Lecture #8 Mendelian Inheritance (Autosomal Traits)

What does homozygous vs heterozygous mean?

Homozygous: same alleles per gene

Heterozygous: different alleles per gene

Who developed the first Punnet square? What animal breed did he produce?

Reginald Punnet

Autosexing Chicken:

a breed of chicken that carried a sex-linked gene that determined color, making males one color and women another

True or False: every gene only has a dominant and recessive allele

False, there can be multiple dominant and recessive genes per allele. If there are more than one, they are denoted with superscripts

What is a lethal allele? What example of lethal alleles did we cover in class?

A allele that if inherited by a specific population is lethal

Ex: in mice, if they obtain two Ay alleles, they get the Lethal Yellow gene, which turns their fur yellow and they die

What is a pedigree?

a chart that tracks which members of a family have a particular trait

What notation is typically used in pedigrees?

- Square: male

- Circle: female

- Diamond: sex

unknown/doesn't matter

- Circle(Line)Square:

partners

- Circle(double line)Square: consanguineous partners

- Shaded: affected individual

- Line through shape: dead

- Arrow pointing at shape: proband (individual that prompted the pedigree)

What are consanguineous pairs?

latin for "with blood"

inbreeding

What is meant by Autosomal Recessive Inheritance?

traits that do not occur on sex chromosomes

* more likely to appear in consanguineous pairs *

- equal frequency in males and females

- skips generations

What caused the blue people of Kentucky to be blue?

homozygous to gene, which caused a deficiency of NADH Diaphorase, which is responsible for turning the blood red

(methemoglobin -> hemoglobin)

What is the Agouti Signaling Protein?

a protein that allows the wildtype banding pattern in many mammals by antagonizing the MC1R receptor

controlling this gene is what causes color variants in domesticated animals

If the Agouti protein is working correctly, what color pattern is resulted? What is the protein is mutated?

Regular (Wildtype): striped hair pattern

Mutated: solid colors

What is autosomal dominant inheritance?

a dominant trait is transmitted through autosomes

- equally likely for each sex to inherit

- does not skip generations

Is Huntington Disease an autosomal dominant or recessive disease?

Dominant

What is trinucleotide expansion? For the example of Huntington's Disease, what gets repeated?

a sequence of nucleotides that gets overly repeated

For Huntington's there is a stretch of 36-100 CAG's

Does Huntington's develop in early or late life?

late

How many CAG repeats are considered normal, and when would it be considered Huntington's disease?

Normal: 11-35

Affected: 36-100

True or False: Huntington's Disease gets worse with every generation because more CAG repeats are encoded

True

The idea that the disease gets worse with every generation is Anticipation

What is Achondroplasia? Is it an autosomal dominant or recessive gene? What gene is affected?

Dwarfism

Dominant

FGFR3

*Lethal in homozygous state*

What does the KIT gene do? If affected, is this a autosomal dominant or recessive trait?

The KIT gene is responsible for normal melanocyte survival and migration (making an animal one uniform color). If mutated, leads to patches of no color

Dominant