Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

BIOL-M 250 > Exam 3 > Flashcards

Exam 3 Flashcards

1
Q

Aerobic Respiration

A

reduces oxygen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Anaerobic respiration

A

reduces anything but oxygen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Geobacter Metallireducens

A
  • Consumes sugars and oil-based pollutants
  • Respires metals including Fe, U & Tc
  • Bioremediation
  • Respires insoluble molecules
  • Pili conduct electrons outside of cell (nanowires)
  • Biofuel Cells
  • Nanowires: allows for respiration of insoluble molecules, conductive pilus anchored in the plasma membrane and part of the ETC
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Lithotrophy

A 
Eat inorganics
Breathe anything (electrons)

Obtaining electrons by consuming inorganic molecules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Organotrophy

A 
Eat organics
Breathe anything (electrons)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q 
Hydrogen Oxidation
(How is ATP, NADH & PMF generated, how do electrons move through tower, example of bacteria/system)
A

ATP: F1F0 ATPase
NADH: Hydrogenase => direct reduction of H2 Gas
PMF: ETC, reduction of O2 => H2O
Tower: Move down H2 => O2
Ex: Subsurface Lithotrophic Microbial Ecosystem (SLiME), Chemolithoautotrophs, require nothing but gas to grow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q 
Sulfur Oxidation
(How is ATP, NADH & PMF generated, how do electrons move through tower, example of bacteria/system)
A 
ATP: F1F0 ATPase
NADH: Reverse ETC
PMF: ETC
Tower: Up S/H2S => NAD+/NADH
Ex: Hydrothermal Vents
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q 
Iron Oxidation
(How is ATP, NADH & PMF generated, how do electrons move through tower, example of bacteria/system)
A 
ATP: F1F0 ATPase
NADH: Reverse ETC
PMF: ETC
Tower: Up Fe3+/Fe2+ => NAD+/NADH
Ex: Lepthothrix bacteria- grow in biofilm in saturated soils with high levels of iron
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Adv/ Disadv of Iron Oxidation

A

Adv: Iron so low in energy that few other bacteria bother to compete, Iron is one of the most abundant resources on earth

Disadv: Takes A LOT of electrons for a little energy, growth could be fantastically slow, doubling times of months or more

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

3 kinds of phototrophy & what kinds of energy do they produce

A

Cyclic: PMF (ATP)
Acyclic: NADH, PMF (ATP)
Bacteriorhodipsin: PMF (ATP); does not use ETC

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is cyclic phototrophy electron donor?

A

Chlorophyll

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is cyclic phototrophy electron acceptor?

A

Chlorophyll

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the role of chlorophyll

A

cofactor that absorbs light

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the purpose of the reaction centers

A

holds an array of chlorophyll molecules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How does electron transfer in cyclic phototrophy work

A

excited electron passed to membrane carriers, ETC makes PMF, electrons can return to any reaction center

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How does making NADH break the cycle

A

electrons must be filled from another source to complete the cycle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How does acyclic phototrophy “fix the cycle”

A

electrons filled from another source to complete the cycle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Two methods used by phototrophs to make NADH

A

Purple/green sulfur: bacteria w strong rxn centers w enough energy to directly reduce NAD+

Purple/green nonsulfur: bacteria w weak rxn centers and must use reverse ETC

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

How does the oxygenic acyclic phototrophy system use water to produce NADH

A

Links 2 different photosystem rxns together, coupled in series
First photosystem has enough resting potential to accept electron from H2O
Second photosystem has enough activated potential to directly reduce NAD+

“eats H2O, gives off O2”

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What are the ways to increase the surface area of the rxn centers to more efficiently use light?

A

1) Membrane Invaginations: increase SA to mount reaction centers
2) Phycobiliproteins: antenna proteins that funnel energy to rxn centers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is the solution to having too much light energy

A

more light energy to carotenoids (cofactors that absorb light energy)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What contributes to bacteria having different pigments

A

Phototrophic bacteria have a wide range of absorbance profiles

Different organisms have evolved different light harvesting pigments

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Halobacterium salinarum

A

Archaeon, extremely halophilic, desiccation/ radiation resistant, very simple photosystem (bacteriorhodopsin), single proton pump directly coupled to light absorption and does not use ETC

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

How do bacteriorhodipsins work

A

Reaction center directly coupled with proton pump

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

From what doe Heterotrophs obtain carbon? What pathways are used?

