Human reproduction lesson 8

1. FertilisationFertilisation
Inheritance and Selection - Lesson 2
Target
To know that during fertilization
genetic information from parent is
combined to make a new unique
animal or plant

2. Sex cellsSex cells
Sex cells are specialised to do a
specific job
They have half the number of
chromosomes of body cells
The sex cells of animals are;
– Sperm (male)
– Egg (female)

3. Copy the table into books and fill it outCopy the table into books and fill it out
using information from the next slidesusing information from the next slides
Sex cell Diagram Specialisation
Sperm –
produced in
Egg
-produced
in

4. Male sex cell - SpermMale sex cell - Sperm
Sperm are produced in the testis

5. Male sex cell - SpermMale sex cell - Sperm
Enzymes in head to get into ovum
Nucleus carrying DNA from male
parent
Mitochondria in middle to provide
energy for swimming
Long tail for locomotion (movement)

6. Female sex cell - OvumFemale sex cell - Ovum
Eggs are produced in the ovaries
Nucleus

7. Female sex cell - OvumFemale sex cell - Ovum
Nucleus contains DNA from female parent
Protective outer layer ensures only one
sperm gets through
Cytoplasm stores food for developing embryo

8. The sperm cells are produced in the testisThe sperm cells are produced in the testis
They swim along the sperm duct and leave the penis

9. The egg cells are produced in the ovaries, andThe egg cells are produced in the ovaries, and
travels down the fallopian tubes to the uterustravels down the fallopian tubes to the uterus
If they are fertilised the embryo will grow inside the uterus

10. FertilisationFertilisation
When the sperm enters the egg it is
said to be fertilised
The chromosomes in the egg (23) and
sperm (23) fuse to make a complete set
(23 pairs)
The chromosomes join randomly which
means brothers and sisters are not
identical

12. TwinsTwins
Twins are children who are born at the
same time as each other from the same
parents
They can be identical or non identical

15. Non identical twinsNon identical twins
2 sperm fertilise 2 eggs
Each baby will have different genes
They may be the same or different
sexes

17. Identical twinsIdentical twins
1 Sperm fertilises 1 egg
The zygote splits
– If it splits more than 12 days after fertilisation the
twins are conjoined
The babies have identical genes
They are always the same sex