Lecture 11

Question 1

regulation of chemotaxis

Answer 1

• modified two-component system

- sense temporal changes in attractants or repellents to regulate flagellar rotation

Question 2

3 main steps response to signal

Answer 2

• sensory proteins sense attractants and repellants
• controlling flagellar rotation
• adaptation

Question 3

methyl accepting chemotaxis proteins

Answer 3

MCPs; bind attractant or repellant and initiate flagellar rotation

Question 4

CheY protein

Answer 4

control flagellar rotation

Question 5

CheY

Answer 5

result in counterclockwise rotation and straight runs

Question 6

CheY-P

Answer 6

result in clockwise rotation and tumbling

Question 7

feedback loop

Answer 7

allow system to reset to continue to sense presence of signal, involve modification of MCPs

Question 8

Che protein also play a role in…

Answer 8

Phototaxis and aerotaxis

Question 9

quorum sensing

Answer 9

mechanism by which bacteria assess their population density; ensure sufficient # of cells are present before initiating a response that requires a certain cell density

Question 10

autoinducer

Answer 10

• diffuse freely across cell envelope
• reaches high conc inside cell if many cells are near
• bind to activator proteins and triggers transcription of genes

Question 11

acyl homoserine lactone

Answer 11

AHL; first autoinducer to be identified

Question 12

Lux operon

Answer 12

encodes bioluminescence system

Question 13

examples of quorum sensing

Answer 13

• virulence factors

- switching from free-living to growing as a biofilm

Question 14

other global control systems

Answer 14

--Stringent Response
– Aerobic and anaerobic respiration – Catabolite repression
– Nitrogen utilization
– Oxidative stress
– SOS response
– Heat shock response

Question 15

stringent response

Answer 15

used to survive nutrient deprivation, environmental street, and antibiotic

Question 16

heat shock response

Answer 16

largely controlled by alternative sigma factors

Question 17

heat shock proteins

Answer 17

counteract damage of denatured proteins and help cell recover from temp. stress

Question 18

sporulation in bacillus is controlled by..

Answer 18

four sigma factors

Question 19

noncoding RNA

Answer 19

RNA that is not translated to protein

Question 20

small RNAs (sRNA)

Answer 20

40-400 nucleotides that regulate gene expression in prokaryotes and eukaryotes

Question 21

how do sRNAs exert regulatory effects?

Answer 21

bybasepairingwith other RNAs with complementary sequence (usually mRNA).

Question 22

riboswitches

Answer 22

RNA molecules that resemble repressors and activators in binding small metabolites and regulating gene expression

Question 23

attenuation

Answer 23

transcriptional control that functions by premature termination of mRNA synthesis

Question 24

tryptophan operon

Answer 24

example of attenuation

Question 25

feedback inhibition

Answer 25

mechanism for temporarily turning off the reactions in a biosynthetic pathway

Question 26

allosteric enzyme

Answer 26

• inhibited enzyme

- 2 binding sites, active and allosteric

Question 27

Binding at allosteric site…

Answer 27

changes conformation, preventing substrate binding.

Question 28

modifications

Answer 28

affect activity

Question 29

sequestration

Answer 29

(binding) of specific regulatory proteins can control their activity