BIO120Concepts of BiologyUnit 2 Lecture Part One Cel.docx
- 1. BIO120 Concepts of Biology Unit 2 Lecture Part One: Cell Biology Microscopy Cell Structure Osmosis & Diffusion In 1665, Robert Hooke was the first person to describe a cell, because no one ever had a lens powerful enough to see one. His first specimen was a piece of cork, the cells reminded him of little rooms (cella). Hence the name. Discovering Cells Microscopy Discovering Cells Discovering Microbes Modern Light Microscopes Cell Image
- 2. Electron Microscope Size of Cells Cell Structure Osmosis & Diffusion Although Hooke was the first person to see a cell, Leeuwenhoek described the most cells in about 1683. He was first to see bacteria and other microbes, because his lens was 10 times more powerful than Hooke’s. Discovering Microbes Microscopy Discovering Cells Discovering Microbes Modern Light Microscopes Cell Image Electron Microscope Size of Cells Cell Structure Osmosis & Diffusion
- 3. Most modern light microscopes can magnify objects up to 400 or 1,000 times the size of what you can see with the naked eye. Some light microscopes are dissecting microscopes, which have a lower magnification, but allow biologist to examine larger objects. Modern Light Microscopes Bright Field MicroscopeDissecting Microscope Microscopy Discovering Cells Discovering Microbes Modern Light Microscopes Cell Image Electron Microscope Size of Cells Cell Structure Osmosis & Diffusion This image shows uterine cervix cells, viewed through a light microscope. The cells were obtained from a Pap
- 4. smear during a gynecological exam. The cells on the left are normal. The cells on the right are infected with human papillomavirus, which can cause cervical cancer. These potential cancerous cells are bigger and appear to be dividing. The cells are blue, because they have been stained to help see them better. Cell Image Microscopy Discovering Cells Discovering Microbes Modern Light Microscopes Cell Image Electron Microscope Size of Cells Cell Structure Osmosis & Diffusion Even more powerful than a light microscope is an electron microscope. Electron microscope uses electrons instead of light to form images and can magnify images 100,000 x. The top images shows the amazing details on an ant head. The lower image shows Salmonella infecting human cells.
- 5. Electron Microscope Microscopy Discovering Cells Discovering Microbes Modern Light Microscopes Cell Image Electron Microscope Size of Cells Cell Structure Osmosis & Diffusion This image summarizes the sizes of cells and their components and what can be seen by the naked eye, light microscope, and electron microscope. Size of Cells Microscopy Discovering Cells Discovering Microbes Modern Light
- 6. Microscopes Cell Image Electron Microscope Size of Cells Cell Structure Osmosis & Diffusion Cells can be classified as either prokaryotes or eukaryotes depending on whether a nucleus is present or absent. Prokaryotes are cells that lack a nucleus. They are single- celled organisms such as the E.Coli bacteria that lives in your intestine. Eukaryotes are cells that contain a nucleus, and are found in animals, plants, and fungi. Some single-cell organisms such as amoebas are eukaryotes. The membrane surrounding the nucleus is called the nuclear envelope. Prokaryote vs Eukaryote Prokaryote Eukaryote Microscopy Osmosis & Diffusion Cell Structure
- 7. Prokaryote vs. Eukaryote Membranes Cytoskeleton Mitochondria Chloroplasts Endomembrane System Exocytosis Endocytosis Phagocytosis Extracelluar Matrix Intercellular Connections One key characteristic of cells is that they are surrounded by a plasma membrane, a phospholipid bilayer with embedded proteins. Membrane proteins help control which molecules pass into and out of cells. Membrane proteins also play a role in communication between cells and adhesion of cells to each other and the surface. In eukaryotes, membranes surround organelles, allowing different parts of the cell to have specialized functions.
