Biology 2 - "Mendelian Inheritance"

Covers: Vocabulary Terms, Mendel's Experiments, and Solving Monohybrid and Dihybrid Cross

Genetics

Genetics

“study of heredity and variation”

Gregor Johann Mendel

“father of

modern genetics.”

Character

a heritable feature that varies among individuals.

Monoecious

it exhibits both male and female reproductive organs in the same individual, allowing for diverse reproductive strategies

capable of self-fertilization and cross pollination

True-breeding

offspring produced in many generations through self-fertilization are identical.

Parental (P) generation

original parents

First filial (F1 generation)

offspring of the P generation

Second filial (F2 generation)

offspring of the F1 generation

Dominant

trait that always shows up

Recessive

trait that is masked

Allele

Alternative version of a gene

The Law of Segregation

“the two alleles for a heritable character segregate from each other during gamete formation and end up indifferent gametes”

Homologous Chromosome

a pair of chromosomes with the same gene sequence in the same location

Phenotype

observable appearance of a trait (e.g. height: short or tall; flower position: axial or terminal)

Genotype

allelic combination underlying phenotypes; represented by symbols:

—> dominant allele – uppercase letter (e.g. R)

—> recessive allele – lowercase letter (e.g. r)

Homozygous

pair of alleles for a character are identical; also represented by symbols:

—> dominant – (RR)

—> recessive – (rr)

Heterozygous

alleles for a character are different;

—> symbol: (Rr)

Punnett Square

diagrammatic device used for predicting the allele composition of offspring from a cross

The Law of Independent Assortment

“two or more genes assort independently—that is, each pair of alleles segregates independently of each other pair of alleles—during gamete formation”

Dihybrid Cross.

a cross between individuals that are heterozygous for both characters

Hybrids

the offspring resulting from combining the qualities of two organisms of different varieties, often exhibiting traits from both parents.

Monohybrid Cross

A cross between individuals that are heterozygous for a single character (i.e. flower color) or gene