Raw Material: Heritable Variation Flashcards
Explain the role of mutation as the ultimate source of all evolutionary variation.
The ultimate source of all genetic variation is mutation. Mutation is important as the first step of evolution because it creates a new DNA sequence for a particular gene, creating a new allele.
Explain the roles of genetic recombinatino and independent assortment in evolutionary variation.
An important source of variation that contributes to evolution is genetic recombination (crossing over event), which is the exchange of genetic material between homologes during meiosis.
Another important source of variation that contributes to evolution is independent assortment, which is the random mixing of maternal and paternal copies of each chromosome during meiosis.
Explain how environmental factors influence the complex relationships between the genotypes and phenotype of an organism.
Define Gene Expression
Gene Expression is the process by which information from a gene is transformed into a product.
Mutations
A. never affect the fitness of the individual inheriting this
change in DNA.
B. can have a cascade effect on many other genes and
their products.
C. in some genes can create mutations in other genes.
D. will always be transmitted to the next generation.
B. Can have a cascade effect on many other genes and their products.
Mutations
A. never affect the fitness of the individual inheriting this
change in DNA.
B. can have a cascade effect on many other genes and
their products.
C. in some genes can create mutations in other genes.
D. will always be transmitted to the next generation.
B. Can have a cascade effect on many other genes and their products.
Define Somatic Mutations
Somatic mutations affect cells in the body (“soma”) of an oganism. These mutations can be transmitted to all daughter cells produced by the affected cell and thus affect the phenotype of the individual. But Somatic mutations are not passed to the offspring, except in cases of vegetative reproduction by plants.
Define Germline Mutations
Germline Mutations affect the gametes (eggs or sperm) of an individual and can be transmitted from parents to offspring.
Define Genotype
The genetic makeup, or set of alleles, of an organism.
Phenotype
The observable physical and physiological traits of an organism, which are determined by its genetic makeup.
Dominant Alleles
Alleles that produce the same phenotype when paired with an identical allele or a diferent allele in a heterozygous state.
Recessive Alleles
Alleles that produce their characteristic phenotype only when paired with an identical allele in a homozygous state.
Addotive Alleles
An allele that yeilds twice the phenotypic effect when two copies are present at a given locus, compared to when just one copy is present. Additive alleles are not influenced by the presence of other alleles.
Pleiotropy
Pleiotropy is a condition in which a mutation in a single gene affects the expression of more than one different phenotypic trait. The different traits often appear to be functionally unrelated.
Antagonistic pleiotropy
Antagonistic pleiotropy occurs when a mutation with benefical effects for one trait causes detrimental effects for other traits.