A

Organic chemicals: C and N enter macromolecules as reduced carbon compounds like AA
Pathways: Glycolysis, PPP, TCA cycle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What macronutrients in the atmosphere can be fixed

A

Carbon (CO2)
Nitrogen (N2 gas)
H, O (H2O)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Definition of Autotrophy

A

Building reduced carbon (sugars) directly from CO2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

How are NADH and NADPH used differently

A

Both have same function to donate electrons

NADH: Catabolism
NADPH: Anabolism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What enzyme enables carboxylation of 5 carbon ribulose

A

RuBiSCO: Ribulose Bisphosphate Carboxylase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

3 Steps in carbon fixation

A

1) Carboxylation: Attaches one CO2 molecule to end of 5C sugar
2) Reduction: “fixes” carbon ation biologically
3) Rearrangement: 1 Carbon donated to make glucose each time.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

How much energy is used in carbon fixation

A

18 ATP, 12 NADPH (6x through cycle)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What happens when CO2 is low? Whats the solution?

A

O2 can compete for the enzyme and be incorporated producing toxic glycolic acid (“phosphorespiration”)
Solution: Carboxysomes (protein shells that contain a lot of RuBiSCO, enrich for CO2 and exclude O2)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

Compare and contrast Chemoorganoheterotrophy and Photoautotrophy

A

Chemoorganoheterotrophy: Glycolysis/TCA cycle, release PMF, release ATP/NADPH, aerobic respiration

Photoautotrophy: Oxygenic acyclic phototrophy, take in ATP/ NADPH, take in PMF, Autotrophy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

How does nitrogen enter the cell

A

1) Directly through premade AA

2) As ammonia attached to Glutamate (AA)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

What are the 2 enzymes involved in the 2 step glutamine synthesis pathway

A

Glutamine Synthetase and Glutamate synthetase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

Wha tis the enzyme involved in the one step glutamate synthesis pathway

A

Glutamate Dehydrogenase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

Where does reduced Nitrogen (ammonia) come from?

A

2) Geothermal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

What is nitrogen fixation

A

Biological conversion of N2 => NH4+

Strictly a bacterial process but not all bacteria can do it

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

How much energy is used in nitrogen fixation

A

Extremely energetically expensive
4 NADPH
18 ATP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

What proteins are involved with nitrogen fixation

A

Nitrogenase enzyme
Fe protein: delivers electrons
FeMo protein: reduces nitrogen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

What is the problem that stems from atmospheric concentrations of N2 and O2

A

Nitrogenase destroyed by oxygen, Active site of iron protein exposed to cytoplasm, O2 reacts with iron, iron in protein rusts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

What are the solutions that have evolved to solve O2 problems in nitrogen fixation

A

1) Anaerobic conditions: no O2 present
2) Extremely rapid respiration: respire O2 so fast that the concentration of O2 is low
3) Heterocysts: specialized, differentiated, non-growing, O2 impermeable cell types found in cyanobacteria.

Oxygenic phototrophy in most of the chain, heterocysts fixes nitrogen and shares with chain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

Sinorhizobium meliloti

A

Legume symbiont
Fixes N2 in plant nodules
different legumes form symbioses with diff bacteria
Bacteriod does not grow
Plant gets N2, bacterium gets carbon (sugars)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

How does cell-cell communication play a role in legume symbiosis

A

plant root sends flavanoid signal to attract bacteria, bacteria sends signal “Nod factor” back to plant.
Signals are specific for both plant and bacterium, ensures proper recognition between partners

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

What does the plant provide in legume symbiosis

A

Carbon (sugars)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

What does the bacteria provide in legume symbiosis

A

Nitrogen (NH3)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

How does this legume symbiosis benefit the group if the bacterioid cannot grow?

A

Rhizopines (check?)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

How are lipid subunits activated

A

Attaching Acyl carrier protein (ACP)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

What do the primer and extender do?

