Mendelian Genetics and Inheritance Patterns

Part 1

DNA and RNA

Carry genetic information.

Genetic code

Shared by all living systems.

Gregor Mendel

Studied inheritance and created two laws that can be applied to the study of genetics.

Pea Plant Traits

Mendel only tracked characteristics that came in two distinct forms.

Examples of Pea Plant Traits

Color (purple or white), Seed shape (round or wrinkled).

True breeding

Organisms that produce offspring of the same variety over many generations of self-pollination.

Example of True Breeding

True breeding purple pea plants will only produce purple offspring with self-pollination.

P generation

True-breeding parental generation.

F1 generation

(First filial) hybrid offspring of P generation.

F2 generation

(Second filial) offspring of the F1 generation.

Punnett squares

Diagrams used to predict the allele combinations of offspring from a cross with known genetic compositions.

Dominant traits

Denoted by capital letters.

Recessive traits

Denoted by lower case letters.

Homozygous

An organism that has a pair of identical alleles for a character.

Homozygous dominant

AA.

Homozygous recessive

aa.

Heterozygous

An organism has two different alleles for a gene.

Example of Heterozygous

Aa.

Genotype

The genetic makeup (alleles) of an organism.

Phenotype

An organism's appearance, which is determined by the genotype.

Testcross

Helps to determine if the dominant trait is homozygous dominant or heterozygous.

Law of segregation

One of the two fundamental principles of heredity developed by Mendel.

Law of independent assortment

The second fundamental principle of heredity developed by Mendel.

Mendel's Model

Explains the 3:1 ratio observed in the F2 generation with four concepts.

Law of segregation

The two alleles for the same trait separate during gamete formation and end up in different gametes.

Somatic cells

Cells that are diploid and contain two copies of each chromosome.

Alleles

Alternative versions of a gene.

True-breeding plants

Plants that have two identical alleles.

P generation

The generation that produces gametes containing one allele for flower color.

F1 generation

The generation that consists of all hybrids, represented as Pp.

F2 generation

The generation produced by crossing F1 hybrids, resulting in a 3:1 ratio.

Monohybrid crosses

A cross between the F1 hybrids.

Dihybrid crosses

A cross between F1 dihybrids.

Law of Independent Assortment

Mendel's principle stating that genes for one trait are not inherited with genes of another trait.

Dihybrid cross

A cross between F1 dihybrids that produces a 9:3:3:1 phenotypic ratio.

Punnett square

A tool used to determine the genotypes of offspring from a genetic cross.

Multiplication rule

The probability that two or more independent events will occur together in some specific combination. (ADD)

Addition rule

The probability that two or more mutually exclusive events will occur.(OR)

Pedigrees

Family trees that give a visual of inheritance patterns of particular traits.

Dominant traits

Traits that do not skip a generation and require at least one parent to have the trait.

X-linked traits

Traits where males are more commonly affected than females.

F1 hybrids

Offspring resulting from a cross between true-breeding plants.

Genotypes

The genetic constitution of an individual.

Phenotypes

The observable characteristics of an individual.

9:3:3:1 ratio

The phenotypic ratio produced from a dihybrid cross.

Mitochondria DNA inherited

our mothers (egg cell)