cell structure and function,composition .ppt
- 1. CELL STRUCTURE AND FUNCTION 1
- 2. The cell is the basic unit of structure and function in living things. Cells vary in their shape size, and arrangements but all cells have similar components, each with a particular function. Some of the 100 trillion of cells make up human body. All human cell are microscopic in size, shape and function. The diameter range from 7.5 micrometer (RBC) to 150 mm (ovum). 2
- 3. - Cell is defined as the fundamental living unit of any organism. - Cell is important to produce energy for metabolism (all chemical reactions within a cell) - Cell can mutate (change genetically) as a result of accidental changes in its genetic material (DNA). - Cytology: the study of the structure and functions of cells. 3
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- 5. 1) THE CELL (PLASMA) MEMBRANE The cell membrane is a thin, dynamic membrane that encloses the cell and controls what enters and leaves the cell. Fluid Mosaic Model composed of a double layer (bilayer) of phospholipid molecules with many protein molecules dispersed within it; 5
- 6. a. The surfaces of the membrane are "hydrophilic" due to the polar phosphate heads; b. The internal portion of the membrane is "hydrophobic" due to the non-polar fatty acid tails; c. The membrane proteins also have both hydrophilic and hydrophobic 6
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- 8. 8 hydrophillic phosphate head hydrophobic fatty acid tails Chemical attractions are Chemical attractions are the forces that hold the forces that hold membranes together membranes together
- 9. Serves as boundary of the cell. Serve as markers that identify the cells. Play significant role in transportation. Cell recognition proteins-allow cell to recognize other cells. 9
- 10. Some membrane proteins have carbohydrates attached to them, forming glycoproteins that act as identification markers Some membrane proteins are receptors that react to specific chemicals, sometimes permitting a process called signal transduction 10
- 11. Is a gel-like matrix of water, enzymes, nutrients, wastes, and gases and contains cell structures (organelles). Fluid around the organelles called cytosol. Most of the cells metabolic reactions occur in the cytoplasm. 11
- 12. network of interconnected parallel membranes (maze), that is continuous with the nuclear membrane; 2. Two types: a. Rough Endoplasmic Reticulum (RER) 1. ER studded with ribosomes; 2. Function = protein synthesis and intraceluar transportation of molecules ; b. Smooth Endoplasmic Reticulum (SER) lacks ribosomes; 1. Function = lipid & cholesterol synthesis and Stores calcium. 12
- 13. 13 Rough Endoplasmic Reticulum (RER) Rough Endoplasmic Reticulum (RER)
- 14. Every cell contains thousand of ribosome's and many of them attached to the RER. Each ribosome is nonmembranous structure, made of two pieces large unit and small unit and each subunit composed of rRNA. Function: protein synthesis Protein released from the ER are not mature, need further processing in Golgi complex before they are able to perform their function within or outside the cell. 14
- 15. 1. flattened membranous sacs (cisternae). 2. arranged in stacks ("stack of pancakes") associated with many vesicles (membrane bound sacs containing proteins); 2. Function = modification, packaging, and transport of proteins; 3. Encloses digestive enyzymes into membranes to form lysosomes. 15
- 16. 1. spherical membranous sacs containing digestive enzymes; 2. "suicide sacs" which destroy anything the cell no longer wants or needs. 3. Autolysis is the process by which worn cell parts are digested by autophagy. 16
- 17. 1. membranous sacs containing oxidase enzymes; 2. Function = detoxification of harmful or toxic substances (i.e. alcohol, formaldehyde, oxygen free radicals); H2O2 (peroxide) ----> water 17
- 18. 1. kidney-shaped organelle whose inner membrane is folded into shelf-like partitions called cristae; 2. "Powerhouse" of the cell = site of cellular respiration where energy is released from glucose. ahmad ata 18
- 19. the central core, control center or "brain" of the cell. 1. the largest organelle of the cell; 2. filled with nucleoplasm; Nuclear Membrane (or nuclear envelope) is a double membrane that separates the contents of the nucleus from the cytoplasm; At various point, these two membranes fuse = nuclear pore. The nuclear membrane is "selectively permeable"; pores serve as sites where mRNA can pass out of the nucleus during protein synthesis, and how ribosomes exit the nucleus. 19
- 20. Nucleolus (s) = a spherical body within the nucleus; composed of RNA and proteins; Function = synthesis of ribosomes. 20
- 21. The cytoskeleton Is a network of fibers extending throughout the cytoplasm Fibers appear to support the endoplasmic reticulum, mitochondria, and free ribosomes ahmad ata 21 Microtubule
- 22. Gives mechanical support to the cell Is involved in cell motility, which utilizes motor proteins Rodlike pieces that provide support and allow movement and mechanisms that can move the cell or its parts 22
- 23. 23 Components of cytoskeleton: Components of cytoskeleton: 1) Microfilaments 1) Microfilaments Solid rods of Solid rods of globular proteins. globular proteins. Important Important component of component of cytoskeleton which cytoskeleton which offers support to cell offers support to cell structure. structure. Microfilaments can Microfilaments can slide past each slide past each other, causing other, causing shortening of the shortening of the cell cell
- 24. Intermediate filaments are twisted protein strands slightly thicker than microfilaments; they form much of the supporting framework in many types of cells 24
- 25. Microtubules Shape the cell Guide movement of organelles (their function is to move things around in the cell) Help separate the chromosome copies in dividing cells 25
- 26. Centrosomes and Centrioles The centrosome An area of the cytoplasm near the nucleus that coordinates the building and breaking of microtubules in the cell Its considered to be a microtubule-organizing center Plays an important role during cell division Contains a pair of centrioles 26
- 27. 27 Centrioles Self-replicating Self-replicating Made of bundles of Made of bundles of microtubules. microtubules. Help in organizing Help in organizing cell division. cell division.