A

Primer: often Acetyl-ACP (2C) but can vary

Extender: always malonlyl-ACP (3C) => donates 2C to primer, elongates chain by 2C

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

How do different types of fatty acids get made? (even #, odd #, branched)

A

Different primers!
Acetyl-ACP: Chains w even #C
Propionyl-ACP: chains w odd # C
Isovaleryl-ACP: chains w odd # chains w branch

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

How does unsaturation of fatty acids occur

A

1) Skip reduction step: reducing enzyme fails at low temps so that double bond is preserved during elongation
1) Monooxygenase: enzyme made at lower temps and adds oxyygen to reintroduce double bond after chainis completed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

What AA is attached to glycerol-phosphate backbone in the phospholipid phosphatidylserine (PS)

A

Serine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

What is removed to make phosphatidylethanolamine (PE)

A

CO2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

How are sugar monomers activated

A

attaching nucleotides (UDP)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

How do polysaccharides polymerize and where?

A

Glucose adds to glycogen chain and UDP released into cytoplasm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

How are peptidoglycan monomers activated

A

1) NAM activated w UDP
2) 5 AA attached sequentially to NAM (pentapeptide)
3) NAM-Peptide is transferred to membrane carrier lipid, lipid carrier becomes new monomer activator
4) NAG activated with UDP
5) NAG Attached to NAM-penta peptide
6) Lipid carrier and bound NAG/NAM-pentapeptide flipped to opposite side of membrane (catalyzed by flippase)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
57
Q

How is peptidoglycan monomer polymerized?

A

7) NAG/NAM polymerized onto existing chain in wall

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
58
Q

How are the chains crosslinked in peptidoglycan

A

8) Pentapeptide crosslinked by penicillin binding protein (PBP)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
59
Q

What steps does penicillin inhibit

A

8) crosslinking

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
60
Q

What step does Vancomycin inhibit?

A

7) Polymerization

61
Q

What steps do Bacitracin inhibit

A

1, 4) UDP activation

62
Q

How doe scientists observe peptidoglycan synthesis

A

Study fluorescently labeled vancomycin wherever they saw fluorescence, synthesis was happening

63
Q

Where did scientists see peptidoglycan synthesis? What were the surprises?

A

Synthesis is localized, not random, 2 patterns of synthesis

64
Q

What were the two patterns of peptidoglycan synthesis?

A

1) As cell elongates, new wall inserted as spiral (MreB)

2) as cell divides, new wall inserted as ring (FtsZ)

65
Q

What is the central Dogma

A

DNA (Transcription =>) RNA (Translation =>) Protein (replication =>) DNA

66
Q

What are the protein synthesis subunits? How many are there

A

20 Amino Acids

67
Q

How are the amino acids activated? What enzyme is involved?

A

tRNAs -> each AA matches a tRNA w specific nucleotide sequence.
Enzyme= Amino Acyl-tRNA synthetases: recognizes proper AA and matches tRNA by anti codon and side loops

68
Q

What enzyme synthesizes proteins?

A

Ribosome: 3 diff rRNAs, 55 diff proteins

69
Q

What are the components of the ribosome

A

30S rRNA, 50s rRNA, and proteins

70
Q

What role does mRNA play in translation

A

template for protein synthesis

71
Q

How is mRNA made

A

transcribed by RNA polymerase from DNA Sequence

72
Q

How is translation initiated? What sequence is required? What enzymes are required

A

1) Ribosome assembles on mRNA at specific ribosome binding site (SD sequence)
2) IF2 (Initiation Factor 2) delivers first activated tRNA to ribosomes
3) EF-tu (elongation factor Tu) delivers all other activated tRNAs to ribosome

73
Q

What is the Shine-Dalgarno Sequence

A

Where the ribosome binds

74
Q

How are peptide bonds formed

A

Catalyzed by 23s rRNA in ribosome
AA bond to tRNA by carboxyl groups, Amino (N) of AA attacks carboxyl (C) of another, proteins synthesized N -> C terminus

75
Q

What direction is mRNA template read? What direction is protein synthesized?

