Lecture Notes: Comparison of Mitosis and Meiosis

Introduction

• Vocabulary in biology can be confusing with terms like chromosome, chromatid, chromatin, transcription, translation, mitosis, and meiosis.
• Understanding similarities and differences between mitosis and meiosis is crucial.
• This lecture provides a side-by-side comparison using split screen visuals.

Basic Concepts

• Mitosis and meiosis involve the creation of new cells.
• Mitosis: Results in body cells.
• Meiosis: Results in gametes (sperm and egg cells).
• Starting cells in both processes are diploid (2n), meaning they have 2 sets of chromosomes (46 in humans).
• Interphase: Precedes both processes; duplicates chromosomes to prepare for division.

Stages of Cell Division

Acronym: PMAT

• Prophase
• Metaphase
• Anaphase
• Telophase

Mitosis Stages

• Prophase: Chromosomes condense and become visible.
• Metaphase: Chromosomes line up in the middle in a single file.
• Anaphase: Chromatids are pulled away to opposite sides.
• Telophase: Chromosomes reach opposite ends, and new nuclei form.
• Followed by Cytokinesis: Splits the cytoplasm, resulting in two identical diploid cells (46 chromosomes each).

Meiosis Stages

Meiosis I

• Prophase I: Chromosomes match with homologous pairs; crossing over occurs creating recombinant chromosomes.
• Metaphase I: Chromosomes line up in pairs in the middle.
• Anaphase I: Whole chromosomes, not chromatids, are pulled apart to opposite sides.
• Telophase I: Similar to mitosis, chromosomes at opposite ends with nuclei forming.
• Cytokinesis follows.

Meiosis II

• Prophase II: Chromosomes condense in both cells but less eventful as no homologous pairs.
• Metaphase II: Chromosomes line up in a single file (similar to mitosis Metaphase).
• Anaphase II: Chromatids are pulled away.
• Telophase II: Chromosomes at opposite ends, new nuclei forming.
• Cytokinesis completes the division resulting in four non-identical haploid gametes (23 chromosomes each).

Importance of Processes

• Mitosis: Essential for organism growth and cell replacement.
• Meiosis: Generates genetic diversity and produces gametes for reproduction.
• Fusion of sperm and egg creates a fertilized egg (zygote), starting development of a new organism via mitosis.

Conclusion

• Mitosis and meiosis have distinct roles and features.
• Understanding their mechanisms is key to grasping biological processes.
• Stay curious and continue exploring!