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microbial physiology > Exam 4 - practice questions > Flashcards

Exam 4 - practice questions Flashcards

1
Q

Amino acids required nitrogen. How is this nitrogen incorporated into each amino acid?

A

Nitrogen is assimilated into a-ketoglutarate making glutamine. It is then transferred from glutamine to other precursors.

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2
Q

Which enzymes requires a molybdenum-iron cofactor to fix atomspheric nitrogen?

A

Dinitrogenase

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3
Q

All bacteria fix nitrogen but only a few bacteria assimilate nitrogen.

A

FALSE

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4
Q

Amino acids required nitrogen. How is this nitrogen incorporated into each amino acid?

A

Nitrogen is assimilated into a-ketoglutarate making glutamine. It is then transferred from glutamine to other precursors

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5
Q

Nucleotides are synthesized by one of two pathways, either [1] or [2] pathway.

A

de novo , salvage

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6
Q

What are the components of lipopolysaccharide?

A

Lipid A
Core
O antigen

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7
Q

Lipopolysaccharide contains a unique sugar found in no other molecule. It is what?

A

Heptose

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8
Q

2-keto-3-deoxyoctulosonic acid (KDO) is part of what molecule?

A

lipopolysaccharide

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9
Q

What is the structure of peptidoglycan monomers?

A

b-1,4-N-acteylglucosamine- N-acteylmuramic acid + pentapeptide crosslinker

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10
Q

Peptidoglycan synthesis occurs where within the cell?

A

cytoplasm plasma membrane and cell wall

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11
Q

What is the major means of cell division for prokaryotes?

A

binary fission

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12
Q

Which of the following are means of cell division for prokaryotes?

A

budding binary fission multiple fission sporulation

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13
Q

Which of the following is the major component of the contractile ring in bacterial cell division?

A

ftsz

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14
Q

mechanisms of penicillins?

A

inhibit cross-linking transpeptidasemimics D-ala-D-ala moiety forms covalent bonds with serine residues at active site of enzyme

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15
Q

fatty acid anabolism is achieved by ______

A

repeated additions of malonyl co-A until the 16 carbons are achieved

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16
Q

what are the two components of the nitrogenease complex

A

Component-I (dinitrogenase) is a molybdenum-iron
protein containing two subunits.

Component-II (dinitrogenase reductase) is an ironsulfur
protein that transfers electrons to dinitrogenase.

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17
Q

what is the Ammonia switch off?

A

a rapid and reversible inhibition of nitrogenase, result of a
covalent modification of the Fe protein (dinitrogenase
reductase) in response to the addition of NH3

inhibition of nitrogenase ( N2 > NH3)– ADP-ribosylation of dinitrogenease reductase > inactivation DRAT > ribosylates dintrogenase reductase to deactivate the protein

DRAG > reverses ribosylation of dinitrogenase reductase
to activate the protein

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18
Q

pyrimidine biosynthesis

A

ring is formed then added to pentose sugar

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19
Q

purine biosynthesis

A

pentose sugar is the foundation then the 2 rings are built on top

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20
Q

what are the measurements of growth?

A

turbidity (light scattering)

Total cell count

viable cell

count dry weight and protein

depletion of nutrients

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21
Q

Growth basics

A
  1. entrance of nutrients into the cell
  2. conversion of nutrients into energy and vital cell constituents
  3. replication of chromosomes
  4. increase in size and mass of cell
  5. division into daughter cells (each with copy of genome)
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22
Q

components of a growth curve

A

lag- adaptation phase exponential

growth- cell mas increase

stationary- balance between available nutrients and inhibitors of growth ( i.e. toxic metabolites, available nutrients)

death - depletion of cellular energy and autolysis

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23
Q

The two steps of cell division

A

DNA replication

cytokenesis

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24
Q

stages of cell separation

A
  1. centripetal penetration of wall under equatorial band
  2. thins cross wall penetrates cell
  3. cross wall thickens > wall band separates
  4. penetration resumes as wall band nears the daughter cell equator
  5. final separation of daughter cells
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25
Q

FtsZ

A

Cytoplasmic
Forms ring in cell center
Made before cell division
Forms the Septal Ring
Under PM, anchors to PM and Peptidoglycan
Forms under the entire cell and then polymerizes
As this ring contracts the rest of the cell will too

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26
Q

FtsA

A

Catalyzes the formation of the FtsZ ring

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27
Q

ZipA

A

Anchors the FtsZ septal ring to the Inner Membrane every few protein subunits

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28
Q

FtsI (PBPi3)

A

Links the Inner Membrane to the Peptidoglycan

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29
Q

Site of septum formation is determined by ?

