Biology- Control of gene expression

Question 1

What are the different types of mutation?

Answer 1

• Deletion
• Addition
• Substitution
• Translocation
• Inversion
• Duplication

Question 2

What are STEM cells?

Answer 2

Cells that are undifferentiated

and can therefore become any human body cell.

Question 3

Define Totipotency

Answer 3

When the cells in the zygote have not yet divided into embryonic or placental cells.

Question 4

Define Pluripotency

Answer 4

When a cell has become an embryonic cell they could differentiate into any human body cell.

Question 5

Define Multipotency

Answer 5

(progenitor cells)

Can only become more specific cells and therefore form more specific tissues.

Question 6

Define Unipotency

Answer 6

Cells onl have one job and therefore cannot diferentiate at all into a different cell.

Question 7

What are IPS Cells?

Answer 7

Induced Pluripotent STEM cells.

Question 8

What are transcription factors?

Answer 8

Factors that stimulate or inhibit the rate of DNA transcription.
They are proteins that are found in the cytoplasm and when activated they move through nuclear pores and into the nucleus.
The transcription factor will bind to a specific binding site on the DNA and activate transcription of a gene.

Question 9

How are transcription factors activated?

Answer 9

1) Oestrogen is lipid soluble and can therefore pass through the phospholipid bilayer of a cell membrane.
2) Oestrogen binds to the receptor sites on the Transcription factor (TF)
3) Oestrogen causes the TF to change shape and become activated.
4) therefore DNA binding site changes shape on the TF.
5) the TF moves into the nucleus from the cytoplasm through nuclear pores.
6) TF binds to specific site on DNA
7) This activates transcription of a gene.

Question 10

What is a chromosome made up of?

Answer 10

DNA that is associated with histone proteins.

Question 11

What is the Epigenome?

Answer 11

Chemical tags found on the top of the DNA or histone proteins that can be switched on or off.
This will make DNA either available to or unavailable to the transcription factors.

Question 12

How is a transcription factor prevented/blocked from binding to DNA?

Answer 12

• Histone proteins become de-acetlyated (acetly group removed)
• DNA becomes Methylated.
• Therefore DNA becomes more coiled and cannot have transcription factors binding to it.

Question 13

How are transcription factors able to bind to DNA?

Answer 13

• Histones become acetylated
• DNA becomes de-methlyated
• Therefore DNA is less coiled and the transcription factors can bind to it.