Cell Division and Tissues Overview

Cell Division and Genetics

• A sperm cell has 22 autosomes and either an X or Y chromosome.
• An egg cell has 22 autosomes and an X chromosome.
• Homologous chromosomes (chromosome pairs) separate and move to opposite poles in meiosis I.
• Meiosis II and mitosis both involve the separation of sister chromatids during anaphase.
• A cell plate forms during cytokinesis in plant cells.
• A cleavage furrow forms during cytokinesis in animal cells.
• MPF (Maturation-Promoting Factor) activity declines at the end of mitosis.
• Cytochalasin B disrupts actin function, affecting cleavage furrow formation.

Tissues and Organ Systems

• Epithelial tissue forms protective layers that line organs and body cavities.
• Adipose tissue stores fat for insulation and energy storage.
• Collagenous fibers provide strength and flexibility to connective tissues.
• Nervous tissue consists of neurons and glial cells.
• Muscle tissue contracts in response to nerve signals, enabling movement.
• Smooth muscle controls involuntary movements.
• Neurons transmit electrical signals.
• Osteons are structural units of compact bone tissue.
• Squamous epithelial cells are flat and suited for diffusion and protection.

Key Terms

• Autosomes: Non-sex chromosomes
• Homologous chromosomes: Chromosome pairs (one from each parent) that are similar in shape and size.
• Cytokinesis: The process where the cytoplasm of a parent cell divides into two daughter cells.
• MPF (Maturation-Promoting Factor): A complex involved in the regulation of the cell cycle.

Cell Phases (from page 2)

• Prophase: Chromatin condenses, nuclear envelope breaks down
• Prometaphase: Microtubules attach to kinetochores
• Metaphase: Chromosomes align at the metaphase plate
• Anaphase: Sister chromatids separate and move to opposite poles
• Telophase: Chromosomes decondense, nuclear envelope reforms
• Cytokinesis: The cytoplasm divides, forming two daughter cells

Cell Cycle Regulation (from page 4)

• Cyclin synthesis begins in late S phase and continues through G2, accumulating during this stage
• Cyclin combines with Cdk to form MPF
• MPF promotes mitosis by phosphorylating proteins, peaking in metaphase
• During anaphase, cyclin is degraded, ending the M phase
• MPF is recycled

Human Life Cycle (from page 5)

• In humans, haploid gametes (n=23) form from diploid cells (2n=46) via meiosis.
• Fertilization of the gametes results in a diploid zygote (2n=46).
• Diploid zygotes undergo mitosis to form multicellular diploid adults.

Epithelial Tissues (from pages 6 & 7)

• Cuboidal Epithelium: Cube-shaped cells found in glands and tubules, used for secretion and absorption
• Simple Columnar Epithelium: Tall, column-like cells lining the digestive tract for absorption and secretion
• Pseudostratified Ciliated Columnar Epithelium: Appears layered but all cells contact the basement membrane; cilia help move mucus; found in respiratory tract
• Stratified Squamous Epithelium: Multiple layers of flat cells, providing protection against abrasion; found in skin, mouth, esophagus
• Simple Squamous Epithelium: Single layer of flat cells; allows diffusion and filtration; found in lungs, blood vessels, kidney glomeruli