BIO505T Official Handouts

Gregor Mendel used garden pea as experimental plant for formulating the laws of heredity, following were the properties of garden pea

•  Seed in a variety of shapes and colors.
•  Self, cross pollinate.
•  Takes up little space.
•  Short generation time
•  Produces many offspring.

Historically, transmission genetics developed first, followed by population genetics, quantitative genetics and finally molecular genetics.

•  Transmission or classical genetics deals with movement of genes and genetic traits from parents to offspring. Mendel s’Laws. It also deals with genetic recombinations.
•  Population genetics is the study of traits in a group of population. In this type of genetics we study heredity in groups for traits determined by one or a few genes.
•  Quantitative genetics is the study of group hereditary for traits determined by many genes simultaneously such as skin color, height, eye color etc
•  Molecular genetics this branch of genetics deals with the molecular structure and function of genes.

Lesson 3

Common Genetics Terminologies

What is Character: A heritable feature (skin color, height etc).

What is Trait: variant for a character (i.e. brown, black, white etc).

What is True-breed: all offspring of same variety.

•  Different generations of a cross can be

P generation (parents)

F1 generation (1st filial generation)

F2 generation (2nd filial generation)

•  Pure Cross: A cross between a true breed plant/animal with another true breeds plant/animal is called pure cross

True breeding X True breeding

WW X ww

•  Hybrid Cross:

F1 generation X F1 generation

Ww X Ww

•  Genotype and Phenotype: Genetic make-up of an organism is called Genotype while physical appearance of an organism is called Phenotype.