A

mRNA-> 5’ -> 3’

Protein N-C

76
Q

WHat enzymes are required for elongation

A

EF-G (Elongation factor G) slides ribosome 3 base pairs downstream on mRNA

77
Q

What enzymes are required for termination

A

Release Factors (RF proteins): recognize stop codons and arrest protein synthesis

78
Q

What does the antibiotic tetracycline do

A

blocks amino acyl tRNA entry

79
Q

What does the antibiotic chloramphenicol do

A

blocks peptide bond formation

80
Q

What does the antibiotic erythromycin do

A

blocks ribosome translocation

81
Q

How is the protein sequence determined

A

Each protein templated by unique mRNA w particular sequence

82
Q

What is the info contained in the mRNA sequence

A

1) Ribosome binding site
2) Translational start site
3) Code for protein translation
4) translational stop site

83
Q

How is the start codon recognized

A

3’ end of 16s rRNA base pairs w complementary site (SD) 6-9 base pairs downstream of SD is translational start site. First AA is ALWAYS f-Met in bacteria, start codon is AUG (also UUG and GUG)

84
Q

What is a codon

A

Series of 3 nucleotides that specify particular AA, initiation codon sets frame which determines all subsequent codons

85
Q

Why use a 3 nucleotide instead of 2 or 1

A

enough possibilities for all AA to have a codon w some to spare

86
Q

How does the cell deal with degeneracy

A

1) one tRNA recognizes multiple codons by loose specificity in 3rd base “wobble position”
2) Make a second tRNA for the same AA to recognize particular codon

87
Q

What are stop codons

A

3 codons that do not code for AA, instruct ribosome to stop translation, recognized by release factors: terminate translation and dissemble ribosome

88
Q

What are the 3 functions of SD sequence

A

1) Ribosome binding site
2) Determines start codon
3) Controls protein copy #: more similar SD is to a perfect match w 16S rRNA, more frequently ribosomes initiate and more protein is translated

89
Q

What are polysomes and why can they from in bacteria

A

Multiple ribosomes on the same template, can occur bc transcription and translation are coupled in bacteria

90
Q

Compare and contrast bacterial and eukaryotic translation

A

1) B: Ribosome recognizes SD sequence
E: Ribosome recognizes 5’ cap modification
2)B: Multiple initiating codons (AUG, UUG, GUG)
E: one initiating codon (AUG)
3) B: f-Met
E: Met
4) B: Transcription and translation occur simultaneously
E: Transcription and translation occur sequentially
5) Different ribosome structure
B: 70S ribosomes 16S rRNA
E: 80S ribosomes, 18S rRNA

91
Q

Three examples of Chaperones

A

DnaK: help fold proteins as they emerge from the ribosome, activated at high temps, part of the Heat Shock Response, helps limit damage
SecB: prevent proteins from folding for delivery to secretion machinery
GroEL: give proteins a second chance to refold if misfolding has already occurred. Activated at high temps to refold denatured proteins

92
Q

What are proteases? Example?

A

Destroy misfolded proteins and recycle AA

Ex: ClpCP

93
Q

What are the three classes of RNA molecules and how do they relate to translation
How are RNA molecules polymerized in transcription

A

1) mRNA: informational RNA, has SD sequence, One specific mRNA for each protein to be translated
2) tRNA: activates AA, decodes mRNA, shared pool, no SD or start codon
3) rRNA: major structural and catalytic component of ribosomes. Shared pool, no SD or start codon

94
Q

How are nucleotides activated in transcription

A

Phosphorylation

ADP -> ATP

95
Q

How are RNA molecules polymerized in transcription

A

5’ -> 3’

96
Q

What enzyme perfomes transcription? Components of the enzyme?

