Genetics and Evolution Flashcards
The combination of alleles one has at a given genetic locus.
Genotype
The observable manifestation of a genotype.
Phenotype
One dominant allele and one recessive allele.
Complete Dominance
More than one dominant allele.
Codominance
Has no dominant alleles; heterozygotes has intermediate phenotypes.
Incomplete Dominance
The proportion of a population with a given genotype who express the same phenotype.
Penetrance
The varying phenotypic manifestations of a given genotype.
Expressivity
States that an organism has two alleles for each gene, which segregate during meiosis, resulting in gametes carrying only one allele for a trait.
Mendel’s First Law (of segregation)
States that the inheritance of one allele does not influence the probability of inheriting a given allele for a different trait.
Mendel’s Second Law (of independent assortment)
This experiment demonstrated the transforming principle, converting non-virulent bacteria into virulent bacteria by exposure to heat-killed virulent bacteria.
Griffith Experiment
This experiment demonstrated that DNA is genetic material because degradation of DNA led to cessation of bacterial transformation.
Avery-MacLeod-McCarty Experiment
This experiment confirmed that DNA is genetic material because only radiolabeled DNA could be found in bacteriophage-infected bacteria.
Hershey-Chase Experiment
What are some nucleotide mutations?
- Point Mutations
- Frameshift Mutations
The substituting of one nucelotide for another.
Point Mutations
Moving the three-letter transcriptional reading frame.
Frameshift Mutations
A mutation that has no effect on the protein.
Silent Mutation
The substitution of one amino acid for another.
Missense Mutation
The substitution of a stop codon for an amino acid.
Nonsense Mutation
Result in a shift in the reading frame of genes, leading to changes for all downstream amino acids.
Insertions/Deletions
Mutations that include much larger-scales and affect whole segments of DNA.
Chromosomal Mutations
What are some chromosomal mutations?
- Deletion mutations
- Duplication mutations
- Inversion mutations
- Insertion mutations
- Translocation mutations
Occurs when a large segment of DNA is lost.
Deletion Mutations
Occurs when a segment of DNA is copied multiple times.
Duplication Mutations
Occurs when a segment of DNA is reversed.
Inversion Mutations
Occurs when a segment of DNA is moved from one chromosome to another.
Insertion Mutations
Occurs when a segment of DNA is swapped with a segment of DNA from another chromosome.
Translocation Mutations
A flow of genes between species through hybrid offspring.
Genetic Leakage
Occurs when the composition of the gene pool changes as a result of chance.
Genetic Drift
Results from bottlenecks that suddenly isolate a small population, leading to inbreeding and increased prevalence of certain homozygous genotypes.
Founder Effect
The likelihood of two alleles being separated during crossing over in meiosis.
Recombination Frequency (theta)
States that if a population meets certain criteria (aimed at a lack of evolution), then the allele frequencies will remain constant.
Hardy-Weinburg Principle
Accounts for mutation and recombination as mechanisms of variation and considers differential reproduction to be the mechanism of reproductive success.
Modern Synthesis Model (Neo-Darwinism)
Considers an organism’s success to be based on the number of offspring, sucess in supporting offspring and the ability of the offspring to then support others.
Inclusive Fitness
Keeps phenotypes in a narrow range, excluding extremes.
Stabilizing Selection
Moves the average phenotype toward one extreme.
Directional Selection
Moves toward two different phenotypes at extremes and can lead to speciation.
Disruptive Selection
Is the rapid emergence of multiple species from a common ancestor, each of which occupies its own ecological niche.
Adaptive Radiation
Occurs when two species sharing a common ancestor become more different.
Divergent Evolution
Occurs when two species sharing a common ancestor evolve in similar ways due to analogous selection pressures.
Parallel Evolution
Occurs when two species NOT sharing a recent ancestor evolve to become more similar due to analogous selection pressures.
Convergent Evolution
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.
Molecular Clock Model
