleus and directs the synthesis of proteins in the cytoplasm at a synthesis of proteins in the cytoplasm at a ______________ ______________
  • 24. Nucleus Nucleus  Structure Structure  Nuclear envelope Nuclear envelope • Two Phospholipid bilayers with Two Phospholipid bilayers with protein lined pores protein lined pores  Each pore is a ring of 8 proteins with an Each pore is a ring of 8 proteins with an opening in the center of the ring opening in the center of the ring  Nucleoplasm – fluid of the nucleus Nucleoplasm – fluid of the nucleus
  • 25. Nuclear pore bilayer facing cytoplasm Nuclear envelope bilayer facing nucleoplasm Fig. 4-17, p.61
  • 26. Nucleus Nucleus  DNA is arranged in chromosomes DNA is arranged in chromosomes  Chromosome – fiber of DNA with Chromosome – fiber of DNA with proteins attached proteins attached  Chromatin – all of the cell’s DNA and Chromatin – all of the cell’s DNA and the associated proteins the associated proteins
  • 27. Nucleus Nucleus  Structure, Structure, continued continued  Nucleolus Nucleolus • Area of condensed DNA Area of condensed DNA • Where ribosomal subunits are made Where ribosomal subunits are made  Subunits exit the nucleus via nuclear pores Subunits exit the nucleus via nuclear pores
  • 29. Endomembrane System Endomembrane System (4.6 – 4.9) (4.6 – 4.9)  Series of organelles responsible for: Series of organelles responsible for:  Modifying protein chains into their final Modifying protein chains into their final form form  Synthesizing of lipids Synthesizing of lipids  Packaging of fully modified proteins and Packaging of fully modified proteins and lipids into vesicles for export or use in lipids into vesicles for export or use in the cell the cell  And more that we will not cover! And more that we will not cover!
  • 30. Structures of the Structures of the Endomembrane System Endomembrane System  Endoplasmic Reticulum (ER) Endoplasmic Reticulum (ER)  Continuous with the outer membrane of Continuous with the outer membrane of the nuclear envelope the nuclear envelope  Two forms - smooth and rough Two forms - smooth and rough  Transport vesicles Transport vesicles  Golgi apparatus Golgi apparatus
  • 32. Endoplasmic Reticulum (ER) Endoplasmic Reticulum (ER)  The ER is continuous with the outer The ER is continuous with the outer membrane of the nuclear envelope membrane of the nuclear envelope  There are 2 types of ER: There are 2 types of ER: • Rough ER – has ribosomes attached Rough ER – has ribosomes attached • Smooth ER – no ribosomes attached Smooth ER – no ribosomes attached
  • 33. Endoplasmic Reticulum Endoplasmic Reticulum  Rough Endoplasmic Reticulum (RER) Rough Endoplasmic Reticulum (RER) • Network of flattened membrane sacs create Network of flattened membrane sacs create a “maze” a “maze”  RER contains enzymes that recognize and RER contains enzymes that recognize and modify proteins modify proteins • Ribosomes are attached to the outside of Ribosomes are attached to the outside of the RER and make it appear rough the RER and make it appear rough
  • 34. Endoplasmic Reticulum Endoplasmic Reticulum  Function RER Function RER • Proteins are modified as they move through Proteins are modified as they move through the RER the RER • Once modified, the proteins are packaged Once modified, the proteins are packaged in transport vesicles for transport to the in transport vesicles for transport to the Golgi body Golgi body
  • 35. Endomembrane System Endomembrane System  Smooth ER (SER) Smooth ER (SER)  Tubular membrane structure Tubular membrane structure  Continuous with RER Continuous with RER  No ribosomes attached No ribosomes attached  Function SER Function SER  Lipids are made inside the SER Lipids are made inside the SER • fatty acids, phospholipids, sterols.. fatty acids, phospholipids, sterols..  Lipids are packaged in transport vesicles and Lipids are packaged in transport vesicles and sent to the Golgi sent to the Golgi
  • 36. Golgi Apparatus Golgi Apparatus  Golgi Apparatus Golgi Apparatus  Stack of flattened membrane sacs Stack of flattened membrane sacs  Function Golgi apparatus Function Golgi apparatus  Completes the processing substances Completes the processing substances received from the ER received from the ER  Sorts, tags and packages fully processed Sorts, tags and packages fully processed proteins and lipids in vesicles proteins and lipids in vesicles
  • 38. Golgi Apparatus Golgi Apparatus  Golgi apparatus receives transport Golgi apparatus receives transport vesicles from the ER on one side of the vesicles from the ER on one side of the organelle organelle  Vesicle binds to the first layer of the Golgi and Vesicle binds to the first layer of the Golgi and its contents enter the Golgi its contents enter the Golgi
  • 39. Golgi Apparatus Golgi Apparatus  The proteins and lipids are modified as they The proteins and lipids are modified as they pass through layers of the Golgi pass through layers of the Golgi  Molecular tags are added to the fully modified Molecular tags are added to the fully modified substances substances • These tags allow the substances to be sorted and These tags allow the substances to be sorted and packaged appropriately. packaged appropriately. • Tags also indicate where the substance is to be Tags also indicate where the substance is to be shipped. shipped.
