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Cell Structure and Function

This chapter explains the cell theory, which states that every organism is composed of one or more cells. It discusses the structure and function of cells, including the plasma membrane, DNA storage, and cytoplasm. The chapter also covers the different types of cells, such as prokaryotic and eukaryotic cells, as well as components like the nucleus, ribosomes, endoplasmic reticulum, Golgi body, vesicles, mitochondria, and cytoskeleton. Additionally, it explores the lipid bilayer, membrane proteins, and the functions of the nucleus, nuclear envelope, nucleolus, chromatin, and cytomembrane system. The chapter concludes with an explanation of cilia, flagella, and the importance of the cytoskeleton in maintaining cell shape and organization.

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Cell Structure and Function

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  1. Cell Structure and Function Chapter 4

  2. Cell Theory 1) Every organism is composed of one or more cells 2) Cell is smallest unit having properties of life 3) Continuity of life arises from growth and division of single cells

  3. Structure of Cells All start out life with: • Plasma membrane • Region where DNA is stored • Cytoplasm Two types: • Prokaryotic • Eukaryotic • Know table 4.3 • Know figure 4:7

  4. Animal Cell Features • Plasma membrane • Nucleus • Ribosomes • Endoplasmic reticulum • Golgi body • Vesicles • Mitochondria • Cytoskeleton

  5. nuclear enevelope nucleolus NUCLEUS DNA + nucleoplasm vesicle microfilaments components of cytoskeleton lysosome microtubules rough ER ribosomes (attached to rough ER and free in cytoplasm) smooth ER plasma membrane vesicle Golgi body pair of centrioles mitochondrion Fig. 4.8b, p. 57

  6. Lipid Bilayer • Main component of cell membranes • Gives the membrane its fluid properties • Two layers of phospholipids

  7. Membrane Proteins • Transport proteins • Receptor proteins • Recognition proteins • Adhesion proteins

  8. oligosaccharide groups cholesterol phospholipid EXTRACELLULAR ENVIRONMENT (cytoskeletal pro-teins beneatch the plasma membrane) open channel protein gated channel proten (open) gated channel proten (closed) active transport protein RECEPTOR PROTEIN LIPID BILAYER ADHESION PROTEIN RECOGNITION PROTEIN (area of enlargment) TRANSPORT PROTEINS CYTOPLASM PLASMA MEMBRANE Fig. 4.4, p. 53

  9. Functions of Nucleus • Keeps the DNA molecules of eukaryotic cells separated from metabolic machinery of cytoplasm • Makes it easier to organize DNA and to copy it before parent cells divide into daughter cells

  10. Components of Nucleus nuclear envelope nucleoplasm chromatin (DNA + proteins) Nucleolus

  11. cytoplasm nucleus plasma membrane nuclear envelope nucleoplasm chromatin (DNA + proteins) nucleus Fig. 4.11, p. 62

  12. Nuclear Envelope • Two outer membranes (lipid bilayers) • Innermost surface has DNA attachment sites • Pores span bilayer

  13. Chromatin • Cell’s collection of DNA and associated proteins • Chromosome is one DNA molecule and its associated proteins • Appearance changes as cell divides

  14. Nucleolus • Dense mass of material in nucleus • Area of intense transcription of rRNA • Materials from which ribosomal subunits are built • Genes that encode Ribosome's are located in this area

  15. Components of Cytomembrane System Golgi bodies Vesicles Endoplasmic reticulum

  16. Endoplasmic Reticulum • In animal cells, continuous with nuclear membrane • Extends throughout cytoplasm • Two regions - rough and smooth

  17. Rough ER • Ribosomes on surface give it a rough appearance. • ER is the site of protein synthesis. • Some polypeptide chains enter rough ER and are folded and modified

  18. Smooth ER • No ribosomes on surface • Lipids assembled inside tubules • Synthesizes steroids, such as estrogen and testosterone. • inactivates wastes, toxic chemicals and drugs

  19. Golgi Bodies • Put finishing touches on proteins and lipids that arrive from ER • Package finished material for shipment to final destinations outside the cell. • Material arrives and leaves in vesicles

  20. Vesicles • Membranous sacs that move through the cytoplasm • Lysosomes • Digests, recycles materials

  21. Mitochondria • ATP-producing powerhouses • Double-membrane system • These reactions require oxygen

  22. Cytoskeleton • Present in all eukaryotic cells • Basis for cell shape and internal organization • Allows organelle movement within cells and, in some cases, cell motility

  23. Cytoskeletal Elements intermediate filament microtubule microfilament

  24. Cilia and Flagella • Cilia and Flagella are made up of microtubules • Cilia functions to move microorganism or the movement of substances in the body • Example: Protozoa move through water by beating their cilia as small ores • Example: Cilia found in the body moves mucus out of the lungs and oocytes down the oviduct • Flagella functions in the transport of cells

  25. Cilia and Flagella • Length of microtubules or microfilaments can change • Parallel rows of microtubules or microfilaments actively slide in a specific direction • As one side lengthens and the other side contracts it causes the flagella or cilia to bend.

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