transcriptional factors

Question 1

in eukaryotes, when can transcription of target genes be stimulated or inhibited ?

Answer 1

• when specific transcriptional factors move from the cytoplasm into the nucleus

Question 2

what can the movement of TF’s into the nucelus from the cytoplasm cause ?

Answer 2

• it can turn genes on or off
• so only proteins are produced in a particular cell

Question 3

what does the turning on or off of particular genes do to cell ?

Answer 3

• it enables the cells to become specialised

Question 4

when will transcription of a protein only occur ?

Answer 4

• when a molecule from the cytoplasm ( transcription factors ) enters the nucleus and binds to the DNA in the nucleus

Question 5

what kind of biological molecule is a transcription factor ?

Answer 5

• a protein

Question 6

what is the function of a transcription factor ?

Answer 6

• each one can bind to different base sequences on the DNA
• enables RNA polymerase to bind
• and this initiates the transcription of genes m

Question 7

what happens once the transcription factors is bound to the DNA ?

Answer 7

• transcription begins
• creates the mRNA molecules for that gene
• which can then be translated in the cytoplasm to create the protein

Question 8

what happens to the gene without the binding of a transcription factor ?

Answer 8

• the gene is inactive
• so protein will not be made

Question 9

what is the example you must know about transcriptional factors ?

Answer 9

• a transcriptional factor which is activated by the binding of oestrogen

Question 10

what is oestrogen ?

Answer 10

• a steroid hormone that can initiate transcription

Question 11

what are the properties of steroid hormones ?

Answer 11

• they are lipid soluble
• so can simply diffuse through the phospholipid bilayer

Question 12

how does oestrogen initiate transcription ?

Answer 12

• by binding to a receptor site on the transcriptional factor
• this happens in the cytoplasm

Question 13

what happens when oestrogen bind to the transcription factor ?

Answer 13

• it causes the DNA binding site shape to change
• change in tertiary structure
• change in shape makes it complimentary in shape to the DNA and able to bind to the DNA to initiate transcription

Question 14

what happens when the TF binds to the DNA sequence ?

Answer 14

• DNA polymerase is able to bind to the DNA and create the mRNA

Question 15

why does transcription only occur once DNA polymerase binds onto the DNA ?

Answer 15

• because DNA polymerase is a protein
• it has a unique 3D shape which is only complimentary to the DNA and transcriptional factor together

Question 16

what are genes regulated by ?

Answer 16

• transcription factors