Week 4: Mendelian Genetics & Pedigrees

A specific place on a chromosome that is occupied by an allele is known as a ___

Locus

An organism’s set of alleles is known as its ___

Genotype

An individual possessing two of the same copies of an allele is known as a ___

Homozygote

An individual possessing two different copies of an allele is known as a ___

Heterozygote

Gregor Mendel examined how many characteristics of Pisum sativum?

7

What is Mendel’s first law?

Principle of segregation

The principle of segregation states that each organism contains ___ alleles for any gene, and one allele goes into each ___

Two, gamete

The concept of dominance states that when two different alleles are present in a genotype, only the trait encoded by the ___ allele is observed in the ___

Dominant, phenotype

Is it possible that crossing over does not take place during meiosis I?

Yes

Mendel’s first conclusion was that a character is encoded by ___ genetic factors

2

Mendel’s second conclusion was that the genetic factors ___ when gametes are formed

Separate

Mendel’s third conclusion was the concept of ___ and ___ traits/alleles

Dominant, recessive

Mendel’s fourth conclusion was that two alleles separate with ___ probability in gametes

Equal

Dihybrid crosses examine how many traits at at time?

2

Dihybrid crosses reveal the principle of ___ ___

Independent assortment

Gametes located on different chromosomes will sort ___

Independently

Incomplete dominance is characterized by the expression of a phenotype that is ___ to those of the parents

Intermediate

During incomplete dominance, the ___ genotype appears as a ‘blend’ of the dominant and recessive genotypes

Heterozygous

What is a species that is known to exhibit incomplete dominance?

Snapdragon flowers

What is a species that is known to exhibit codominance?

Appaloosa horses

What phenotypes are codominant in Appaloosas?

GG (gray) and WW (white)

The idea of multiple alleles is displayed in ___ ___

Blood types

A diagram that shows the occurrence and appearance or phenotypes of a particular gene in relation to an organism and its ancestors is known as a ___

Pedigree

For autosomal dominant diseases, the ___ is the most commonly affected phenotype

Heterozygote

Heterozygotes with an autosomal dominant condition are how likely to pass the condition to their offspring?

50%

Homozygosity for autosomal dominant traits is statistically (likely/unlikely)

Unlikely

For autosomal recessive conditions, generations can be ___ in expression of the disease if all the offspring are heterozygotes

Skipped

There is no male-to-male transmission with ___-___ ___ conditions

X-linked recessive

Sons and daughters both have a ___% chance of inheriting mutant X-linked recessive alleles, but only ___ will express the disease

50, sons

Sickle cell, thalassemias, xeroderma pigmentosum, and PKU are examples of what type of inheritance?

Autosomal recessive

Marfan’s syndrome, familial hypercholesterolemia, Ehlers-Danlos syndrome, and Huntington’s disease are examples of what kind of inheritance?

Autosomal dominant

Hemophilia, color blindness, muscular dystrophy, and Lesch-Nyhan syndrome are examples of what kind of inheritance?

X-linked recessive

With X-linked dominant inheritance, affected males will give the disease to their daughters ___% of the time

100

Women carrying an X-linked dominant disorder will (always/sometimes) express symptoms of the disease

Always

Hypophosphatemic rickets is an example of what kind of inheritance?

X-linked dominant

With X-linked dominant conditions, females may have (more/less) severe symptoms due to the presence of a non-mutated allele

Less

If a cell’s mitochondria contains both normal and mutated genomes, the term used is ___

Heteroplasmy

If a cell’s mitochondria contains all the same genomes, the term used is ___

Homoplasmy

Mitochondrial inheritance is (maternal/paternal)

Maternal

With mitochondrial inheritance, ___% of the children of an affected mother will express the disease

100

With mitochondrial inheritance, ___% of the children of an affected father will express the disease

0

Leber’s hereditary optic neuropathy is passed through ___ inheritance

Mitochondrial