Cytology = the study of cells. Chapter 4 CELL STRUCTURE

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1 Cytology = the study of cells Chapter 4 CELL STRUCTURE Cellular basis of life: Basic unit of life Lowest level with all attributes of life Organisms composed of one or more cells Cell structure correlated to function All cells are related

2 BIOLOGY Chapter 4 CELL STRUCTURE

3 Which cellular structure is common to all 3 domains of life? a) Nucleus b) Endoplasmic reticulum c) Mitochondria d) Phospholipid bilayer cell membrane e) Endocytotic vesicles

4 Figure 4.6 Prokaryotic Eukaryotic

5 50 m Figure 6.3 Light Microscopy (LM) Electron Microscopy (EM) Brightfield (unstained specimen) Confocal Longitudinal section of cilium Cross section of cilium Cilia Brightfield (stained specimen) 2 m 1 m 10 m 50 m Deconvolution Scanning electron microscopy (SEM) 2 m Transmission electron microscopy (TEM) Phase-contrast Cellular observations microscopy Differential-interferencecontrast (Nomarski) Super-resolution Fluorescence 10 m

6 Figure 6.4 TECHNIQUE Cellular fractionation To study organelle function Tissue cells Centrifuged at 1,000 g (1,000 times the force of gravity) for 10 min Supernatant poured into next tube 20,000 g 20 min Homogenization Centrifugation Differential centrifugation Homogenate Pellet rich in nuclei and cellular debris 80,000 g 60 min 150,000 g 3 hr Pellet rich in mitochondria (and chloroplasts if cells are from a plant) Pellet rich in microsomes (pieces of plasma membranes and cells internal membranes) Pellet rich in ribosomes

7 Figure 4.5 size 1 10 µm Nucleoid Circular DNA plasmid Cell wall Gram + Gram -

8 Prokaryotes DNA not membrane bound Lack membrane bound organelles No histone proteins Peptidoglycan Widespread Size (0.5 5 µm) Bacteria or Archaea

9 Fig Diplo- Staphylo- Strepto- 1 µm (a) Spherical (cocci) 2 µm (b) Rod-shaped (bacilli) (c) Spiral 5 µm

10 Prokaryotic Reproduction Binary Fission Genetic Diversity via Horizontal Gene Transfer Transformation Transduction Conjugation

11 Fig Cell Surface Structures Hans Christian Gram Gram Staining LPS component O polysacch antigens for ID (E. coli O157:H7) Lipid A endotoxin toxic (fever/shock) antibiotics Cell wall Peptidoglycan layer Plasma membrane Carbohydrate portion of lipopolysaccharide Cell wall Outer membrane Peptidoglycan layer Plasma membrane Protein Protein Grampositive bacteria (a) Gram-positive: peptidoglycan traps crystal violet. Gramnegative bacteria 20 µm (b) Gram-negative: crystal violet is easily rinsed away, revealing red dye.

12 Fig. 27-3c Grampositive bacteria Gramnegative bacteria 20 µm

13 Figure 6.6 Outside of cell TEM of a plasma membrane Phospholipid bilayer Cholesterol Proteins Carbohydrates Inside of cell 0.1 m Carbohydrate side chains Hydrophilic region Outside cell cholesterol Hydrophobic region Hydrophilic region Phospholipid Proteins Inside cell (b) Structure of the plasma membrane 8 m

14 Figure 4.7 Why are cells so small? Efficiency in: Acquisition of nutrients Disposal of wastes What makes this possible? High surface areas to volume ratio

15 Cell size & plasma membrane shape affect SA:V a) One large cell. b) Eight small cells. c) Cell with microvilli on one surface. Which cell has the larger SA? Larger Vol? Larger SA:V ratio?

16 Figure 4.8 Figure 4.8

17 5 m 10 m Cell structure reflects eukaryotic cell s function How are these cells similar? What makes these cells different? 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). Animal Cells Cell Fungal Cells Parent cell Buds 1 m Cell wall Vacuole Figure 6.8b Human cells from lining of uterus (colorized TEM) Nucleus Nucleolus Yeast cells budding (colorized SEM) A single yeast cell (colorized TEM) Nucleus Mitochondrion

18 Endomembrane System

19 Nuclear Envelope Nucleus Genetic control ctr DNA synthesis RNA synthesis Nuclear pores Ribosome Nuclear envelope: Inner membrane Figure 6.9a Nucleolus Chromatin Outer membrane Nuclear pore Pore complex Nucleus Rough ER Close-up of nuclear envelope Chromatin

20 Figure 4.12 Chromatin a) DNA + histone proteins (8) nucleosome b) Replicated chromosome

21 Nucleolus Ribosome production Free or bound» Protein synthesis Nucleolus Nuclear membrane Nuclear pores Nuclear membrane A transmission electron micrograph (X 6,000) of Figure 3.15

