Gene Expression

Question 1

Define gene mutation

Answer 1

Change to one or more of the nucleotide bases in DNA. These might arise during DNA replication

Question 2

Name the six types of gene mutation

Answer 2

Substitution/ Deletion / Addition/ Duplication /inversion/ translocation

Question 3

What does substitution case?

What are the three possible effects?

Answer 3

When nucleotides are replaced by another with a different base

Forms a stop codon
Forms codon for different aa
Form same aa due to degenerative code

Question 4

Gene mutations can occur________

Answer 4

Gene mutations can occur spontaneously

Question 5

Name two types of mutagenic agents

Answer 5

High ionisation radiation energy

Chemicals

Question 6

What is a zygote?

Answer 6

Fertilized egg

Question 7

Name 4 places were stem cells are found

Answer 7

Embryo
Umbilical cord blood
Placental
Adult - bone marrow

Question 8

Name the four types of stem cells

Answer 8

totipotent
pluripotent
multipotent
unipotent

Question 9

Where are totipotent and pluripotent found?

Answer 9

Embryo

Question 10

Where are multipotent stem cells found?

What is their limitation?

Answer 10

Found in the adults

Can specialise into specific number of cells

Question 11

How many types of cells can a unipotent stem cell turn into ?

Answer 11

one

Question 12

What are iPS?

How are they produced?

Answer 12

Induced pluripotent stem cells

Produced from unipotent stem cells using appropriate protein transcription factor

Question 13

Name the DNA-Histone complex

Answer 13

-Chromatin

Question 14

Define acetylation

Answer 14

When acetyl group is transferred to a molecule

Question 15

Describe what occurs when deacetylation occurs

Answer 15

makes histones more positive
so increases attraction to phosphate
so association of complex is stronger so transcription factors are less accessible
more difficult to switch on genes

Question 16

Define methylation

Answer 16

Addition of CH3 group to a molecule

Question 17

Describe was occurs when increased methylation happens

Answer 17

Prevents binding of transcriptional factor to DNA
Attact proteins that condense the complex
so gene switched off

Question 18

Explain how the methylation of tumour suppressor genes can lead to cancer.

Answer 18

Methylation prevents transcription of gene;
Protein not produced that prevents cell division/
causes cell death/apoptosis;
No control of mitosis;

Question 19

Suggest how transcription factors can reprogramme cells to form iPS cells

Answer 19

attach 2 gene + stimulate RNA polymerase

Question 20

Describe how alterations to tumour suppressor genes can lead to the development of
tumours.

Answer 20

(Increased) methylation (of tumour suppressor
genes);
Mutation (in tumour suppressor genes);
Tumour suppressor genes are not
transcribed/expressed
OR
Amino acid sequence/primary structure altered;
Results in) rapid/uncontrollable cell division;