Functional Anatomy of Prokaryotic Cells

Chapter 4

Prokaryotic and Eukaryotic Cells

Prokaryote comes from the Greek words for prenucleus.Eukaryote comes from the Greek words for true nucleus.

Prokaryote

One ci rcular chromosome, not in a membraneNo histonesNo organellesPeptidoglycan cell wallsBinary fission

Eukaryote

Paired chromosomes, in nuclear membrane

Histones presentO rganellesPolysaccharide cell wallsMitosis

Figures 4.1a, 4.2a, 4.2d, 4.4a, 4.4b, 4.4c

Basic Shapes/MorphologyBacillus (rod-shaped)

Coccus (spherical)

SpiralSpirillumVibrioSpirochete

Scientific name: BacillusShape: Bacillus

Unusual Shapes of Bacteria

Hyphal/F ilamentous bacter ia

Figures 4.1a, 4.1d, 4.2b, 4.2c

B A C T E RI A L A RR A N G E M E N T

Pairs: Diplococci, diplobacilli

Chains: Streptococci, streptobacilli

C lusters: Staphylococci

Bacter ial A r rangement

Clusters:

Tetrads

Sarcinae

monomorphic

vs.

pleomorphic

Rhizobium, Corynebacterium

Significance of Size

1. Typical size of prokaryote vs. typical eukaryote

1-2 m vs. 10-100 m 1 m = 10-6 m

2.Epulopiscium sp.

3. Observing a bacter ium vs. a colony

4. Advantage of small size

Figure 4.6

Functional Anatomy of Prokaryotic Cells

A . G lycocalyx

Outside cell wallUsually stickyCompositionTwo types of G lycocalyx:Capsule vs. Slime layer

A . G lycocalyx

Functions of G lycocalyx:Slime layer allows cell to attachCapsules prevent phagocytosis

B . Cell Wall

1. FunctionPrevents osmotic lysis, r igidity, shape

2. Composition and Structure

Peptidoglycan (PG)

Peptidoglycan (PG)

1. Disaccharide polymer (N A G and N A M)2. Tetrapeptide side chains3. Peptide cross br idges

Polymer of disaccharide:N-acetylglucosamine (NAG) N-acetylmuramic acid (NAM)

Figure 4.13a

Peptidoglycan

Two types of cell walls

Differentiation based on amount of PG and other componentsG ram-positive vs. G ram-negative

1) G ram-positive (Gm+) cell walls

a. Thick layers of PGb. Presence of

teichoic acids (A lcohol/Glycerol plus phosphate)-May regulate movement of cations-Provide antigenic variation

2) G ram-negative (Gm ) cell walls

a. Thin layer of PG + outer membrane

b. No teichoic acids

c. Outer membrane: made up ofL ipopolysaccharides (LPS)LPS = O polysaccharide + L ipid A

G ram-negative (Gm ) cell walls

L ipid A is an endotoxinO polysaccharide antigen, e.g., E . coli O157:H7

Thick peptidoglycanTeichoic acids

G ram-positiveCell Wall

Figure 4.13b c

Thin peptidoglycanOuter membrane

G ram-negativeCell Wall

How penicillin affects bacter ial

E ffect on G ram-positive vs. G ram- negative

Atypical Cell Walls

a. Acid Fast cell wallWaxy lipid (Mycolic acid) bound to peptidoglycan in acid-fast cell walls.

MycobacteriumNocardia

Atypical Cell Walls

b. MycoplasmasLack cell wallsSterols in plasma membrane

c. A rchaeaWalls of pseudomurein (lack N A M and D-amino acids)

Figure 4.14a

C . The Plasma Membrane or Cytoplasmic membrane

C . The Plasma Membrane

1. Phospholipid bilayer and Proteins

2. F luid Mosaic Model

C . The Plasma Membrane

3. Functions of plasma membraneSelective permeability allows passage of some moleculesEnzymes for ATP productionPhotosynthetic pigments Damage to the membrane by alcohols, quaternary ammonium (detergents), and polymyxin antibiotics causes leakage of cell contents

4. Movement Across Plasma Membrane

1. Passive T ransporta. Simple diffusion: C O2, O2b. Facilitated diffusion: G lycerolc. Osmosis: water

2. Active transporta. Active T ransportb. G roup T ranslocation

Figure 4.17a

Passive T ransporta. Simple diffusion:

Movement of a solute from an area of high concentration to an area of low concentration

Figure 4.17b-c

Passive T ransportb. Facilitated diffusion: Solute combines

with a transporter protein in the membrane

Figure 4.18a

Passive T ransportc. Osmosis:

The movement of water across a selectively permeable membrane from an area of high water to an area of lower water concentration

Figure 4.18c e

Osmolarity of the solution outside bacterial cells and its significance

Active transport

a. Active T ransportUsing either PM F or A TP

b. G roup T ranslocation

Endocytosis and Exocytosis????

G roup T ranslocation

D . F lagella

1. Function

2. Made up of 3 partsa. filament: F lagellinb. A ttached to a

protein hook

c. anchored to the wall and membrane through basal body

Flagella proteins are H antigens (e.g., E . coli O157:H7)

a. Monotrichous b. amphitr ichousc. Lophotr ichous d. per itr ichous

3. F lagellar ar rangement on a bacter ial cell surface

4. Run and tumble

5. chemotaxis and phototaxis

6. H elicobacter pylorii

7. other types of bacter ial motility

1. Who has them?

2. F imbriae

3. Pili -Facilitate transfer of DN A from one cell

to another-G liding motility-Twitching motility

E . F imbriae and Pili

No Cytoskeleton

No membrane bound organelles

F . Cytoplasm

1. bacter ial chromosome character isticsNo nuclear membraneNo H istonesCircular DN AHaploid

2. size and packaging: Supercoiling

G . Nucleoid

1. What are they?

2. Advantages to bacter ia

3. Transfer

H . Plasmids

I . Ribosomes

1. Function2. Composition/structure

3. Antibiotic effect on r ibosomes

J. Inclusions/storage granules

1. M etachromatic/volutin/polyphosphate granulesdiagnostic use: Corynebacterium diphtheriae

2. Polysaccharide G ranules

3. L ipid Inclusions PH B:poly- -hydroxy butyric acid

4. Sulfur G ranules

K . Endospores

1. Who produces?

2. N O T reproductive! Resting structures

3. When are they produced?

4. How long can they survive?

Formation of Endospores by Sporulation

Figure 4.21a

5. Structure of a free endopsore (DPA)

6. G ermination

7. Importance of endospores medically and infood processing

8. Destroying endospores

a. John Tyndall and tyndallizationb. autoclave and pressure cooker