z Genetics is the study of how characteristics are passed on from one generation to another.
z Inherited characteristics are passed on from parents to their children by genes. Acquired characteristics are learned throughout our life.
z Chromosomes are found in the nucleus of a cell. They are made up of protein and a chemical called DNA.
z A gene is a short section of the DNA in a chromosome.
z All human body cells contain 46 chromosomes, except gametes. Gametes contain 23 chromosomes.
z The male gamete is a sperm. The female gamete is an egg.
z Traits can be dominant or recessive.
z A species is a group of organisms that can breed with each other to produce fertile offspring.
z Variation describes all of the differences in traits that exist in members of the same species. In most cases, variation is due to a combination of environmental and genetic factors.
The BIGChallenge
In groups, look through newspapers and magazines and find a photograph of a famous family that includes a mother, a father and their children. (The children can be grown-ups!)
Stick the picture to a piece of card and label the characteristics that the children have inherited from their parents. Suggest which parent the trait was inherited from. What does it tell you about the parents’ genes?
Remember that some visible traits might be acquired rather than inherited. Maybe someone has dyed their hair!
Present your poster to the rest of the class. 78 Take the
Go to your Portfolio to check what you have learned in this chapter.
z Natural selection is the process by which the members of a species who are best suited to their environment are most likely to survive and reproduce.
z Evolution is the gradual change in the inherited characteristics of a species over time. Evolution can lead to new species. The theory of evolution by natural selection was introduced by Charles Darwin.
z Mutation is a change in a gene or chromosome. It can introduce useful variation in genes but may also cause certain genetic diseases.
z Biotechnology is the use of living things or their parts to make useful products and to perform useful services.
z Genetic engineering is deliberately changing genes to produce desirable characteristics.
