Mendel's Rules
Mendel used this as his model system
Pea plants
This type of inheritance is always passed from an affected father to his sons. Affected sons always pass to their sons. Chromosomally typical females cannot inherit the trait.
Y-linked inheritance
Feather length in chickens is controlled by two alleles. Chickens with two alleles for long feathers have long feathers, while chickens with two alleles for short feathers have short feathers. Heterozygous chickens have medium-length feathers.
This is an example of which type of inheritance?
Incomplete dominance
Does this pedigree show autosomal dominant or autosomal recessive inheritance?
Autosomal Dominant
The term used by Mendel to describe homozygous individuals
True-breeding
Attached earlobes (e) are recessive to free earlobes (E). A man who is homozygous for recessive earlobes has children with a woman who is heterozygous. What is the probability they will have a child with attached earlobes?
50% or 0.5
In this type of inheritance, the trait is passed from mothers to all of their children. The trait can only be passed from females to their children. Males can never pass on the trait to any of their children.
Mitochondrial inheritance
A mutation in just one gene causes a person to have long limbs, vision problems, and heart abnormalities.
What is the term used to describe this phenomenon?
Pleiotropy
Does this pedigree show X-linked recessive or X-linked dominant inheritance?
X-linked recessive
This term describes when one gene masks or alters the expression of another gene.
Epistasis
Genotypic ratio of a monohybrid cross
1:2:1
Red green color blindness is an X-linked recessive trait. A man and a woman have a son. Neither parent is color blind, but one of their sons is somehow color blind.
What are the parents genotypes?
Mom: XdX
Dad: XY
You can also write these genotypes as XdXD and XDY
In camellia flowers, petal color is controlled by codominance. A scientist crosses a red flower with a red-and-white flower.
What are the predicted phenotypes of their offspring?
2 red
2 red-and-white
If this trait is not X-linked. How is it likely inherited?
Mitochondrial inheritance
Sometimes genes can be moved from one location in the genome to another location. This can change how that gene is expressed. Especially if that gene is moved into a region of heterochromatin. This is known as:
The position effect
Mendel found that tall stems (T) are dominant over short stems (t). He finds a tall pea plant in his garden, but does not know its genotype. He decides to cross that tall plant with a short pea plant.
If the offspring are all tall, what is the genotype of the tall parent plant?
TT - Homozygous dominant
Incontinentia pigmenti is an X-linked dominant genetic disorder the impacts hair, skin, and teeth. A woman who is heterozygous for the disorder has children with a man who has the disorder.
What is the probability a son will inherit the disorder?
What is the probability a daughter will inherit the disorder?
Sons: 50%
Daughters: 100%
A woman with type A blood (IAi) is married to a type B person (IBIB). What blood types could their children have?
This trait is autosomal recessive. What is the genotype of the individual labelled 9?
Dd
When two populations with the same phenotype are mated and the offspring share the same trait as the parents, this suggests that the mutations are in the same gene. This is known as ______________.
Allelic Heterogeneity
Name two of Mendel's postulates
1. Alleles are in pairs
2. One allele is dominant and one is recessive
3. Alleles segregate randomly (egg and sperm get 1 copy)
4. Independent Assortment
A trait which is determined by the mother’s genotype rather than the offspring's genotype is an example of:
Maternal Effects
If the mother of a child is blood type O and the child is A, what are the possible genotypes of the father?
(all possible must be listed)
IAIA
IAi
IAIB
This trait is X-linked. Determine how it is inherited and the genotype of individual II-4
People in a family share a mutation that causes vision loss. This mutation causes some family members to go completely blind and others to have mild vision loss. This is an example of ______
Variable Expressivity