W11 L1 - Mendelian Genetics and Evolution

Flashcards about Mendelian Genetics and Evolution lectures on Moodle.

What is pleiotropy?

When one gene has multiple functions or affects multiple phenotypes.

What is the law of segregation?

Each individual has two copies of each allele and passes on one of those at random to each gamete.

What is the purpose of a Punnett Square?

A Punnett Square is an accounting device, it helps you keep track of the alleles that are being passed on from one generation to another.

How do you build a Punnett Square?

Identify the genotypes of the parents, determine the gametes each parent can produce, set up the rows and columns, fill in the squares with the resulting genotypes, and then work out the phenotype.

What does it mean if a trait is expressed in every generation of a pedigree?

It is a signature of a dominant disease, where every generation carrying the allele shows the trait.

What does it indicate in a pedigree if a trait skips a generation and then reappears?

It suggests a recessive trait, where carriers in one generation can pass on the recessive allele, and the phenotype reappears when two carriers have offspring.

Why might a lecturer use made-up examples in genetics problems?

To encourage students to focus on the logical application of genetic principles rather than relying on prior knowledge of specific real-world cases.

If a plant breeds true, what does this mean for its offspring?

The offspring consistently have the same genotype as the parent, generation after generation.

Which offspring will exhibit the recessive phenotype?

Only the offspring with two copies of the recessive allele (homozygous recessive).

Why was using true-breeding strains of peas important for Mendel's experiments?

It allowed him to control the parental genotypes and accurately determine the rules governing inheritance in subsequent generations.

What is a test cross?

A cross used to determine the genotype of an unknown parent by crossing it with a homozygous recessive individual.

Why must you use a homozygous recessive parent with a test cross?

To ensure that the recessive allele from the known parent does not mask any information being passed by the other parent.

Why is it important to consider additional information when calculating probabilities in genetics problems?

Because additional information, such as knowing that an individual has a certain phenotype, can change the probability of them being a carrier for a particular trait.

When analyzing a pedigree, what can be said about a person with cystic fibrosis?

They are definitely dual recessive for the affected alleles.

What does it mean for an individual to be a dual heterozygote?

It means an individual that is heterozygous at both of the loci.

What are the possible gametes an individual heterozygous for two genes can produce?

They can produce four possible gametes: both dominant alleles together, dominant of the first and recessive of the second, recessive of the first and dominant of the second, and both recessive alleles together.

If a question asks what fraction of offspring

The answers must be converted into a decimal, or stay as a fraction. To appreciate it's a fraction of the offspring.