Genetics of Quantitative Characters II Flashcards
Define Anisogamy
the fusion of two gametes that differ greatly in size
Define Patrilineal Inheritance
Male inherited genes- genes passed to offspring on the Y-chromosome.
What are the PAR 1 and PAR 2?
Pseudo-Autosomal Regions are small sections on the end of the Y-chromosome where recombination takes place.
Why is recombination suppressed in the Y chromosome?
To prevent male determining genes being lost to the X chromosome and to prevent the redundant Y-chromosome regions disrupting the X chromosome.
Describe the content of the Y-chromosome.
- filled with redundant genes and mutations
- main functional gene is the SRY sex determining region
- Huge palindromic regions
What is a possible function of the palindromic regions on the Y-chromosome?
Many of the functional genes are present in palindromic regions- possible that the palindromy is intentional as a form of mutation correction.
Describe the function of the SRY gene
Codes for transcription factors that bind to DNA, bends and unwinds it. Promotes transcription of Sox9 which induces male reproductive system
Why is the Y chromosome useful in tracing ancestry?
Males who share a common patrilineal ancestor also have common CY which are pretty identical besides divergence in accumulated mutations. Common Haplotypes detected.
Define Haplotype
A collection of specific alleles in a cluster of tightly linked genes that tend to be inherited with each other.
Describe the story of the Lemba people.
- always claimed jewish ancestry
- genetic tests have shown men of Buba clan carry Y chromosome haplotypes unique to Cohanim Jews.
Define Matrilineal Inheritance
Female Inherited genes- genes passed on the X-chromosome
Give an example of Matrilineal inheritance in plants
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.
Give an example of mitochondrial inheritance in prokaryotes.
Inheritance of poky in the fungus Neurospora. Poky mutation causes slow growth and development. Gene is found in cell mitochondria.
What are the principles behind The Endosymbiotic Theory?
Organelles that carry their own nucleic acids were once unicellular organisms
Give an example of Endosymbiosis that is detrimental to host organism
Ladybirds carry Wolbachia which can only live inside the egg cell. The bacteria kill male larvae to increase their chance of survival.
What is Leber’s Hereditary Optic Neuropathy an example of?
Mitochondrial Inheritance- its a degeneration of the Optic nerve due to deletion in MT DNA.
What is Myoclonic Epilepsy with Ragged Red Fibres (MERRF) an example of?
Mitochondrial Inheritance- caused by a point mutation in mitochondrial DNA disrupts OXPHOS leads to clumps of MT, appear as “ragged red fibres”
Describe the effect of age on Mitochondrial related disorder
- MTs are damaged during aging; drooping of muscles by muscle weakness
- Damaged MTs take over in tissue as they are smaller (deleted DNA)
What is a likely cause of MT decay?
- 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
Explain how mice have been used in creating 3 parent offspring
- egg nucleus of an MT disorder female
- inserted into an enucleated egg cell of healthy female
- fertilised with regular sperm
