Genetics and evolution

• What are the two interconnected areas of biology discussed?

  Genetics and evolution
• How does genetics explain traits?

  It explains inheritance from one generation to the next
• What does evolution explain about species?

  How species change over time
• What is the significance of variation in a population?

  • Differences in traits among individuals
  • Important for natural selection
  • Allows certain individuals to survive and reproduce
• What are mutations?

  Changes in the DNA sequence
• What are point mutations?

  A change in a single nucleotide base
• What are insertions or deletions in mutations?

  Addition or loss of nucleotides
• What are chromosomal mutations?

  Large-scale changes in chromosomal regions
• What can cause mutations?

  Errors during DNA replication or exposure to mutagens
• What types of effects can mutations have?

  Beneficial, neutral, or harmful
• What does modification refer to in genetics?

  Changes in phenotype due to environmental factors
• What is epigenetics?

  The study of environmental influences on gene expression
• What can affect gene activity in epigenetics?

  Changes in DNA methylation or histone modification
• What are Mendel's Laws of Inheritance?

  1. Law of Segregation: Alleles segregate during gamete formation.
  2. Law of Independent Assortment: Genes on different chromosomes are inherited independently.
• What is a dominant allele?

  An allele that expresses its trait in presence of another
• What is a recessive allele?

  An allele that expresses only when homozygous
• What is the difference between genotype and phenotype?

  Genotype is genetic makeup; phenotype is observable traits
• What are Punnett Squares used for?

  To predict genotype and phenotype of offspring
• What is multiple allelism?

  • Some genes have more than two alleles
  • Example: ABO blood group system
  • Alleles: IA, IB, and i
• What phenotypes are produced by the ABO blood group alleles?

  A, B, AB, and O blood types
• What is recombination in genetics?

  • Exchange of genetic material during meiosis
  • Leads to new combinations of alleles
  • Increases genetic diversity
• What occurs during crossing over?

  Sections of chromatids break and exchange places
• What is genetic linkage?

  Genes close together on the same chromosome are inherited together
• What are sex-linked traits?

  • Traits carried on sex chromosomes (X or Y)
  • Most are X-linked in humans
  • Males express X-linked traits more often
• Why are males more likely to express recessive X-linked traits?

  They have only one X chromosome
• What does the Hardy-Weinberg principle describe?

  • Condition where genetic composition remains constant
  • Assumes no evolution in the population
  • Allele frequencies remain unchanged
• What are the conditions for Hardy-Weinberg equilibrium?

  1. No mutations
  2. Random mating
  3. No natural selection
  4. Large population size
  5. No gene flow
• What is the Hardy-Weinberg equation?

  $p^2 +$$2pq +$$q^2 =$$1$
• What do the variables in the Hardy-Weinberg equation represent?

  p = dominant allele frequency; q = recessive allele frequency
• What does the Hardy-Weinberg equation allow researchers to calculate?

  Allele and genotype frequencies in a population
• What are the mechanisms of evolution?

  1. Natural Selection
  2. Genetic Drift
  3. Gene Flow (Migration)
  4. Mutation
  5. Non-Random Mating
• What is natural selection?

  Traits become common due to survival advantages
• What does "survival of the fittest" mean?

  Individuals with advantageous traits survive and reproduce
• What is genetic drift?

  Random changes in allele frequencies due to chance
• What is the bottleneck effect?

  A large-scale reduction in population size
• What is the founder effect?

  Genetic makeup differs in a new population from the original
• What is gene flow?

  Migration of individuals introducing new genetic material
• How do mutations contribute to evolution?

  They introduce new alleles into a population
• What is non-random mating?

  Mating not based on chance, favoring certain traits
• What is sexual selection?

  A form of non-random mating based on mate preference