Gene Expresssion

Question 1

Define frame shift with regard to genetic mutations

Answer 1

Frameshift- addition of one base or deletion of one base which causes all bases to shift changing all the codons
This can cause impacts to many amino acids likely producing proteins that cannot function properly

Question 2

Describe the different gene mutations that can occur

Answer 2

1. Addition
   Insertion of 1 or more nucleotides
2. Deletion
   Removal of 1 or more nucleotides
3. Substitution
   1 or more nucleotides replaced with another
4. Inversion
   A cut portion of a gene is inverted 180oc then rejoined in the same place
5. Duplication
   A whole gene or section of a gene is duplicated so that 2 copies appear on the same chromosome
6. Translocation
   A section of a gene is attached to a separate gene

Question 3

Name and describe the 3 forms of substitution mutation

Answer 3

Silent mutation - the mutation doesn’t alter the amino acids likely producing sequence (DNA = Degenerate)

Missence - the mutation alters a single amino acidd in the polypeptide chain

Nonsense - the mutation create a premature stop codon preventing the rest of the chain from undergoing translation

Question 4

Mutations occur spontaneously, what does that mean

Answer 4

Mutations occur continuously and spontaneously without exposure to mutagenic agents

Question 5

Def of stem cell

Answer 5

Self-renewing undifferentiated cell that has the ability to differentiate into any other specialised cell

Question 6

Explain the ability of stem cells

Answer 6

All genes present in the cell can be transcribed therefore it has the potential to synthesise all proteins

Question 7

What are the 3 groups of stem cells
+ explain them

Answer 7

1. Totipotent
   - divide to produce any cell type including trophoblast
2. Pluripotent
   - all cell types of an organism (not trophoblast)
3. multipotent
   - limited number of cell types

Question 8

What can totipotent cells divide to produce

Answer 8

Any type of body cells

Question 9

What happens to totipotent cells during development

Answer 9

During development, totipotent cells translate only part of their DNA, resulting in cell specialisation

Question 10

Where are the 3 types of stem cells found

Answer 10

Pluripotent
- found in embryos
Multipotent
- mature mammals
Unipotent
- mature mammals

Question 11

all conditions being treated with stem cells, involve transplants of bone marrow tissue from a donor to a patient.
Explain why this is an effective therapy for many disorders of the blood or immune system?

Answer 11

Disorder of the blood or immune system arise due to faulty blood cells
Donor bone marrow contains stem cells that will produce healthy blood cells
The patients own bone cells are destroyed with chemotherapy

Question 12

How do we obtain embryonic stem cells

Answer 12

1. Embryo allowed to develop at blastocyst stage
2. Inner cell mass cells are harvested
   (consisting of undifferentiated and pluripotent cells)

Question 13

Explain the ethnical and medical concerns of use of embryonic stem cells

Answer 13

Ethical
- involved destruction of human embryo
Medical
- antigens on embryonic cells would be recognised as foreign by patient therefore immunosuppressants would need to be taken
- ability of stem cells to continuously divide may lead to tumours developing