Bio230 Lecture 3

Front 1

Negative Prokaryotic Gene Regulation:

Back 1

Competition between RNA polymerase and repressor protein for promoter binding

Front 2

Positive Prokaryotic Gene Regulation

Back 2

activator protein recruits RNA polymerase to the promoter to activate transcription

Front 3

In Prokaryotic Gene Regulation are found where?

Back 3

typically close to the transcriptional start site of prokaryotic genes but also far upstream of gene, downstream of gene (eukaryotes), within gene (introns;eukaryotes)

Front 4

In Prokaryotic Gene Regulation, if some regulatory elements are distant from the transcriptional start how can they incluence transcription?

Back 4

DNA Looping
Lac repressor is a tetramer (four identical subunis) and can bind two operator simutaneously
increases affinity of repressor for the Lac promoter

Front 5

what is a tetramer?

Back 5

has four identical subunits and can bind two operators simultaneously

Front 6

what is an example of a tetramer?

Back 6

the Lac repressor

Front 7

What is the bacteriophage lambda?

Back 7

its virus that infects bacterial cells

Front 8

how are the lifestyles of bacteriophage lambda regulated?

Back 8

through positive and negative regulatory mechanisms work together to regulate the lifestyes
two proteins repress each other sysnthesis

Front 9

how does the bacteriophage lambda exist

Back 9

can exist as one of two states in bacteria
under favorable bacterial growth condition
when host cell is damaged
two gene regulatory proteins are responsible for initiating this switch

Front 10

which regulatory proteins are responsible for initiating the switch between prophage and lytic pathways

Back 10

lambda repressor protein and Cro protein

Front 11

what are the two pathways that the bacteriophage lambda can exist in?

Back 11

prophage pathway
underfavorable bacterial growth condition
lytic pathway
when host cell is damaged

Front 12

explain what happens in bacteriophage lambda in its prophage stage

Back 12

lambda repressor occupies the operator
blocks sythesis of Cro
activates its own synthesis
most bacteriophage DNA not transcribed

Front 13

explain what happens in bacteriophage lambda in its lytic stage

Back 13

cro occupies the operator
blocks synthesis of repressor
allows its own synthesis
most bacteriophage DNA is extensively transcribed
DNA is replicated, packaged, new bacteriophage released by host cell lysis

Front 14

how does bacteriophage lambda switch between phases

Back 14

using a genetic switch

Front 15

what triggers the switch between prophage and lytic states in bacteriophage lambda

Back 15

host response to DNA damage inactivates repressor
-switch to lytic state
under good growth conditions repressor protein turns off Cro and activates itself, positive feedback loop
-maintains prophage state
example of transcriptional circuit
different types exist, control various biological processses

Front 16

what are examples of transcriptional circuits

Back 16

repressor protein
cro/repressor switch

Front 17

in transcriptional circuits what can positive feedback loops be used for?

Back 17

to create cell memory

Front 18

In transcriptional circuits what can feed-forward loops do?

Back 18

they can measure the duration of a signal
-both A and B required for transcription of Z

Front 19

what can be constructed using synthetic biology

Back 19

scientists can construct artificial circuits and examine their behavior in cells

Front 20

what is "the repressilator"

Back 20

using synthetic biology can create a simple gene oscillator using a delayed negative feedback circuit

Front 21

what was predicted to happen in the "the repressilator"

Back 21

that delayed negative feedback gives rise to oscillations

Front 22

what transcriptional circuits are found in drosophila

Back 22

a delayed negative feedback loop
used in control of circadian gene regulation of the biological clock of a 24 hour cycle

Front 23

what is transcription attenuation

Back 23

it happens in both prokaryotes and eukaryotes where there can be a premature termination of transcription

Front 24

what happens in transcription attenuation

Back 24

RNA adopts a structure that interferes with RNA polymerase
regulatory proteins can bind to RNA and interfere with attentuation
prokaryotes, plants and some fungi also use riboswitches to regulate gene expression

Front 25

what uses riboswitches

Back 25

in transcription attenuation, prokaryotes, plants and some fungi also use riboswitches to regulate gene expression

Front 26

what are riboswitches

Back 26

they are an example of transcription attenuation
they are short RNA sequences that change conformation when bound by a small molecule

Front 27

what is an example of riboswitches

Back 27

prokaryotic riboswitch that regulates purine biosynthesis

Front 28

what are bases that make up DNA/RNA

Back 28

pyrimidines (C,T,U) and purines (A,G)

Front 29

in the prokaryotic riboswitch that regulates purine biosynthesis what happens with low guanine levels

Back 29

transcription of purine biosynthetic gene is on

Front 30

in the prokaryotic riboswitch that regulates purine biosynthesis what happens with high guanine levels

Back 30

guianine binds riboswitch
riboswitch undergoes conformational change
causes RNA polymerase to terminate transcription
transcription of purine biosynthetic gene is off