Chapter 3:- genetics

Heredity

Transmission of genetically based characteristics from parents to offspring

Variations

Any difference between individuals of the same species

Character

Any inheritance feature of an organism

Trait

Alternate forms of a character

XX

Female

XY

Male

Allele

Different forms of a gene

R

Dominant

r

Recessive

Square

Male

Circle

Female

RR

Both dominant

Rr

One dominant
One recessive

rr

Both recessive

Genotype

Set of genes present in the cells of an organism

Phenotype

An organisms physical appearance or visible traits

Homozygous

Organism that has two identical alleles for a trait

Heterozygous

An organism that has two different alliance for a trait

Sex linked inheritance

Inheritance of a genetic trait located on the sex chromosome

Phenotypic ratio

3 :1

Genotypic ratio

1:2:1

Law of dominance

Only one character expresses itself while others are surpressed

Mutation

A sudden change in 1 or more genes or in the structure of chromosome

Monohybrid cross

Cross between individuals that involves one pair of contrasting traits

Dihybrid cross

Across between individuals that have different allele for the same gene