Lecture 4 BIOA11

Meiosis

• Meiosis is a specialized type of cell division that reduces chromosome numbers by half, resulting in four non-identical gametes.
• It occurs during the formation of gametes: sperm and eggs in animals, and spores in plants.

Purpose of Cell Division

• Cell division is essential for growth, development, and tissue repair.
• In asexual reproduction, offspring are genetically identical to the parent because they arise from a single parent cell, undergoing mitosis.

Genetic Variation

• In sexual reproduction, offspring are genetically different due to the combination of genetic material from two parents and processes like crossing over and random assortment.

Citing Information Sources

• Citing sources ensures credibility, allows verification of information, and gives credit to original authors.

Tumor Suppressor Genes

• Tumor suppressor genes regulate cell division and can prevent uncontrolled cell growth, playing a crucial role in cancer prevention.

Cell Cycle Checkpoints

• Three primary checkpoints in the cell cycle: G1 (checks DNA damage), G2 (ensures DNA replication is complete), and M (monitors proper chromosome alignment).

Proto-Oncogenes

• Proto-oncogenes are normal genes that, when mutated, become oncogenes leading to cancer by promoting cell division uncontrollably.

Processes During Meiosis

• Meiosis involves two rounds of division: Meiosis I (reduction division) and Meiosis II (equational division).
• Crossing over occurs during Prophase I, where homologous chromosomes exchange genetic material.

Karyotype

• A karyotype is a visual representation of an individual's chromosomes, used to identify chromosomal abnormalities.

Crossing Over

• Crossing over results in genetic recombination, increasing genetic diversity in gametes.
• Random alignment during Metaphase I arranges homologous chromosomes independently, contributing to variability.

Impact of Random Alignment

• Random alignment leads to different combinations of maternal and paternal chromosomes in gametes, enhancing genetic diversity.

Major Organ Systems

• There are eleven major organ systems in the human body, including the circulatory, respiratory, and nervous systems.

Tissue Types

• Four basic types of tissue in the human body: epithelial, connective, muscle, and nervous tissue.

Definition of Organs

• Organs are structures composed of two or more types of tissues that perform specific functions within an organ system.

Interaction of Organ Systems

• Organ systems collaborate to maintain homeostasis, support metabolism, and facilitate physical function of the body.

DNA Replication

• DNA replication is the process of copying DNA, ensuring genetic information is passed on during cell division, involving key enzymes like DNA polymerase.

Function of Tumor Suppressors

• Tumor suppressors prevent the transition from G1 to S phase unless conditions are favorable, helping control the cell cycle.

Mitosis Process

• Mitosis involves the division of a parent cell into two identical daughter cells, maintaining chromosomal number and genetic consistency.

Purpose of Cytokinesis

• Cytokinesis is the final step of cell division, dividing the cytoplasm and organelles, resulting in two separate cells.

Order of Cell Cycle Phases

• The correct order of phases in the cell cycle: G1, S (DNA synthesis), G2, M (mitosis), followed by cytokinesis.

Test your knowledge on cell cycle control mutations and tumor suppressor genes with this quiz. Learn about the role of BRCA1 gene, the importance of tumor suppressor proteins, and the effects of mutated tumor suppressor proteins on tumor growth.