human reproduction lesson 8
TRANSCRIPT
FertilisationFertilisation
Inheritance and Selection - Lesson 2TargetTo know that during fertilizationgenetic information from parent iscombined to make a new uniqueanimal or plant
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)
Copy the table into books and fill it out Copy 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
Male sex cell - SpermMale sex cell - Sperm
Sperm are produced in the testis
Male sex cell - SpermMale sex cell - SpermEnzymes 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)
Female sex cell - OvumFemale sex cell - Ovum
Eggs are produced in the ovaries
Nucleus
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
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
The egg cells are produced in the ovaries, and The 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
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
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
Non identical twinsNon identical twins
2 sperm fertilise 2 eggs
Each baby will have different genes
They may be the same or different sexes
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