Eukaryotic gene regulation (25/26)

Question 1

Control elements

Answer 1

Are additional regulatory proteins bind at a specific DNA

Question 2

Activator proteins

Answer 2

Increases gene transcription of a gene or set of genes. Can be bind to a enhancer

Question 3

Chromatin

Answer 3

DNA and histone proteins

Question 4

Euchromatin

Answer 4

can be transcriptionally active, more relaxed packed

Question 5

Heterochromatin

Answer 5

not transcriptionally active, more tightly packed

Question 6

Nucleosome

Answer 6

packed DNA around histone

Question 7

Explain how DNA methylation and histone acetylation affect chromatin structure and transcription

Answer 7

DNA Methylation
attachment of methyl group (CH3) to bases in the DNA
condenses the chromatin and slows or inactivates gene transcription, associated with long term gene activity
Histone Acetylation
- adding a COCH3 (negative) to the ‘tails’ of histone proteins in the nucleosomes, neutralising their positive charges
– forms a looser chromatin structure that makes the DNA more available for transcription
– is a reversible process

Question 8

Compare and contrast gene structure and the ways gene expression is regulated in prokaryotes and eukaryotes

Answer 8

Prokaryotic gene regulation occurs in cytoplasm while eukaryotic transcription occurs in nucleus and translation in cytoplasm

Question 9

Describe the roles of RNA polymerase II, transcription factors, control elements and activator proteins in transcription

Answer 9

Transcription factors are proteins that help turn specific genes “on” or “off” by binding to nearby DNA
Activator protein increase transcription
Control elements - Are additional regulatory proteins bind at a specific DNA
RNA polymerase II is what binds to the promoter

Question 10

Explain the roles of control elements and activator proteins in determining expression of the required sets of genes in the correct cell types

Answer 10

Control elements
cell regulates and controls the gene expression process. The control of gene expression may occur at several levels in the cell. For example, genes rarely operate during mitosis, when the DNA fibres shorten and thicken to form chromatin.Other levels of gene control can occur during and after transcription.
Activator proteins
During the lac operon process (metabolism/absorption of lactose), when there is no glucose present but lactose present an activator protein is activated to enable the lactose to be transcribed this is done through a protein called CAP, CAP also requires cAMP (derivative of ATP) to produce enough energy for the CAP to activate the promoter the RNA polymerase to bind to. If there is lactose present there is allolactose present, resulting in allolactose binding the the lac operon repressor therefore allowing the transcription to occur across the Lac Z, Lac Y, Lac A.
If there is glucose present then very little lactose is required because glucose is easier for the body to metabolise. No activator protein is required for transcription to continue as glucose provides enough energy for the expression to occur.