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Flashcards in Control of gene expression Deck (12)
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1

Properties of Stem cells

  • Will keep replicating, hence replacing themselves;
  • Undifferentiated so can differentiate into other cells (totipotent)

2

How can injecting stem cells to patients with heart disease help improve muscle contraction

  • stem cells would develop into heart muscle cells;
  • the relevant genes would be expressed

3

Explain how unspecialised cells can develop into different types of tissue

  • cells are totipotent meaning they can develop into any cell type
  • different genes expressed
  • so different enzymes and proteins produced

4

Why should a person's stem cells be used in an experiment

  • Own stem cells used to minimise risk of rejection 
  • Totipotent so can divide into 'required cells' and fight appropriate issue

5

Describe the role of oestrogen in protein synthesis

  1. Oestrogen is a lipid, so crosses the cell membrane by lipid diffusion and enters the cytoplasm.
  2. Oestrogen binds to its receptor protein in the cytoplasm to form a hormone-receptor complex. Receptors changes shape and the inhibitor molecules is released, exposing the binding site
  3. This complex is now a transcription factor.
  4. The activated transcription factor diffuses into the nucleus through a nuclear pore.
  5. Complex can act as an activator or repressor so it can inhibit RNA P or facilliate it
  6. In the nucleus the transcription factor binds to the DNA promoter
  7. This binding stimulates RNA polymerase to transcribe genes and so stimulates protein synthesis.

6

Structure of siRNA

  • small as it consists of only 20–25 nucleotides;
  • double-stranded RNA

7

How does siRNA interfere with gene expression

  • single siRNA strand;
  • binds to mRNA;
  • by complementary pairing;
  • enzyme cuts up mRNA
  • this prevents translation 

8

How can  addition/ deletion of DNA cause cancer?

  • Inactivates tumour suppressor gene;
  • Unable to control cell division
  • Rate of cell division increased

9

Role of transcriptional factors in making proteins

  • Binds to DNA at specific region (promoter );
  • Activates RNA polymerase
  • Stimulate transcription
  • It can turn on gene 

10

How can siRNA be used in treating diseases?

  • Some diseases are genetic
  • siRNA will stop non-functional protein of this gene being made 

11

Why doesn't siRNA only affect the expression of other genes

  • base sequence of siRNA complementary to one mRNA;
  • will only bind to and destroy this mRNA

12

What is a transcriptional factor

  • A Protein that moves from cytoplasm to nucleus;
  • TF  binds to promoter
  • They can allow/prevent RNA polymerase to bind to DNA;
  • Leads to/prevents pre mRNA production