Professor Moon lecture 4+5+6

Question 1

dihybrid ratio when heterozygous

Answer 1

typically 9:3:3:1
9-dominant alleles
3-one recessive allele
1-both alleles recessive

Question 2

dihybrid testcross

Answer 2

produces equal number of parental and recombinant type of progeny, if the 2 genes are on diff chromosomes

Question 3

tester

Answer 3

homozygous recessive to the genes being tested

Question 4

chi squared test

Answer 4

Question 5

Recombinant

Answer 5

The genotypes that are not identical to the parental input
-they are produced during meiosis

Question 6

when does crossover occur

Answer 6

occurs after DNA replication in the four chromatid stage between nonsister chromsomes to increase genetic diversity

Question 7

multiple crossovers

Answer 7

• the number of chromatids involved in the crossover depends on the number of parental genotypes that appear in the product
  ex. if only 1 parental genotype is present in the final step, the crossover was between 3 chromatids

Question 8

gene distance

Answer 8

the farther apart the genes are the more likely they are to crossver and produce recombinants (relative distance is reflected in the recombination frequency, as the more likely it will be to occur the closer the RF is to 50%)

Question 9

three point testcross

Answer 9

used to test if the three genes are linked together, if the recombination frequency is less than 50% for the recombinants they are linked
-if there are 2 crossover events that occur, you multply the number of genes that recombine by 2

Question 10

How do you use chi square test to infer linkage?

Answer 10

you create a hypothesis that if A and b are not linked their segregation is determined by independent assortment
(when percent of chi square test is below 0.05 then the hypo is rejected)

Question 11

How to map a gene with molecular markers?

Answer 11

-You can use a PCR test since the molecular markers are seen as bands on a gel, they are used to map a gene of interest to determine linkage

Question 12

What are molecular makers?

Answer 12

they are small DNA sequence differences (polymorphisms) that are present at specific chromosomal locations

Question 13

Simple sequence length polymorphisms (SSLPs)

Answer 13

-different numbers of copies of these short simple DNA repeats are present in diff individuals

Question 14

Difference between minisatellite markers and microsattelite markers

Answer 14

minisat markers (known as DNA fingerprints) have variations in the number of tandem repeats of repeating units 10-100bp long
-microsat markers are variable number of tandem repeats ofa simpler sequence

Question 15

What do the patterns produced on gel electrophoresis/PCR for simple sequence length polymorphisms (SSLP) mean?

Answer 15

-the patterns on the gel by SSLPs at multuple locations on the genome can function as DNA fingerprint

Question 16

How can DNA fingerprints be used to solve violent crimes?

Answer 16

distant cousins of the criminal are likely to share some of the markers in the DNA

Question 17

what is the criteria for something to be classified as a single nucleotide polymorphisms (SNP)?

Answer 17

-the variant must be found in at least 1 percent if any population, if it is less than this the variant is just a mutation of an individual.

Question 18

Where are SNPs found in a gene?

Answer 18

SNPs are found in the intergenic region, within a gene or in a regulatory region near a gene

Question 19

Do SNPs effect health/development?

Answer 19

-most SNP do not have effect on health or development
-Some SNPs, found within a gene or regulatory region near a gene may play a role in susceptibiliity of a diases/sensitivity to an external factor

Question 20

What does mapping of short sequence link polymorphisms (SLLP) indicate?

Answer 20

the shared gene/allele positions can show what traist were inherited from which parent/individual.

Question 21

What type of deletion results in cystic fibrosis (CF)

Answer 21

-3 nucleotide deletion, loss of Phe508

Question 22

What is a haplotype?

Answer 22

its the physical grouping of genomic variants (or polymorphisms) that tend to be inherited together as a single group

Question 23

DOes the environment influence gene variances?

Answer 23

Yes it does for example, native to high altitude regions have adapted to life there, whereas low altitude individuals would have a hard time there.

Question 24

What genes allow for higher number of RBC at higher altitudes?

Answer 24

The SNP (short nucelotide polymorphism) in a gene called EPAS1 regulates the number of RBC that our bodies produce in response to the level of oxygen in our tissue