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Cell Structure and Composition

Cell Structure and Composition. Prepared by: Ms. Bernabeth Jo T. Tendero. Major Parts of the Cell. Nucleus Cytoplasm Cell Surface. Nucleus. Region of the cell where the genetic material is located Generally oval-shaped or spherical shaped Most conspicuous part of the cell

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Cell Structure and Composition

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  1. Cell Structure and Composition Prepared by: Ms. Bernabeth Jo T. Tendero

  2. Major Parts of the Cell • Nucleus • Cytoplasm • Cell Surface

  3. Nucleus • Region of the cell where the genetic material is located • Generally oval-shaped or spherical shaped • Most conspicuous part of the cell • Regulates and coordinates all the activities of the cell • Denser than surrounding cytoplasm

  4. Parts of the Nucleus

  5. Parts of the Nucleus • Chromosomes - in form of chromatin - contains genetic information - Composed of DNA - Thicken for cellular division - Set number per species (i.e. 23 pairs for human)

  6. Chromosomes

  7. Chromatin

  8. Nuclear Membrane • Surrounds the nucleus • Double membrane • Has numerous opening called nuclear pores which serves as pathways for exchange of materials between the nucleus and the cytoplasm

  9. Nuclear Membrane

  10. Nucleolus • Spherical shape • Visible when cell is not dividing • Contains RNA for protein manufacture

  11. Nucleolus

  12. Cytoplasm • Protoplasm found outside the nucleus • Collective term for cytosol and organelles • Colloidal suspension • Cytosol composed mainly of water with free floating molecules • Viscosity constantly changes

  13. Organelles • Discrete structures of a cell having specialized functions

  14. Centrioles: Helper in Cell Division • Paired cylindrical organelles near nucleus • Composed of nine tubes, each with three tubules • Involved in cellular division • Lie at right angles to each other

  15. Centrioles

  16. Cytoskeleton: Framework of the Cell • Composed of microtubules • Supports and provides shape • Aids movement of materials in and out of cells • Microtubules provide pathways for certain cellular molecules to move about

  17. Cytoskeleton

  18. Endoplasmic Reticulum: Manufacturers and Builders of the Cell • Tubular network fused to nuclear membrane • Goes through cytoplasm onto cell membrane • Stores, separates and serves as cell’s transport system

  19. Endoplasmic Reticulum

  20. Endoplasmic Reticulum: Manufacturers and Builders of the Cell • 2 types Rough Endoplasmic Reticulum (RER) - occurs as flattened sheets studded on its outer surface with small spherical bodies called ribosomes - aids in protein synthesis - prevalent in cells that specializes in secreting proteins

  21. Rough Endoplasmic Reticulum

  22. Endoplasmic Reticulum: Manufacturers and Builders of the Cell • 2 types Smooth Endoplasmic Reticulum (SER) - occurs as tubes of membranes without ribosomes attached - site for fat metabolism and forms vesicles for transporting large molecules to other cell parts

  23. Smooth Endoplasmic Reticulum

  24. Golgi Apparatus: Packaging Counters of the Cell • Discovered and named after Camillo Golgi in 1898 by observing nerve cells of an owl • A system of membrane-bound sacs that look like a stack of pancakes • Believe to be part of ER and where new membranes for the ER are manufactured • Believe to prepare proteins for secretion after they are released from the ER

  25. Golgi Apparatus

  26. Lysosomes: Suicide Bags of the Cell • “Lyso” – dissolving power and “some” – body • Discovered in 1952 • Contains hydrolytic/digestive enzymes for proteins, lipids and carbohydrates • Transports undigested material to the cell membrane for removal • Destroys cells when lysosomes burst

  27. Lysosomes

  28. Mitochondria: Powerhouses of the Cell • 2nd largest organelle with its own DNA (mtDNA) • Double layered outer membrane with inner folds called cristae • Energy-producing chemical reactions (produces ATP) takes place on cristae • Controls level of water and other materials in cell • Recycles and decomposes proteins, fats and carbohydrates, and forms urea

  29. Mitochondria

  30. Mitochondria

  31. Ribosomes: Protein Factories of the Cell • Composed of nucleic acids (RNA) and proteins • Numerous in cells • Manufacture proteins

  32. Ribosomes

  33. Ribosomes

  34. Vacuoles: Storage Tanks of the Cell • Membrane-bound sacs for storage, digestion and waste removal • Contains water solution • Contractile vacuoles for water removal

  35. Vacoules

  36. Peroxisome • Contain enzymes that transfer hydrogen to various substrate of oxygen to produce hydrogen peroxide • Use oxygen to break fats to use as fuel for cellular respiration • Detoxify alcohol and other harmful compounds

  37. Peroxisomes

  38. Chloroplast: Site of Photosynthesis • Plastid found in plant cells • Contains green chlorophyll where photosynthesis takes place • Has its own DNA and ribosomes • Double membrane bound organelle • Mobile and move around the cell through cytosleleton

  39. Chloroplast

  40. Cell Surface • Protectively surrounds the cell • Plasma membrane • Cell wall • Plasmodesmata

  41. Plasma Membrane • Double layer of phospholipid molecules • Each phospholipid is composed of fats, phosphate and carbohydrates (oligosaccharide) • Protein molecules are embedded in phospholipids • Because of its structure the membrane has a semi-permeable property that allows only chosen substances to enter and leave the cell

  42. Plasma Membrane

  43. Cell Wall • Lies outside the plasma membrane • Compose of cellulose • Protects the cells and provide rigid structure for cells • Remains intact even after the rest of the cell has died

  44. Cell Wall

  45. Cell Wall

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