A

Nucleoid occlusion system

Min System

30
Q

What are the Min System proteins

A

MinC/D complex

MinE

31
Q

Function of Min System

A

Set up to stop the formation of the septal ring at poles of the cell
Back and forth motion of E trying to clear C/D out from each end of the cell as the ring forms in the middle

32
Q

minE mutant

A

Do not get the ring splitting the chromosome in the middle but get formation of the rings on both poles and could give unequal partitions of the chromosomes between the 2 daughter cells

Get cell division but doesn’t work right

33
Q

Min Proteins and their function

A

minC- blocks formation of FtsZ, forms complex with minDminD- forms complex with minC minE- regulates minCD complex, relives minCD inhibition of FtsZ ring formation

34
Q

Function of Nucleoid Occlusion

A

FtsZ ring does not form where a nucleoid is
Relies on SimA
DNA activated FtsZ polymerization antagonist
Binds DNA in the nucleoid and stops the polymerization of FtsZ proteins to stop the ring formation

35
Q

Nucleoid Occlusion mutant

A

No form of ring at either pole but do get it in the middle even on top of the chromosome

36
Q

which enzyme breaks atomospheric nitrogen?

A

dinitrogenase

Breaks the triple bond using molybdenum-iron protein

37
Q

what is the cofactor of dinitrogenase

A

molybdenum-Iron

38
Q

what is the cofactor of dinitrogenase reducatase

A

iron-sulfur

39
Q

which enzyme transfers elecrons in the fixation of atm. nitrogen

A

dinitrogenase reducatase

40
Q

how is nitrogenase regulated?

A

ADP-ribosylation of the iron-protein using DRAT to be the deactivator

when NH3 is in [high]

41
Q

how many carbons added when making fatty acids

A

2

42
Q

which nucleotide is built onto a ribose

A

purine

43
Q

which nucleotide family is made then added onto the ribose?

A

pyrimidine

“make the pyramids then move them”

44
Q

amino acids of alpha ketoglutarate

A

glutamate

Proline

Arginine

Glutamine

45
Q

amino acids of pyruvate

A

alanine

leucine

valine

46
Q

amino acids of oxaloacetate

A

aspartate

asparagine

threonine

methionine

47
Q

amino acids of 3-phosphoglycerate

A

serine

cystine

glycine

48
Q

amino acids of PEP

A

tyrosine

tryptophan

phenylalanine

49
Q

true or false

Nucleotide biosysnthesis is highly complex and, energy intensive and regulated process

A

true

50
Q

where does histidine come from

A

Erythrose-5-P

51
Q

erythrose + PEP=?

A

aromatic family

52
Q

where do the 13 metabolites come from?

A

complete metabolism of glucose

53
Q

what can the 13 metabolites make?

A

lipids
nucleic acids
amino acids
vitamins and cofactors

54
Q

stage of growth where rate of growth and rate of death are equal

A

stationary

55
Q

how is the lag phase described?

A

low cell #

dilution of extracellular enzymes

synthesis of new genes

56
Q

where are peptidoglycan monomers assembled prior to integration into the nascent chain?

A

cytoplasm and adjacent to cell membrane

57
Q

what is the outer membrane of gram (-)

A

LPS

58
Q

what is the outer membrane of gram (+)

A

peptidoglycan

59
Q

what form of peptidoglycan is sent to the outer membrane?

A

the assembled structure entirely

60
Q

order of LPS biosynthesis

A 
Lipid A 
KDO
Heptose 
Core
O-Antigen
61
Q

is MDO part of LPS?

A

no

62
Q

what is peptidoglycan

A

heteropolymer of NAG and NAM wwith pentapeptide linkers

63
Q

significance of the wall band

A

location of cell division

64
Q

which protein anchors the septal ring to cell membrane

A

zipA

65
Q

which of the cytoplasmic proteins polymerize to form the physical septal ring

A

ftsZ

66
Q

which expression allows the calculation of growth of a bacterial colony during exponential phase

A

2^n

67
Q

where is bacterial DNA

A

nucleoid

68
Q

how do beta lactam antibiotics interact with gram + cell walls

A

penicillin binding proteins

inhibits the cross-linking transpeptidase by binding to the active site if the transpeptidase because it mimics the D-Ala-D-Ala and forms covalent bond with serine in the AS

irreversibly inhibited

69
Q

the alteration to which part of the LPS will change the immunospecificity of the bacteria?

A

O-Antigen

70
Q

in gram negative bacteria which part houses the peptidoglycan

A

in between the two periplasmic spaces

microbial physiology (1 decks)

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