Bacterial Structure 2&3. 3

Question 1

Cell wall of bacteria

Answer 1

a structure exterior to the cell membrane that provides rigidity and stability to the bacterial cell

• Cell walls consist of Peptidoglycan
• G- or G+

Question 2

Gram (+) composed of?

Answer 2

peptidoglycan and teichoic acid (purple)

Question 3

Gram (-) composed of?

Answer 3

peptidoglycan and an outer membrane (red)

Question 4

Peptidoglycan consists of?

Answer 4

strands of alternating repeats of N-acetyl glucose-like sugars
•N-acetylglucosamine (NAG)
•N-acetylmuramic acid (NAM)

Question 5

N-acetylmuramic acid (NAM) is cross linked between?

Answer 5

strands by short peptides

Question 6

Our body prodcuces what enzyme that destroys peptidoglycan? This leads to?

Answer 6

Lysozyme

*leads to lysis of bacteria cell

Question 7

NAG and NAM are linked by?

Answer 7

a beta 1-4 glycosidic covalent bond -this is the lysozyme sensitive region

Question 8

What four AA make the tetrapeptide bound to NAM in peptidoglycan?

Answer 8

• L-alanine
• D-alanine
• D-glutamic acid
• either lysine or diaminopimelic acid

Question 9

Tetrapeptide cross-links are formed by? Provide the cell wall with what physical traits?

Answer 9

Tetrapeptides interaction on separate strands of peptidoglycan; provide the cell wall of prokaryotes with extreme strength and rigidity

Question 10

define peptidoglycan interbridge

Answer 10

Tetrapeptide cross-links between layers of peptidoglycan

Question 11

In G+, peptidoglycan interbridge is often?

Answer 11

a pentaglycine

Question 12

In G-, peptidoglycan interbridge is often?

Answer 12

a direct link between one tetrapeptide that often contains a diaminopimelic acid (DAP) and the other tetrapeptide

Question 13

Penicillin preevnts?

Answer 13

prevents crosslinkage of cell wall peptidoglycan (weakening the cell wall) aka transpeptidation

Question 14

A hydrophobic alcohol called _______ facilitates transport of new glycan units across cytoplasmic membrane for formation of peptidoglycan

Answer 14

bactoprenol

Question 15

bactoprenol and vancomycin inhibit?

Answer 15

the bactoprenal dependent process of transporting glycan units across cytoplasm

Question 16

How thick is G+ Peptidoglycan layer? composed of?

Answer 16

• about 200-800 Angstroms (1 Angstrom = 10-8 centimeter) thick
• composed of many layers of peptidoglycan

Question 17

Teichoic acids are associated with

Answer 17

peptidoglycan of Gram (+) bacteria

Question 18

Teichoic acids function in? Bind?

Answer 18

adherence; binds Mg++ ions for the cell

Question 19

describe the 3 types of Teichoic acid

Answer 19

1) one type -contains
glycerols (3-carbon sugar alcohol)
repeated again and again and linked
by phosphates with D-ala or Dglucose
2) second type -contains ribitols (a 5-
carbon sugar alcohol) repeated
again and again linked by
phosphates with D-ala or D-glucose
3) third type - lipoteichoic – contains
glycerols or ribitols with a terminal
fatty acid that is integrated into the
cytoplasmic membrane

Question 20

Mycobacteria is? contain? Peptidoglycan is bound with?

Answer 20

an acid fast bacteria

• contain mycolic acid layer that is exterior to peptidoglycan (mycobacteria outer membrane)
• Peptidoglycan is bound with Arabinogalactan

Question 21

In addition to peptidoglycan, the outer membrane of G- contain?

Answer 21

• lipopolysaccharide (LPS),
• proteins
• Lipoproteins
• Phospholipids
• type I, II, III, IV, and V secretion devices

Question 22

Periplasm

Answer 22

space between membranes, contains other proteins, mainly for transport

Question 23

Porin proteins are integrated with?

*Provides channel for?

Answer 23

both leaflets of the outer
membranes of G-
*provide a channel to shuttle small nutrients from the outside to the inside

Question 24

G- bacteria have an outer membrane that can be? Therefore it is referred to as?

Answer 24

physiologically toxic to the host during an infection

*referred to as endotoxin

Question 25

Shwartzman reaction follows the release of large amounts of?

Answer 25

endotoxin into the bloodstream

Question 26

Neisseria bacteria shed large amounts of a related molecule to endotoxin called lipooligosaccharide (LOS). This results in?

Answer 26

resulting in fever and severe | symptoms

Question 27

penicillin is much less effective against Gram (-) or Gram (+) peptidoglycan? Why?

Answer 27

Gram (-) peptidoglycan | *Peptidoglycan of Gram (-) bacteria is thicker! But no more than 1 to 2 layers

Question 28

Exterior portion of Lipopolysaccharides of G- are composed of

Answer 28

"O" specific polysaccharide

Question 29

"O" specific polysaccharide are often called? | Has a what motif?

Answer 29

* often called repeat polysaccharide (up to 40x) | * has various six carbon sugar motifs that are repeated again and again

Question 30

Middle portions of Lipopolysaccharides of G- are composed of ?

Answer 30

``` core polysaccharide-that contains •ketodeoxyoctonate (KDO), •heptoses, •glucose, •galactose, •NAG (N-acetylglucosamine) ```

Question 31

•Inner portions of Lipopolysaccharides of G- are composed of?

Answer 31

***•Lipid A** •diphospho-(NAG)2 •fatty acids are attached •Lipooligosaccharide (LOS) of Neisseria species lacks the O-antigen portion of LPS, has a core polysaccharide plus lipid A, and is readily shed from the Neisseria bacteria

Question 32

example of endotoxin

Answer 32

G- bacteria'souter membrane- can be physiologically toxic to the host during an infection

Question 33

Protoplasts are?

Answer 33

are wallless bacteria that can survive in isotonic solutions but not hypotonic solutions •In hypotonic solutions protoplasts lyse

Question 34

How is it possible for a protoplast to survive without a cell wall? How do the mycoplasma species do it?

Answer 34

1) produce unusually tough membranes 2) live in osmotically protected habitats, such as the animal body =Mycoplasma species** 3) evolve to survive in an animal body without cell walls due to selective pressure of penicillin (L-forms). They are penicillin resistant

Question 35

Gram stain reaction gives us what information?

Answer 35

If the bacteria is G+ (purple) or G- (red)

Question 36

What is responsible for differences in the Gram stain reaction?

Answer 36

The structural differences between the cell walls of gram-positive and gram-negative Bacteria

Question 37

Alcohol can readily penetrate the lipid rich outer membrane of? Alcohol then extracts?

Answer 37

G- bacteria | *alcohol extracts the insoluble crystal violet-iodine complex from the cell