- 8. Membranes Microscopy Osmosis & Diffusion Cell Structure Prokaryote vs. Eukaryote Membranes Cytoskeleton Mitochondria Chloroplasts Endomembrane System Exocytosis Endocytosis Phagocytosis Extracelluar Matrix Intercellular Connections Cells contain proteins that provide internal structural
- 9. support similar to how we need our bones to stand up right and move. In eukaryotes, there are three types of cytoskeletal molecules from largest to smallest: • Microtubules • Intermediate filaments • Microfilaments (actin filaments) Cytoskeleton Microscopy Osmosis & Diffusion Cell Structure Prokaryote vs. Eukaryote Membranes Cytoskeleton Mitochondria Chloroplasts Endomembrane System Exocytosis
- 10. Endocytosis Phagocytosis Extracelluar Matrix Intercellular Connections Mitochondria are the powerhouses of the cells, because they synthesize large quantities of ATP, the main energy carrier in the cell. Mitochondria Microscopy Osmosis & Diffusion Cell Structure Prokaryote vs. Eukaryote Membranes Cytoskeleton Mitochondria Chloroplasts Endomembrane System
- 11. Exocytosis Endocytosis Phagocytosis Extracelluar Matrix Intercellular Connections Chloroplasts are found in plant cell and other cells that perform photosynthesis: the synthesis of sugar from light, water, and carbon dioxide. Chlorophyll is the pigment inside chloroplasts that absorb light and give these organelles their green appearance. Chloroplasts Microscopy Osmosis & Diffusion Cell Structure Prokaryote vs. Eukaryote Membranes Cytoskeleton Mitochondria
- 12. Chloroplasts Endomembrane System Exocytosis Endocytosis Phagocytosis Extracelluar Matrix Intercellular Connections The endomembrane system is an interconnected system of membranes from several organelles: nuclear envelope, endoplasmic reticulum (ER), Golgi apparatus, plasma membrane, lysomes, and vacuoles. The rough endoplasmic reticulum (RER) synthesizes membrane proteins & secreted proteins that are then modified by the Golgi apparatus and sorted to their final destination. Endomembrane System Microscopy Osmosis & Diffusion Cell Structure
- 13. Prokaryote vs. Eukaryote Membranes Cytoskeleton Mitochondria Chloroplasts Endomembrane System Exocytosis Endocytosis Phagocytosis Extracelluar Matrix Intercellular Connections Exocytosis is the process in which cells secrete molecules such as hormones, neurotransmitters, and growth factors by fusing a vesicle with the plasma membrane Exocytosis Microscopy Osmosis & Diffusion
- 14. Cell Structure Prokaryote vs. Eukaryote Membranes Cytoskeleton Mitochondria Chloroplasts Endomembrane System Exocytosis Endocytosis Phagocytosis Extracelluar Matrix Intercellular Connections Endocytosis is the process in which cells internalize molecules. There are three forms: • Phagocytosis: plasma membrane surrounds the particle (which can be the size of bacteria) and pinches it off to form an intracellular vacuole.
- 15. • Pinocytosis: the cell membrane surrounds a small volume of fluid and pinches off to form a vesicle. • Receptor-mediated endocytosis: molecules bind to specific receptors on the membrane that pinch off and internalize the molecule. (credit: modification of work by Mariana Ruiz Villarreal) Endocytosis Microscopy Osmosis & Diffusion Cell Structure Prokaryote vs. Eukaryote Membranes Cytoskeleton Mitochondria Chloroplasts Endomembrane System Exocytosis Endocytosis Phagocytosis
- 16. Extracelluar Matrix Intercellular Connections After endocytosis, the vesicles are sorted to different parts of the cells. For example, macrophages are a type of white blood cells that destroy bacteria. During phagocytosis of a bacterium, the vesicle fuses with a lysosome that contains enzymes that will breakdown the bacterium. Phagocytosis Microscopy Osmosis & Diffusion Cell Structure Prokaryote vs. Eukaryote Membranes Cytoskeleton Mitochondria Chloroplasts Endomembrane System
- 17. Exocytosis Endocytosis Phagocytosis Extracelluar Matrix Intercellular Connections Cells also secrete molecules that surround the cell, forming the extracellular matrix that play several roles include protecting the cells. Extracelluar Matrix Microscopy Osmosis & Diffusion Cell Structure Prokaryote vs. Eukaryote Membranes Cytoskeleton Mitochondria Chloroplasts
- 18. Endomembrane System Exocytosis Endocytosis Phagocytosis Extracelluar Matrix Intercellular Connections Cells form four types of connections with other cells: a. Plasmodesmata is a channel between the cell walls of two adjacent plant cells. b. Tight junctions form water-tight seal between adjacent animal cells. c. Desmosomes join two animal cells together. They form strong connections but are not as water-tight as tight junctions. d. Gap junctions act as channels between animal cells. Both gap junctions and plasmodesmata connect the cytoplasm between adjacent cells allow the tissue to act together. Intercellular Connections Microscopy
- 19. Osmosis & Diffusion Cell Structure Prokaryote vs. Eukaryote Membranes Cytoskeleton Mitochondria Chloroplasts Endomembrane System Exocytosis Endocytosis Phagocytosis Extracelluar Matrix Intercellular Connections Diffusion is the process of molecules moving from an area of high concentration to a low concentration (concentration gradient). Some nonpolar molecules can diffuse through membranes. Polar and charged molecules require transport proteins to cross the membrane.
