Chapter 4 Flashcards
Microevolution
Occurs on gene frequencies, relatively few genes changing from generation to generation. Slow accumulation over time.
Macroevolution
Significant physical changes based on many genetic changes.
Deme
Local population that interbreeds
Gene Pool
All the genetic information in a breeding pop.
Reproductive isolation:
mechanism that prevents two populations from interbreeding (diff. continents)
Species
groups of reproductively isolated organisms
Homologous chromosomes
A pair of chromosomes that carry genes for the same set of traits
Gene
A segment of DNA that codes for some trait
Allele
A variant of a gene that expresses a trait in different form
Homozygous
An individual who inherits two of the same allele for a particular trait.
Heterozygous
An individual who inherits two different alleles for a particular trait
Dominant Alleles
Always expressed in the phenotype if present. AA, Aa.
Recessive Alleles
Only expressed if the genotype is aa (recessive genes).
Skin colour
Determined by melanocytes = produce melanin, determines how dark or light someone will be.
Random Assortment
The chance distribution of chromosomes to daughter cells during meiosis; along with recombination, a source of genetic variation (but not new alleles) from meiosis
Hardy-Weinberg Equilibrium
Predicting genotype frequencies in the next generation, ie. if evolution will take place.
Mutation
Molecular alteration in genetic material. Only source of new alleles. Chromosomal duplications: Klinefelter’s syndrome, trisomy.
Fitness
Most optimal for that situation, not necessarily large + strong. Could be small.
Exogamous vs. Endogamous marriage
Marrying outside (more gene flow) vs. inside (less gene flow) a cultural/genetic group.
Founder Effect
Type of genetic drift. Occurs when a small band of “founders”leaves its parent group and forms a colony elsewhere.
Recombination
Affects how some genes act, and slight changes of gene function can become material for natural selection to act upon.
Sickle-Cell Anemia
severe inherited hemoglobin disorder in which red blood cells collapse when deprived of oxygen. Results from 2 copies of a mutant allele.
Mendelian Inheritance
Lots of these traits are considered to be these, ABO blood syst. one of them.
What is sickle-cell anemia?
Balanced polymorphism.
Huntington Disease
Caused by a dominant mutation on chromosome 4.
What makes natural selection?
Survival of the fittest and reproduction of the fittest.
What Causes Evolution?
Mutation, Natural Selection, Genetic Drift, and Gene Flow
