Genetics

Question 1

DNA is two parallel strands true/false

Answer 1

false - anti-parallel

Question 2

DNA copies in a 3’ to 5’ fashion continuously true/false

Answer 2

false - 5’ to 3’

Question 3

what are the stages of the cell cycle and what happens during each stage

Answer 3

G1 - growth phase
S - DNA replication
G2 - growth phase inc. protein synthesis
M - mitosis
G0 - resting phase where no replication occurs

Question 4

what are the phases in which mutation can occur

Answer 4

between G1 and S

between G2 and M

Question 5

describe the process of DNA replication

Answer 5

DNA helicase unzips DNA
DNA polymerase copies 5’-3’ strand fully and 3’-5’ in okazaki fragments
the lagging strand is joined by DNA ligase

Question 6

with 90 bases present how many amino acids are expected to form

Answer 6

30

Question 7

what is a single nucelotide polymorphism

Answer 7

sequence changes in DNA between genes - does not always cause disease but may predispose

Question 8

what is aneuploidy

Answer 8

added or missing chromosome

Question 9

what is trisomy

Answer 9

addition of chromosome

Question 10

what is misomy

Answer 10

missing chromosome

Question 11

what is reciprocal translocation

Answer 11

rearranging of chromosomes by swapping the two areas

Question 12

what is robertsonian translocation

Answer 12

addition of part of another chromosome near the centromere of another

Question 13

Downs syndrome chromosome arrangement is

Answer 13

47XY + 21

Question 14

47XY + 18 is what condition

Answer 14

Edwards syndrome

Question 15

45XO is what condition

Answer 15

Turners syndrome

Question 16

47XXY is what condition

Answer 16

Kleinfelters syndrome

Question 17

describe the penetrance of a mutation

Answer 17

the likelihood of a mutation causing disease

Question 18

tumour supressors

Answer 18

inhibit cell division

p53 and BRCA

Question 19

oncogenes

Answer 19

promote cell division

ras and raf

Question 20

name some examples of mendelian inheritance

Answer 20

autosomal dominant
autosomal recessive
X linked
mitochondrial

Question 21

mendelian inheritance has high/low penetrance

Answer 21

high penetrance - disease caused by a single gene

Question 22

describe autosomal dominant mutations

Answer 22

only require one mutation to show disease
50% of children will be affected
present in all generations

Question 23

describe autosomal recessive mutations

Answer 23

require 2 faulty copies of the gene for disease

25% of children will be affected

Question 24

describe X linked mutations

Answer 24

cannot be passed on from father to son

random X inactivation may mean child is not affected

Question 25

how is mitochondrial mutations passed on

Answer 25

from mother to child only

Question 26

describe multifactorial disease

Answer 26

genetics is just one factor affecting change of developing disease
cancer is example of multifactorial disease - lots of underlying factors

Question 27

what does DNA methylation inhibit

Answer 27

DNA replication as it modifies histones

Question 28

describe mosaicism

Answer 28

cells from the same person have different genetic makeup