Flashcards
Genetics and Evolution III
Flashcards do conjunto (22)
- 1What can you use to identify genes responsible for a trait?Recombination
The closer 2 genes are on a chromosome the less likely they are to be separated by recombination and the more likely these alleles are to be co-inherited
Recombination mapping narrows down the region to help find the gene - 2Draw a diagram used to explain finding yfgparental chromosomes
marker mutants for regions
Red chromosome has wild type alleles homologous to the mutant alleles.
Blue chromosome is allowed to recombine with the red chromosome, producing a female that's heterozygous, with each egg produced from that female potentially having a recombination event - 3What do you force the parents to do you sexually depraved git?Sexy types wild type with all mutants, see whether the offsprings chromosomes each has a copy of these mutations or not
Use the markers to tell whether a specific region has come from the blue or red chromosome. - 4What does SNP stand for?Molecular marker known as a single nucleotide polymorphism
The chromsomes being studied have a nucleotide at a specific position in the genome e.g.
GATTTAGAATTC
GATTTAGAAGTC - 5What is RFLP?Restriction Fragmentation Length Polymorphism
(e.g. using EcoR1 restriction site).
GAATTC is a recog site for EcoR1 to exise the DNA at that site, it won't recognise allele 2 as the sequence has been altered. - 6Describe the banding this would causeIf DNA that was homozygous for allele 1 was taken,amplified, then cut with EcoR1, 2 bands would be produced, being 2kb an 1kb
Look at the lecture for this again - 7Name one more example of a markerVariable repeat lengths
PCR using flanking primers can be used to amplify the variable length region
These regions are highly variable and so are present as multiple different alleles in the population.
Basis for genetic finger printing.
(Diagram). - 8Why are chromosome deletions not so bad?(a) Most wild type alleles are dominant to loss of function alleles
(b) Therefore mutations or complete removal of one copy of the gene isn't detrimental to survival
(c) Chromosome deletions can remove just a tiny bit of DNA or remove large regions, there is a maximum size deletion that is tolerated. - 9What is the basis of identifying actively expressed DNA?Actively transcribed DNA has to be more open in structure and less compact, as a result it stains less darkly with dye.
As some genes are active and some aren't you'll get variable bands of lighter/darker DNA. - 10How can this staining be used to find chromosome deletions?If there's chromosomal deletion in one copy of the DNA and not in the homologue, pairs of chromosomes will loop out during synapses as there's nothing to bind to.
We can then study these loops to see if the gene is in the missing bit or not by mapping the deletions. - 11What will occur if mfg is part of the deletion?Investigating whether mfg is in the chromosomal deletion represented in red
If mfg is part of the deletion then no functional copy of the gene will exist as the mutant will have no functional copy as the gene is recessive, and that will show as the phenotype of interest (male sterility) will occur. - 12What will occur if mfg isn't part of the deletion?Normal fertile flies will be produced
We'll know that it's not in the overlapping region with vir130 a the offspring wouldn't be sterile if it were. - 13What is the region defined by?Physical break boxes, this then has to be mapped back to the genome and can be found by comparing to proximal genes to the gene of interest.
- 14What is HoloprosencephalyHoloprosencephaly causes neural and facial ventral midline defects
cyclopia, close eyes, incomplete forebrain separation
single central incisor - 15What can cause HPE?At least 12 different loci
first 3: SHH at 7q36
HP34 is mapped to a haplo-insufficient region in 18p11 - 16What does haplo-insufficient mean?Phenotype present only in one functional copy of a locus.
- 17Why was HPE4 easy to find?As the mutation is dominant (haplo-insufficient).
Deletions of a region of Chromosome 15 are visible cytologically in some patients.
TGIF, a gene important in the formation of the ventral midline was already identified in that region - 18How do you map recessive mutations in family?Do a pedigree analysis to look at those inbred dirty fuckers
- 19Describe infantile-onset symptomatic epilepsy syndromecaused by a homozygous loss-of-function mutation of GM3 synthase.
Autosomal recessive
found cos inbred asf amish family - 20Honing in on the gene"We carried out a genome-wide screen for linkage and identified a single region of homozygosity on chromosome 2p12 - p11.2 spanning 5.1 cM
Molecular markers were used to see which bits of the genome were homozygous in all affected individuals and in more of the unaffected individuals.
Marker is so close to the gene of interest that it hasn't recombined in any of the meiosis events
Lots of variable length repeat PCRs (In a high thoroughput system.)
Makers distributed over the whole genome - 21How will an individual who is homozygous for mfg be for a marker that's extremely close to it?mfg will be homozygous for it, and not homozygous to distant markers.
- 22Why do most marker alleles segregate independently of the disease status?As they're on different chromosomes or far away on the same chromosome
specific alleles of
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- O usuário eliminou as informações de disciplina FlashCards sobre Genetics and Evolution III, criado por Usuário eliminado em 05-03-2018.
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- Criado por J yadonknow · 27 fev 2018
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