Biology Genetics & Evolution Flashcards
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Read the first 7 Biology Genetics & Evolution flashcards as text
What is the bottleneck effect in evolutionary biology?
Answer: A drastic reduction in population size followed by recovery, reducing genetic diversity
The bottleneck effect occurs when a population is greatly reduced in size, causing random loss of alleles and reduced genetic diversity in the surviving population.
How does a testcross help determine whether an organism showing a dominant phenotype is homozygous or heterozygous?
Answer: Cross it with a homozygous recessive organism and observe offspring
Crossing with a homozygous recessive (aa) reveals the unknown genotype: if any offspring show the recessive phenotype, the parent is heterozygous.
Which process allows bacteria to rapidly acquire new genes, including antibiotic resistance genes, from other bacteria?
Answer: Horizontal gene transfer
Horizontal gene transfer, including conjugation, transformation, and transduction, allows bacteria to acquire genes from other organisms outside of vertical inheritance.
What distinguishes homologous structures from analogous structures in evolution?
Answer: Homologous structures share common ancestry; analogous structures are functionally similar but evolved independently
Homologous structures reflect shared common ancestry (e.g., vertebrate forelimbs), while analogous structures result from convergent evolution in unrelated lineages.
Which of the following describes pleiotropy?
Answer: One gene controls multiple phenotypic traits
Pleiotropy occurs when a single gene influences two or more seemingly unrelated phenotypic traits, such as the PKU gene affecting brain and pigment development.
What is the significance of the 3' to 5' exonuclease activity of DNA polymerase?
Answer: It removes mismatched nucleotides to proofread newly synthesized DNA
The 3' to 5' exonuclease activity allows DNA polymerase to remove incorrectly incorporated nucleotides, dramatically increasing replication fidelity.
Which of the following is NOT a condition required for Hardy-Weinberg equilibrium?
Answer: High mutation rate
Hardy-Weinberg equilibrium requires no mutation, no selection, random mating, no gene flow, and a large population; a high mutation rate violates the no-mutation assumption.