Genetic Linkage & Mapping (Chapter 5)
What type of cross or data is analyzed to determine whether two genes are independently assorting or linked?
A test cross or pedigree.
What enzyme possesses accuracy and proofreading capabilities to help prevent spontaneous mutations?
DNA polymerase.
What is the term for the protective ends of a chromosome?
Telomeres
What principle allows you to calculate the expected frequencies of genotypes and phenotypes in a population?
The Hardy-Weinberg principle.
What enzymes are used to digest linear or circular DNA to form specific restriction fragment sizes?
Restriction enzymes.
When analyzing the arrangement of alleles on homologous chromosomes, what two types of gametes can be identified?
Parental and recombinant gametes.
What are the two competing hypotheses regarding how mutations arise in a population?
The random mutation hypothesis and the adaptive mutation hypothesis.
What is the structural difference between euchromatin and heterochromatin?
Euchromatin is generally loosely packed, while heterochromatin is tightly packed.
What type of natural selection favors one extreme phenotype over others, directly contrasting with balancing natural selection?
Directional selection.
What piece of circular DNA is often mapped based on the results of restriction enzyme digestion?
A plasmid.
What metric is calculated from test cross data to determine the distance between two genes?
Recombination frequency.
What type of mutation specifically changes a purine to a purine, or a pyrimidine to a pyrimidine?
A transition mutation.
What meiotic error in either the mother or the father leads to gametes with an abnormal number of chromosomes?
Nondisjunction
What two mechanisms can cause rapid population evolution by moving alleles between different populations?
Migration and gene flow.
What biochemical process is used to place a gene into a cloning vector?
Insertion (or ligation).
Given map units or centimorgans, what two types of frequencies can you predict in the progeny of a cross?
Genotypic and phenotypic frequencies.
Base analogs, deaminating agents, and UV irradiation are all examples of what?
Mutagens
What term describes the genetic makeup of tissues when an individual has two or more populations of cells with different genotypes?
Mosaicism
What evolutionary mechanism describes random fluctuations in allele frequencies and has a stronger effect on small populations?
Genetic drift.
What term describes the loss of genetic variation that occurs when a new, smaller population is established by a very small number of individuals breaking off from a larger population?
The founder effect.
Why are physical distance and recombination distance on a genetic map not always equivalent?
Because of variation in recombination rates (or the presence of recombination hot spots/cold spots).
What are two examples of DNA repair mechanisms that may introduce additional errors into the DNA sequence?
Translesion DNA synthesis and double-strand break repair
What condition describes an organism or cell having more than two complete sets of chromosomes, a phenomenon that has distinct phenotypic consequences?
Polyploidy
What type of event drastically reduces genetic diversity and happens when a population's size is suddenly and severely reduced?
A genetic bottleneck.
When analyzing a population, determining the proportion of individuals with a specific genetic makeup (like homozygous dominant or heterozygous) means you are calculating what type of frequency?
Genotypic frequency.