A

RNA polymerase
4 complex proteins make up core: a, a, B, B’ (responsible for catalyzing polymerization of RNA)
sigma: determines which promoters RNAP binds to and controls specificity
Core + Sigma = Holoenzyme

97
Q

What are promoters

A

DNA sequences that indicate where to start transcription

98
Q

What are sigma factors

A

proteins that bind specific promoter sequences and instruct RNAP where to begin transcribing. Bind at -35 and -10 box

99
Q

What sequence is important for sigma factors

A

consensus sequence

100
Q

What is a consensus sequence

A

average of all promoters recognized by a sigma factor

101
Q

How are 2 strands of DNA separated

A

RNAP melts a bubble of dsDNA to single strands

102
Q

What is the pairing of nucleotides bn RNA and DNA

A

A=U/T

G=C

103
Q

Which strand is the template strand in DNA

A

bottom DNA strand

104
Q

What does Rho-dependent termination require

A

Rho protein binds to untranslated mRNA, rolls along transcript and knocks RNAP off.
Rho binds to rut sites (C bases w regular periodicity)
ATP must be consumed, energy dependent process, ribosomes block rut sites normally

105
Q

What does Rho-independent termination require

A

Terminated by sequence in RNA itself. “Hairpin” stable stem loop followed by poly U tract knocks RNAP off DNA template and halts transcription

106
Q

What is a gene/cistron

A

Segment of DNA that codes for a functional product for each gene, multiple transcripts are made depending on promoter consensus

107
Q

What is an operon

A

when multiple genes are expressed from common promoter, each gene has its own SD, translational start/stop

108
Q

when multiple genes are expressed from common promoter, each gene has its own SD, translational start/stop

A

When translational start/stop sequences of 2 adjacent genes overlap. Instead of ribosome falling off transcript, it backs up and begins translating again. Ensures “translationally coupled proteins” are always made together and at the same copy number.

109
Q

How are tRNAs and rRNAs encoded on the genome? What does RNase III do?

A

Coded in operons, encoded on same transcript.

RNase III enzymatically cuts to separate

110
Q

What are alternative sigma factors

A

Different sigma factors recognize diff promoter sequences. Diff genes can be expressed by changing sigma factors

111
Q

How do alternative sigma factors differ from sigma A?

A

Diff consensus sequences, recognize diff promoter sequences, express diff genes

112
Q

Bacillus subtilis

A

Industrial workhorse: produces proteases, riboflavin, fungicide, powerful genetic system
“Component” takes up free DNA from the environment
sporulation, cascade of sigma factors: certain sigma factors activate others
Spore is metabolically dormant, resistant to heat, desiccation, and radiation

113
Q

What are activators and how do they work

A

Proteins that bind to specific DNA sequences and activate expression from downstream promoters
Often compensate for a weak -35 sequence

114
Q

Lac Operon: How does CAP function?

A

Activates lac operon transcription by binding to a specific DNA sequence but requires cAMP to do so.

115
Q

Lac operon: what does cAMP do

A

Activates CAP and is synthsized by adenylate cyclase. Enables quaternary structure, acts as glue bn dimers

116
Q

Under what conditions are the lac genes transcribed and how does CAP influence this

A

transcribed when lactose is present and glucose is not present. CAP inhibited by glucose which also inhibits cAMP

117
Q

What are repressors and how do they work

A

proteins that bind to a specific DNA sequence and inhibit gene transcription. Repressor binding overlaps promoter and blocks RNAP access

118
Q

How does LacI function

A

Inhibits transcription unless lactose is present. Severely bends DNA and prevents access of RNAP to lac promoter. LacI inhibited by lactose.

119
Q

In two component systems, what is HPK and what does it do

A

Histidine Protein Kinase receives signal, then autophosphorylates and transfers phosphate to an aspartase on RR

120
Q

What is the RR, what does it do?

A

Response Regulator that controls gene expression. Phosphorylation of RR activates DNA binding and RNAP recruitment

121
Q

Fremyella diplosiphon

A

Cyanobacterium that fixes carbon and nitrogen. Heterocysts protect nitrogenase. Oxygenic phototrophy, makes gas vesicles, Chromatic acclimation: controlled by 2 component system
HPK: RcaE RR: RcaC
In green light: makes green absorbing pigment (default)
In red light: RcaC phosphorylated and binds to DNA activates red light and supresses green light

122
Q

What is a riboswitch and what are two ways that it functions

A

RNA sequence pattern in 5’ leader of mRNA that folds to regulate transcription
Functions:
1) Inhibits transcription: riboflavin binds directly to transcript and it folds to form transcriptional terminator at front of operon
2) inhibits translation: mRNA secondary structure blocks ribosome from binding to SD sequence. Binding of MOLECULE allows translation

123
Q

How do Riboswitches accomplish feedback inhibition

A

product of a pathway inhibits synthesis of enzymes that make it
Riboflavin produced and then it stops transcription

124
Q

How do sRNAs work? What protein is required?

