Genetics of Quantitative Characters II

Question 1

Define Anisogamy

Answer 1

the fusion of two gametes that differ greatly in size

Question 2

Define Patrilineal Inheritance

Answer 2

Male inherited genes- genes passed to offspring on the Y-chromosome.

Question 3

What are the PAR 1 and PAR 2?

Answer 3

Pseudo-Autosomal Regions are small sections on the end of the Y-chromosome where recombination takes place.

Question 4

Why is recombination suppressed in the Y chromosome?

Answer 4

To prevent male determining genes being lost to the X chromosome and to prevent the redundant Y-chromosome regions disrupting the X chromosome.

Question 5

Describe the content of the Y-chromosome.

Answer 5

• filled with redundant genes and mutations
• main functional gene is the SRY sex determining region
• Huge palindromic regions

Question 6

What is a possible function of the palindromic regions on the Y-chromosome?

Answer 6

Many of the functional genes are present in palindromic regions- possible that the palindromy is intentional as a form of mutation correction.

Question 7

Describe the function of the SRY gene

Answer 7

Codes for transcription factors that bind to DNA, bends and unwinds it. Promotes transcription of Sox9 which induces male reproductive system

Question 8

Why is the Y chromosome useful in tracing ancestry?

Answer 8

Males who share a common patrilineal ancestor also have common CY which are pretty identical besides divergence in accumulated mutations. Common Haplotypes detected.

Question 9

Define Haplotype

Answer 9

A collection of specific alleles in a cluster of tightly linked genes that tend to be inherited with each other.

Question 10

Describe the story of the Lemba people.

Answer 10

• always claimed jewish ancestry

- genetic tests have shown men of Buba clan carry Y chromosome haplotypes unique to Cohanim Jews.

Question 11

Define Matrilineal Inheritance

Answer 11

Female Inherited genes- genes passed on the X-chromosome

Question 12

Give an example of Matrilineal inheritance in plants

Answer 12

Mirabilis Jalapa- 4 o clock plant. Leaf colour gene is found in chloroplasts. Variegated leaves occur when eggs have varying copies of the gene, varying levels are expressed.

Question 13

Give an example of mitochondrial inheritance in prokaryotes.

Answer 13

Inheritance of poky in the fungus Neurospora. Poky mutation causes slow growth and development. Gene is found in cell mitochondria.

Question 14

What are the principles behind The Endosymbiotic Theory?

Answer 14

Organelles that carry their own nucleic acids were once unicellular organisms

Question 15

Give an example of Endosymbiosis that is detrimental to host organism

Answer 15

Ladybirds carry Wolbachia which can only live inside the egg cell. The bacteria kill male larvae to increase their chance of survival.

Question 16

What is Leber’s Hereditary Optic Neuropathy an example of?

Answer 16

Mitochondrial Inheritance- its a degeneration of the Optic nerve due to deletion in MT DNA.

Question 17

What is Myoclonic Epilepsy with Ragged Red Fibres (MERRF) an example of?

Answer 17

Mitochondrial Inheritance- caused by a point mutation in mitochondrial DNA disrupts OXPHOS leads to clumps of MT, appear as “ragged red fibres”

Question 18

Describe the effect of age on Mitochondrial related disorder

Answer 18

• MTs are damaged during aging; drooping of muscles by muscle weakness
• Damaged MTs take over in tissue as they are smaller (deleted DNA)

Question 19

What is a likely cause of MT decay?

Answer 19

• MTs evolved to be aerobic
• Produce reactive O2 species
• These damage DNA over time
• Worse in organs that rarely divide (brain, heart) as toxic product build up

Question 20

Explain how mice have been used in creating 3 parent offspring

Answer 20

• egg nucleus of an MT disorder female
• inserted into an enucleated egg cell of healthy female
• fertilised with regular sperm