Genetic information
Offsprings resemble parents as genetic information are pass from the parents
Chromosomes and genes
Chromosomes are found in the nucleus of cells and contains many genes.
A gene is a section of a DNA which carries coding for a particular protein.
Different genes control the development of different characteristics of organisms.
Variation
Genetic
Inherited variation- offsprings carry half of their inherited features from each parent.
Environmental factors
Climate, diet, accidents and lifestyle can cause changes in animals and plants.
E.g Eating too much causes you to be heavier.
Reproduction
Sexual reproduction produces offspring that are not identical
Asexual reproduction produces offspring that are genetically identical to their parents
Sex cells are called gametes.
Male have sperm
Female have eggs or ova.
Fertilisation is when a sperm and egg fuse together, genetic information is mixed from both parents.
Gametes contain 23 chromosomes and when they fuse they contain 46 chromosomes which is what a normal cell has.
Asexual reproduction only needs one parent offsprings are clones.
Asexual reproduction mostly happen in plants
Artificial cloning in plants
This allows us to produce a lot of identical new plants.
Cuttings
A branch from the parent is cut off.
Its lower leaves removed and the stem planted.
Plant hormones are often used to encourage new roots to develop.
The cutting is often covered in a clear plastic bag to keep it moist and warm.
Roots develop and a new plant is produced.
Tissue culture works with tiny tissues from the parent plant.
Sterile agar jelly with plant hormones with lots of nutrient allows it to grow into a plant.
Artificial cloning in animals.
Allows features of an animal to be reproduced several times.
Embryo transplant
A developing embryo is removed from a pregnant animal.
Cells are separated and grown for a while and transplanted into host mothers.
Adult cell cloning
Nucleus is removed from an unfertilised cell egg.
A Nucleus is removed from an adult body cell and injected into the empty egg cell.
An electric shock is applied to make the egg cell begin to divide to form an embryo.
The embryo continues to grow and develop.
Dolly the sheep is the first animal to be cloned using this method.
Genetic modification.
it modifies a gene in an organism for unique features.
DNA from an organism can be cut using certain enzymes.
The gene can be removed and placed into a gap in the DNA of another organism.
E.g. New genes can be transferred to crop plants to make them resistant to herbicides.
GM can be useful in many cases but some people think it is unethical as it has limitless possibilities. Some say that they may harm humans.
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