1. © 2004 Wadsworth – Thomson Learning Chapter 4 Prokaryotic and Eukaryotic Cells

2. © 2004 Wadsworth – Thomson Learning Prokaryotic vs. Eukaryotic Prokaryotic No nucleus No membrane- bound organelles Cell wall contains peptidoglycan Size: less than several micrometers Eukaryotic Nucleus Membrane-bound organelles No peptidoglycan if cell wall even present Size: may be 10 times larger

3. © 2004 Wadsworth – Thomson Learning Prokaryotes--Cell Structure Appendages on outside Capsule and envelope –outer membrane (some) –periplasmic space between two membranes –cell wall (most) –cytoplasmic membrane Cytoplasm –nucleoid –ribosomes –storage granules Figure 4.3

4. © 2004 Wadsworth – Thomson Learning Prokaryotes: Outer membrane Lipid bilayer –phospholipid –lipopolysaccharide (LPS) endotoxin –lipid A –porins –lipoprotein anchors to cell wall unique to bacteria Figure 4.5

5. © 2004 Wadsworth – Thomson Learning Prokaryotes: Cell wall Provide shape Withstand turgor pressure (osmotic pressure) Composition –peptidoglycan: murein part protein (peptido-) part polysaccharide (-glycan) chains of alternating polysaccharide –N-acetylglucosamine (NAG) –N-acetylmuramic acid (NAM) cross-linked with peptides Figure 4.6

6. © 2004 Wadsworth – Thomson Learning Spherical bacteria Cocci (Coccus) –single –pair diplococcus –group of four tetrads –chain streptococcus –clusters staphylococcus Figure 4.7

7. © 2004 Wadsworth – Thomson Learning Rod-shaped bacteria Bacilli (Bacillus) Arrangement –single –pair diplobacillus –chain streptobacillus Figure 4.7

8. © 2004 Wadsworth – Thomson Learning Spiral and other shaped Spiral shaped –spirilla (spirillum) Comma shaped –vibrio Other –Square –Star-shaped Figure 4.7

9. © 2004 Wadsworth – Thomson Learning Cytoplasmic membrane Contain the cytoplasm Both Eucaryotic and Procaryotic regulate passage into and out of cell Components –phospholipid bilayer –proteins transmembrane cytoplasmic peripheral Fluidity of membrane Figure 4.8

10. © 2004 Wadsworth – Thomson Learning Prokaryotes: Appendages Pili (Pilus) or fimbriae –attachment Flagella (flagellum) –locomotion propeller-like motion –structure helical-shaped filament –hook attached to anchor –basal body anchors in membrane Figure 4.10

11. © 2004 Wadsworth – Thomson Learning Prokaryotes: Movement Chemotaxis –sense chemicals Phototaxis –sense light intensity Aerotaxis –favorable oxygen concentrations Magnetotaxis –move along magnetic lines

12. © 2004 Wadsworth – Thomson Learning Prokaryotes: Chemotaxis Run: swimming motion –propelled by flagella working in unison Tumble: senses the chemical concentration –flagella loosen apart repeat actions changing direction slightly Figure 4.12

13. © 2004 Wadsworth – Thomson Learning Prokayrotes: Outermost layer Capsule, slime layer, glycocalyx –Slimy or gummy substance –Composition varies –Most made of polysaccharides Function –Protection Against drying out Against phagocytosis –Adhere to surface –pathogenesis

14. © 2004 Wadsworth – Thomson Learning Prokaryotes: Cytoplasm Primarily water Site of metabolism Nucleoid –region contains DNA Ribosomes –site of protein synthesis Inclusion bodies –storage granules –Gas vacuoles –Chlorosomes –magnetosomes

15. © 2004 Wadsworth – Thomson Learning Prokaryotes: Endospores Resting structures formed inside cell Conditions unfavorable for growth –extreme heat –dehydration –toxic chemicals –radiation Long-term survival –hundreds of years

16. © 2004 Wadsworth – Thomson Learning Sporulaton Unequal cell division begins Cytoplasm divides –vegetative cell –forespore DNA in both parts Figure 4.15

17. © 2004 Wadsworth – Thomson Learning Sporulation Thick protective wall forms –peptidoglycan--different than vegetative cell –keratinlike Spore body contains all essential cell components Vegetative cell lyses--releases endospore Germinates when conditions become favorable Figure 4.15

18. © 2004 Wadsworth – Thomson Learning Structure of Archaea Cell walls –archaea have protein or pseudomurein Plasma membrane –fatty acids attached to glycerol differently bacteria--ester bond archaea-ether bond –stronger bond –withstand harsh conditions Figure 4.16