- 20. Diffusion Microscopy Cell Structure Osmosis & Diffusion Diffusion Osmosis Tonicity Electrochemical Gradient Na/K Pump Osmosis is the diffusion of water through a semi-permeable that allows water but not large molecules to move across. Water flows from higher to lower amount of water until the concentration of solutes is equivalent on both sides of the membrane. Osmosis Microscopy Cell Structure Osmosis & Diffusion
- 21. Diffusion Osmosis Tonicity Electrochemical Gradient Na/K Pump Tonicity is the concentration of salt and other solutes. Hypertonic solution have high salt concentration that draws water out of the cells and shrink them. Isotonic solution are balanced with the cytoplasm resulting in no net change in water or shape. Hyptonic soltions are low salt concentrations, forcing water into the cell and expanding them or causing them to lyse (break apart). In plant cells, the cell wall resists this change in cell shape, creating an opposing pressure called turgor pressure Tonicity Microscopy Cell Structure Osmosis & Diffusion
- 22. Diffusion Osmosis Tonicity Electrochemical Gradient Na/K Pump The movement of charge molecules is dependent upon two forces: • The diffusion from high to low concentration (concentration gradient). • The diffusion towards the opposite electrical charge (electrical gradient). The end result is a electrical potential across the membrane of about – 60 mV Electrochemical Gradient Microscopy Cell Structure Osmosis & Diffusion Diffusion Osmosis
- 23. Tonicity Electrochemical Gradient Na/K Pump The sodium-potassium pump uses energy from ATP to moves potassium and sodium ions across the plasma membrane in order to main and regulate the electrochemical potential across the membrane. Na/K Pump Microscopy Cell Structure Osmosis & Diffusion Diffusion Osmosis Tonicity Electrochemical Gradient Na/K Pump Button 3: Page 1: Page 21: Page 32: Page 43: Page 54: Page 65: Page 76: Page 87: Page 98: Page 109: Page 1110: Page 1211:
- 24. Page 1312: Page 1413: Page 1514: Page 1615: Page 1716: Page 1817: Page 1918: Page 2019: Page 2120: Page 2221: Page 2322: Assignment for BIO120 Concepts in Biology Unit 2 Cell Processes Due: Midnight Sunday of Unit 2 Compare and contrast the processes of osmosis, diffusion, facilitated transport, and active transport of molecules across a cell membrane. The paper should be at least 400- 500 words (~ 1 double-spaced, APA formatted page). Students: Be sure to read the criteria, by which your paper/project will be evaluated, before you write, and again after you write. Evaluation Rubric for Unit 2 Cell Processes Assignment CRITERIA Deficient (0 Points) Proficient (1 Points) Exemplary (2Points) Points Possible 1. Describes osmosis Does not include osmosis Includes osmosis but does not describe it accurately. Includes osmosis and describes how it differs from other transport processes. 2 2. Describes diffusion
- 25. Does not include diffusion Includes diffusion but does not describe it accurately. Includes diffusion and describes how it differs from other transport processes. 2 3. Describes facilitated transport Does not include facilitated transport Includes facilitated transport but does not describe it accurately. Includes facilitated transport and describes how it differs from other transport processes. 2 4. Describes active transport Does not include active transport Includes active transport but does not describe it accurately. Includes active transport and describes how it differs from other transport processes. 2 5. Grammar, spelling, and formatting The essay does NOT follow the APA format guidelines or contains more than six grammatical errors or misspellings. The essay follows the APA format guidelines but contains three to six grammatical errors or misspellings. The essay follows the APA format guidelines and contains no more than three grammatical errors or misspellings. 2 6. Clear and professional writing Writing is not well-organized or cannot be easily followed or understood. Uses choppy or rambling sentences. Writing is organized and can be followed, The essay contains effective transitions between sentences. Writing is clear, professional, and well-organized. Essay is can be easily followed and uses effective transitions between
