Flashcards in Ch. 10.5 : Types of Variation Deck (10):
Define variation ( in this context )
The differences in characteristics between organisms
What is interspecific and intraspecific variation?
Interspecific : variation between members of different species
Intraspecific : variations between organisms of the same species
What are the causes of variation?
An organisms genetic material - differences in the genetic material an organism inherits from its parents leads to genetic variation.
The environment in which the organism lives - this causes environmental variation.
What are the causes of genetic variation?
How do alleles cause genetic variation?
With a gene for a particular characteristic, different alleles produce different effects. Individuals in a species population may inherit different alleles of a gene.
How do mutations cause genetic variation?
Changes to the DNA sequence and therefore to genes can lead to changes in the proteins that are coded for. These protein changes can affect physical and metabolic characteristics. If a mutation occurs in somatic ( body ) cells, just the individual is affected. If a mutation occurs in the gametes it may be passed on to the organisms offspring.
How does meiosis cause genetic variation?
Gametes are produced by meiosis. Each gametes receives half the genetic content of a parent cell. Before the nucleus divides and chromatids of a chromosome separate, the genetic material inherited from the two parents is 'mixed up' by independent assortment and crossing over. This leads to the gametes of an individual showing variation.
How does sexual reproduction cause genetic variation?
The offspring produced from two individuals inherits genes ( alleles ) from each of the parents. Each individual produced therefore differs from the parents.
How does chance cause genetic variation?
Many different gametes are produced from the parental genome. During sexual reproduction it is a result of chance as to which two combine ( random fertilisation ). The individuals produced therefore also differ from their siblings as each contains a unique combination of genetic material.