Cytology I Study of Cells

Transcription

1 Cytology I Study of Cells Biology 20

2 Which cell type has organelles such as mitochondria, nuclues, Golgi bodies, etc? A) prokaryotic B) eukaryotic C) bacterial D) viral E) none of these

3 Cellular Basis of Life 1. Basic unit of Life 2. Composed of one or more cells 3. Arises from pre-existing cells Asexual (Mitosis)/Sexual (Meiosis) 4. Surrounded by a membrane 5. Transform energy 6. Information retention (genes) Cell Theory

4 What level in life s hierarchy possess all the attributes of life? A) molecular B) organ C) tissue D) cellular E) all of these

5 Cell Doctrine All living things are composed of cells Cell is the smallest unit that exhibits all of the attributes of life All cells come only from preexisting cells

6 Two Basic Cell Types Classified by Internal Organization Prokaryotic Cells Plasma membrane No nucleus Cytoplasm: fluid within membrane No true organelles 1 10 um What type of cell do you have? Eukaryotic Cells Plasma membrane Nucleus: information center Cytoplasm: fluid within membrane Organelles: compartments with specialized functions um

7 Figure 3.6 Ribosomes Cytoplasm a. Nucleoid (DNA) Cell membrane Cell wall Capsule Flagellum b. c. d. SEM (false color) 2 μm SEM (false color) 2 μm SEM (false color) 2 μm

8 Figure 3.2 Atoms Small molecules Proteins Viruses Most bacteria and archaea Most plant and animal cells Frog eggs Ant Range of electron microscope Range of light microscope Range of human eye

9 Plasma membrane Cell wall Cytoplasm Organelles Nucleus a) A eukaryotic animal cell has a large nucleus and numerous small organelles. The cytoplasm is enclosed by a flexible plasma membrane. b) Prokaryotic cells such as this bacterium have a rigid cell wall surrounding the plasma membrane. The genetic material is not surrounded by a membrane, and there are no organelles in the cell. The elongated bacterium in the center of the photo is about to divide in two, as its genetic material is concentrated at both ends of the cell. Figure 3.1

10 Cell structure reflects eukaryotic cell s function a) A portion of several muscle cells of the heart (X 1,500). b) Nerve cells of the central nervous system (X 830). c) Cells lining a tubule of a kidney (X 250). How are these cells similar? What makes these cells different? Figure 3.2

11 Figure 3.23 Cell structure reflects eukaryotic cell s function a. LM b. 40 µm LM 400 µm c. LM d. 35 µm LM 50 µm

12 Why are cells so small? Efficiency in: Acquisition of nutrients Disposal of wastes What makes this possible? High surface areas to volume ratio

13 The cells of an ant and an elephant are, on average, the same small size; an elephant just has more of them. What is the advantage of small cell size? a) small cells are less likely to burst than large cell; b) small cells are less likely to be infected by bacteria; c) small cells can better take up what they need from their environment; d) it takes less energy to make an organism out of small cells; e) small cells can "morph" more easily than larger cells.

14 Plasma or cell membrane 8 hm Boundary Selectively permeable Receptor protein Channel protein (always open) Extracellular environment Hydrophobic interactions Fluid Mosaic Model Gated channel protein (closed position) Carbohydrate groups Figure 3.5 Cytoskeleton filaments Phospholipid Cytoplasm Lipid bilayer Transport protein Glycoprotein Cholesterol

15 Plasma or cell membrane Lipids and small, nonpolar molecules Ions and large, polar, or charged molecules Figure 3.11 Hydrophilic Hydrophobic Phospholipid bilayer Hydrophilic Water Phospholipid bilayer Water

16 Fluid Components 1) Phospholipid Hydrophilic Hydrophobic Amphipathic 2) Cholesterol Cold prevents packing Hot limits movement

17 Mosaic Components 3) Proteins Intergral: w/in membrane Peripheral: inside cell (cytoplasmic)

18 Membrane Protein Functions 1) Transport In or out of the cell Molecule specific 2) Ion channel Na +, K +, Ca ++, Cl -.

