Chapter 13: Extensions of and Deviations from Mendelian Genetic Principles Flashcards
Multiple alleles?
- in a population of individuals a given gene can have multiple alleles (usually one wild type and the rest mutant) not just two as previously we’ve been studying.
Wild type allele?
- most common in the population
Multiple allele example?
- blood types
Multiple alleles:
- Blood Types
L> two possible antigens?
L> four possible blood groups ?
L> rules for each blood group?
L> A and B
L> AB, A, B, O (phenotypes)
L> do not have antibodies against self antigens - do not have antibodies against non self antigens
What are the genotypes of O, A, B and AB?
- ii
- IAIA or IAI
- IBIB or IBI
- IAIB
For the blood genotypes what kind of expression goes on?
IA andIB are dominant to i (no surface antigens)
IA and IB are codominant with each other!
IA and IB code for what?
- glycosyl transferase…each enzyme modifies the H structure on the red blood cell surface in a different way.
Since IA and IB are codominant what does this mean for their structure?
- Both H structure mods are present on the RBC
In RBC the i allele produces what kind of enzyme?
- nonfunctional
Multiple Alleles…..Codominance example with Drosophila!
- X-linked eye colour gene:
W+= red eye colour
W= white eye colour
We= eosin eye colour
ranking?
W+ is dominant to We and W
We is dominant to W
(see slides for run through example of this)
Incomlete dominance?
- when one allele of a gene is not completely dominant to another allele of the same gene….the phenotype of a heterozygote lies within the range of the phenotypes of the homozygotous parents….this phenotype is called an intermediate
Incomplete dominance?
- this is called ___ dominance
- Heterozygous pheno is an ____ with repsect to the phenotype of the homozygous for either allele.
- An F2 ratio of _:_:_ from mating of heterozygous F1’s.
- intermediate
- 1:2:1
Codominance?
- the heterozygote exhibits phenotypes of both homozygotes
Ex: blood type IAIB
Complete dominance?
- this is called a ___ condition. Meaning?
- heterozygous condition
- Haplosufficient: 1/2 production sufficient for normal cell phenotype; dominant phenotype
- dominant allele is transcribed twice as frequently to result in an increase of protein production
(involves one gene)
Incomplete dominance?
- _____ condition
- called?
L>meaning?
- heterozygous condition
- haploinsufficient: 1/2 product is insufficent for normal cell phenotype; resulting in an intermediate phenotype
- gene product from one allele results in a mixed intermediate.