Variation Flashcards
What is variation?
Differences in the characteristics of individuals in a population
What is variation caused by?
Inherited genes
Environment in which they have developed
Combination of both of these
What is mutation?
A lot of genetic variation in a species arises from random mutation
Change in DNA sequence
Occur continuously
Very rarely lead to a change in phenotype
What is selective breeding?
Selective breeding is the process by which humans breed plants and animals for particular genetic characteristics
Choose parents with the desired characteristic from a mixed population
Breed them together
Choose offspring with the desired characteristic and breed them
Continue over many generations until all offspring show the desired characteristic
What are examples of characteristics that are chosen for usefulness or appearance?
Disease resistance in food crops
Animals that produce more meat or milk
Domestic dogs with gentle nature
Larger or unusual flowers
Disadvantages of selective breeding
Inbreeding
Reduces variation
What is cloning?
A clone is an individual that has been produced asexually and is genetically identical to its parent. There are several different methods for producing both plant and animal clones , but there are benefits and risks associated with cloning.
How does adult cell cloning work?
Sheep A - nucleus removed from adult cell e.g skin
Sheep B - nucleus removed from mature egg to leave empty egg
Electric shock
Fusion occurs
Divides to start to form an embryo
Embryo implanted into uterus of Sheep C
Lamb born is clone of Sheep A
What is a tissue culture?
Small groups of cells from part of a plant are used to grow identical new plants. This is important for preserving rare plant species and growing plants commercially in nurseries.
What is cutting?
An order simple method, used by gardeners to produce many identical plants from a parent plant.
What is embryo transplant?
Cells split apart from the developing animal embryo before they become specialised, then the identical embryos are transplanted into host mothers.
What are benefits of methods of cloning?
Larger number of identical offspring produced
Quick and economical
Desired characteristics guaranteed
What are risks to methods of cloning?
Limits variation and causes reduction in gene pool
Clones may be vulnerable to diseases or changes in the environment
Ethical considerations around cleaning living organisms
What is genetic engineering?
Is a process that involves changing the genome of an organism by introducing a gene from another organism to produce the desired characteristic
Examples of genetic engineering
Bacterial cells have been genetically engineered to produce useful substances, such as human insulin to treat diabetes
Plant crops have been genetically engineered to be resistant to diseases, insects or herbicides or to produce bigger and better fruit and high yields, crops that have undergone genetic engineering are called genetically modified (GM)
How goes genetic engineering work?
Cell with vector (usually bacterial plasmid or virus)
Vector taken out of cell and split open
Cell from organism with desired gene
Enzymes used to cut out the design gene
Gene is inserted into the vector
Vector used to insert gene into required cell at an early stage in development
As the organism grows it develops with the desired characteristics from the other organism.
