Biology 210 - Mendelian Genetics

Gregor Mendel

Augustinian monk and botanist whose experiments in breeding garden peas led to his eventual recognition as founder of the science of genetics (1822-1884)

Law of Segregation

Mendelian law stating that two alleles for each trait separate during meiosis

Law of Dominance and Recessiveness

Some alleles are dominant and others are recessive. A dominant allele can cover up or mask a recessive allele.

Law of Independent Assortment

Mendel's second law, stating that allele pairs separate from one another during gamete formation

Monohybrid Crosses

1:2:1

Dihybrid Crosses

9:3:3:1

Cystic Fibrosis

A genetic disorder that occurs in people with two copies of a certain recessive allele; characterized by an excessive secretion of mucus and consequent vulnerability to infection; fatal if untreated.

PKU

Autosomal Recessive Genetic disorder - cannot metabolize the amino acid phenylalanine, can cause intellectual disability

Tay Sachs

Autosomal recessive, lack of an enzyme needed to break down lipids required for normal brain function; results in blindness and early death

Achondroplasia (Dwarfism)

autosomal dominant

Huntington's disease

Incomplete dominance

A pattern of inheritance in which two alleles, inherited from the parents, are neither dominant nor recessive. The resulting offspring have a phenotype that is a blending of the parental traits.

Codominance

A condition in which both alleles for a gene are fully expressed

Pleiotropy

A single gene having multiple effects on an individuals phenotype, sickle cell anemia "gift that keeps on giving"

Polygenics

multiple genes affect traits such as your height, skin tone, eye color

Sex-linked traits

Traits controlled by genes located on sex chromosomes.

Non-disjunction

meiosis in which there is a failure of paired homologous chromosomes to separate or sister chromatids

Karyotype

A display of the chromosome pairs of a cell arranged by size and shape.

Autosomes

non-sex chromosomes

Sex chromosomes

Chromosomes that determine the sex of an individual, male: XY, female: XX

Monosomy

2n-1 (missing a chromsome in a pair)

Trisomy

3 copies of a chromosome

Down Syndrome

Trisomy 21,

Turner Syndrome

XO female

Klinefelter syndrome

XXY,

Probability (rule of multiplication

Multiplying the likelihoods of two different events together to see the exponential chance of both events happening

Test Cross

the crossing of an individual of unknown genotype with a homozygous recessive individual to determine the unknown genotype

Genotype

genetic makeup of an organism

Phenotype

An organism's physical appearance, or visible traits.

Allele

one of a number of different forms of a gene

Trait

A characteristic that an organism can pass on to its offspring through its genes.

Punnet Square

A chart that shows all the possible combinations of alleles that can result from a genetic cross

Gametes

reproductive cells

Blood types

I^A, I^B, I^AI^B, ii = A, B, AB, & O

Recessive Disorders

disorders that occur when a child inherits an allele for the trait from both parents.

Autosomal Mutations

mutations within genes located on the autosomes

Sex-linked Mutations

Mutated gene located on the x chromosome; usually only expressed in males because they only have one x chromosome