Chapter 4: Extensions of Mendelian Inheritance Flashcards
What is simple mendelian inheritance?
involves a single gene with 2 different alleles and display a dominant/recessive relationship
What kind of ratio does simple mendelian have?
3:1 (Rr x Rr)
Incomplete pentrance is
% based
Give an example of incomplete pentrance
everyone has the genetics to run a 10second 100m dash but only 10% of the population actually does. The other 90% does not.
Variable Expressivity is
spectrum based
Give an example of Variable expressivity
Skin color, autism
- dark, medium, white
Incomplete dominance is
the blending of colors
give an example of incomplete dominance
flowers: one red, two pink, one white (1:2:1 ratio)
In complete dominance what does A/A, A/a, and a/a mean (what color)?
A/A - red
A/a - pink
a/a - white
Red flower x white flower = pink flower (intermediate of those two phenotypes)
Overdominance/Heterozygote Advantage
The heterozygote A/a has greater fitness than A/A
Give an example of over dominance/heterozygote advantage
Sickle Cell
AA = no sickle cells, no malaria resistance
A/A = No sickle cells, malaria resistance
a/a = sickle cell disease, malaria resistance
Codominance is
where 2 dominant alleles are expressed at the same time
Give an example of codominance
white cow x brown cow = roan cow
white AND brown spots
X-linked is
- associated genes with the X-chromosome
- males receive X from Mom
- female receives one X from Dad
Sex-influenced Inheritance
Both males and females have the same genetics for a trait but its commonly seen in one sex vs the other
give an example of sex-influenced inheritance
Baldness
BB = bald in either sex
Bb = bald in males only
bb = bald in females only
Breast cancer
Sex-limited Inheritance
Both sexes have it but only one sex will ever express it
Example of Sex limited inheritance
- Horns only in Males not females. (even if they get D/D they do not have the hormones to produce horns
- female mammals breast milk
Lethal Alleles
occurs when 2 dominant alleles contributes to death of an organism
- YY = dead
What is a gene interaction?
- when two or more genes influence the outcome of a single trait
- morphological traits like height, weight, eye color, pigmentation are affected by many different genes in combination with environmental factors
List 3 examples of environmental factors
- Siamese cats - dark hair around sensitive areas
- PKU - enzyme deficiency (build up of uric acid)
- Facets of Flies eyes (temperature impacts how many facets they have)
What is epistasis?
- idea that genes can interact with one another and cause different phenotypes
- one gene is controlling the expression of another gene
- the Umbrella (complementation goes around it)
What is complementation?
When 2 different organisms or 2 different phenotypes that mate together will bring back the original wild type or dominant phenotype
What is gene knockout?
due to gene redundancy, loss of function alleles may have no effect on the phenotype so geneticists have developed techniques to generate loss of function alleles called gene knockout
