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A Tour of the Cell: Cell Structure and Function

Explore the fascinating world of cells with this comprehensive tour. Learn about the discovery of cells, cell diversity, basic parts of a cell, cellular organization, organelles and features, and more.

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A Tour of the Cell: Cell Structure and Function

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  1. CHAPTER 4 A Tour of the Cell Cell Structure and Function

  2. I. The Discovery of Cells: The Cell is the basic unit of life • Robert Hooke-1665 • Coined the word “cell” • Looked at cork cells • Leeuwenhoek (1673) • 1st to look at living cells • Invented the microscope • Matthias (1883) • Plants are made of cells • Schwann (1884) • Animals are made of cells • Virchow (1821-1902) • Cells come from cells (Cell Theory) • Living things are composed of cells

  3. THE CELL Theory • Cells are the basic units of life • All living things are made of cells • Cells come from pre-existing cells

  4. II. Introduction of Cells • A. Cell Diversity • Cell function limits cell size • Cell size is from 1 to 100 um • Cells need to exchange nutrients and wastes with their external environment through the plasma membrane • Need a large surface to volume ratio • Need a short distance from surface to center

  5. B. Basic Parts of a cell • Plasma membrane: • Cytoplasm: • Region of cell within plasma membrane • Includes fluid, cytoskeleton and organelles except nucleus • Cytosol: • Fluid part of cytoplasm • Nucleus: • Control center, controls cells functions • Contains chromosomes/genes/DNA • Cells outer boundary • Regulates what enters and leaves

  6. C. Two Basic Types of Cells • Prokayotes: • Lack nucleus and membrane bound organelles • DNA contained in nucleiod region • Examples: Domains: Bacteria and Archaea • Eukaryotes: • Have nucleus and organelles • Organelles: • Intracellular specialized structures

  7. D. Cellular organization • Colonies: • Collection of genetically identical cells that live together in a group • Multicellularity: • Many celled • Tissue: • Group of similar cells perform specific functions. • Organs: • Group of tissues that perform a particular job in an organism. • Organ system: • group of organs that accomplish related tasks. • Many celled

  8. Generalized Animal and Plant Cell AnimalCell Chloroplasts Centrioles Mitochondria Golgi Nucleus EndoplasmicReticulum PlantCell

  9. Generalized Plant and Animal Cell AnimalCell Nucleolus Ribosomes Central Vacuole PlantCell Smooth E.R. Cell Wall

  10. III. Cells Organelles and Features A. Plasma membrane – regulates what enters and leaves the cells. • Membrane lipids/phospholipids – double layer of lipids/bilayer • Membrane proteins – proteins embedded in the cell membrane • Fluid mosaic model – acts like a fluid more then a solid B. Nucleus – control center • Chromosomes – made of DNA and protein • Nuclear envelope – double membrane surrounds the nucleus, contains pores to provide passage for RNA • Nucleolus – makes ribosomes, stores RNA

  11. Ribosomes Chromatin Nucleolus Pore Nuclear envelope Figure 4.9

  12. The Nucleus Nucleolus Pores Chromatin Threads(Chromosomes) NuclearEnvelope

  13. III. Cells Organelles and Features C. Mitochondria – powerhouse of the cell involved in respiration • Mitochondrial DNA – they have their own DNA D. Ribosomes – make proteins, found on rough ER and in the cytoplasm E. Endoplasmic reticulum – membranous tubes and sacs • Rough ER – studded with ribosomes, site of protein synthesis • Smooth ER – no ribosomes, makes lipids

  14. Endoplasmic Reticulum UnitMembrane Ribosomes Vesiclesforming

  15. After the rough ER synthesizes a molecule it packages the molecule into transport vesicles 4 Transport vesicle buds off Secretory protein inside transport vesicle Ribosome 3 Protein 1 Rough ER 2 Polypeptide Figure 4.12

  16. III. Cells Organelles and Features F. Golgi Apparatus – modifies and packages proteins G. Vesicles – membrane sacs • Lysosomes – conain digestive enzymes that break down organic molecules • digest bacteria • Digest worn out organelles

  17. The Golgi Complex Material ReceivedFrom ER Material Destinedfor Export TEM

  18. Lysosomes have several types of digestive functions • They fuse with food vacuoles to digest the food Lysosome Digestive enzymes Plasma membrane Digestion Food Food vacuole (a) Lysosome digesting food Figure 4.14a

  19. They break down damaged organelles Lysosome Digestion Damaged organelle (b) Lysosome breaking down damaged organelle Figure 4.14b

  20. The Flow of Membrane Destined forExport Lysosome Golgi EndoplasmicReticulum Destined forGolgi

  21. A review of the endomembrane system Rough ER Transport vesicle from ER Golgi apparatus Secretory vesicle from Golgi Vacuole Lysosome Secretory protein Plasma membrane Figure 4.16

  22. III. Cells Organelles and Features H. Cytoskeleton – network of tubes and filliments used for support • Microtubules – hollow tubes, hold organelles in place, maintain cell shape, act as tracts to guide organelles • Microfilaments – involved in cell movement and contraction of muscle cells • Intermediate filaments – anchor some organelles in place, maintain internal shape

  23. III. Cells Organelles and Features H. Cytoskeleton continued: • Cilia – hair like structure, short and are numerous, aid in movements • Flagella – are few, move in whip like fashion, used for movement • Centrioles – found in animal cells, involved in cell division

  24. IV. Unique Features of Plant Cells • Plant Cells – unique features include the following • Cell wall – rigid layer outside plasma membrane, protection and support, made of cellulose • Central vacuole – large fluid filled space, aids in support and shape • Other vacuoles – food vacuoles or vacuoles that hold toxins • Contractile Vacuole – is involved in osmoregulation.

  25. Plant Wilting &the Central Vacuole NormalPlant Cell In SaltWater Normal Cytoplasm In Salt Water Vacuole(tonoplast) Space between Cell Walland Cell Membrane Cell Wall

  26. IV. Unique Features of Plant Cells D. Plastids – unique to plants • Chloroplasts – contain green pigment chlorophyll, involved in photosynthesis in plants • Chromoplasts – contain other color pigments other then green • Luecoplasts – colorless plastids store starch

  27. Prokaryotes Eukaryotes - Lack nucleus - Have nucleus - lack membrane organelles - Have membrane organelles Animal Cell Plant Cell - Lack cell wall - Have cell wall - No central vacuole - central vacuole - No plastids - Plastids - Have centrioles - No centrioles

  28. The Endof Chapter 4

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