B14 Variation and Evolution Flashcards
Variation
Differences in the characterisics of individuals in a population
What causes variation
A combination of the genes they have inherited and the environment/ conditions they have developed in
Theory of evolution by natuaral selection states
that all species of living things have evolved from simple life forms that first developed more than three billion years ago.
What is a genetic mutation
Changes to the sequences of bases in DNA
What is Selective Breeding
This is the process by which humans breed plants and animals for particular genetic characteristics.
What is genetic engineering
This is a process which involves modifying the genome of an organism by introducing a gene from another organism to give a desired characteristic.
What are the three types of cloning:
Tissue culture, cuttings, embryo transplants
Describe the process of adult cell cloning
The nucleus is removed from an unfertilised egg cell.
• The nucleus from an adult body cell, such as a skin cell, is inserted into the egg cell.
• An electric shock stimulates the egg cell to divide to form an embryo.
• These embryo cells contain the same genetic information as the adult skin cell.
• When the embryo has developed into a ball of cells, it is inserted into the womb of an adult female to continue its development.p
When is a new species formed
If two populations of one species become so different in phenotype that they can no longer interbreed to produce fertile offspring they have formed two new species.
What is inbreeding
where some breeds are particularly prone to disease or inherited defects and this is caused by selective breeding
Tissue Culture
using small groups of cells from part of a plant to grow identical new plants. This is important for preserving rare plant species or commercially in nurseries.
Cuttings
an older, but simple, method used by gardeners to produce many identical new plants from a parent plant.
Embryo Transplants
splitting apart cells from a developing animal embryo before they become specialised, then transplanting the identical embryos into host mothers.
Describe the process of genetic engineering
- enzymes are used to isolate the required gene; this gene is inserted into a vector, usually a bacterial plasmid or a virus
- the vector is used to insert the gene into the required cells
- genes are transferred to the cells of animals, plants or microorganisms at an early stage in their development so that they develop with desired characteristics.
How have plant crops been genetically engineered
to be resistant to diseases or to produce bigger better fruits.
How have bacterial cells been genetically engineered
to produce useful substances such as human insulin to treat diabetes.
What are GM crops?
Crops that have had their genes modified in this way are called genetically modified
Concerns about GM crops
Concerns about GM crops include the effect on populations of wild flowers and insects. Some people feel the effects of eating GM crops on human health have not been fully explored.
What do GM crops include and what do they cause
GM crops include ones that are resistant to insect attack or to herbicides. GM crops generally show increased yields.
What are some modern medical researches exploring with GM crops
possibility of genetic modification to overcome some inherited disorders.
