mutations

Question 1

define mutation

Answer 1

a change in DNA structure, amount or arrangement

Question 2

where do mutations usually occur

Answer 2

in somatic cells- cells undergoing meiosis

Question 3

define muatgen

Answer 3

chemicals or radiation which increase the rate of mutation

Question 4

give some examples of mutagens

Answer 4

1) ionising radiation

2) chemicals such as polycyclic hydrocarbons

Question 5

what is a carcinogen

Answer 5

a mutation which causes caner

Question 6

list the two different types of mutation and give an example of what it may cause

Answer 6

1) chromosome mutation- down syndrome

2) gene mutation- sickle cell anemia

Question 7

define a chromosome mutation

Answer 7

a mutation causing large changes in chromosome structure and number affecting many genes and visible under a light microscope

Question 8

define a gene mutation

Answer 8

small changes in the base sequence, only affecting a single gene, and is a result of a fault in DNA replication

Question 9

what are the different types of mutation

Answer 9

1) deletion- a base is lost or deleted
2) insertion- an extra-base is added or inserted
3) substitution- one base is substituted for another

Question 10

what affects can a substitution mutation have

Answer 10

1) changes in the amino acid produced= missense mutation
2) no change in aminoacid produced= scilent mutation
3) changes the amino acid to a STOP= nonsense mutation

Question 11

outline sickle cell anaemia

Answer 11

1) a substitution mutation in beta hemoglobin resulting in the 6th amino acid (glutamic acid) being replaced by valine
2) changes the primary structure which in turn alters secondary, tertiary, and quaternary structure
3) causes haemoglobin to stick together forming long fibres making the sickle shaped
4) change in shape of red blood cells decreases ability to bind to oxygen

Question 12

If a homozygous individual who has sickle cell anaemia (HBs HBs) what will happen to their cells

Answer 12

are their cells will be effected and poteinally fateal

Question 13

fif an individual is heterozygous for sickle cell anemia ( HBa HBs) what will happen

Answer 13

an example of codominance- half their cells will be affected and oxygen carriage dorps 20%

Question 14

define cancer

Answer 14

uncontrolled cell division resulting in the production of a tumour made p of undifferentiated cells

Question 15

what is meant by a malignant tumor

Answer 15

when cells of te tumour break off and are carried in the blood stream forming a secondary tumour

Question 16

How can mutations increase cancer

Answer 16

1) changes to tumor suppressant gene- lack of proteins which halt cell division
2) proto-oncogenes- changes in the production of oncogenes which releases an excess of proteins stimulating cell division
3) mutations leading to lack of proteins involved in normal mechanisms of cell death (apoptosis)

Question 16

How can mutations increase cancer

Answer 16

1) changes to tumor suppressant gene- lack of proteins which halt cell division
2) proto-oncogenes- changes in the production of oncogenes which releases an excess of proteins stimulating cell division
3) mutations leading to lack of proteins involved in normal mechanisms of cell death (apoptosis)

Question 16

How can mutations increase cancer

Answer 16

1) changes to tumor suppressant gene- lack of proteins which halt cell division
2) proto-oncogenes- changes in the production of oncogenes which releases an excess of proteins stimulating cell division
3) mutations leading to lack of proteins involved in normal mechanisms of cell death (apoptosis)