BIO301 Merged Slides Handouts Topics 1-167

MUHAMMAD IMRAN

Bio 301 – Essentials of Genetics

Topic no 1 to 83 in mid term and 84 to 167 final term syllabus

Lesson 1 What is Genetics?

Genetics is the study of genes, heredity and variation.

It is considered as a field of Biology.

The principles of heredity were explained by Gregor Mendel in 1866.

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.

Lesson 2 Sub Types of Genetics

There are four sub disciplines of genetics which are as follows, although some of the Geneticist classify Genetics in many sub disciplines ➢ Transmission (Classical) Genetics ➢ Population Genetics ➢ Quantitative Genetics ➢ Molecular Genetics

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.

➢ Dominant and Recessive: when one characteristic expresses itself over the other i.e. round over wrinkled was dominant in Gregor Mendel experiments while the trait that does not show through in the first generation is called as recessive trait i.e. wrinkled.

Lesson 4 Mendel s’ law of dominance

Mendel s’ law of dominance describes that in a cross of parents, that are pure for contrasting traits, only one form of the trait will appear in the next generation. In the monohybrid cross, one version will be disappeared

Example:

Cross of two true-breeding plants. First plant is with purple color flowers while second is with white color flowers. During F1 generation, all plants will be with purple color flowers. It can be concluded that purple color dominant to white.

It can concluded that hybrids will show dominant phenotype

Example:

PP = purple pp = white Pp = purple