Structure of Prokaryotic & Eukaryotic Cells

Transcription

1 Structure of Prokaryotic & Eukaryotic Cells

2 Review of Prokaryotic & Eukaryotic Cells Nucleus vs nucleoid DNA : circular vs linear, presence of histones Membranous organelles Cell wall-peptidoglycan Cell division: binary vs mitosis Ribosomes: 70S vs 80S Cytoskeleton

3 Shape Cocci Diplococci Streptococci Tetrads Sarcinae Staphylococci

4 Bacillus Coccobacilli Diplobacilli Streptobacilli

5 Vibrio-curved rods Spiral Spirilla-helical & rigid Spirochetes-helical & flexible Other shapes Pleomorphic

6 Glycocalyx Glycolipids or glycoproteins Surrounds cell Capsule or slime layer Capsule more organized & attached to wall Advantages of capsule

7 Slime Layer(Biofilm) Surrounds cell Loosely organized & not attached Tangled mass of fibers-dextran Attachment to surfaces -S. mutans Shields bacteria from immune defense & antibiotics

8 Glycocalyx -Eukaryotes Animal cells have one Made of carbohydrates No do not have a cell wall Surround plasma membrane Stabilizes PM

9 Flagella Movement Spins like propeller Clockwise or counter clockwise Chemotaxis- movement toward or away

10 Arrangements Monotrichous: one at end Amphitrichous: both ends Lophotrichous: tuft at end or ends Peritrichous: around the cell

11 Structure Composition-protein subunits: flagellin (H protein) E. coli H7 Chains twisted together with hollow core Helical shaped Filament, hook, basal body Hook Basal body:

12 Flagella Basal body Classified by flagella protein

13 Axial Filament Spirochetes Treponema pallidum-syphilis Borrelia burgdorferi-lyme disease Bundle of fibrials within a sheath Corkscrew motion

14 Movement Eukaryotes Flagella & cilia 9+2 arrangement of microtubules Cilia in Paramecium & respiratory cells

15 Prokaryote Fimbriae & Pili Made of pilin: string of subunits Function: attachment Few to hundreds Fimbrae Pili-longer & fewer Not in eukaryotes

16 Cell Wall Function Basis of Gram stain

17 Composition Peptidoglycan Repeating subunits of disaccharides N-acetyl glucosamine (NAG) N-acetyl muramic acid (NAM) Linked alternately in rows Attached by polypeptides Tetrapeptide side chains link NAM subunits Cross bridge of amino acids link tetrapeptides Forms lattice

18 Peptidoglycan Confers shape & prevents lysis Cell growth Autolysins break cross linkages in peptidoglycan Transpeptidases seal breaks Penicillin inactivates these enzymes Existing cells Treat with lysozyme-tears, saliva etc. Destroys linkages between carbohydrates

19 Gram Positive Cell Wall Thick layers: 40-80% of dry wt, up to 30 layers Contains teichoic acid Alcohol and phosphate Negative charge Cell growth-prevents lysis Antigenic properties

20 Gram Negative Cell Wall Few layers of peptidoglycan- 10% Outer membrane: bilayer Periplasm

21 LPS Strong negative charge Barrier to some antibiotics Outer membrane-endotoxin O polysaccharides Lipid-lipid A

22 Gram Stain Differential stain dev by Hans Gram 1880s Classifies bacteria into 2 groups Based upon cell wall composition Gram variable stain unevenly Gram non reactive do not stain or stain poorly

23 Gram positives Comparison

24 Gram Negatives ETOH disrupts outer layer CV-I complex is washed out of thin peptidoglycan layer Counterstain

25 Atypical Cell Walls Streptococci Mycobacteria Mycoplasma PM unique with sterols protect from lysis

26 Mycoplasma Lack a cell wall so pleomorphic Classified with gram positives Smallest genome of any bacteria Droplet spread-use regular mask Why can t you use penicillin?

27 Cell wall of Eukaryotes Simpler than prokaryotes Algae & plants Fungi Yeasts Protozoa Animals

28 Plasma Membrane Thin, fluid structure inside cell wall-viscous Proteins Phospholipids-2 layers

29 Functions of Membrane Selective permeability Passive transport: Active transport: Enzymes break down nutrients Infoldings

30 Plasma Membrane of Eukaryotes Phospholipids and proteins Carbohydrates and sterols-cholesterol More rigid than prokaryotic PM Endocytosis Exocytosis

31 Cytoplasm of Prokaryotes 80% water, thick, solutes Increase in osmotic pressure on membrane Rigid cell wall prevents lysis Contains DNA Ribosomes Inclusion bodies

32 Cytoplasm of Eukaryotes Cytosol-fluid portion Cytoskelton Microfilaments: Microtubules: Intermediate filaments: Cytoplasmic streaming

33 Ribosomes 2 subunits of protein and rrna 70s ribosomes Polyribosomes-chains Protein synthesis Eukayotes-80s

34 Inclusions Polysaccharide granules Sulfur granules Reserve deposits-volutin (phosphates)

35 Endospores Unique to bacteria: Clostridium & Bacillus Sporulation-formation of spores

36 Germination Triggered by damage to coat Enzymes break down endospore Water enters & metabolism begins Not a reproductive structure

37 Nuclear Area of Bacteria Single, ds DNA chromosome Attached to PM at some point Nucleoid area, not a nucleus Plasmids

38 Nucleus Largest structure in cell Nucleoli DNA associated with proteins -histones

39 Organelles in Eukaryotes Unique to eukaryotes Membranous structures Endoplasmic reticulum Smooth & rough Golgi complex Lysosomes Mitochondria Cloroplasts

40 ER Flattened membranous sacs Rough ER-ribosomes attached Smooth ER- no ribosomes Free ribosomes- proteins don t need processing

41 Golgi Complex Stacks of membranous sacs Receive transport vesicles from ER Modify molecules to form glycoproteins, glycolipids lipoproteins Transported in secretory vesicles to PM or to outside cell

42 Lysosomes Formed from Golgi Contain digestive enzymes: proteases & nucleases Break down old parts of cell Breaks down pathogens

43 Mitochondria Double membrane Generation of ATP

44 Chloroplasts Thylakoids-flattened membranous sacs Contain DNA 70s ribosomes Stroma thick fluid in center- Calvin cycle Generation of ATP & sugars