22 Nucleolus/nucleoli Ribosome production Free or bound Protein synthesis 0.25 m Free ribosomes in cytosol Figure 6.10 Endoplasmic reticulum (ER) A transmission electron micrograph (X 6,000) of the nucleus of an animal cell Nucleolus Nuclear membrane TEM showing ER and ribosomes Ribosomes bound to ER Nuclear pores Nuclear membrane Figure 3.15 Large subunit Small subunit Diagram of a ribosome

23 Endoplasmic Reticulum Rough ER Smooth ER Rough ER Smooth ER Nuclear envelope ER lumen Cisternae Ribosomes Transitional ER Smooth ER Transport vesicle Rough ER 200 nm Figure 6.11

24 Endomembrane Organelles Rough Endoplasmic Reticulum (RER) Ribosomes Protein synthesis

25 Endomembrane Organelles Smooth Endoplasmic Reticulum No ribosomes Some functions: Carbo metabolism Ca ++ storage Detoxification Phospholipid synthesis

26 Endomembrane Organelles Golgi apparatus/body/complex warehouse Receives Modifies Stores Ships cis face ( receiving side of Golgi apparatus) Cisternae 0.1 m trans face ( shipping side of Golgi apparatus) TEM of Golgi apparatus

27 Figure Endomembrane System Nucleus Rough ER Smooth ER cis Golgi trans Golgi Plasma membrane

28 Endomembrane Figure 6.13a Nucleus 1 m Lysomsome Organelles Contains hydrolytic enzymes Breaks down stuff Lysosome Intracellular digestion of nutrients Digestive enzymes Lysosome Plasma membrane Digestion Food vacuole (a) Phagocytosis

29 Endomembrane Organelles Lysomsome Contains hydrolytic enzymes Breaks down stuff Mitochondrion fragment Peroxisome fragment Intracellular digestion of nutrients Garbage man dead organelles Programmed cell destruction Tay Sachs Disease Peroxisome Lysosome Vesicle containing two damaged organelles 1 m Figure Vesicle Mitochondrion Digestion (b) Autophagy

30 Figure 6.14 Central vacuole Cytosol Nucleus Central vacuole Cell wall Chloroplast 5 m

31 Figure Endomembrane System Nucleus Rough ER Smooth ER Plasma membrane

32 Figure Endomembrane System Nucleus Rough ER Smooth ER cis Golgi trans Golgi Plasma membrane

33 Figure Endomembrane System Nucleus Rough ER Smooth ER cis Golgi trans Golgi Plasma membrane

34 Enzymes responsible for biosynthesis of membrane lipids would be located in what part of the cell? a) endoplasmic reticulum. b) nucleus. c) lysosomes. d) Golgi. e) plasma membrane

35 Endomembrane Organelles Lysomsome Contains hydrolytic enzymes Breaks down stuff Intracellular digestion of nutrients Garbage man dead organelles Programmed cell destruction Tay Sachs Disease

36 Endomembrane Organelles Vacuoles Food Temp. storage of food Contractile Expels waste

37 Types of Vesicles Storage & shipping vesicles Secretory vesicles Endocytic vesicles Vacuoles Food Contractile Expels waste Peroxisomes Contain enzymes that detoxify Lysosomes Peroxisome Golgi apparatu s Contain digestive enzymes Bacterium Harmless waste Alcohol Cell toxic waste Lysosome Residual body Plasma membrane

38 Endomembrane System A membrane protein synthesized in the rough ER may be directed to: a) peroxisomes. b) lysosomes. c) mitochondria. d) all of the above

39 Golgi Brefeldin A is a drug that disrupts transport from the ER to the Golgi apparatus. What other organelles and membranes are affected? A. lysosomes, vacuoles, plasma membrane B. lysosomes, peroxisomes, plasma membrane C. vacuoles, mitochondria, plasma membrane D. lysosomes, vacuoles, nuclear membrane E. all intracellular organelles and membranes

40 Endosymbiotic Eukaryotic Origins Engulfing of oxygenusing nonphotosynthetic prokaryote, which becomes a mitochondrion Mitochondrion Endoplasmic reticulum Nuclear envelope Nucleus Ancestor of eukaryotic cells (host cell) Nonphotosynthetic eukaryote At least one cell Engulfing of photosynthetic prokaryote Chloroplast Mitochondrion Figure 6.16 Photosynthetic eukaryote