  • 41. Transport Vesicles Transport Vesicles  Transport Vesicles Transport Vesicles  Vesicle = small membrane bound sac Vesicle = small membrane bound sac  Transport modified proteins and lipids from Transport modified proteins and lipids from the ER to the Golgi apparatus (and from Golgi the ER to the Golgi apparatus (and from Golgi to final destination) to final destination)
  • 42. Endomembrane System Endomembrane System  Putting it all together Putting it all together  DNA directs RNA synthesis DNA directs RNA synthesis   RNA RNA exits nucleus through a nuclear pore exits nucleus through a nuclear pore   ribosome ribosome   protein is made protein is made   proteins proteins with proper code enter RER with proper code enter RER   proteins proteins are modified in RER and lipids are made are modified in RER and lipids are made in SER in SER   vesicles containing the vesicles containing the proteins and lipids bud off from the ER proteins and lipids bud off from the ER
  • 43. Endomembrane System Endomembrane System  Putting it all together Putting it all together  ER vesicles merge with Golgi body ER vesicles merge with Golgi body   proteins and lipids enter Golgi proteins and lipids enter Golgi   each is each is fully modified as it passes through fully modified as it passes through layers of Golgi layers of Golgi   modified products are modified products are tagged, sorted and bud off in Golgi tagged, sorted and bud off in Golgi vesicles vesicles   … …
  • 44. Endomembrane System Endomembrane System  Putting it all together  Golgi vesicles either merge with the Golgi vesicles either merge with the plasma membrane and release their plasma membrane and release their contents OR remain in the cell and contents OR remain in the cell and serve a purpose serve a purpose  Another Another animation
  • 45. Vesicles Vesicles  Vesicles - small membrane bound sacs Vesicles - small membrane bound sacs  Examples Examples • Golgi and ER transport vesicles Golgi and ER transport vesicles • Peroxisome Peroxisome  Where fatty acids are metabolized Where fatty acids are metabolized  Where hydrogen peroxide is detoxified Where hydrogen peroxide is detoxified • Lysosome Lysosome  contains digestive enzymes contains digestive enzymes  Digests unwanted cell parts and other wastes Digests unwanted cell parts and other wastes
  • 46. Lysosomes Lysosomes (4.10) (4.10)  The lysosome is an example of an The lysosome is an example of an organelle made at the Golgi apparatus. organelle made at the Golgi apparatus.  Golgi packages digestive enzymes in a Golgi packages digestive enzymes in a vesicle. The vesicle remains in the cell and: vesicle. The vesicle remains in the cell and: • Digests unwanted or damaged cell parts Digests unwanted or damaged cell parts • Merges with food vacuoles and digest the contents Merges with food vacuoles and digest the contents • Figure 4.10A Figure 4.10A
  • 47. Lysosomes Lysosomes (4.11) (4.11)  Tay-Sachs disease occurs when the Tay-Sachs disease occurs when the lysosome is missing the enzyme needed lysosome is missing the enzyme needed to digest a lipid found in nerve cells. to digest a lipid found in nerve cells.  As a result the lipid accumulates and nerve As a result the lipid accumulates and nerve cells are damaged as the lysosome swells cells are damaged as the lysosome swells with undigested lipid. with undigested lipid.
