Classical Genetics and Heredity

Flashcards on the classical genetics and heredity lecture

Who is considered the father of classical genetics and heredity?

Gregor Mendel

What simplifying assumption is made about traits in classical genetics?

Some traits have an all or nothing property.

What is an allele?

A specific version of a gene.

What is the difference between a gene and an allele?

A gene is a location on a chromosome that codes for a trait, while an allele is a specific version of that gene.

What is a locus?

The location of a gene on a chromosome.

If you have two different versions of a gene, one from your mom and one from your dad, what are you called?

A heterozygote, or heterozygous genotype.

What is a genotype?

The exact versions of the alleles someone has.

If you have two identical alleles, what are you called?

A homozygote, and the genotype is homozygous.

What is a phenotype?

What is expressed or what you see.

What is dominance in genetics?

The idea that one trait overpowers or masks the expression of another trait.

In the example given, which eye color is considered dominant?

Brown eyes

In the example given, which eye color is considered recessive?

Blue eyes

If someone has a brown-eyed allele and a blue-eyed allele and brown is dominant, what eye color will they have?

Brown eyes

What is homozygous dominant?

Having two dominant alleles for a trait.

What is a heterozygote also called?

A hybrid

What happens during meiosis that contributes to genetic diversity?

Chromosomes line up in meiosis one, and we don't know which way they line up, leading to different combinations of alleles in the gametes.

If both parents are heterozygous for eye color (one brown allele, one blue allele), what is the probability that their child will have blue eyes?

25%

Can you determine genotype by looking at phenotype?

No, many different genotypes can code for the same phenotype.

What is a Punnett square used for?

To make predictions about the probabilities of different outcomes in genetics.

If both parents are heterozygous for a trait, what is the probability they will produce a heterozygote offspring?

50%

What do homologous chromosomes code for?

The same genes

What is the probability that two heterozygous parents for eye color will have a child with brown eyes?

75%

What are the assumptions made when using a Punnett square?

Assumptions about the genes and whether one is dominant or recessive.

What event did Gregor Mendel study well before knowing about DNA?

How traits are passed from one generation to the next.

What is the chance that a child will have blue eyes if both parents are big B little b?

25%

What determines the genotype of a child?

Which chromosome is inherited from mom and dad

Is it possible to work backwards to determine the the genotype of parents based of of the phenotype of the offspring?

Yes

What is classical genetics?

The study of what gets passed on and how it gets passed on.

When did the study of DNA really become a big deal?

The middle of the twentieth century

How did Gregor Mendel study classical genetics?

He would mess around with plants and cross them and traits got passed and which traits didn't get passed to try and understand how traits are passed from one generation to another.

What is an example of a dominant phenotype?

Darker pigmentation

How does darker pigmentation typically interact with lighter pigmentation?

The darker one seems to dominate, that is the darker phenotype is what is observed.

Why is it convenient to study simple traits?

It can give a little bit of sense of how to predict what might happen in future generations.

True of False: Many traits have an all or nothing property

False, it is a gross oversimplification to say that traits have an all or nothing property.

Do most genes have two alleles?

No, in the given example of blood types, it is stated that there are 4 types of blood.

How many chromosome do humans have?

Humans have two copies of each chromosome and this is the copy from mom and dad.

Would a little b from mom and little b from dad cause someone to be a heterozygote?

No, a heterozygote means that there needs to be two different versions like Big B and little b.

Are eye colors actually inheritied in a simple way?

No this is a gross oversimplification.

What would the genotype of someone with brown eyes be?

Could be Big B Big B or Big B little b

What would the genotype of someone with blue eyes be?

little b little b

Can two parents with the same genotype have children with different phenotypes?

Yes

What is the definition of a hybrid?

Different versions of the allele for that gene

What steps of meiosis create different genetic outcomes?

When the chromosomes replicate first, and so you have these two chromatids on a chromosome but they line up in meiosis one during the metaphase, and we don't know which way they line up.

What is the probability of parents producing another child?

Each of the scenarios are equally likely.

Given what this lecture mentions, what is the probability of blood types being produced?

The probability would not be easy to determine since there are 4 four blood types being produced.

True or False: many traits can be studied in a simple way

True, but especially some of the things that Gregor Mendel studied.

When in the process of meiosis does the chromosome first replicate?

Well they replicate first

If mom has brown-eyed dominant, and also has blue eyed recessive allele, and dad has brown-eyed dominant, and also has blue eyed recessive allele, what the probability of offspring with big b and big b?

25%

If mom is a homozygote and dad is a heterozygote does it make the kid more likely to be a homozygote or a heterozygote?

You can't say

Are there only two types of blood?

No, there's four