Genetic Variation quiz #3 Flashcards
Genetic Variation quiz #3
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How do mutations affect an organism's fitness, and what are the three main categories of mutations?
Mutations can be beneficial (increase fitness), neutral (no effect on fitness), or deleterious (decrease fitness). Beneficial mutations are rare and can be favored by natural selection, neutral mutations have no impact and are not affected by selection, and deleterious mutations are often removed from the population by natural selection. Describe two mechanisms, other than point mutations, by which new genes can arise in a population.
New genes can arise through gene duplication, where a segment of a chromosome is copied, allowing one copy to evolve a new function, and through horizontal (lateral) gene transfer, where genes are transferred between different species, a process common in bacteria and sometimes seen in eukaryotes. What are the two main sources of genetic variation in a population?
The two main sources are new alleles created by mutations and new combinations of alleles produced by sexual reproduction and recombination. How do mutations introduce genetic variation?
Mutations change the DNA sequence, creating new alleles or even new genes, which increases genetic diversity in a population. What are the three main categories of mutations based on their effect on fitness?
Mutations can be beneficial (increase fitness), neutral (no effect on fitness), or deleterious (decrease fitness). Why are beneficial mutations considered rare compared to other types of mutations?
Beneficial mutations are rare because most random changes to DNA are either neutral or harmful, and only a few improve an organism's fitness. Describe two mechanisms, other than point mutations, by which new genes can arise in a population.
New genes can arise through gene duplication, where a gene is copied and one copy evolves a new function, and through horizontal gene transfer, where genes move between different species. How does sexual reproduction contribute to genetic variation?
Sexual reproduction mixes alleles from two parents, creating offspring with unique combinations of alleles. What is the role of recombination and independent assortment in genetic variation?
Recombination (crossing over) and independent assortment shuffle alleles and chromosomes during meiosis, producing new genetic combinations in gametes. Why is genetic variation important for evolution and natural selection?
Genetic variation provides the raw material for evolution, allowing natural selection to act on different traits and enabling populations to adapt to changing environments.
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