Genetics

Question 1

how many pairs of chromosomes in humans

Answer 1

23

Question 2

2 types pf nucelobases found in DNA

Answer 2

purine

pyrimidines

Question 3

purine bases

Answer 3

A, G

Question 4

pyrimidine bases

Answer 4

C, U, T

Question 5

nucelobases are attached to..

Answer 5

sugar molecule called deoxyribose

Question 6

what is attached to the deoxyribose

Answer 6

phosphate

Question 7

what is the structure of a nucelotide

Answer 7

deoxyribose
nucleobase
phosphate

Question 8

what are mutations

Answer 8

heritable permanent changes in the base sequence of DNA

Question 9

what is a point mutation

Answer 9

transition

transversion

Question 10

what is a deletion/ insertion

Answer 10

loss or gain of nucleotides that may cause a FRAME SHIFT

Question 11

what is a silent mutation

Answer 11

change in the nt. sequence but not in the aa that is coded for

Question 12

mis-sense mutation

Answer 12

change in the nt. sequence and the aa that is coded for

Question 13

non-sense mutation

Answer 13

change of the aa code to a stop codon= truncated protein

Question 14

mutations arise due to

Answer 14

1. (low) error rate of DNA polymerase (1 in 10^10). DNA polymerase has 3’5 exonuclease activity
2. physical factors: ionising radiation, non-ionising radiation
3. chemical factors: base analogues, nitrous acid, alkylating agents

Question 15

what is another term for single gene disorders

Answer 15

monogenic disorder. traceable to a single mutated gene

Question 16

name 3 major monogenic RECESSIVE disorders

Answer 16

1. cystic fibrosis- recurrent lung infections
2. sickle-cell anaemia - anaemia
3. thallessaemias- anaemia

Question 17

what is the effect of nitrous acid

Answer 17

GC to AT transitions

de-aminates cytosine to uracil