Gene Technology

Question 1

A substitution mutation can be divided into three types what are they?

Answer 1

Mis-sense - the substituted base leads to a new amino acid
Non- sense - the substituted base leads to a stop codon being formed
Silent - degenerate nature of DNA means that Same amino acid is still formed

Question 2

Describe duplication and inversion mutations

Answer 2

Duplication is where base repeat themeselves

Inversion where group of bases detach and rotate 180 degrees before reattaching

Question 3

Describe translocation as a mutation

Answer 3

Group of bases detaches from the chromosome and inserts itself on a different chromosome

Question 4

Give two examples of mutagenic agents

Answer 4

High energy radiation e.g. Alpha and beta particles

Chemicals e.g. TP53 that inactivates a tumour suppressor gene

Question 5

Name the type of cell that has the ability to differentiate into any other cell

Answer 5

A totipotent cell

Question 6

Give some places within the body stem cells may be found

Answer 6

Embryonic
Umbilical cord
Placental

Question 7

Give four types of stem cell

Answer 7

Totipotent - can differentiate into any cell - zygote
Pluripotent - differentiate into almost any cell- embryos
Multi potential cells - differentiate into a type of cell, e.g. Blood cell
Unipotent cell - have the ability to differentiate into one type of cell only

Question 8

Give pros and cons to stem cell usage

Answer 8

Cons

• undermining respect of human life
• 14 day old embryos considered adults ?
• Move reproductive cloning

Pros

• wrong to allow suffering when it could be prevented
• feetility treatment creates them so may as well use them

Question 9

Describe how transcription can be controlled use the example of oestrogen

Answer 9

Oestrogen is lipid soluble so diffuses through the lipid bilayer
Complementary to the receptor molecule on a transcriptional factor
Oestrogen causes a shape change in the transcriptional factor
Transcriptional factor enters nucleus and can bind to the specifc DNA sequence that enables the gene to be transcriped

Question 10

Describe transcriptional control

Answer 10

Transcriptional factors can bind to a specific sequence on DNA
This binding triggers transcription
Hence forms mRNA

Question 11

Define the epigome

Answer 11

The chemical tags on histone proteins that cause genes to be expressed more or less easily

Question 12

Describe acetyls effect on the epigenome

Answer 12

Deacetylation is the removal of acetyl groups from histones
Increases the positive charge on the histones
Histones more attracted to the phosphate on DNA
The histone complex is wound more tightly
Genes turned off as DNA cant be reached by transcriptional factors

Question 13

Describe methylations effect on the epigenome

Answer 13

Addition of methyl groups to cytosine bases
Prevents transcriptional factors from binding
Attracts proteins that induce deacetylation

Question 14

What is a way of treating epigenetic conditions ?

Answer 14

Use enzyme inhibitors that target methylating enzymes

Reactivates a gene

Question 15

Describe how translation can be controlled

Answer 15

Inhibit by breaking down mRNA

1) enzyme cuts double stranded RNA into small sections
2) small interfering RNA (siRNA) combines with enzyme
3) siRNA binds to complementary section of mRNA
4) the attached enzyme breaks the mRNA down
5) mRNA is no longer translated

Question 16

What is the cause of cancer?

Answer 16

Damage to the genes responsible for mitosis regulation

Hence unregulated division occur

Question 17

What are the two types tumour?

Answer 17

Benign

• slow growths
• normal nuclei
• compact
• can cause disruption to organs
• surgery used to remove

Malignant

• rapid growth
• unspecialised cells
• not compact so can move to other parts of the body
• treated with radiotherapy

Question 18

Describe proto oncogenes and what they may mutate into

Answer 18

Proto-oncogenes stimulate division when a growth factor is attached
Activates genes to replicate

May mutate into an oncogene
Permanently activated either because a receptor protein is turned on or the oncogene codes for a growth factor
Leads to rapid cell division

Question 19

Describe the role of tumour suppresor genes in cancer

Answer 19

Tell cells to die through apoptosis
Slows dell division and removes mutated cells

If the tumour suppressor gene is turned off this wont occur and cell growth is no longer inhibited

Question 20

how may a tumour suppressor gene may become turned off?

Answer 20

Hyper methylation