Mendelian Genetics

Question 1

What was the correct hypothesis of inheritance of traits? (Genes)

Answer 1

Individual units of inheritance deliver specific traits that are maintained in offspring

Question 2

Who discovered the basic principles of heredity by breeding garden peas?

Answer 2

Gregor Mendel

Question 3

We didn’t know about genes being encoded by ____ until ____ and ____ until _____

Answer 3

DNA

1944 (Griffith)

DNA structure

1953 (Watson and Crick…and Franklin)

Question 3

Traits that are controlled by many genes

Answer 3

Polygenic

Question 4

Crossing two contrasting ‘true-breeding varieties’ (PPxpp) is called?

Answer 4

Hybridization

Question 5

The result of Mendel’s experiments came the two fundamental principles of genetics, which are…

Answer 5

1. The Law of Segregation
2. The Law of Independent Assortment

Question 6

What were Mendel’s conclusions?

Answer 6

1. There are “heritable units” that can be passed on to progeny called alleles
2. For each character, an organism receives two copies of any given gene, one from each parent
3. If alleles differ at a locus, then one must be dominant
4. The Law of segregation: The two alleles separate from each other during gamete formation and end up in different gametes

Question 7

What is a phenotype?

Answer 7

An observed trait of a characteristic (what you can see)

Question 8

What is a genotype?

Answer 8

The genetic makeup that produces the phenotype

Question 9

What is a test cross?

Answer 9

Breeding the individual with the dominant phenotype, with a true-breeding parent that displays the recessive phenotype to determine the genotype of the dominant phenotype

Question 10

Law of Independent Assortment

Answer 10

Two or more genes will assort independently into gametes

Question 11

If genes are really close on a chromosome, they are ____?

Answer 11

Linked

Question 12

How do you determine the probability that two or more independent events will occur together in some specific combination?

Answer 12

The multiplication rule

Ex. Rr x Rr. 50% chance of getting R or r from each parent. 1/2 x 1/2 = 1/4

Question 12

If genes are really far apart on the same chromosome, the odds of them crossing over is very likely, so they are _____ ?

Answer 12

Not linked, assort independently

Question 13

How do you determine the probability that two or more mutually exclusive events will occur together in some specific combinations?

Answer 13

The addition rule

ex. The probability of Rr, with the R coming from the sperm is 1/4. The probability of Rr, with the R coming from the egg is 1/4. 1/4+1/4 = 1/2

Question 14

What is complete dominance?

Answer 14

Phenotype is dominant in heterozygotes

Question 15

Incomplete dominance

Answer 15

The phenotype is a blend of both in heterozygotes

Question 16

Co-dominance

Answer 16

Both alleles are expressed

Question 17

Pleiotropy

Answer 17

One gene affects multiple phenotypes

Question 18

If a homozygous genotype doesn’t always produce a specific phenotype in all members of the group, it is known as?

Answer 18

Penetrance

Even if you have the genotype, you may not get the phenotype

Question 19

When in a group of individuals with the genotype for a specific gene, a range of traits is displayed it is called?

Answer 19

Expressivity

The amount of the phenotype produced

Question 20

Epistasis

Answer 20

The phenotypic expression of a gene at one locus affects the phenotypic expression at a second locus

ex. Labs. If they have the ee gene, no matter what the other gene codes for, the dog will be yellow

Question 21

Multifactorial

Answer 21

The phenotype depends on the genotype and the environment

Question 22

Polygenic inheritance

Answer 22

Many genes contribute to a single phenotype

Question 23

What are polygenic traits affected by?

Answer 23

The environment

Ex. Human skin can be affected by exposure to sunlight

Question 24

Pedigree analysis

Answer 24

Traces a character through family generations

Question 25

If a trait is dominant it will:

Answer 25

1. Appear more often in the progeny
2. An offspring displaying that trait will always have a parent with the trait

Question 26

If a trait is recessive, it will:

Answer 26

1. Appear less often in the progeny
2. An offspring displaying that trait can have parents that do not display that trait (can skip generations)

Question 27

A recessive allele usually results in?

Answer 27

A protein malfunction or lack of protein altogether

Question 28

Carriers are what genotype?

Answer 28

Heterozygote

Question 29

Which allele is usually the harmful one?

Answer 29

Recessive

Question 30

Some recessive alleles are ____ if an individual is homozygous recessive

Answer 30

Lethal

Question 31

Some alleles are lethal when in the _____ state

Answer 31

Homozygous

Dominant lethal alleles are much more rare than recessive lethal alleles