Final Exam Review and Genetics Concepts

Extra Credit Opportunities

• Attendance Points: Visiting instructor or SI sessions earns up to 10 points added to your final exam score.
• Continued Extra Credit: Extra credit from SI sessions and attendance will be included in the exam category for greater impact on overall grades.

Lab Grades and What-If Scenarios

• Lab Grades Timing: Lab grades are only finalized at the end of the course.
• What-If Grades Tool: Use current lab percentage to visualize how it impacts your overall grade.
• Minimum Requirements: At least 60% in both lab and lecture is required to pass.
• Communication: Stay in touch if you’re worried about grades; the instructor can provide suggestions for study strategies.

Final Exam Details

• Cumulative Exam: The final exam includes content from throughout the course, but focuses on major topics, not every detail.
• Study Guide Availability: A study guide will be provided summarizing key chapters and concepts to focus on.
• Study Strategy: Review older material first to reinforce understanding before moving to recent topics.

Key Concepts in Genetics

• Mendelian Genetics: Mendel identified hereditary factors (now called genes) during his studies on pea plants, but the understanding of how these factors operated in relation to chromosomes evolved with the study of mitosis and meiosis.
• Chromosome Theory of Inheritance:
  • Chromosomes contain genes which behave independently during meiosis, known as independent assortment.
  • This process allows for diverse genetic combinations in gametes.

Independent Assortment and Its Importance

• Definition: Independent assortment refers to the random arrangement of homologous chromosomes during metaphase I of meiosis, leading to unique combinations of alleles in gametes.
• Impact on Diversity: The randomness increases genetic variation; if chromosomes did not assort independently, offspring would have less diversity in traits.

Thomas Morgan's Experiment with Fruit Flies

• Study with Drosophila: Morgan used fruit flies to demonstrate genetic inheritance and the relationship between traits and chromosomes.
• Eye Color Gene Example:
  • Mating red-eyed female and white-eyed male flies produced only red-eyed offspring in the F1 generation.
  • F2 generation exhibited a 3:1 ratio of red to white eyes, indicating a sex-linked inheritance pattern.
• Sex-Linked Traits: Genes located on sex chromosomes, often showing varying expression rates in males and females.

Sex Chromosomes in Humans

• Chromosome Types: Women typically have two X chromosomes (XX), while men have one X and one Y chromosome (XY).
• Size Difference: The Y chromosome is smaller and has fewer genes than the X chromosome, leading to specific characteristics of sex-linked inheritance, such as traits found on the X chromosome not having equivalents on the Y.

Implications of Sex-Linked Traits

• Example with Blood Clotting: The blood clotting gene resides on the X chromosome.
  • Since the Y chromosome lacks a corresponding gene, mutations on the X chromosome that affect blood clotting will express more commonly in males than females due to the absence of a backup gene on Y.