Brainscape's Knowledge GenomeTM

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


See full index

organisation & control of the prokaryotic genome > organisation of the prokaryotic genome > Flashcards

organisation of the prokaryotic genome Flashcards

1
Q

what is the definition of an operon?

A
  • an operon is a unit of prokaryotic gene expression & regulation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what does an operon consist of?

A
  • an operon consists of a cluster of structural genes that code for enzymes of a single biochemical pathway of related functions
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what are the structural genes in an operon controlled by?

A
  • a common promoter & a common operator!
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what binds to the operator of the operon?

A
  • the product of the regulatory gene of the operon
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what are the 4 regions in a typical bacterial operon?

A
  • promoter
  • operator
  • structural genes
  • terminator
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what are the control elements in an operon?

A
  • promoter

- operator

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what is the definition of a promoter?

A
  • it is a sequence of DNA where RNA polymerase recognises & attaches to initiate transcription
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what is the function of a promoter?

A
  • it specifies the start site of transcription
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

do different operons have the same promoter sequences?

A
  • NO
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

do all bacteria have the same promoter sequence?

A
  • NO!!
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

where is the promoter located in the operon?

A
  • it is located upstream of the structural genes in the operon
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what are the 2 recognition sites in the promoter for RNA polymerase?

A
  • RNA polymerase recognition site (-35 region)

- RNA polymerase binding site / Pribnow box (-10 region)

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

what are the features of the RNA polymerase recognition site?

A
  • it has a consensus sequence of 5’ TTGACA 3’ at the -35 region of the non-template strand
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what purpose does the consensus sequence of the promoter serve?

A
  • the sigma factor subunit of the RNA polymerase will recognise the consensus sequence before transcription occurs
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what are the features of the Pribnow box (-10 region)?

A
  • it has a consensus sequence of 5’ TATAAT 3’ at the -10 region of the non-template strand
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what purpose does the consensus sequence on Pribnow box serve?

A
  • the region is AT-rich, and is where the RNA polymerase begins to unwind & separate DNA strands for transcription
17
Q

are there any basal transcription factors involved in prokaryotic transcription?

A
  • NO !!!!
18
Q

if basal transcription factors are not involved in prokaryotic transcription, then what first recognises & binds to the promoter?

A
  • the sigma factor!!
19
Q

where is the start site of prokaryotic transcription?

A
  • +1
20
Q

what does the term ‘operator’ mean?

A
  • the operator is a short DNA sequence that a repressor protein binds to, hence regulating the transcription of structural genes
21
Q

what is the function of the operator?

A
  • it regulates the transcription of structural genes by controlling the access of RNA polymerase to the promoter
22
Q

where is the operator located in the operon?

A
  • between the promoter & the 1st structural gene
23
Q

what happens when the repressor is not bound to the operator?

A
  • RNA polymerase can bind to the promoter,
  • & transcribe the structural genes of the operon
  • thus, the operon is switched on
24
Q

what happens when the repressor is bound to the operator?

A
  • the repressor blocks the attachment of RNA polymerase to the promoter,
  • preventing the transcription of structural genes
  • thus, the operon is switched off
25
Q

what is the difference between prokaryotes & eukaryotes in terms of the control elements regulating transcription?

A
  • in eukaryotes, the silencer of a gene is located a few thousand nucleotides upstream from the gene to be transcribed,
  • while in prokaryotes, the operator is located next to the 1st structural gene in the operon
26
Q

what does the term ‘structural genes’ mean?

A
  • a structural gene codes for a protein that forms part of a structure,
  • OR has an enzymatic function?
27
Q

where are structural genes of an operon located?

A
  • the structural genes of an operon usually lie adjacent to one another
28
Q

how is a single polycistronic mRNA formed?

A
  • RNA polymerase moves from 1 structural gene to the next, continuously transcribing all the genes into a single polycistronic mRNA
29
Q

what happens to the polycistronic mRNA after it is translated?

A
  • it is translated into several distinct polypeptides that become various proteins / enzymes of a metabolic pathway
30
Q

what is the definition of a regulatory gene?

A
  • a regulatory gene codes for a specific protein product that regulates the expression of the structural genes?
31
Q

where is the regulatory gene found?

A
  • upstream of an operon
32
Q

does each regulatory gene have its own promoter?

A
  • YES!!
33
Q

are there introns in prokaryotic mRNA?

A
  • THEY ARE ABSENT
34
Q

what causes termination of transcription?

A
  • a terminator at the end of each operon
35
Q

what are present upstream of each operon?

A
  • regulatory genes, which code for regulatory proteins that control the switching on & off of the operon
36
Q

why are genes clustered into operons in bacterial DNA?

A

organisation & control of the prokaryotic genome (10 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions