3.8.2

Question 1

What are stem cells?

Answer 1

Unspecialised cells that can develop into other types of cell
Divide to become new cells

Question 2

Where are stem cells found?

Answer 2

Embryo’s
Some adult tissues

Question 3

What are totipotent cells?

Answer 3

Cells that can develop into any type of body cell

Question 4

What are pluripotent cells?

Answer 4

Specialise into any cell except cells that make up the placenta

Question 5

What are multipotent cells?

Answer 5

Specialise into A few different types of cell

Question 6

What is a unipotent cells ?

Answer 6

Specialise into one type of cell

Question 7

How do stem cells become specialised?

Answer 7

During development they only transcribe and translate part of their DNA
Stem cells all contain the same genes
During development not all of the genes are expressed

Question 8

What are cardiomyocytes?

Answer 8

Heart muscle cells
Can’t divide to replicate themselves
Can be replaced from unipotent stem cells in the heart

Question 9

What is a transcription factor?

Answer 9

A protein that controls the transcription of genes so that only certain parts of the DNA are expressed

Question 10

How do transcription factors work?

Answer 10

Move from the cytoplasm into nucleus
Bind to promoter region upstream of target gene
Makes it easier or more difficult for RNA polymerase to bind to gene, this increases or decreases rate of transcription

Question 11

How does oestrogen work?

Answer 11

Diffuses through cell membrane
Forms oestrogen - oestrogen receptor complex
Complex enters the nucleus and acts as a transcription factor

Question 12

SiRNA

Answer 12

1. Once mRNA has been transcribed, it leaves the nucleus and goes to the cytoplasm
2. Double stranded siRNA associates with proteins and unwinds
3. One single strand is selected and the other is broken down
4. Strand binds to the target mRNA
5. Proteins associated with the siRNA cut the mRNA into fragments so it can no longer be translated