  • 48. Mitochondria Mitochondria (4.15) (4.15)  Function – synthesis of ATP Function – synthesis of ATP  3 major pathways involved in ATP 3 major pathways involved in ATP production production 1. 1. Glycolysis Glycolysis 2. 2. Krebs Cycle Krebs Cycle 3. 3. Electron transport system (ETS) Electron transport system (ETS)
  • 49. Mitochondria Mitochondria  Structure: Structure:  ~1-5 microns ~1-5 microns  Two membranes Two membranes • Outer membrane Outer membrane • Inner membrane - Highly folded Inner membrane - Highly folded  Folds called cristae Folds called cristae  Intermembrane space (or outer compartment) Intermembrane space (or outer compartment)  Matrix Matrix • DNA and ribosomes in matrix DNA and ribosomes in matrix
  • 51. Mitochondria Mitochondria (4.15) (4.15)  Function – synthesis of ATP Function – synthesis of ATP  3 major pathways involved in ATP 3 major pathways involved in ATP production production 1. 1. Glycolysis - cytoplasm Glycolysis - cytoplasm 2. 2. Krebs Cycle - matrix Krebs Cycle - matrix 3. 3. Electron transport system (ETS) - Electron transport system (ETS) - intermembrane space intermembrane space
  • 54. Vacuoles Vacuoles (4.12) (4.12)  Vacuoles are membrane sacs that are Vacuoles are membrane sacs that are generally larger than vesicles. generally larger than vesicles.  Examples: Examples: • Food vacuole - formed when protists bring food Food vacuole - formed when protists bring food into the cell by endocytosis into the cell by endocytosis • Contractile vacuole – collect and pump excess Contractile vacuole – collect and pump excess water out of some freshwater protists water out of some freshwater protists • Central vacuole – covered later Central vacuole – covered later
  • 55. Cytoskeleton Cytoskeleton (4.16, 4.17) (4.16, 4.17)  Function Function  gives cells internal organization, shape, and gives cells internal organization, shape, and ability to move ability to move  Structure Structure  Interconnected system of microtubules, Interconnected system of microtubules, microfilaments, and intermediate filaments microfilaments, and intermediate filaments (animal only) (animal only) • All are proteins All are proteins
  • 57. Microfilaments Microfilaments  Thinnest cytoskeletal elements (rodlike) Thinnest cytoskeletal elements (rodlike)  Composed of the globular protein Composed of the globular protein actin actin  Enable cells to change shape and move Enable cells to change shape and move
  • 58. Cytoskeleton Cytoskeleton  Intermediate filaments Intermediate filaments  Present only in animal cells of Present only in animal cells of certain tissues certain tissues  Fibrous proteins join to form a Fibrous proteins join to form a rope-like structure rope-like structure • Provide internal structure Provide internal structure • Anchor organelles in place. Anchor organelles in place.
  • 59. Cytoskeleton Cytoskeleton  Microtubules – long hollow Microtubules – long hollow tubes made of tubulin proteins tubes made of tubulin proteins (globular) (globular)  Anchor organelles and act as Anchor organelles and act as tracks for organelle movement tracks for organelle movement  Move chromosomes around Move chromosomes around during cell division during cell division • Used to make cilia and flagella Used to make cilia and flagella
  • 60. Cilia Cilia and and flagella flagella (structures for cell motility) (structures for cell motility)  Move whole cells or materials across the cell surface Move whole cells or materials across the cell surface  Microtubules wrapped in an extension of the plasma Microtubules wrapped in an extension of the plasma membrane (9 + 2 arrangement of MT) membrane (9 + 2 arrangement of MT)
  • 61. Plant Cell Structures Plant Cell Structures  Structures found in plant, but not animal Structures found in plant, but not animal cells cells  Chloroplasts Chloroplasts  Central vacuole Central vacuole  Other plastids/vacuoles – chromoplast, Other plastids/vacuoles – chromoplast, amyloplast amyloplast  Cell wall Cell wall
  • 62. Chloroplasts Chloroplasts (4.14) (4.14)  Function – site of photosynthesis Function – site of photosynthesis  Structure Structure  2 outer membranes 2 outer membranes  Thylakoid membrane system Thylakoid membrane system • Stacked membrane sacs called granum Stacked membrane sacs called granum  Chlorophyll in granum Chlorophyll in granum  Stroma Stroma • Fluid part of chloroplast Fluid part of chloroplast
