Lecture 11: Allelic Interactions

What concept describes the phenomenon where multiple alleles can interact to affect phenotypes?

Pleiotropy.

What is the expected phenotypic ratio from a heterozygous cross in simple Mendelian genetics?

3:1 phenotypic ratio.

What does independent assortment refer to in genetics?

Independent assortment refers to the way different genes independently separate from one another when reproductive cells develop.

What is it called when a gene has variations that influence multiple traits?

Pleiotropy.

What is Marfan syndrome?

Marfan syndrome is a genetic disorder that affects connective tissue, leading to elongated limbs and heart problems.

What phenotypic ratio might indicate a recessive lethal allele in a genetic cross?

2:1 ratio.

Why did Mendel's observations not account for multiple alleles?

Mendel did not recognize how multiple alleles and gene products could interact.

What gene is associated with Huntington's disease, and when does it typically manifest?

Huntington's disease is associated with the Huntington gene, which usually manifests in mid-twenties.

What is the basic outcome of a heterozygous cross with a plant exhibiting incomplete dominance?

A 1:2:1 genotypic ratio.

What is antagonistic pleiotropy?

Antagonistic pleiotropy is when a single gene influences multiple traits in ways that may benefit some traits while harming others.

What is the significance of p53 in human biology?

P53 is a crucial protein that prevents cell growth and plays a role in cancer prevention.

How does one identify if a genetic trait follows incomplete dominance?

By observing a phenotypic ratio of 1:2:1 in the offspring.

What is the expected genotypic ratio from a cross of two heterozygous yellow agouti mice?

2:1 ratio indicating a lethal allele.

What does the term complete penetrance mean?

Complete penetrance means that all individuals with a particular genotype express the corresponding phenotype.

What can a 2:1 phenotypic ratio indicate about a gene?

A 2:1 ratio can indicate that the missing phenotype is associated with a lethal allele.

What results did Lucian observe with his agouti mice upon crossing them?

He consistently got a 2:1 phenotypic ratio of yellow to brown.

What kind of inheritance pattern results in a condition where one genotype never produces offspring?

Recessive lethal inheritance.

What genetic principle states that traits are inherited independently of one another?

The law of independent assortment.

In genetic crosses, what does a 3:1 ratio typically represent?

A typical dominant-recessive inheritance pattern.

What is the fundamental principle that Mendel used to derive his laws of inheritance?

Mendel used pea plants to demonstrate how traits are passed down through generations.

What kind of expression of a gene might be influenced by environmental conditions such as temperature?

Conditional gene expression.