Bacterial Transcription Flashcards
- For which of the following nitrogenous bases does DNA substitute thymine?
Guanine
Cytosine
Uracil
Inosine
Adenine
Uracil
A consensus sequence found in a bacterial promoter region
Is only found in front of genes in Gram positive bacteria
Is only found in front of genes in Gram negative bacteria
Is a sequence that is found in front of all bacterial genes
Is an idealised sequence that shares much sequence similarity for many genes
Is an idealised sequence that shares much sequence similarity for many genes
The coding strand of DNA is also known as the
Lagging strand
Non-template strand
Template strand
Sequence strand
Non-template strand
Transcription begins when -
RNA polymerases find a 3’ UTR
RNA polymerase recognises a promoter sequence, binds to the DNA, and
synthesizes RNA from the 5’ end towards the 3’ end of the new piece
An open reading frame is discovered
When the first AUG in a template is recognised
RNA polymerase recognises a promoter sequence, binds to the DNA, and
synthesizes RNA from the 5’ end towards the 3’ end of the new piece ✓
. mRNA has a base sequence which is complementary to the anticoding strand of DNA
True
False
False
. When a repressor protein binds to the operator sequence—
Transcription of the downstream gene is up regulated
Transcription of the downstream gene is inhibited
Transcription of the downstream gene is strongly enhanced
Transcription of the downstream gene is mildly promoted
Transcription of the downstream gene is inhibited
The direction of synthesis for -
DNA is 5’ to 3’ and it is 5’ to 3’ for RNA also
DNA is 5’ to 3’ while it is 3’ to 5’ for RNA
DNA is 3’ to 5’ while it is 3’ to 5’ for RNA also
DNA is 3’ to 5’ while it is 5’ to 3’ for RNA
DNA is 5’ to 3’ and it is 5’ to 3’ for RNA also ✓
RNA polymerase synthesizes-
An RNA copy of the gene using the antisense strand as template
A DNA copy of the sequence from promoter to terminator
An RNA copy of the gene using the sense strand as template
A DNA copy of the gene using the antisense strand as template
An RNA copy of the gene using the antisense strand as template ✓
Hairpin loop structures are found
In DNA
In lipids
In mRNA
In protein
In mRNA ✓
An example of an allosteric protein is-
Lactose when acting as a signal molecule
The lac operon
The lac repressor
Maltose when acting as a signal molecule
The lac repressor ✓
The operon is kept off in the presence of glucose by:
Glucose binds to CRP. CRP then binds to region b, which prevents RNA polymerase
binding to the promoter.
In the presence of glucose, cAMP is low. Thus, cAMP will not bind to CRP. CRP will
not bind to region b, the CRP site, which is needed for RNA polymerase to bind to
the promoter
In the presence of glucose, cyclic AMP is low. Without cAMP, CRP will not bind to
region c. This binding is needed for transcription.
In the presence of glucose, cAMP is low and therefore not able to activate the sigma
factor needed for transcription of this operon
In the presence of glucose, cAMP is low. Thus, cAMP will not bind to CRP. CRP will
not bind to region b, the CRP site, which is needed for RNA polymerase to bind to
the promoter ✓
The global activation of this operon is carried out by==
The sigma factor is needed to turn on most default transcription in E. coli.
IPTG, when glucose is present
CRP in the presence of cAMP, which activates other operons as well
CRP in the presence of lactose, which activates other operons as well
CRP in the presence of lactose, which activates other operons as well
A high level of transcription from the lac operon can be achieved under the following conditions–
Low glucose, low cAMP low Lactose
High glucose, High cAMP, high Lactose
High glucose, low cAMP, low lactose
Low glucose, high cAMP, high lactose
Low glucose, high cAMP, high lactose
Binding of the maltose to its activator protein will ultimately-
Inhibit cellular glucose breakdown
Deactivate cellular maltose breakdown
Activate cellular maltose breakdown
Inhibit cellular glucose and lactose breakdown
Activate cellular maltose breakdown ✓
Inverted repeats make a–
Single stranded stem and a double stranded loop
Single stranded loop and a double stranded stem
Double stranded loop and a double stranded stem
Double stranded loop and a single stranded loop
Single stranded loop and a double stranded stem ✓
