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Mutations
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What id genetic variation?
Genetic Variation is a measure of the genetic differences there are within populations or species. For example, a population with many different alleles at a locus may be said to have a lot of genetic variation at that locus. Genetic variation is essential for natural selection to operate since natural selection can only increase or decrease frequency of alleles already in the population
What is one difference between single gene trait and a polygenic trait?
Polygenic traits result in more variation because so many more alleles are involved in the process of reproduction.
What does the notation AA means to genetics?
AA means that a trait is homozygous dominate. A person only has one variation of a gene (trait) and it is dominate.
Does fertilization create new combinations of alleles?
Yes- each gamete cell is haploid, containing half the mother or father's full set of chromosomes. when the two fuse, then a new diploid cell is created, with a full number of chromosomes- half from the mother and half from the father. It has a new genetic combination- the cells of offspring created via sexual reproduction are not genetically identical to their parents' cells.
What would be the consequences for evolution if there were no reproductive variation?
There would be no adaptive change due to natural selection and only genetic drift due to random events and gene flow due to population mixing would occur. Alleles would change, but without reproductive variation speciation could not occur.
Do all metamorphic rocks have layers?
No. The layering or foliation only occurs when there is a variation in the composition of the original rock. If the rock is homogeneous, then there will be no foliation.
What are the alleles of a gene?
That depends on the gene: some genes have only a few alleles, some genes have hundreds or even thousands of alleles.
Is it true that recessive alleles are never present when dominant alleles are present?
No. They are present but not expressed (seen). Only the dominant alleles are expressed.
What is the difference between continuous and discontinuous genetic variation?
Continuous variation is a variation that is distributable; under a normal curve. Height is an example of this with all heights being along a continuum of heights within populations, at least. This distribution of traits is usually controlled by many alleles in a additive fashion. Polygenic. Discontinuous variation is of one trait, allele, or the other. Blood groups are an example of this. A, B , O. You can only have two alleles here, so AA and AB and OO and AO, AB etc. are the expressed ( less the recessive O, except homozygous ) traits. These are single variations based on one allele and are not distributable along a continuum.
Why does the baby have only two alleles if the inheritance of blood type is controlled by three alleles?
Everyone only has two alleles for blood type. The parents each pass one down to the child.
Multiple alleles can be studied only in individuals?
Multiple alleles can be studied only in populations, not individuals. An example of multiple alleles would be blood type, each person has only one blood type, but a population has a many permutations.
Which allele is expressed even if only one copy is present in genotype?
dominant alleles
