genetic linkage

Genetic LinkageGenetic patterns can be altered when genes are:1) On sex chromosomes2) On the same chromosome

Sex-Linkage

Genes are on the X chromosome

Sex LinkageA white-eyed male Drosophila and a red

eyed female produce equal numbers of offspring of each eye color. Can you rule out sex linkage with this data? Why or why not?

A red eyed male whose father had white eyes mates with a white eyed female. All of the daughters (56) have red eyes and all of the son’s (47) have white eyes.◦Use a chi square analysis to reject the

hypothesis that eye color is located on an autosome.

LinkageGenes that are on the same

chromsome are linked. Because of crossing over ratios differ from independent assortment.

How are these patterns different than expected?

For the previous cross…Use a Punnett Square to

determine the expected results from a test cross.

Use a chi square to determine if the data corresponds with the null hypothesis that the genes assort independently.

Linkage maps can determine location of genes on a chromosomeCrossover frequencies:

◦b-cn = 9%◦b-vg = 17%◦cn-vg = 9.5%

Linkage Map

Another linkage map:Crossover frequencies:

◦bz-c = 4.6 cM◦c-sh = 3.0 cM

◦What is a possible way to map these genes?

◦What additional information would help confirm your map?

Inheritance Patterns QuizMost genetic disorders show this

inheritance pattern.

QuizThis inheritance pattern would

alter the phenotypic ratio of the offspring and in some cases you might not see individuals with the recessive trait.

QuizThe term used to describe the

fact that skin color is based on the cumulative effects of 3 different genes.

QuizCarriers, heterozygous and this

term all refer to genotypes such as Bb!

QuizSome diseases are not caused by

DNA mutations but are caused by chromosomal mutations which can be observed through a karyotype. Name an example of one of these diseases.

QuizIn blood types, if an individual

carries the allele for type A and the allele for type B both markers are present on their blood cells. This is an example of.

QuizThe production of melanin can be

influenced by the environment which a person lives in. If a person lives at the North Pole, they will produce less melanin than an individual with the same genotype who lives at the equator. This trait is considered.

QuizMost albino’s have inherited a

hair color. Often, however, they have the phenotype of white hair. Usually pigment product is a pathway, and one of the transcription factors that controls that pathway is causing the albinism. This type of inheritance is considered.

QuizCystic fibrosis is a recessive

disorder that affects many body systems including the respiratory system and the digestive system. It is a single gene mutation, and it is considered…

Quiz..Hemophelia occurs more often in

males. This disease is inherited…

QuizAn individual heterozygous for

two traits is test crossed. The offspring that look like either of the parental phenotypes are 200 and the offspring that are recombinants are 50. This data suggests that the genes are…

MutationsTypes of mutations are:

◦ Point Silent Missense Nonsense

◦ Insertions/Deletions without frameshift◦ Insertions/Deletions with frameshift

Mutate the DNA sequence below with each of the above. Then explain how each might affect the protein function.

TAC CCA GAC CCC TTT AAA AUC