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Genetics- is the study of heredity
Heredity-is the relation between
successive genes.
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.

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

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