19 Membrane Protein Function 3) Enzymatic Chemical rxn Energy production

20 Membrane Protein Function 4) Receptor site For chemical messengers Signal transduction Cell recognition

21 Membrane Protein Function 5) Cytoskeleton attachment Cell shape Coordinate extracellular & intracellular changes

22 Membrane Protein Functions 6) Cell adhesion

23 Membrane Protein Functions 6) Cell adhesion CELLS OF SMALL INTESTINE TIGHT JUNCTION Figure 3.27 ANCHORING (ADHERING) JUNCTION GAP JUNCTION

24 Mosaic Components 4) Carbohydrates Glycoproteins glycolipids Function: Cell-cell recognition Ex. Blood type

25 Which component of the cell membrane is the cell s ID tag (or identifies the cell as its particular type? A) cholesterol B) carbohydrates C) phospholipids D) proteins E) All of these

26 Which of the following allows for cell to cell recognition? A) cholesterol B) carbohydrates C) phospholipids D) proteins E) I think it s two of these

27 Membrane Permeability Size: Charge: Small molecules Uncharged easy Charged: can not Lipid solubility Hydrophobic molecules Carrier proteins Assist small charged Assist non-soluble

28 Membrane Transport Simple Diffusion [High] [Low] Down its [gradient] Passive no energy

29 Membrane Transport Facilitated diffusion Carrier protein Passive no energy Ions, water

30 Membrane Transport Table 4.2

31 3 types of passive transport Higher concentration Lower concentration Diffusion through the lipid layer. Lipid-soluble molecules such as O 2 and CO 2 diffuse freely through the plasma membrane. Diffusion through channels. Some polar and charged molecules diffuse through protein channels that span the membrane. Water is a typical example. Facilitated transport. Certain molecules bind to a protein, triggering a change in protein shape that transports the molecule across the membrane. Glucose typically enters cells by this method.

32 Sodium ions (Na + ) diffuse across the cell membrane, but they need assistance. This would be an example of: a) simple diffusion b) facilitated diffusion; c) active transport; d)osmosis; e) huh?

33 Membrane Transport Osmosis Diffusion of water Across a selectively permeable membrane Passive Hypotonic Isotonic Lower [solute] & High [H 2 O] Equal/same [solute] & equal/same [H 2 O] Hypertonic Higher [solute] & Low [H 2 O] Hypotonic hypertonic

34 Membrane Transport - Osmosis

35 Membrane Transport - Osmosis Figure 4.16

36 Membrane Transport - Osmosis Isotonic solution Equal/same [solute] Ex. Inside cell: 3% NaCl, 97% H 2 O Beaker: 3% NaCl, 97% H 2 O Animal cells Normal Plant cells normal 3% NaCl 97% H 2 O

37 Membrane Transport - Osmosis Hypotonic solution Lower [solute], has more water Inside cell: 3% NaCl, 97% H 2 O Beaker: 0% NaCl, 100% H 2 O H 2 O: more IN than out Animal cells burst/lyse Plant cells turgid (stiff) Why? 0% NaCl 100% H 2 O

38 Membrane Transport - Osmosis Hypertonic solution Higher [solute], less water Inside cell: 3% NaCl, 97% H 2 O Beaker: 50% NaCl, 50% H 2 O H 2 O: more OUT than in Animal cells shrinks Plant cells plasmolysis 50% NaCl 50% H 2 O

39 Osmosis hypertonic solutions Animal cells Shrinks/shrivels Plant cells Plasmolysis Cell membrane separates from cell wall 5% NaCl 95% H 2 O

40 Isotonic Hypertonic Hypotonic 0.9% salt 10% salt DI water The amount of water movement is indicated by the sizes of the arrows. Scanning of electron micrographs of red blood cells placed in similar solutions.

41 Isotonic Hypertonic Hypotonic Figure 4.17

42 Figure 4.18

43 Tonicity & the potato Hypertonic Isotonic Initial (3 cm) Hypotonic

44 You're rushed to the ER and given an IV (intravenous) saline (salt) solution to rehydrate you. The nurse was not sleeping during biology this time and happened to give you an isotonic IV solution. What would happen to your RBC's (red blood cells) in your blood vessels? a) shrivel; b) lyse/burst; c) nothing; d) you're thinking lawsuit aren't you?

45 Membrane Transport Active Transport [lower] [higher] Against [gradient] Carrier protein REQUIRES energy

46 Active Transport Na + /K + pump

47 Membrane Transport Bulk transport Large molecules Endocytosis = in take 1. Phagocytosis = cell eating 2. Pinocytosis = cell drinking

48 Membrane Transport Figure 4.20

49 Membrane Transport Large molecules Endocytosis = in take 1. Phagocytosis = cell eating 2. Pinocytosis = cell drinking 3. Receptor mediated Substance triggers receptor protein

50 Membrane Transport Figure 4.21

51 Membrane Transport Bulk Transport Large molecules Exocytosis Getting rid of substances Transport vessicle fuses w/ cell membrane Contractile vacuole

52 Comparison of endocytosis & exocytosis Extracellular environment Plasma membrane Cytoplasm Vesicle a) Endocytosis. In endocytosis, material is surrounded by the cell membrane and brought into the cell. b) Exocytosis. In exocytosis, a membranous vesicle fuses with the plasma membrane, expelling its contents outside the cell. c) Photomicrograph showing various stages of endocytosis.