regulation of transcription and translation

Question 1

what are the things can control transcription called

Answer 1

transcription factors

Question 2

what are the 2 types of transcription factors

Answer 2

activator transcription factors

repressor transcription factors

Question 3

describe the action of activator transcription factors (4 marks)

Answer 3

• the activation transcription factor moves into the nucleus from the cytoplasm (through nuclear pores)
• transcription factor (Tf) binds to the promoter region of the specified gene
• Tf allows RNA polymerase to bind to promotor
• gene is transcribed

Question 4

describe the action of repression transcription factors (4 marks)

Answer 4

• the repressor transcription factor moves into the nucleus from cytoplasm (through nuclear pores)
• transcription factor (Tf) binds to promoter region of specified gene
• Tf blocks RNA polymerase from binding to promotor
• gene is not transcribed

Question 5

what is the role of transcription factors

Answer 5

The role of transcription factors.

Transcription factors move from the cytoplasm to
the nucleus.

In the nucleus they bind to specific DNA sites
called promoters, which are found near the start of
their specific genes – the genes they control the
expression of.

Transcription factors control expression by
controlling the rate of transcription.

Question 6

define activator transcription factor

Answer 6

Activators are transcription factors that increase
the rate of transcription – e.g. they help RNA
polymerase bind to the start of the target gene
and activate transcription.

Question 7

define repressor transcription factor

Answer 7

Repressors decrease the rate of transcription e.g.
they bind to the start of the target gene,
preventing RNA polymerase from binding,
stopping transcription.

Question 8

what is the role of oestrogen in transcription (2 marks)

Answer 8

Oestrogen is a hormone (steroid not protein) that can
affect transcription by binding to a transcription factor
called an oestrogen binding receptor, forming an
oestrogen-oestrogen receptor complex.

Question 9

explain how oestrogen affects gene transcription

Answer 9

• oestrogen is lipid soluble and enters the cell through the cell surface membrane
• binds to a complementary receptor on transcriptional factor
• activates transcriptional factor by changing the shape of the DNA binding site
• transcriptional factor enters nucleus through DNA pore and binds to a specific DNA sequence causing transcription

Question 10

what type of nucleic acid can gene expression also be influenced by

Answer 10

small interfering RNA (siRNA)

Question 11

what is siRNA

Answer 11

siRNA molecules are short, double-stranded RNA
molecules that can interfere with the expression of
specific genes.

Their bases are complementary to specific sections
of a target gene and the mRNA that’s formed from
it.

Question 12

how does SiRNA affect translation

Answer 12

RNA interference

• Double stranded siRNA unwinds
• Single stranded sections bind to specific regions of DNA with associated enzymes
• The siRNA and enzymes cut up the DNA into sections meaning it becomes unable to be transcribed

Question 13

what is the process called where SiRNA affects translation

Answer 13

RNA interference