Regulation of Transcription and Translation Flashcards
What binds to the DNA promoter region?
Transcription Factors
These are proteins with specific tertiary structures
The promoter region is located BEFORE or WITHIN the gene?
Before
Sometimes this is referred to as ‘upstream’ of the gene
transcription factors are found in the [1] and upon activation can enter the [2].
[1] cytoplasm
[2] nucleus
What happens after the transcription factor binds to the promoter region?
stimulates RNA polymerase;
transcription begins and mRNA increases;
TRUE or FALSE:
Transcription factors binding to the promoter regions always increase transcription.
FALSE
Some transcription factors inhibit transcription
How does oestrogen enter cells?
- Lipid-soluble (steroid hormone);
- Diffuses through the phospholipid bilayer;
What does oestrogen bind to?
oestrogen receptor (ER alpha)
What happens to the oestrogen receptor (ER alpha) upon binding with oestrogen?
Changes its tertiary structure;
The receptor now acts as a transcripton factor;
TRUE or FALSE:
Oestrogen is a transcription factor
FALSE
Its receptor when activated by oestrogen binding = transcription factor
Osterogen binds to its receptor becuase it has a _____________ shape
complementary
The activiated ooestrogen receptor (ER alpha) is a [1] and binds to the [2] region.
This stimulates [3] and leads to transcription of a gene. This increases [4] and leads to more protein synthesis.
[1] transcription factor
[2] promoter
[3] RNA polymerase
[4] mRNA
Steroid hormones are hydrophobic.
Explain why steroid hormones can rapidly enter a cell by passing through its cell-surface membrane [2 marks].
- Lipid soluble;
- Diffuse through phospholipid bilayer;
In the cytoplasm, testosterone binds to a specific androgen receptor (AR).
An AR is a protein.
Suggest and explain why testosterone binds to a specific AR (2 marks).
- Testosterone has a specific tertiary structure;
- This has a complementary shape to the receptor;
Many hormones are ‘modified’ proteins
The binding of testosterone to the androgen receptor (AR) changes the shape of the AR.
This AR molecule now enters the nucleus and
stimulates gene expression.
Suggest how the AR could stimulate gene expression (2 marks)
- AR is a transcription factor;
- Binds to DNA promoter region;
- Stimulates RNA polymerase;
RNA interference (RNAi) inhibits the ________________ of mRNA
translation
Types of RNA interfering molecules
small interfering RNA (siRNA)
micro RNA (miRNA)
Are siRNA and miRNAs single OR double stranded?
single stranded
siRNA binds to specific [1] molecules via [2] base pairing.
This guides enzymes which [3] mRNA.
[4] is prevented.
[1] mRNA
[2] complementary
[3] destory
[4] translation
If a specific protein is still produced in smaller quantities this could be because not all mRNA has been __________________ by RNA interference
destroyed
Define epigenetics
Inheritable changes in gene function;
without changes to the DNA base sequence;
Types of epigenetic changes
Methylation
Acetylation
TRUE or FALSE:
Changes in the environment lead to changes in methylation and acetylation which determine whether a gene is expressed.
TRUE
During methylation, a methyl group is added to a ______ _______.
DNA base
Methylation of DNA bases in the [1] region, prevents transcription [2] from binding.
This [3] transcription.
[1] promoter
[2] factors
[3] decreases / inhibits
Chromosomal DNA in eukaryotes is wrapped around _____________
histones
**TRUE or FALSE: **
During acetylation DNA bases are modified
FALSE
Acetylation of histone makes them [1] packed.
This makes the promoter region and target gene more accessible to transcription factors and [2].
This [3] transcription.
[1] loosely
[2] RNA polymerase
[3] increases
Decreasing methylation,
________________ transcription
stimulates / increases
Explain why decreasing acetylation of histones decreases transcription.
- Histones are more tightly packed;
- Prevents transcription factors from binding to the promoter region;
- Prevents RNA polymerase from accessing the target gene;
