L5-6. Cellular organization.ppt
- 1. Cell – the basic unit of life
- 2. Cells • Smallest living unit • Most are microscopic
- 3. Discovery of Cells • Robert Hooke (mid-1600s) – Observed bark of oak tree – Saw “row of empty boxes” – Coined the term cell
- 4. Cell theory • (1839)Theodor Schwann & Matthias Schleiden “ all living things are made of cells” • (50 yrs. later) Rudolf Virchow “all cells come from cells”
- 5. Principles of Cell Theory • All living things are made of cells • Smallest living unit of structure and function of all organisms is the cell • All cells arise from preexisting cells
- 6. The origin and evolution of cells • On the basis of presence of nucleus cells are divided into two groups: – Prokaryotic cells: lack a nuclear envelope – Eukaryotic cells: have a nucleus in which the genetic material is separated from the cytoplasm. • Prokaryotic cells are generally smaller and simpler than eukaryotic cells; their genomes are less complex and they do not contain cytoplasmic organelles.
- 7. Eukaryotic Cells • Eukaryotes, animals, plants, fungi have a membrane- enclosed nucleus in each of their cells. • Eukaryotic cells: – tend to be larger than prokaryotic cells. – have a variety of membrane-enclosed compartments called organelles. – have a protein scaffolding called the cytoskeleton.
- 8. Eukaryotic Cells • Compartmentalization is the key to eukaryotic cell function. • Each organelle has a specific role defined by chemical processes. • Membranes surrounding these organelles keep away inappropriate molecules and also act as traffic regulators for raw materials into and out of the organelle.
- 10. Things in common Cell membrane Cytoplasm Genetic Material Energy Currency Enzymes
- 11. Plasma Membrane • Every cell is surrounded by a plasma membrane, a continuous membrane composed of a lipid bilayer with proteins floating within it and protruding from it. • The current model of how membranes are constructed is known as Fluid-Mosaic Model. • Proposes that various molecules of membrane are able to flow and move about.
- 12. Phospholipids • Polar – Hydrophylic head – Hydrophobic tail • Interacts with water
- 13. Proteins • Can be found on the surface of the membrane or within the membrane among phospholipids.
- 14. • Roles of the plasma membrane: – Acts as a selectively permeable barrier. – Is an interface for cells where information is received from adjacent cells and extracellular signals. – Allows cells to maintain a constant internal environment. – Has molecules that are responsible for binding and adhering to adjacent cells.
- 15. Membranous Organelles • Endoplasmic Reticulum • Golgi Apparatus • Lysosomes • Mitochondrion • Peroxisomes • Nucleus
- 16. Nucleus • Known as the “ control centre of the Cell” • a membrane-bound sac evolved to store the cell’s chromosomes(DNA) • stores the genetic material of the cell in the form of multiple, linear chromosomes • To control the activity of cell by regulating gene expression
- 17. • Nuclear membrane: • separates the nucleoplasm, liquid material in the nucleus, from the cytoplasm. • Nuclear pores: • Exchange of materials • allows thousands of large molecules such as RNA to pass into and out of the nucleus each minute.
- 18. • Nucleolus: • Inside nucleus • Location of ribosome factory • Made of RNA
- 19. Endoplasmic Reticulum • Is a set of folded membranes and tubes throughout the system. • The general structure :membranous network of cisternae. • Two types: rough endoplasmic reticulum smooth endoplasmic reticulum
- 21. Functions • Provides a large surface area on which chemical reactions can take place. • It synthesizes lipids, phospholipids . • It also carries out the metabolism of carbohydrates, drug detoxification. • RER involved in protein synthesis
- 22. Golgi Bodies • The Golgi is composed of stacks of membrane-bound structures known as cisternae. • The cisternae stack has two main functional regions: the cis- Golgi network and trans-Golgi network. • Vesicles from the endoplasmic reticulum fuse with the network and subsequently progress through the stack to the trans Golgi network, where they are packaged and sent to their destination
- 23. Mitochondria • Have their own DNA- semiautonomous Structure : 1. the outer mitochondrial membrane 2. the intermembrane space 3. the inner mitochondrial membrane 4. the cristae space 5. the matrix
- 24. Mitochondria • Break down fuel molecules (cellular respiration) – Glucose – Fatty acids • Release energy – ATP Mitochondria found in both plants and animals are called the power houses of the cell. They convert the energy in the bonds of glucose and oxygen to readily available energy in the form of ATP. This process is called aerobic respiration.
- 25. 25 Chloroplasts Chloroplasts -organelles present in cells of plants and some other eukaryotes -contain chlorophyll for photosynthesis -surrounded by 2 membranes -thylakoids are membranous sacs within the inner membrane -grana are stacks of thylakoids
- 27. Functions • Site of synthesis and packaging of molecules produced in cells. • Involved in transportation of molecules s/a carbohydrates, proteins, insulin outside the cell.
- 28. Lysosomes • Lysosomes are cellular organelles that contain hydrolase enzymes that break down waste materials and cellular debris.
- 29. Functions • Cell damaged- membranes of Lysosomes break- enzymes release- components of cells broken- available for surrounding cells. • Used in destruction of engulfed harmful microbes
- 30. Peroxisomes • Peroxisomes are small membrane bound vesicles. • In human cells, peroxisomes produce hydrogen peroxides that is used to destroy invading microbes. • They contain enzymes responsible for breakdown of fatty acids and cholesterol synthesis.
- 31. NON MEMBRANEOUS • Ribosomes • Cytoskeleton • Cillia and Flagella
- 32. Ribosomes • A ribosome is made from complexes of RNAs and proteins -ribonucleoprotein. • Each ribosome is divided into two subunits: the smaller subunit and the larger subunit
- 33. 33 Cytoskeleton Cytoskeleton -network of protein fibers found in all eukaryotic cells -supports the shape of the cell -keeps organelles in fixed locations -helps move materials within the cell
- 34. 34 Cytoskeleton Cytoskeleton fibers include - microfilaments – responsible for cellular contractions, crawling, “pinching” -microtubules – provide organization to the cell and move materials within the cell -intermediate filaments – provide structural stability
- 35. 35 Cytoskeleton
- 36. • both cilia and flagella are constructed from microtubules • both provide either locomotion for the cell or move fluid pass the cell Cilia and flagella