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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
FtsZ
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
26
FtsA
Catalyzes the formation of the FtsZ ring
27
ZipA
Anchors the FtsZ septal ring to the Inner Membrane every few protein subunits
28
FtsI (PBPi3)
Links the Inner Membrane to the Peptidoglycan
29
Site of septum formation is determined by ?
Nucleoid occlusion system Min System
30
What are the Min System proteins
MinC/D complex MinE
31
Function of Min System
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
minE mutant
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
Min Proteins and their function
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
Function of Nucleoid Occlusion
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
Nucleoid Occlusion mutant
No form of ring at either pole but do get it in the middle even on top of the chromosome
36
which enzyme breaks atomospheric nitrogen?
dinitrogenase Breaks the triple bond using molybdenum-iron protein
37
what is the cofactor of dinitrogenase
molybdenum-Iron
38
what is the cofactor of dinitrogenase reducatase
iron-sulfur
39
which enzyme transfers elecrons in the fixation of atm. nitrogen
dinitrogenase reducatase
40
how is nitrogenase regulated?
ADP-ribosylation of the iron-protein using DRAT to be the deactivator when NH3 is in [high]
41
how many carbons added when making fatty acids
2
42
which nucleotide is built onto a ribose
purine
43
which nucleotide family is made then added onto the ribose?
pyrimidine "make the pyramids then move them"
44
amino acids of alpha ketoglutarate
glutamate Proline Arginine Glutamine
45
amino acids of pyruvate
alanine leucine valine
46
amino acids of oxaloacetate
aspartate asparagine threonine methionine
47
amino acids of 3-phosphoglycerate
serine cystine glycine
48
amino acids of PEP
tyrosine tryptophan phenylalanine
49
true or false | Nucleotide biosysnthesis is highly complex and, energy intensive and regulated process
true
50
where does histidine come from
Erythrose-5-P
51
erythrose + PEP=?
aromatic family
52
where do the 13 metabolites come from?
complete metabolism of glucose
53
what can the 13 metabolites make?
lipids nucleic acids amino acids vitamins and cofactors
54
stage of growth where rate of growth and rate of death are equal
stationary
55
how is the lag phase described?
low cell # dilution of extracellular enzymes synthesis of new genes
56
where are peptidoglycan monomers assembled prior to integration into the nascent chain?
cytoplasm and adjacent to cell membrane
57
what is the outer membrane of gram (-)
LPS
58
what is the outer membrane of gram (+)
peptidoglycan
59
what form of peptidoglycan is sent to the outer membrane?
the assembled structure entirely
60
order of LPS biosynthesis
``` Lipid A KDO Heptose Core O-Antigen ```
61
is MDO part of LPS?
no
62
what is peptidoglycan
heteropolymer of NAG and NAM wwith pentapeptide linkers
63
significance of the wall band
location of cell division
64
which protein anchors the septal ring to cell membrane
zipA
65
which of the cytoplasmic proteins polymerize to form the physical septal ring
ftsZ
66
which expression allows the calculation of growth of a bacterial colony during exponential phase
2^n
67
where is bacterial DNA
nucleoid
68
how do beta lactam antibiotics interact with gram + cell walls
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
the alteration to which part of the LPS will change the immunospecificity of the bacteria?
O-Antigen
70
in gram negative bacteria which part houses the peptidoglycan
in between the two periplasmic spaces

microbial physiology (1 decks)

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