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MCAT Bio Ch. 12

TermDefinition
Chromosomes Contain: Genes in a linear sequence
Alleles Are: Alternative forms of a gene
A Dominant Only Requires: One copy to be expressed
A Recessive Allele Requires: Two copies to be expressed
A Genotype Is: The combination of alleles one has at a given genetic locus
Having Two Of The Same Allele Is Termed: Homozygous
Having Two Different Alleles Is Termed: Heterozygous
Having Only One Allele Is Termed: Hemizygous (such as male sex chromosomes)
A Phenotype Is: The observable manifestation of a genotype
Complete Dominance Has: One dominant allele and one recessive allele
Codominance Has: More than one dominant allele
Incomplete Dominance Has: No dominant alleles. Heterozygotes have intermediate phenotypes.
Penetrance Is: The proportion of a population with a given genotype who express the phenotype
Expressivity Refers To: The varying phenotypic manifestations of a given genotype
Mendel's First Law (Of Segregation) States: An organism has two alleles for each gene, which segregate during meiosis, resulting in gametes carrying only one allele for a trait
Mendel's Second Law (Of Independent Assortment) States: The inheritance of one allele does not influence the probability of inheriting a given allele for a different trait.
The Griffith Experiment Demonstrated The Transforming Principle By: Converting non-virulent bacteria into virulent bacteria by exposure to heat-killed virulent bacteria
The Avery-MacLeod-McCarty Experiment Demonstrated That: DNA is the genetic material because degradation of DNA led to a cessation of bacterial transformation.
The Hershey-Chase Experiment Confirmed That: DNA is the genetic material because only radiolabeled DNA could be found in bacteriophage-infected bacteria.
All Of The Alleles In A Given Population Constitute: The gene pool
Mutations Are: Changes in a DNA sequence
Point Mutationts Are: The substituting of one nucleotide for another
Frameshift Mutations: Moving the three-letter transcriptional reading frame.
Silent Mutation Has: No effect on the protein
Missense Mutation Results In: The substitution of one amino acid for another
Nonsense Mutation Results In: The substitution of a stop codon for an amino acid
Insertions And Deletions Result In: A shift in the reading frame, which leads to changes for all downstream amino acids
Deletion Mutations Occur When: A large segment of DNA is lost
Duplication Mutations Occur When: A segment of DNA is copied multiple times
Inversion Mutations Occur: When a segment of DNA is reversed
Insertion Mutations Occur: When a segment of DNA is moved from one chromosome to another
Translocation Mutations Occur: When a segment of DNA is swapped with a segment of DNA from another chromosome
Genetic Leakage Is: A flow of genes between species through hybrid offspring
Genetic Drift: Occurs when the composition of the gene pool changes as a result of chance
The Founder Effect Results From: Bottlenecks that suddenly isolate a small population, leading to inbreeding and increased prevalence of certain homozygous genotypes
Punnett Squares Visually Represent: The crossing of gametes from parents to show relative genotypic and phenotypic frequencies
The Parent Generation Is Represented By: P
Filial (Offspring) Generations Are Represented By: F1, F2, etc in the sequence
A Monohybrid Cross Accounts For: One gene
A Dihybrid Cross Accounts For: Two genes
In Sex-Linked Crosses, Sex Chromosomes Are Used To: Indicate sex as well as genotype
Recombination Frequency () Is: The likelihood of two alleles being separated during crossing over in meiosis
Genetic Maps Can Be Made Using: Recombination frequency as the scale in centimorgans
The Hardy-Weinberg Principle States That: If a population meets certain criteria (aimed at a lack of evolution), then the allele frequencies will remain constant (Hardy-Weinberg equilibrium)
Natural Selection States That: Chance variations exist between individuals and that advantageous variations (those that increase an individual's fitness for the environment) afford the most opportunity for reproductive success
Modern Synthesis Model (Neo-Darwinism) Accounts For: Mutation and recombination as mechanisms of variation and considers differential reproduction to be the mechanism of reproductive success
Inclusive Fitness: Considers an organism's success to be based on the number of offspring, success in supporting offspring, and the ability of the offspring to then support others; survival of offspring or relatives ensures continuation of genes in subsequent generations
Punctuated Equilibrium Considers Evolution To Be: A very slow process with intermittent rapid bursts of evolutionary activity
Stabilizing Selection Keeps Phenotypes: In a narrow range, excluding extremes
Directional Selection Moves The Average Phenotype: Towards one extreme
Disruptive Selection Moves Toward: Two different phenotypes at the extremes and can lead to speciation
Adaptive Radiation Is: The rapid emergence of multiple species from a common ancestor, each of which occupies its own ecological niche.
A Species Is: The largest group of organisms capable of breeding to form fertile offspring
Species Are Reproductively Isolated From each Other By: Pre- or postzygotic mechanisms
Divergent Evolution Occurs When: Two species sharing a common ancestor become more different
Parallel Evolution Occurs When: Two species sharing a common ancestor evolve in similar ways due to analogous selection pressures
Convergent Evolution Occurs When: Two species not sharing a recent ancestor evolve to become more similar due to analogous selection pressures
According To The Molecular Clock Model, The Degree Of Difference In The Genome Between Two Species Is Related To: The amount of time since the two species broke off from a common ancestor.
Created by: SamB91