genetics and reproduction

• What is the key role of cell division in organisms?

  To produce more of their own kind
• What type of cell division is mitosis?

  Cell division resulting in identical daughter cells
• Where does mitosis occur?

  In somatic cells
• What type of cell division is meiosis?

  Produces cells with half the genetic information
• Where does meiosis occur?

  In germ cells
• What is the structure of a replicated chromosome?

  Consists of sister chromatids
• How is sex determined in many animals?

  By the chromosomal basis of sex determination
• What system do mammals use for sex determination?

  X-Y system
• What do homologous chromosomes consist of?

  Paternal and maternal sets of chromosomes
• How many chromosomes do humans have in somatic cells?

  46 chromosomes
• What is the chromosome count in human germ cells?

  23 single chromosomes
• What phase accounts for about 90% of the cell cycle?

  Interphase
• What occurs during the mitotic phase of cell division?

  Cell division occurs in all dividing cells
• What happens to nerve cells during the cell cycle?

  They are stuck in G1 phase
• What is the first phase of mitosis?

  Prophase
• What is produced at the end of mitosis?

  Two identical daughter cells
• What is the significance of crossing over in meiosis?

  It increases genetic variation
• What are the three mechanisms that contribute to genetic variation?

  Random fertilization, independent assortment, crossing over
• What does the chromosomal theory of inheritance state?

  Genes occupy specific loci on chromosomes
• How do incomplete dominance and co-dominance differ?

  Incomplete dominance shows blended phenotypes
• What is the phenotype of F1 hybrids in incomplete dominance?

  Somewhere between the two parental phenotypes
• What are the differences between mitosis and meiosis?

  • Mitosis: 1 cell division, identical daughter cells
  • Meiosis: 2 cell divisions, varied daughter cells
  • Crossing over occurs in meiosis
• What are the implications of genetic variation mechanisms?

  • Random fertilization: any sperm can fuse with any ovum
  • Independent assortment: chromosomes sort independently
  • Crossing over: exchange of genetic material
• What are the exceptions to Mendelian segregation?

  • Incomplete dominance
  • Co-dominance
  • Genetic linkage
  • Sex-linkage
• What is the complexity of inheritance patterns?

  • Genotype-phenotype relationship is complex
  • Not all traits are determined by one gene
  • Basic principles of segregation and independent assortment apply