Cell Structure & Function

1. Cell Structure & Function Chapter 4

2. The History of Cell Biology Robert Hooke: 1665 Created the first microscope Studied cork and saw “little boxes”

3. Robert Hooke

4. Anton von Leeuwenhoek: 1673 • Dutch trader, considered to be the father on microbiology • Made better lens The History of Cell Biology

5. Leeuwenhoek

6. The History of Cell Biology • Protists: Spirogyra, Vorticella • “Wee little beasties”

7. The Cell Theory • All living organisms are composed of one or more cells. • Cells are the basic units of structure and function in an organism • Cells come only from the reproduction of existing cells.

8. Characteristics of Life: • organized parts • obtain energy from surroundings • metabolism • change with time • respond to their environments • reproduce • homeostasis • Relatedness

9. Cell Diversity • Cell Shape: The diversity of cell shapes reflects the different functions of cells. ex. nerve cell, muscle, skin. • Cell Size: limited by its surface area-to-volume ratio

10. Basic Parts of the Cell • Plasma Membrane: outer covering, barrier controlling access to cell • Cytoplasm: all the goo and lumps inside a cell except the nucleus • Nucleus/Nucleoid Region: DNA: control/heredity

11. Two Basic Types of Cells Prokaryotes: Eukaryotes: membrane-bound organelles upper-limit on size is much greater than prokaryotes membrane-bound organelles increases the surface area within the cell making it more efficient • no membrane-bound organelles, • necessary enzyme systems are imbedded on the inside of the plasma membrane. • upper limit of size is smaller than eukaryotes

12. Cellular Organization Colonies True Multicellularity As organisms evolved, their cells became more specialized eventually were unable to survivie independently groups of cells took on specific roles Tissues  Organs  Organ Systems  Organism • collections of genetically identical cells • live together in a connected group • few cell activities are coordinated

13. Cell Organelles and Features

14. Plasma Membrane • phospholipids: part polar (like water), part non-polar (lipid or “anti-water”) • bilayer • Membrane Proteins: integral proteins are “integrated” into the membrane to some degree • some, emerge from only one side like cell-surface markers: cell-cell recognition, dock for viruses • others, go clear across the bilayer of membrane like receptor or transport proteins. • active transport proteins • passive transport protein channels for ions or large molecules. • still others, lie on only one side of the membrane but are not embedded into it. For example, enzymes.

15. Nucleus • nucleoplasm • DNA in the form of chromosomes • DNA is copied into RNA in nucleus

16. Nuclear Envelope • double membrane (two bilayers) with protein pores

17. Nucleolus • site of RNA synthesis

18. Mitochondria • inner and outer membranes • outer separates it from cytosol • inner is folded to increase surface area • break down glucose to make ATP • contains its own DNA

19. Ribosomes: • protein + RNA • organize production of protein • free ones make protein to be kept by cell • attached ones make protein for export

20. Endoplasmic Reticulum: “highway” • Rough endoplasmic reticulum • interconnected flattened sacs • covered with ribosomes • digestive glands and antibody-producing cells • Smooth Endoplasmic Reticulum • lacks ribosomes so looks smooth • builds lipids such as cholesterol • ex. sex hormones • releases Calcium (Ca) • detoxify /s.ER production / drug tolerance

21. Golgi Apparatus • system of flattened sacs • ER  Golgi  Vesicles  ? export by exocytosis • Golgi modifies, adds “address labels,” packages

22. Vesicles • small, spherical sacs, single membrane, classified on contents • Lysosomes: hydrolytic enzymes • Peroxisomes: different enzyme  hydrogen peroxide • Food vacuoles: store food • Contractile Vacuoles: contract to rid cell of excess water

23. Cytoskeleton • network of thin tubes and filaments that crisscross cytosol • used like tent poles to support structure • used as internal tracks on which items move or anchor

24. Cilia and Flagella • membrane on outer surface, microtubules 9 + 2 • Cilia: short and numerous, in ear: vibrate with sound, protists use to “row”, get food by sweeping into “mouth” • Flagella: long and few in #, propulsion

25. Centrioles • two short cylinders of microtubules at right angles to each other • animal cells only • organize cell division • basal bodies have same structure (cilia and flagella)

26. Unique Features of Plant Cells

27. Cell Walls • rigid • Contain cellulose • It lays outside plasma membrane • pores allow water, ions and some molecules to enter/exit

28. Large Central Vacuole • Stores water, enzymes, metabolic wastes etc. • formed by smaller vacuoles fusing together • when dry, vacuole loses water, cells shrink, plant wilts

29. Plastids • Unique feature of plant cells • double membrane • DNA • Examples: chloroplasts, chromoplasts, & leucoplasts

31. Types of Plastids • Chloroplasts • chloroplast system of flattened, membranous sacs called thylakoids • chlorophyll in thylakoids captures light energy • Green pigment • descendents of ancient prokaryotes • endosymbiosis

32. Types of Plastids • Chromoplasts • contain colorful pigments and may or may not take part in photosynthesis • carotene in carrots • red, purple, yellow, or white pigments in flower petals

33. Types of Plastids • Other Plastids • Amyloplasts: store starch • Proplastid: common precursor to all the above

34. Comparing Cells:Plant to AnimalOrganellesunique to each