MCAT Lecture Series: Year Two Introduction and Biology Chapter 2

Lecture Logistics

• Live Stream Information

  • Available on YouTube, every Tuesday and Wednesday at 6:30 p.m. EST.
  • Join via a permanent Zoom link available in the video description.
  • Physical location: 2310 Ingersol Hall, Brooken College.
  • WhatsApp chat link for updates and interaction.

• Resources

  • Google Drive link with study guides and sign-up for email updates.
  • Notes, study guides, and other materials available for MCAT preparation.
  • Option to support via "Buy Me a Coffee," with 50% proceeds to charity (Doctors Without Borders).

Introduction Recap

• Apology for technical issues on the first day.
• Encouragement to grow the program organically by sharing with friends.

Lecture Focus: Chapter 2 of General Biology - Reproduction

Overview

• Recognized as one of the hardest chapters in the MCAT.
• Covers cellular and sexual reproduction, and what constitutes life (cell theory).

Cellular Reproduction

The Cell Cycle

• Phases: G1, S, G2, M

  • G1 (Presynthetic Gap): Cell growth, organelle increase.
  • S (Synthesis): DNA replication.
  • G2 (Postsynthetic Gap): Quality control and error checking.
  • M (Mitosis): Division into two daughter cells.

• Key Concepts

  • Autosomal (2N) vs. Germ cells (N)
  • Chromosomes are DNA packages.
  • 2N implies double the genetic material compared to N (haploid).

Mitosis

1. Prophase: DNA condenses, centrioles separate, nuclear membrane dissolves.
2. Metaphase: Chromosomes align at metaphase plate.
3. Anaphase: Sister chromatids split and move to opposite poles.
4. Telophase: Spindle breakdown, nuclear membrane reforms, cytokinesis.

• Human Genome: Starts with 46 chromosomes (2N, single-stranded), becomes 92 chromatids (4N) during replication.

Human Reproduction

Gametes and Meiosis

• Gametes (sex cells) are haploid (N), created through meiosis.

• Meiosis Stages:

  • Meiosis I: Reductional division (homologous chromosomes separate).
    • Prophase I: Crossing over occurs, increases genetic variability.
    • Metaphase I, Anaphase I, Telophase I: Homologous chromosomes separate.
  • Meiosis II: Equational division (sister chromatids separate, like mitosis).

• Key Differences

  • Crossing over increases genetic diversity.
  • Results in four haploid cells from one diploid cell.

Relevance to MCAT

• Understanding cell cycle and reproduction is critical for MCAT Biology.
• Emphasis on grasping complex processes like genetic variability and cell division.

Additional Notes

• Encouragement to review lecture content and prepare for upcoming topics.
• Interaction during lectures through Zoom and in-person is encouraged for better learning.