- 28. 1. Cilia / Cilium a. short, hair-like cellular extensions (eyelashes); b. help move substances through passageways; c. located in lining of respiratory tract & fallopian tube. 2. Flagella a. tail-like projection; b. only one per cell in humans; c. aids in cell locomotion; d. sperm cell. 3. Microvilli: a. small finger-like extensions of the external surface of the cell membrane; b. Function = to increase surface area. c. located in the lining of the digestive tract. 28
- 29. Tight junction impermeable junction that encircles impermeable junction that encircles the cell & prevents leakage the cell & prevents leakage Blood brain barrier Blood brain barrier - Skin - Skin Desmosome anchoring junction scattered along the anchoring junction scattered along the sides of cells. Prevents tissues from fraying sides of cells. Prevents tissues from fraying Stomach, uterus , bladder Stomach, uterus , bladder Gap junction allows chemical substances to pass allows chemical substances to pass between cells between cells Heart Heart 29
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- 33. 2 types Passive transport Active Transport require no ATP( energy) Substances move High to low conc. Examples include Simple diffusion Osmosis facilitated diffusion filtration 33
- 34. random mixing of particles in solution substances move down concentration gradient- particles eventually become evenly distributed - Equilibrium reached ahmad ata 34
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- 36. Diffusion Through channel proteins or transport proteins allow passage of small inorganic ions Na+ , K+, Ca+2 Glucose, water soluble vitamins(B,C) generally slower than diffusion across lipid portion Depends upon the number of transporters available 36
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- 38. passive process diffusion of water across a selectively permeable membrane from Hi. Conc. of WATER ( low solute) to lower concentration of WATER( Hi. solute) 38
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- 40. Describes how a solution affects cell volume hypertonic solution with more solutes Blood cells shrink and crenate hypotonic solution with less solutes Blood cells swell up and hemolyse isotonic both solutions have similar concentrations of solutes. Cell size is unchanged 40
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- 42. Active transport - movement of a substance from a lower concentration to a higher concentration using a carrier and energy Endocytosis - brings substances into the cells 42
- 43. solutes moving against concentration gradient-Uses carrier proteins can be driven by ATP use or via energy stored in ionic concentration Types : Primary active transport Secondary active transport 1. Endocytosis 2. Exocytosis 3. Tanscytosis 43
- 44. ahmad ata 44 uses ATP and transporter proteins sodium potassium pump
- 45. A form of active transport. Transport of large particles across the plasma membrane Types : 1.Phagocytosis 1.Pinocytosis 45
- 46. only a few body cells are capable Ex. WBC (macrophages , neutrophils) particle binds to plasma membrane pseudopods extend and surround particle forming phagosome phagosome fuses with lysosomes which destroy invader 46
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- 48. Also called cellular drinking most body cells carry out process especially absorptive cells in intestines and kidneys tiny droplets of extracellular fluid taken into cell lysosomes fuse and degrade particles into smaller useable particles 48
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- 50. releases materials form a cell all cells carry out process Ex. i. secretory cells release digestive enzymes, hormones, mucus, or other secretions Ii. nerve cells release neurotransmitters vesicles fuse with plasma membrane and release contents into extracellular fluid 50
- 51. vesicle fuses with the plasma membrane and then ruptures; used in hormone and neurotransmitter release ahmad ata 51
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