Exam 4 - practice questions Flashcards
Amino acids required nitrogen. How is this nitrogen incorporated into each amino acid?
Nitrogen is assimilated into a-ketoglutarate making glutamine. It is then transferred from glutamine to other precursors.
Which enzymes requires a molybdenum-iron cofactor to fix atomspheric nitrogen?
Dinitrogenase
All bacteria fix nitrogen but only a few bacteria assimilate nitrogen.
FALSE
Amino acids required nitrogen. How is this nitrogen incorporated into each amino acid?
Nitrogen is assimilated into a-ketoglutarate making glutamine. It is then transferred from glutamine to other precursors
Nucleotides are synthesized by one of two pathways, either [1] or [2] pathway.
de novo , salvage
What are the components of lipopolysaccharide?
Lipid A
Core
O antigen
Lipopolysaccharide contains a unique sugar found in no other molecule. It is what?
Heptose
2-keto-3-deoxyoctulosonic acid (KDO) is part of what molecule?
lipopolysaccharide
What is the structure of peptidoglycan monomers?
b-1,4-N-acteylglucosamine- N-acteylmuramic acid + pentapeptide crosslinker
Peptidoglycan synthesis occurs where within the cell?
cytoplasm plasma membrane and cell wall
What is the major means of cell division for prokaryotes?
binary fission
Which of the following are means of cell division for prokaryotes?
budding binary fission multiple fission sporulation
Which of the following is the major component of the contractile ring in bacterial cell division?
ftsz
mechanisms of penicillins?
inhibit cross-linking transpeptidasemimics D-ala-D-ala moiety forms covalent bonds with serine residues at active site of enzyme
fatty acid anabolism is achieved by ______
repeated additions of malonyl co-A until the 16 carbons are achieved
what are the two components of the nitrogenease complex
Component-I (dinitrogenase) is a molybdenum-iron
protein containing two subunits.
Component-II (dinitrogenase reductase) is an ironsulfur
protein that transfers electrons to dinitrogenase.
what is the Ammonia switch off?
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
pyrimidine biosynthesis
ring is formed then added to pentose sugar
purine biosynthesis
pentose sugar is the foundation then the 2 rings are built on top
what are the measurements of growth?
turbidity (light scattering)
Total cell count
viable cell
count dry weight and protein
depletion of nutrients
Growth basics
- entrance of nutrients into the cell
- conversion of nutrients into energy and vital cell constituents
- replication of chromosomes
- increase in size and mass of cell
- division into daughter cells (each with copy of genome)
components of a growth curve
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
The two steps of cell division
DNA replication
cytokenesis
stages of cell separation
- centripetal penetration of wall under equatorial band
- thins cross wall penetrates cell
- cross wall thickens > wall band separates
- penetration resumes as wall band nears the daughter cell equator
- final separation of daughter cells
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
FtsA
Catalyzes the formation of the FtsZ ring
ZipA
Anchors the FtsZ septal ring to the Inner Membrane every few protein subunits
FtsI (PBPi3)
Links the Inner Membrane to the Peptidoglycan
Site of septum formation is determined by ?
Nucleoid occlusion system
Min System
What are the Min System proteins
MinC/D complex
MinE
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
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
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
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
Nucleoid Occlusion mutant
No form of ring at either pole but do get it in the middle even on top of the chromosome
which enzyme breaks atomospheric nitrogen?
dinitrogenase
Breaks the triple bond using molybdenum-iron protein
what is the cofactor of dinitrogenase
molybdenum-Iron
what is the cofactor of dinitrogenase reducatase
iron-sulfur
which enzyme transfers elecrons in the fixation of atm. nitrogen
dinitrogenase reducatase
how is nitrogenase regulated?
ADP-ribosylation of the iron-protein using DRAT to be the deactivator
when NH3 is in [high]
how many carbons added when making fatty acids
2
which nucleotide is built onto a ribose
purine
which nucleotide family is made then added onto the ribose?
pyrimidine
“make the pyramids then move them”
amino acids of alpha ketoglutarate
glutamate
Proline
Arginine
Glutamine
amino acids of pyruvate
alanine
leucine
valine
amino acids of oxaloacetate
aspartate
asparagine
threonine
methionine
amino acids of 3-phosphoglycerate
serine
cystine
glycine
amino acids of PEP
tyrosine
tryptophan
phenylalanine
true or false
Nucleotide biosysnthesis is highly complex and, energy intensive and regulated process
true
where does histidine come from
Erythrose-5-P
erythrose + PEP=?
aromatic family
where do the 13 metabolites come from?
complete metabolism of glucose
what can the 13 metabolites make?
lipids
nucleic acids
amino acids
vitamins and cofactors
stage of growth where rate of growth and rate of death are equal
stationary
how is the lag phase described?
low cell #
dilution of extracellular enzymes
synthesis of new genes
where are peptidoglycan monomers assembled prior to integration into the nascent chain?
cytoplasm and adjacent to cell membrane
what is the outer membrane of gram (-)
LPS
what is the outer membrane of gram (+)
peptidoglycan
what form of peptidoglycan is sent to the outer membrane?
the assembled structure entirely
order of LPS biosynthesis
Lipid A KDO Heptose Core O-Antigen
is MDO part of LPS?
no
what is peptidoglycan
heteropolymer of NAG and NAM wwith pentapeptide linkers
significance of the wall band
location of cell division
which protein anchors the septal ring to cell membrane
zipA
which of the cytoplasmic proteins polymerize to form the physical septal ring
ftsZ
which expression allows the calculation of growth of a bacterial colony during exponential phase
2^n
where is bacterial DNA
nucleoid
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
the alteration to which part of the LPS will change the immunospecificity of the bacteria?
O-Antigen
in gram negative bacteria which part houses the peptidoglycan
in between the two periplasmic spaces