41 Mitochondrion/mitochondria Double membrane Inner membrane Cristae energy production Matrix energy production DNA 1 chromosome Binary fission All aerobic eukaryotes Intermembrane space Outer membrane 10 m Mitochondria Free ribosomes in the mitochondrial matrix DNA Inner membrane Cristae Matrix (a) Diagram and TEM of mitochondrion 0.1 m Mitochondrial DNA Nuclear DNA (b) Network of mitochondria in a protist cell (LM)

42 Figure 6.17a Mitochondrion/mitochondria Intermembrane space Outer membrane DNA Free ribosomes in the mitochondrial matrix Inner membrane Cristae Matrix (a) Diagram and TEM of mitochondrion 0.1 m

43 Chloroplasts Double membrane Thylakoid (granum/grana) Sunlight NRG chemical NRG Photosynthetic pigments Stroma Uses chemical NRG Sugar production Own DNA Ribosomes Stroma Inner and outer membranes Granum DNA Thylakoid Intermembrane space (a) Diagram and TEM of chloroplast 1 m

44 According to the endosymbiont theory, which of the following organelles were once endosymbiotic prokaryotic organisms? a) Mitochondria and lysosomes b) Mitochondria and chloroplasts c) Chloroplasts and Golgi apparatus d) Golgi apparatus and ribosomes e) Ribosomes and lysosomes

45 Peroxisome Single membrane Plants & animals Detoxifies cells H 2 O 2 1 m Figure 6.19 Chloroplast Peroxisome Mitochondrion

46 Figure 6.21 ATP Vesicle Receptor for motor protein (a) Motor protein (ATP powered) Microtubule of cytoskeleton Microtubule Vesicles 0.25 m (b)

47 Table m 10 m 5 m Column of tubulin dimers 25 nm Actin subunit Keratin proteins Fibrous subunit (keratins coiled together) Tubulin dimer 7 nm 8 12 nm

48 Microtubule Function Taxol, a drug approved for treatment of breast cancer, prevents depolymerization of microtubules. What cellular function that affects cancer cells more than normal cells might taxol interfere with? a) maintaining cell shape b) cilia or flagella c) chromosome movements in cell division d) cell division (cleavage furrow formation) e) cytoplasmic streaming

49 Figure 6.22 Centrosome Microtubule Centrioles 0.25 m Longitudinal section of one centriole Microtubules Cross section of the other centriole

50 Direction of swimming (a) Motion of flagella 5 m Direction of organism s movement Power stroke Recovery stroke (b) Motion of cilia Figure m

51 Figure m Outer microtubule doublet Dynein proteins Plasma membrane Central microtubule Radial spoke Microtubules Plasma membrane Basal body (b) Cross section of motile cilium Cross-linking proteins between outer doublets 0.5 m 0.1 m (a) Longitudinal section of motile cilium Triplet (c) Cross section of basal body

52 Figure 6.25 Microtubule doublets ATP Dynein protein (a) Effect of unrestrained dynein movement Cross-linking proteins between outer doublets ATP Anchorage in cell (b) Effect of cross-linking proteins (c) Wavelike motion

53 Figure 6.27 Muscle cell Actin filament Myosin filament Myosin head (a) Myosin motors in muscle cell contraction 0.5 m Cortex (outer cytoplasm): gel with actin network Inner cytoplasm: sol with actin subunits 100 m Extending pseudopodium (b) Amoeboid movement Chloroplast (c) Cytoplasmic streaming in plant cells 30 m

54 Figure 6.27a Locomotion Muscle cell Actin filament Myosin filament Myosin head (a) Myosin motors in muscle cell contraction 0.5 m

55 Figure 6.27b Cytoplasmic streaming Cortex (outer cytoplasm): gel with actin network Inner cytoplasm: sol with actin subunits 100 m Extending pseudopodium (b) Amoeboid movement

56 Figure 6.27c Cyclosis/Cytoplasmic streaming Chloroplast (c) Cytoplasmic streaming in plant cells 30 m

57 Cytoskeleton & extracellular matrix Collagen EXTRACELLULAR FLUID Polysaccharide molecule Proteoglycan complex Microfilaments Carbohydrates Fibronectin Core protein Integrins Plasma membrane Proteoglycan molecule Proteoglycan complex CYTOPLASM

58 Figure 6.32 TEM Cellular Junctions Tight Anchoring Gap Tight junctions prevent fluid from moving across a layer of cells Tight junction TEM 0.5 m Tight junction Intermediate filaments Desmosome Gap junction TEM 1 m Ions or small molecules Plasma membranes of adjacent cells Space between cells Extracellular matrix 0.1 m

59 Figure 6.28 Plasmodesmata Secondary cell wall Primary cell wall Middle lamella 1 m Central vacuole Cytosol Plasma membrane Plant cell walls Plasmodesmata

60 Figure 6.UN01 Nucleus (ER) (Nuclear envelope)

61 Semen & Ovum