BY: LUNGILE N NGCONGO

Learning outcomes

At the end of the power point presentation you should be able to:

Define what is a Gene?

How we end up with certain features like our parents

Crossing of variation traits (monohybrid crossing & dihybrid crossing)

Inheritance of ABO blood group

Inherited diseases

An excise sheet

What is a gene?

A gene is the basic physical and functional unit of heredity.

Genes are made of DNA. One strand of our DNA. contains many genes.

Found in the chromosome

We get genes from our father from sperm

We get genes from our mother from an egg.

Genes are the reason brothers and sisters look alike.The father and the child have the same color

TEST CROSS

This able us to predict the F1 or F2 generation

By crossing both the genes of the parent

During the crossing of the genes certain characters are herited

Example

Homozygous plants (GG) are pure breeding Heterozygotes (Gg)

p1 GG * Gg

Meoisis

Gametes G G G g

fertilization

An example of crossings

G G

G GG GG

g Gg Gg

Monohybrid

Monohybrid it’s the crossing between 2 organism where we look at a single contrasting trait/ character

Dihybrid It’s a cross between 2 organism where we look at two contrasting

There are four ABO blood groups

Continue…

Groups

Phenotype Genotype

A IAIA IAIO

B IBIB IBIO

AB IAIB

O IOIO

example

A homologous A group mother is crossed with a heterozygous B group father

P1 *

Meiosis

Gametes

fertilization

Punnet square crossing

Results

F1 generation

Genotype: 2*

2*

Phenotype: 2* Ab

2* A

Haemolytic disease of the newborn

When a Rh+ foetus develops within a Rh- mother, some of the D antigen released by worn out red cells may pass via the placenta into the mother. This usually occurs at delivery.

The mother then forms anti-D antibodies.

continue

If the mother has another Rh+ foetus, these antibodies diffuse into the foetal circulation causing agglutination and then haemolysis.

This condition is known as haemolytic disease of the newborn.

This is rare in first pregnancy, but may occur following any sensitising incident such as abortion, amniocentesis or any bleeding during pregnancy

The end!!!