Prok Biology Exam 1

how much peptidoglycan is found in the cell wall?

G+ = lots of peptidoglycan

G- = thin layer of peptidoglycan

what do archea use instead of peptidoglycan?

pseudomurein, s-layers, sugars

what is the periplasm?

space between cell wall and plasma membrane containing lipoproteins that anchor outer membrane to inner membrane

What are the functions of the LPS layer?

1. negativley charged permeability layer

2. important for virulence, adhesion, and resistance of phagocytosis

3. antigenic variation to avoid detection

4. biofilm formation for pathenogenisis

What are the subunits that make up the peptidoglycan layer?

NAG and NAM subunits

How are NAG and NAM subunits cross-linked?

G+ : cross-linked using peptide interbridge

G- : not adjacently crosslinked

What part of the LPS layer causes TSA?

Lipid A is the endotoxin

What are the characteristics of a G+ cell wall?

1. HAS NO OUTER MEMBRANE

2. Massive peptidoglycan layer, which is porous

3. Leaky periplasm

4. Periplasmic enzymes are linked to membrane or secreted (exoenzymes)

5. Enzymes anchored with lipotechoic acid

What are the characteristics of the archeal cell wall?

1. DOES NOT MAKE PEPTIDOGLYCAN

2. Cell walls are environmentally specific

What are some components found in the cytoplasm?

1. Cytoskeleton

2. Storage granules

3. Nucleoid

What is the nucleoid?

A loose association of the genome that is bound with histones or histone like proteins

FtsZ purpose?

Ring for cell division, found in the center of the cell

FtsA

Actin homolog for cell division, binds FtsZ

MreB/Mbl

Maintain rod structure/shape

CreS

Provides curved shape in specific bacteria

What are the 3 different forms of motility?

1. Swimming motility

2. Gliding motility

3. Twitching motility

How does swimming motility happen?

Flagellum rotation is switched from CCW to CW to alternate between runs and tumbles through a protein cascade powered by proton gradient

What kind of secretion system is flagella built by?

Type III secretion system

What are the characteristics of archeal flagella?

1. The flagella filament is NOT hollow

2. The flagella is powered by ATP hydrolysis

How does twitching motility work?

Type IV pili push microbe across solid surface, which is powered by ATP

How does gliding motility work?

2 modes of movement:

1. Adventurous motility - single, exploratory

2. Social motility - wolfpack

Can involve motors, jets of polysaccharide, and type IV pilli

What are the 3 kinds of transport?

1. Passive

2. Facilitated

3. Active

How does passive transport work?

1. Follows concentration gradient

2. Molecules must be SMALL AND UNCHARGED

3. permeates membrane

How does facilitated diffusion work?

1. Follows concentration gradient

2. Uses compound specific permeases

3. DOES NOT REQUIRE ENERGY

How does active transport work?

Uses 2 kinda of transporters:

1. ABC (ATP) Family transporters w/ substrate binding proteins

2. Ion : solute transporters that use the proton motive force

How do Ton-B dependent transporters work?

1. TonB interacts with TonB box in transporter to open transporter

2. Proton motive force used provide energy for transport (can also use ATP)

3. Siderophores are transported in

4. ONLY IN GRAM NEGATIVES !!!

What is group transport/the phosphotransferase system?

1. Both use phosphorylation to modify incoming sugars

2. Have compound specific proteins (EIIB,C..)

3. PTS uses PEP as phosphate donor

What causes minicelling?

FtsZ overexpression

Do low copy plasmids segregate?

YES

Do high copy plasmids segregate?

NO

What is bactoprenol?

Carries peptidoglycan precursors across membrane for them to be integrated into membrane by autolysins

When is peptidoglycan integrated into cell wall?

In cocci: after division plane is formed

In bacilli: into sidewalk or poles before division plane is formed

What keeps FtsZ from the poles of the cells?

Oscillation of MinD

What kind of bacteria is capable of sporulating?

GRAM POSITIVE

How does a spore form?

1. Regulatory Cascade initiates sporulation

2. Endospore forms

3. Mother cell genome disintegrates

4. Spore emerges with genome contained inside

What is the exosporium?

Found in bacillus, it is a membrane that encloses the spore

What does the spore coat do/contain?

1. CwIJ to initiate termination

2. Provides environmental resistance

3. SpolVA links to cortex

What is the cortex made of?

Cross-linked peptidoglycan

What is the core made of?

Dipicolinic acid that is unique to spores

DNA bound to DNA binding proteins

Protein regulators of stalked cell reproduction?

DnaA: replication

GcrA: replication

CtrA: flagella formation and gene expression for swarmer cell

what do El and Hpr regulate?

sugar uptake

what does MinC prevent?

Polymerization of FtsZ

What does MinC bind to to activate?

MinD-ATP

What does the MinE ring look to bind?

MinD-ATP

What effect does the MinE ring have on MinD-ATP?

it forces ATP hydrolysis converting MinD-ATP to MinD-ADP

which sugar specific proteins are preferentially phosphorylated?

glucose-specific sugar proteins

Describe the sporulation phosphoregulatory system

1. nutrient starvation induces phosphorylation of KinA/KinB

2. KinA-P/KinB-P phosphorylate Spo0F

3. Spo0F-P phosphorylates Spo0B

4. Spo0B-P phosphorylates Spo0A

5. Spo0A-P activates the sigma cascade that induces sporulation

how do two component systems respond to a signal?

through the transfer of a phosphate group

what is the signal sensor?

the histadine/sensor kinase which is phosphorylated at the histadine

what is the signal output?

the DNA-binding response regulator, phosphorylated at aspartic acid