B1.7 - Genetic Variation & Control Flashcards
What is a gene?
Small section of DNA in a chromosome. Many of our characteristics are controlled by genes.
What is a gamete?
A sex cell (e.g. sperm and eggs)
What is a genetic cause of variation?
Hair colour, eye colour, skin colour.
What is an environmental cause of variation?
Muscle strength, accent.
What is sexual reproduction?
When a sperm cell fuses with an egg cell to produce a fertilised cell. Two parents are involved. Produces variation in the offspring.
What is asexual reproduction?
Only one parent involved. All the offspring are genetically identical and are called clones.
Describe cloning using tissue cultures.
Cells are taken from the tip of a shoot and placed on a jelly that contains nutrients and a chemical that helps the cells to divide. They make a small ball of cells called a callus. The callus can be split to make new calluses. Each callus is then put on a jelly that contains different chemicals to encourage roots and shoots to form. When the new plants are large enough, they are planted into compost. Tissue culture makes it easier to grow thousands of new plants from one original one.
Describe cloning using embryo transplant.
An egg is fertilised with a sperm in a lab. When It has divided to make 4 or 8 cells, before they start to specialise, the cells are separated to start making new embryos. These are transplanted into the womb of host mothers where they grow until they are ready to be born.
Describe adult cell cloning.
The nucleus of an unfertilised egg cell I removed and replaced with the nucleus of a body cell from an adult animal. The egg cell can then be given an electric shock so that it starts to divide like a normal embryo. The embryo will contain the same genetic information as the adult body cell.
What is genetic engineering?
The process of taking genes from one organism and putting them into cells of another so that the cells include the characteristic of the new gene.
What is meant by the term “genetically modified” (GM)?
An organism that has been genetically engineered.
Give examples of GM crops
Herbicide resistant crops
What are the concerns associated with GM crops?
The seeds cost more than normal seeds, gene transfer through pollination and safety of the foods produced by genetic modification.