  • 64. Plastids/Vacuoles in Plants Plastids/Vacuoles in Plants  Chromoplasts – contain colored pigments Chromoplasts – contain colored pigments • Pigments called carotenoids Pigments called carotenoids  Amyloplasts – store starch Amyloplasts – store starch
  • 65. Central Vacuole Central Vacuole  Function – storage area for water, sugars, Function – storage area for water, sugars, ions, amino acids, and wastes ions, amino acids, and wastes  Some central vacuoles serve specialized Some central vacuoles serve specialized functions in plant cells. functions in plant cells. • May contain poisons to protect against predators May contain poisons to protect against predators
  • 66. Central Vacuole Central Vacuole  Structure Structure  Large membrane bound sac Large membrane bound sac  Occupies the majority of the volume of the Occupies the majority of the volume of the plant cell plant cell  Increases cell’s surface area for transport of Increases cell’s surface area for transport of substances substances   cells can be larger cells can be larger
  • 67. Cell surfaces protect, support, and join cells Cell surfaces protect, support, and join cells  Cells interact with their environments and Cells interact with their environments and each other via their surfaces each other via their surfaces  Many cells are protected by more than the Many cells are protected by more than the plasma membrane plasma membrane
  • 68. Cell Wall Cell Wall  Function – provides structure and protection Function – provides structure and protection  Never found in animal cells Never found in animal cells  Present in plant, bacterial, fungus, and some protists Present in plant, bacterial, fungus, and some protists  Structure Structure  Wraps around the plasma membrane Wraps around the plasma membrane  Made of cellulose and other polysaccharides Made of cellulose and other polysaccharides  Connect by plasmodesmata Connect by plasmodesmata (channels through the walls) (channels through the walls)
  • 71. Typical Plant Cell –add the labels Typical Plant Cell –add the labels
  • 72. Origin of Mitochondria and Origin of Mitochondria and Chloroplasts Chloroplasts  Both organelles are believed to have once Both organelles are believed to have once been free-living bacteria that were been free-living bacteria that were engulfed by a larger cell. engulfed by a larger cell.
  • 73. Proposed Origin of Mitochondria Proposed Origin of Mitochondria and Chloroplasts and Chloroplasts  Evidence: Evidence:  Each have their own DNA Each have their own DNA  Their ribosomes resemble bacterial Their ribosomes resemble bacterial ribosomes ribosomes  Each can divide on its own Each can divide on its own  Mitochondria are same size as bacteria Mitochondria are same size as bacteria  Each have more than one membrane Each have more than one membrane
  • 74. Cell Junctions Cell Junctions (4.18) (4.18)  Plasma membrane proteins connect Plasma membrane proteins connect neighboring cells - called cell junctions neighboring cells - called cell junctions  Plant cells – plasmodesmata provide Plant cells – plasmodesmata provide channels between cells channels between cells
  • 75. Cell Junctions Cell Junctions (4.18) (4.18)  3 types of cell junctions in animal cells 3 types of cell junctions in animal cells 1. 1. Tight junctions Tight junctions 2. 2. Anchoring junctions Anchoring junctions 3. 3. Gap junctions Gap junctions
  • 76. Cell Junctions Cell Junctions 1. 1. Tight junctions – membrane proteins seal Tight junctions – membrane proteins seal neighboring cells so that water soluble neighboring cells so that water soluble substances cannot cross between them substances cannot cross between them • See between stomach cells See between stomach cells
  • 77. Cell Junctions Cell Junctions 2. 2. Anchoring junctions – cytoskeleton fibers Anchoring junctions – cytoskeleton fibers join cells in tissues that need to stretch join cells in tissues that need to stretch • See between heart, skin, and muscle cells See between heart, skin, and muscle cells 3. 3. Gap junctions – membrane proteins on Gap junctions – membrane proteins on neighboring cells link to form channels neighboring cells link to form channels • This links the cytoplasm of adjoining cells This links the cytoplasm of adjoining cells
  • 79. Plant Cell Junctions Plant Cell Junctions  Plasmodesmata Plasmodesmata form channels between form channels between neighboring plant cells neighboring plant cells
  • 80. Vacuole Walls of two adjacent plant cells Plasmodesmata Layers of one plant cell wall Cytoplasm Plasma membrane