- 26. sentences. 2 Total Points: 12 Genome Mitosis Cytokinesis G-Zero (G 0 ) Cell Cycle Regulation Cancer Eukaryote Cell Division Cell Cycle Prokaryotes: Binary Fission BIO120 Concepts of Biology Unit 2 Lecture Part Two: Cell Division
- 27. Genome Mitosis Cytokinesis G-Zero (G 0 ) Cell Cycle Regulation Cancer Eukaryote Cell Division Cell Cycle Prokaryotes: Binary Fission The ultimate purpose of cell division is to transmit genetic material to the next generation of cells. The sum of all genes or genetic material of an organism is called the genome. • In prokaryotes, the genome is single circular piece of DNA • In eukaryote, the genome consists of multiple, linear chromosomes (23 pairs in humans) Eukaryote cells can have more than one copy of each chromosome, a condition called diploidy. Haploid cells have
- 28. one copy; diploid cells have two. For example, human gametes (sperm and eggs) are haploid with 23 chromosomes. The rest of the cells of the body (somatic cell) are diploid with 23 pairs of chromosomes. Each pair of matched chromosomes are homologous chromosomes (e.g. the chromosomes 1 from your dad and from you mom are homologous chromosomes). Different species have different number of chromosomes, which provides a reproductive barrier between species. Genome Genome Mitosis Cytokinesis G-Zero (G 0 ) Cell Cycle Regulation Cancer Eukaryote Cell Division Cell Cycle Prokaryotes: Binary Fission
- 29. Prokaryotes reproduce asexually in which the daughter cells are clones of the original cell. The most common form of asexual reproduction in prokaryotes is binary fission. During binary fission, DNA starts to replicate at a specific site on the DNA: the origin of replication. After DNA replication, the chromosome attach to opposite sides of the cell. A protein called Ftsz then forms a ring between the genomes. A septum (a partition) then forms between the cells causing them to pinch off from each other. Prokaryotes: Binary Fission Genome Mitosis Cytokinesis G-Zero (G 0 ) Cell Cycle Regulation Cancer Eukaryote Cell Division Cell Cycle Prokaryotes: Binary Fission
- 30. Eukaryote cells have two forms of cell division: mitosis and meiosis. Cells divide by mitosis to create two daughter cells that have same genetic material. Mitosis allows multicellular organisms to grow and differentiate. Cells divide by meiosis to produce gametes that have half the genetic material of the starting cells. In this unit, we focus on mitosis. We will return to meiosis in Unit 4. Eukaryote Cell Division Genome Mitosis Cytokinesis G-Zero (G 0 ) Cell Cycle Regulation Cancer Eukaryote Cell Division Cell Cycle Prokaryotes: Binary Fission
- 31. Cells grow and divide by progressing through a series of stages called the cell cycle. There are two phases in eukaryotes: interphase and mitotic phase. During interphase, cells grow and replicate their DNA. Interphase has three subdivisions: • G1 (Gap 1) when cells are growing to prepare for DNA replication. • S phase when cells are synthesizing and replicating DNA and also duplicate centrosomes • G2 cells check that DNA reproduction occurred correctly and continue to grow and prepare for mitosis. After G2, cells entire the mitotic phase. During mitosis, the chromosomes and centrosomes that were duplicated in the S phase are now separated into the daughter nuclei. The cell then usually divides the cytoplasm among the two daughter cells, a process called cytokinesis. Cell Cycle Genome Mitosis Cytokinesis G-Zero (G 0 ) Cell Cycle
