Exam 1- Mendel's Laws /Human Pedigree

__ discovered the basic principles of genetics

Gregor Mendel

A ___ is a region of DNA that encodes a protein or RNA

gene

__ is the way that genes transmit traits from parents to offspring

Heredity

__ was the first applied genetic technique

Artificial selection

What are the two misleading theories of inheritance

1. Homunculus

2. Blended inheritance

What is the theory called when→ inherited features of offspring are contributed mainly by only one parent

The homunculus

What is the theory called when→ Parental traits become mixed and changed in the offspring

Blended inheritance

What are the three major benefits of using the pea plants:

1. Short time between generations

2. Large # of offspring

3. Antagonistic pairs: visibly different traits

What can be used to study inheritance?

Pedigrees

__ are orderly diagrams of a family’s relevant genetic features

Pedigrees

A __ pattern of inheritance indicates a rare dominant trait

vertical

A __ pattern of inheritance indicates a rare recessive trait

horizontal

Three key aspects of pedigrees with dominant traits:

1. Affected children always have at least 1 affected parent

2. Dom traits→ vertical pattern

3. Two affected parents can produce unaffected (if BOTH are hetero)

Four key aspects of pedigrees with recessive traits:

1. Affected individuals can be the children of 2 unaffected children ( AS a result of consanguineous matings)

2. All children of 2 affected parents→ affected

3. Rare traits→ horizontal pattern

4. Recessive traits may show a vertical pattern if the trait is extremely common in the population

There are 4 phenotypic variation that pose a challenge to Mendelian analysis

1. No definitively dominant or recessive allele

2. More than two alleles exist

3. Multiple genes involved

4. Gene-environment interactions

What is a complete dominance relationship?

Hybrid that resembles one of the two parents

What is an incomplete dominance relationship?

Hybrid that resembles neither parent

What is a codominance relationship?

Hybrid that shows traits from both parents

Crosses of pure-breeding red with pure-breeding white results in all pink F1 progeny. What relationship does this represent?

Incomplete dominance

___is the phenomenon of a single gene determining several distinct and seemingly unrelated characteristics

Pleiotropy (pleio= many, trophic= effect)

There are two types of lethal alleles:

1. Recessive lethal alleles

2. Dominant lethal alleles

__lethal alleles: 2 copies of the mutant allele required for the lethal phenotype

recessive

__ lethal alleles: only 1 copy of the mutant allele required for the lethal phenotype

dominant

Two genes can interact to determine a single trait. What are they

1. Novel phenotypes

2. Epistasis

__phenotypes resulting from additive gene interactions

Novel phenotypes

__is when an allele at one gene masks the phenotype of allele at another gene

Epistasis

Genes that perform the same function are __

redundant

The allele that does the masking is __ to the other gene

epistatic

The gene that is masked is __ to the other allele

hypostatic

What is it called when 2 copies of 1 allele needed to mask the other gene?

Recessive

What is it called when 2 copies of each gene can mask the dominant allele of the other gene?

Reciprocal recessive

What is it called when mutations in 2 or more genes cause the same phenotype?

Locus heterogeneity

There are 4 factors that can give rise to “continuous” traits

1. Incomplete dominance

2. Codominance

3. Various combinations of genetic interactions

4. Environmental effects

__traits give clear-cut, “either-or” phenotypic differences between alternative alleles

Discontinuous traits

__traits are determined by segregating alleles of many genes that interact together and with the environment

Continuous traits

What is polygenic?

Controlled by multiple genes

T/F: Height and skin color are continuous traits

True

Phenotypic variation for some traits can occur because of 3 things:

1. Penetrance

2. Expressivity

3. Effects of modifier genes

__ is the percentage of individuals with a particular genotype that show the expected phenotype

Penetrance

__is the degree or intensity with which a particular genotype is expressed in a phenotype

Expressivity

T/F: A single phenotype can be affected by many different genetic factors

TRUE. (Multiple alleles, codominance and incomplete dominance, penetrance + expressivity, modifier genes, environmental effects, epistasis + additive effects + redundancy, multiple genes controlling the same trait)