GENETICS AND INHERITANCE

Genetics- is the study of

heredity

Heredity-is the relation

between successive genes.

GENETICS

THE FATHER OF GENETICS

The father of Genetics is

Gregory Mendel

He discovered the basic

principles of heredity by

breeding the garden peas in a

carefully planned experiment.

FATHER OF GENETICS

Cross pollination-Is the fertilization between different plants.

True breeding-The organisms with only one variety type (white flowers can only produce white flowers).

Hybridization-Mating two true breeding, contrasting varieties.

FATHER OF GENETICS

Law of segregation states that two alleles for a heritable character separate (segregate) during gamete formation and end up in different gametes

LAW OF SEGREGATION

TWO TYPES OF GENETIC CROSSES

Monohybrid cross-A cross between 2 organisms where we only look an one pair of contrasting traits.

Dihybrid cross-A cross between 2 organisms where we look at two pairs of contrasting traits at the same time.

MONOHYBRID CROSSES

DIHYBRID CROSSES

Law of independent assortment states that each pair of alleles segregates independently of each other pair of alleles during gamete formation.

LAW OF INDEPENDENT ASSORTMENT

Two varieties of chromosomes: The larger X and the smaller Y

SRY gene on the on the Y chromosome codes for testes development.

Females are XX and Males are XY

DERTEMINING SEX OF THE BABBY

THE DIAGRAM TO DERTEMINE THE SEX OF THE BABY

sex chromosomes have genes for many characters unrelated to sex

gene located on either sex chromosome is called a sex-linked gene

For a recessive sex-linked trait to be expressed• A female needs two copies of the allele• A male needs only one copy of the allele

INHERITANCE OF SEX LINKED GENES

DISORDERS CAUSED BY RECESSIVE ALLELES ON THE X CHROMOSOME IN HUMANS:

Colour blindness

Duchene muscular dystrophy

Haemophilia

D I S O R D E R S C A U S E D BY R E C E S S I V E A L L E L E S O N T H E X C H R O M O S O M E I N H U M A N S :