- 32. Regulation Cancer Eukaryote Cell Division Cell Cycle Prokaryotes: Binary Fission Animal cell mitosis is divided into five stage: • Prophase – chromosomes condense and nuclear membrane breaks down. • Prometaphase - mitotic spindles from the centrosomes attach to chromosomes • Metaphase – chromosomes line up in the middle of the cell from the metaphase plate. • Anaphase – sister chromatids are separated into opposite ends. • Telophase— the reformation of the nuclear envelope in the daughter cells. • Cytokinesis – final separate of cells into two daughter cells. Mitosis
- 33. Genome Mitosis Cytokinesis G-Zero (G 0 ) Cell Cycle Regulation Cancer Eukaryote Cell Division Cell Cycle Prokaryotes: Binary Fission Animal and plants cells undergo cytokinesis differently. In animal cells (a), a cleavage furrow forms at the former metaphase plate in the animal cell. The plasma membrane is drawn in by a ring of actin fibers contracting just inside the membrane. The cleavage furrow deepens until the cells are pinched in two. In plants (b), Golgi vesicles coalesce at the former metaphase plate and then fuse to form the cell plate. The cell plate grows from the center toward the cell walls. New cell walls are made from the vesicle contents. Cytokinesis
- 34. Genome Mitosis Cytokinesis G-Zero (G 0 ) Cell Cycle Regulation Cancer Eukaryote Cell Division Cell Cycle Prokaryotes: Binary Fission Cells that no longer need to divide can exit the cell cycle and enter G 0 . In some cases, this is a temporary condition until triggered to enter G1. In other cases, the cell will remain in G 0 permanently (e.g. neurons, muscle cells).
- 35. G-Zero (G 0 ) Genome Mitosis Cytokinesis G-Zero (G 0 ) Cell Cycle Regulation Cancer Eukaryote Cell Division Cell Cycle Prokaryotes: Binary Fission The cell cycle is controlled at three checkpoints. Integrity of the DNA is assessed at the G1 checkpoint. Proper chromosome duplication is assessed at the G2 checkpoint. Attachment of each kinetochore to a spindle fiber is assessed at the M checkpoint. Disruption of these cell cycle check
- 36. points by say mutations, can lead to uncontrolled growth. Cell Cycle Regulation Genome Mitosis Cytokinesis G-Zero (G 0 ) Cell Cycle Regulation Cancer Eukaryote Cell Division Cell Cycle Prokaryotes: Binary Fission Cancer can results from mutations in different genes. Most mutations either have no effect or cause enough damage to cause the cell to activate a controlled, self-destruct sequence (apoptosis). However, some mutations will disrupt regulation of the cell cycle leading to uncontrolled growth. One of the most commonly mutated genes is the p53 gene, which encodes a protein that monitors for DNA damage. If the
- 37. DNA damage is repaired, the cell resumes division. If the p53 gene is mutated, then DNA damage accumulates undetected, which can result in additional loses of cell cycle regulation. Most cancers are believed to require at least two mutations before the cells take on characteristic of cancer cells. Even after the cancer grows into a tumor, some tumors are benign and do not pose a serious risk. However, some tumors can acquire additional mutations that allow cancer cells to travel in the blood to latch on to other organs, a process called metastasis. A cancer that has metastasized is very dangerous. Some treatments for cancer such as radiation therapy and chemotherapy infer with cell division. Because cancerous cells tend to divide faster than noncancerous cells, these treatments should be more damaging to cancerous cells than noncancerous cells. More recent therapies are aimed at better targeting treatments to only cancerous cells and reduce the side effects of other treatments. Cancer Button 3: Page 1: Page 21: Page 32: Page 43: Page 54: Page 65: Page 76: Page 87: Page 98: Page 109: