Cell wall stuff

Question 1

What is cell wall responsible for?

Answer 1

Shape of cell

Question 1

What are the major functions of the cell wall?

Answer 1

Prevents bacterial cells from rupturing when pressure of water inside the cell is greater than the outside

Maintains shape and is anchor point for flagella

Contributes to the ability of some species to cause disease

Site of action for some antibiotics

Question 2

What is cell wall composed of?

Answer 2

Macromolecular network called peptidoglycan

Question 3

What does peptidoglycan consist of?

Answer 3

A repeating disaccharide connected by polypeptides which forms a lattice that surrounds and protects the cell

Question 4

What is the disaccharide portion of peptidoglycan made of?

Answer 4

Monosaccharides NAG and NAM
These are related to glucose

Question 5

Gram Positive bacteria

Answer 5

Have many layers of peptidoglycan
Thick rigid structure
Contain techoic acids
Polyssacharides and techoic acids provide antigenic specificity

Question 6

Techoic acids info

Answer 6

Lipotechoic acids links cell wall to plasma membrane
Wall techoic acid links the peptidoglycan
Carries negative charge because of phosphate
Regulates movement of cations

Question 7

Gram Negative bacteria have how many layers of peptidoglycan?

Answer 7

One or very few
Contains an outer membrane as well

Question 8

Gram negative cell walls do not contain teichoic acids because they’re more susceptible to mechanical breakage. True or false?

Answer 8

True

Question 9

What is periplasm? (Gram Negative)

Answer 9

Gel- like fluid in periplasmic space

Question 10

What do gram negative bacteria protect against?

Answer 10

Phagocytes
Complement
Antibiotics

Question 11

What are gram negative bacteria made out of?

Answer 11

Lipopolysaccharide (LPS)

Question 12

What does Lipopolysaccharide conain?

Answer 12

O polysaccharide : functions as antigen
Core polysaccharide: Unusual sugars
Lipid A :Endotoxin embedded in top layer

Question 13

Gram positive gram stains

Answer 13

Alcohol dehydrates peptidoglycan
CV1 crystals do not leave

Question 14

Gram negative gram stains

Answer 14

Alcohol dissolves outer membrane and leaves holes in peptidoglycan
CV1 washes out; cells are colorless
Safranin added to stain cells

Question 15

Atypical cell wall examples

Answer 15

Archaea
Mycoplasma

Question 16

Mycoplasma

Answer 16

Smallest known bacteria that can grow and reproduce outside living host cells
Plasma membranes contain lipids called sterols which protects them from lysis

Question 17

Archaea

Answer 17

Lack cell walls or have unusual walls made of polysaccharides and proteins but has peptidoglycan
Contain pseudomurein

Question 18

Pseudomurein (archaea)

Answer 18

Contain N-acetyltalosaminuronic instead of NAM
Lacks d amino acid
Cannot be gram stained but appear gram negative

Question 19

What is the acid fast stain used to identify?

Answer 19

Bacteria of genus Mycobaterium
Pathogenic species of Nocardia

These bacteria contain high concentrations of hydrophobic waxy lipid which prevents uptake of dyes

Question 20

Acid fast bacteria can be stained with?

Answer 20

Carbolfuchsin

Question 21

What does the carbofuchsin do?

Answer 21

Penetrates cell wall and binds to cytoplasm