Molecular Genetics

Question 1

how many chromosomes in a eukaryote?

Answer 1

46 (23 pairs)

Question 2

what are autosomes?

Answer 2

the 1st 22 pairs of chromosomes

Question 3

What are sex chromosomes?

Answer 3

the 23rd pair of chromosomes

Question 4

what are alleles?

Answer 4

different forms of one gene

Question 5

what are allotypes?

Answer 5

different forms of one protein (isoforms)

Question 6

what is polymorphic?

Answer 6

alternative forms of one gene (many alleles)

Question 7

what is oligomorphic?

Answer 7

few forms of one gene (few alleles)

Question 8

what is monomorphic?

Answer 8

no polymorphism

Question 9

what is homozygous?

Answer 9

same allele on both inherited chromosomes

Question 10

what is heterozygous?

Answer 10

different allele on both inherited chromosome

Question 11

what type of cells divide in a) mitosis b) meiosis?

Answer 11

mitosis: division of somatic cells
meiosis: division of germline cells

Question 12

what three codons are stop codons?

Answer 12

TAG, TGA, TAA

Question 13

what is a mutation?

Answer 13

an alteration or change in the genetic material

Question 14

three things that can cause mutation?

Answer 14

1. inherited
2. error in DNA replication/repair
3. exposure to mutagenic agents

Question 15

classes of genetic diseases?

Answer 15

1. chromosomal
2. monogenic - one gene
3. multifactorial - genetic and environmental factors
4. polygenic - many genes
5. somatic - mutation in somatic cells
6. mitochondrial - mutation in mitochondrial genome

Question 16

what causes single gene disorders?

Answer 16

a change in one or both copies of a particular pair of genes

Question 17

what are the three common types of single gene disorders?

Answer 17

1. autosomal dominantv(expressed if at least one chromosome affected i.e. heterozygous)
2. autosomal recessive (expressed if both chromosomes affected i.e. homozygous)
3. X-linked (only on X chromosome so females affected but males only affected if they inherit mutant gene)

Question 18

Explain what it means for males and females if the X-linked disorder is recessive and if its dominant?

Answer 18

recessive:
for males they’ll have the disorder but can’t pass it on to male kids, only female kids.
for females, only have the disorder if mother gives them the recessive allele also.
Dominant:
fatal for both males and females

Question 19

where does one inherit their mitochondrial DNA from?

Answer 19

the egg

Question 20

what are numerical chromosome abnormalities?

Answer 20

the gain or loss of complete chromosomes

Question 21

what are chromosome aberrations?

Answer 21

1. deletion (section missing)
2. translocation (section shifts from one chromosome to the other)
3. inversion (section snipped off then reinserted the wrong way round)

Question 22

what type of gene therapy is currently available to humans?

Answer 22

somatic gene therapy

Question 23

what are three theoretical types of gene therapy?

Answer 23

1. replacement (of mutant gene with correct one)
2. correction (mutated area corrected and remainder left unaffected)
3. augmentation (foreign genetic material into cell to compensate for defective product of mutant gene)-this is the only gene therapy available atm