A

RNA chaperone Hfq binds to sRNAS. Hfq delivers sRNAs to target transcript. sRNAs interact with specific transcript and block SD sequence to inhibit translation

125
Q

How does CsrA work

A

RNA binding protein, binds over the top of SD sequence, inhibits translation by blocking ribosomes.

126
Q

Bacterial genomes generally consist of

A

single, closed circular chromosome

127
Q

What are the monomers of DNA synthesis activated by?

A

phosphorylation

128
Q

How is replication initiated? What sequence is required? What protein binds to that sequence? What is terC?

A

Origin is specific DNA sequence where replication begins (oriC) DnaA protein binds to oriC and recruits DNAP to begin replication.
ter C=terminus , DNA region where each replication fork ends during replication

129
Q

What direction is DNA synthesized in? Which strand is continuous? Which strand is discontinuous?

A

DNA synthesized 5’-3’, DNAP III polymerizes DNA
Leading strand is continuous
Lagging strand is discontinuous

130
Q

What direction does DNAP move from oriC? What is the name of this type of replicaton?

A

Bidirectional: sets off in opposite directions

Called theta replication because replicating chromosome is thought to look like Greek letter theta

131
Q

What sequence is important for termination? What protein is required

A

ter sites
Protien Tus binds to ter sites and prevents anterograde replication
Tus stops DNAP near dif site

132
Q

Why do the chromosomes need to be decatenated

A

After replication chromosomes are linked together like rings in a chain

133
Q

What sequence is important for decatenation? What proteins are required?

A

dif site: recognized by proteins XerC/XerD that recruit DNA topoisomerase IV (cuts one chromosome at dif site, separates and then repairs)

134
Q

Does DNAP stay positioned or does it move? What about the chromosomes?

A

DNP stays stationary at midcell, oriC moves toward poles

135
Q

How does the cell deal with replication that is slower than cell divivion

A

Multiple replication forks: new rounds of replication begin before old round ends, each will inherit partially replicated genome.
At high growth rates, genes near origin have high copy #

136
Q

Why are mutations in DNA more detrimental than mutations in RNA or errors in protein synthesis

A

DNA mutations alter all proteins encoded by that gene, alters all proteins of all descendants of mutant strain

137
Q

What are the 3 causes/types of errors

A

Mismatch: DNAP makes mistake
Slipped Strand mispairing: DNAP tracks over repetitive sequence and slips forward or reverse
Mutagens: environmental factors that damage DNA

138
Q

What is the most commonly occurring cause of errors in DNA? least common?

A

Mutagen: most common
Mismatch: least common

139
Q

Why are mutagens heritable?

A

If unrepaired mutations are copied, and passed to next generation

140
Q

Term for strain that has inherited a mutation

A

mutant

141
Q

What is a genotype

A

DNA sequence of gene/chromosome

142
Q

What is a phenotype

A

measurable/ observable trait conferred by a gene, mediated by proeins

143
Q

What is an allele

A

version of a gene

144
Q

What are the consequences of mutation

A

Change in gene sequence = change in protein sequence = change in protein function and shape
random mutation will almost always result in protein loss of function.
VERY rarely, gain of function mutation will occur that increases or changes protein activity

145
Q

What is a missense mutation

A

Single base pair change that changes codon to a different AA

146
Q

What is a nonsense mutation

A

single base pair change that changes codon to premature stop codon

147
Q

What is a silent mutation

A

Change in codon, but codes for the same AA due to degenerativity. “silent” in protein sequence but may have a phenotype

148
Q

What is a frameshift mutation

A

Insertion or deletion of base pairs in amounts not /3, completely alters subsequent AA sequence

149
Q

What is polarity

A

Side effect of mutations within operons

BIOL-M 250 (11 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions