Mutations

Question 1

Define a mutation

Answer 1

A permanent change in the genetic material of an organism

Question 2

what are the 2 types of negative genetic disorders?

Answer 2

Genome mutation

Gene mutation

Question 3

Name 2 genome mutations

Answer 3

Aneuploidy - caused by excess or deficiency of chromosomes e.g trisomy 21

Chromosome mutations - rearragenement of genetic material

Question 4

Name 2 types of gene mutation

Answer 4

1. single gene mutations - caused by a mistake in a single gene e.g sickle cell anaemia
2. Multifactorial inheritance disorders - arise from an interplay of multiple genetic changes and environmental factors e.g cancer

Question 5

what are try 5 types of chromosome mutation and explain

Answer 5

1. Deletions - removal of a large chromosomal region leading to loss of genes
2. duplications (or amplifications) - lead to multiple copies of a chromosome region, increasing the number of genes.
3. insertions - addition of material from one chromosome to a non homologous chromosomes
4. Inversions - reverse the orientation of a chromosome segment
5. Translocations - interchange of genetic material

Question 6

Name some chromosome mutation disorders

Answer 6

trisomy 21 - Down syndrome 
Trisomy 18- Edwards syndrome additional copy of chromosome 18 
Trisomy 13 
Turner syndrome - monosomy x
monosomy 18P

Question 7

what is a gene mutation?

Answer 7

Results when the specific sequence of a gene changes - can occur at any time during the life cycle of a cell.

Question 8

what are the causes of gene mutations??

Answer 8

viruses
cigarette smoke
alcohol 
radiation 
chemicals

Question 9

Are all mutations heritable and copied in replication?

Answer 9

Yes

Question 10

Are all mutations passed onto the future generations?

Answer 10

No - only changes that affect the genetic information contained in reproductive cells - called germ line mutations will be passed onto the offspring.
Somatic mutations in non germ line tissue are not passed on e.g mutation In tumour

Question 11

what are frame shift mutations?

Answer 11

1. addition (insertion) - extra base is inserted into the genetic code and all bases after it are affected, the new gene does not make sense
2. Deletion - base is deleted from the genetic code, all bases after it are affected and the new gene does not make sense

Question 12

what is a point mutation?

Answer 12

a base is added, deleted or changed - but the new gene may still make sense. (change in nucleotide sequence)

Question 13

Name and describe 4 point mutations diseases

Answer 13

1. Sickle cell anaemia - point mutation in haemoglobin gene (sickle shape RBC, can’t move easily and block blood vessels leading to tissue damage)
2. Cystic fibrosis - mutation in CFTR gene. CFTR gene usually creates a protein that regulates Na and Cl in cells. This mutation means this does not happen - build up of thick sticky mucus in lungs
3. neurofibromatosis - tumours grow along nerves, mutation or deletion in neurofibromin 1 gene
4. Epidermolysis bullosa - inherited skin disorder which skin becomes fragile. Mutations in genes encoding the basal epidermal keratin 5 and K14

Question 14

How can we repair DNA? 2 ways

Answer 14

Extra copy of DNA provides a template in order to repair itself.
Errors are corrected via;
1. Homology directed repair
2. Non homologous end joining

Question 15

what is homology directed repair?

Answer 15

It repairs broken DNA strands by using the undamaged DNA template. (hence it is error free due to use of template) e.g. important in suppression of cancer formation

Question 16

what is non homologous end joining? (4)

Answer 16

Inserts or deletes base pairs, creates a frameshit.

• Disrupts gene expression
• Prone to exon skipping
• Not perfect

Question 17

How can we treat genetic disorders?

Answer 17

Gene therapy to correct defective genes.

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Question 18

what does gene therapy do?

Answer 18

Insert wild type gene into genome to replace mutated gene.
DO this by using a carrier molecule “vector” to deliver the gene to target cells (in vivo) - a common vector is a virus that has been genetically altered to carry human DNA.