19. © 2004 Wadsworth – Thomson Learning Eukaryotes: Appendages Flagella –Purpose motility wave-like motion (not propeller-like) –Composition microtubules –9 pair surrounding 2 central Cilia –shorter –more numerous

20. © 2004 Wadsworth – Thomson Learning Eukaryotes: Cell wall and cytoplasmic membrane Cell wall –great diversity –many cells don’t have (animal cells) –composition varies Cytoplasmic membrane –similar to prokaryotes

21. © 2004 Wadsworth – Thomson Learning Eukaryotes: Cytoskeleton Function –structure –movement cytoplasmic streaming transport of molecules –cell division Fibrous protein structures –three types Microtubules Microfilaments Intermediate filaments Figure 4.17a

22. © 2004 Wadsworth – Thomson Learning Eukaryotes: Nucleus Function –contain the DNA Nuclear membrane –lipid bilayer surrounding nucleus –nuclear pores passage of material Nucleoplasm –gelatinous matrix of nucleus Nucleoli –dense masses of RNA and protein

23. © 2004 Wadsworth – Thomson Learning Eukaryotes: Cytomembrane system Function –sorting and transport of synthesized molecules Components –Endoplasmic reticulum (ER) rough ER –ribosomes attached smooth ER –no ribosomes Figure 4.21

24. © 2004 Wadsworth – Thomson Learning Eukaryotes: Cytomembrane system –Golgi apparatus stacks of flattened membrane sacs molecules are modified –Vessicles transport from ER to Golgi from Golgi to final destination –inside the cell –outside the cell Figure 4.22

25. © 2004 Wadsworth – Thomson Learning Eukaryotes: Mitochondria and Chloroplasts Energy production Double membrane system –outer membrane--separate from rest of cell –inner membrane--highly folded Mitochondria –respiration Chloroplasts –photosynthesis

26. © 2004 Wadsworth – Thomson Learning Cell Division: Mitosis Cell division ending in two identical cells Stages: –Interphase DNA decondenses DNA replicated –Mitosis Prophase Metaphase Anaphase Telophase Figure 4.19

27. © 2004 Wadsworth – Thomson Learning Cell division: Mitosis Early prophase –double number of chromosomes –chromosomes condense Late prophase –spindle forms –chromosomes condensed Figure 4.19

28. © 2004 Wadsworth – Thomson Learning Cell division: Mitosis Metaphase –chromosomes attach to spindle fibers –chromosomes line up middle of cell Anaphase –chromosomes moved to opposite ends of cell Figure 4.19

29. © 2004 Wadsworth – Thomson Learning Cell division: Mitosis Telophase –chromosomes decondense –nuclear membrane reforms –cell separation occurs Interphase –identical daughter cells Figure 4.19

30. © 2004 Wadsworth – Thomson Learning Cell division: Meiosis Cell division in reproductive cells Final cells –half the chromosome number –haploid number Meiosis I –duplication of chromosomes –crossing-over genetic variability Meiosis II –reduce chromosome number

31. © 2004 Wadsworth – Thomson Learning Cell division: Meiosis Prophase I –Homologous chromosome pair up Crossing over –Nuclear membrane disintegrates –Chromosomes condense Metaphase I –Chromosomes align in center –Attach to spindle fibers Figure 4.20

32. © 2004 Wadsworth – Thomson Learning Cell division: Meiosis Anaphase I –Chromosome pairs separate to different ends Telophase I –Cells divide –Single set of chromosomes (haploids) Figure 4.20

33. © 2004 Wadsworth – Thomson Learning Cell division: Meiosis Prophase II –Duplicates of each chromosome Metaphase II –Chromosomes line up in the middle –Attached to fibers Figure 4.20

34. © 2004 Wadsworth – Thomson Learning Cell division: Meiosis Anaphase II –Chromosome separate to opposite ends Telophase II –Cell divides –Each daughter cell has single copy of each chromosome –Reproductive cell Egg or sperm Figure 4.20

35. © 2004 Wadsworth – Thomson Learning Simple diffusion Molecules move randomly Evenly distribute Figure 4.24

36. © 2004 Wadsworth – Thomson Learning Osmosis Water movement Cross membrane –from low concentration of solute to high High solute concentration –hypotonic –cell swells Low solute concentration –hypertonic –shrinks Equal solute concentration –Isotonic Figure 4.25

37. © 2004 Wadsworth – Thomson Learning Membrane transport Facilitated diffusion –no energy required –carrier protein –high to low concentration Active transport –energy required –carrier protein –low to high concentration Group translocation –unique to bacteria –modification as well as transport Figure 4.26

38. © 2004 Wadsworth – Thomson Learning Eukaryotic membrane transport Endocytosis bring inside the cell –phagocytosis engulfing cells –pinocytosis cell drinking Exocytosis exporting out Figure 4.26