Mutation and Mutagenesis

Question 1

Detecting mutagens in maize

Answer 1

Triploid endosperm, recessive 'white' allele, C
Cross cc (female) x CC (male) → Ccc (coloured)
Any mutation creates single white seed, can count mutations

Question 2

Detecting mutations in mice

Answer 2

aa bb cc ++ ++ x ++ ++ ++ dd ee → a+ b+ c+ d+ e+

Mutates at c allele → white coat mice, can be counted

Question 3

Detecting mutations in humans

Answer 3

Ames test - using Salmonella to determine whether a chemical is a mutagen
Spontaneous dominant mutations eg. Neurofibromatosis can be used to calculate mutation rate

Question 4

Detecting mutations using molecular biology

Answer 4

Screen proteins + DNA for changes between offspring and parents

Question 5

Detecting mutations using molecular biology

Answer 5

Screen proteins + DNA for changes between offspring and parents

Question 6

Mutagens

Answer 6

Agents that increase mutation rate

Question 7

Ionising radiation

Answer 7

Radon watch-dial painters 1920’s died of bone cancer

Muller found the linear effect of x-rays, studied recessive lethals using ‘balancer’ technique

Question 8

DNA repair mechanisms

Answer 8

Mutational damage repaired over time
Dinococcus radiodurans + naked mole rat withstand higher radiation doses
Effects of radiation at Hiroshima and Nagasaki: short term = radiation sickness, long term only 6 differences between parents and offspring - not evidence of germinal mutation, slight increase in thyroid cancer

Question 9

Chemical mutagens

Answer 9

War gases caused mutations
Ames test
Alfatoxin from certain fungi - highly carcinogenic
Natural mutagens - black pepper
Antimutagens - vitamin C

Question 10

Mutation is inevitable property of the genome

Answer 10

Certain genes increase mutation rate in others
Failures of repair enzymes are involved in cancers
Some cancers emerge from somatic mutation of normal allele in individual who is heterozygous for a recessive allele that predisposes towards cancer

Question 11

Mutation is inevitable property of the genome

Answer 11

Certain genes increase mutation rate in others
Failures of repair enzymes are involved in cancers
Some cancers emerge from somatic mutation of normal allele in individual who is heterozygous for a recessive allele that predisposes towards cancer

Question 12

Darwin Evolution

Answer 12

Descent with modification

Question 13

William Jones

Answer 13

Made parallels with change in language

Question 14

Evolution of skin pigmentation

Answer 14

Leaving Africa associated with necessity to synthesise Vitamin D, origin of blondes

Question 15

Different geographical pop. of humans

Answer 15

Genetically more similar than different geographical populations of chimps

Question 16

Humans vs. Chimps

Answer 16

Large deletions in human genome - less sexual selection
Surface area of intestine is 1/5 size of chimps - inability to digest raw food
Chimps produce 6x as much sperm to flood out previous mate
Deleted male hormone receptor in humans - lack Androgen receptor - effect hairiness in mice and spines in penis of humans

Question 17

HIV and AIDS

Answer 17

SIV = chimp version of HIV, not as dangerous
AIDS = natural selection, certain types of surface receptor will prolong time until infection
No. copies of CCL3L1 is higher in those species that have been exposed to more HIV - natural selection as it helps survival

Question 18

Evolution of humans from primates

Answer 18

Forkhead Box [Fox13] gene mutation → lack of hair except on top of head
Deletion in human sarcomeric myosin → not as strong
Increased brain size + neuronal connectivity → ability to speak, ‘Brocas’ area [Foxp2] locus allowed development of language, verbal dyspraxia = disruption of Brocas area