chapter 3 and 4 easy notes

Chapter 3: Cellular Organelles and Division

• Cellular Organelles: Understanding the structures and functions is crucial.

  • Mitochondrion: Site of aerobic respiration.

  • Endoplasmic Reticulum (ER): Rough ER synthesizes proteins; Smooth ER synthesizes lipids and detoxifies.

  • Golgi Complex: Modifies, sorts, and packages proteins.

  • Lysosomes: Contain digestive enzymes.

  • Peroxisomes: Contain oxidative enzymes.

• Mitosis:

  • Interphase: Period between divisions.   

  - $G_1$ Phase: Metabolic activity, organelle duplication. Cells stuck here are in $G_0$.  

  - S Phase: DNA and centrosome replication.   

  - $G_2$ Phase: Cell growth and enzyme synthesis continue.

  1. Prophase: Chromatin condenses, nuclear envelope disappears, centrosomes move to poles.

  2. Metaphase: Chromosomes align at the metaphase plate.

  3. Anaphase: Chromatids separate and move to opposite poles.

  4. Telophase: Nuclear membranes form around daughter chromosomes.

  • Recognize mitosis images focusing on chromatin condensation and alignment.

• Differences between Mitosis and Meiosis:

  • Mitosis produces two identical diploid cells, while meiosis produces four genetically unique haploid gametes.

  • Meiosis includes crossing over and synapsis of homologous chromosomes during Prophase I.

• Plasma Membrane:

  • Types of Transmembrane (Integral) Proteins: Include channels, transporters, receptors, enzymes, cell-identity markers, and linker proteins.

  • Types of Gradients: Concentration gradient, electrical gradient, and electrochemical gradient.

  • Passive Processes: Does not require cellular energy (ATP)

  • Simple Diffusion: Movement of small, nonpolar molecules (e.g., $O<em>2$, $CO</em>2$).

  • Facilitated Diffusion: Uses transmembrane proteins for polar/charged molecules (e.g., glucose, ions).

  • Osmosis: Movement of water across the membrane.

  • Active Processes: Does require energy

  • Primary Active Transport: Uses ATP to move substances against their concentration gradient.

  • Secondary Active Transport: Depends on concentration gradients established by primary active transport.

• Tonicity: Effects of solutions on cell shape.

  • Isotonic: No net water movement; cell size remains the same.

  • Hypotonic: Water moves into the cell; cell may lyse or burst.

  • Hypertonic: Water moves out; cell shrinks.

• Transport by Vesicles: Includes Endocytosis (cell engulfing substances) and Exocytosis (vesicles releasing contents).

  • Types include receptor-mediated endocytosis, phagocytosis, and bulk-phase endocytosis.

• Cancer: Involves uncontrolled cell division.

• Transcription vs. Translation:

  • Transcription: Occurs in the nucleus; DNA is copied to form mRNA.

  • Translation: Occurs in the cytoplasm; mRNA directs the synthesis of proteins at ribosomes.

Chapter 4

Types of Tissue

• Tissue: A group of cells that usually have a common embryonic origin and function together to carry out specialized activities.

• The Four Basic Tissue Types:

  • Epithelial Tissue: Covers body surfaces and lines hollow organs, body cavities, and ducts; it also forms glands.

  • Connective Tissue: Protects and supports the body and its organs. Various types bind organs together, store energy reserves as fat, and help provide the body with immunity to disease-causing organisms.

  • Muscular Tissue: Composed of cells specialized for contraction and generation of force. Generates heat that warms the body.

  • Nervous Tissue: Detects changes in a variety of conditions inside and outside the body and responds by generating electrical signals called nerve impulses (action potentials).

Types of Epithelial Tissue

• Classifications by Layers:

  • Simple: A single layer of cells.

  • Pseudostratified: Appears to have multiple layers but all cells rest on the basement membrane.

  • Stratified: Two or more layers of cells.

• Classifications by Shape:

  • Squamous: Thin, flat cells.

  • Cuboidal: Cube-shaped; about as tall as wide.

  • Columnar: Tall and cylindrical like columns.

  • Transitional: Cells change shape depending on the degree of stretch.

• Locations in the Body:

  • Simple Squamous: Alveoli in lungs, lining of blood vessels (endothelium).

  • Simple Cuboidal: Kidney tubules, ducts of small glands.

  • Simple Columnar: Lining of the stomach, intestines, and some glands (like salivary glands).

• Glands:

  • Endocrine Glands:

  • Ductless, secrete hormones directly into the bloodstream; examples include the pituitary gland (located below the brain) and thyroid gland (in the neck).

  • Exocrine Glands:

• Secrete products into ducts; examples include sweat glands (located in the skin), salivary glands (in the mouth), and digestive enzymes from the pancreas (located behind the stomach).

  Types of Connective Tissue

• Locations in the Body:

  • Found throughout the body, including bones, cartilage, blood, and adipose tissue.

• Examples:

  • Loose Connective Tissue: Areolar tissue.

  • Dense Connective Tissue: Tendons and ligaments.

  • Cartilage: Hyaline and fibrocartilage.

  • Bone: Compact and spongy.

Types of Muscle Tissue

• Skeletal Muscle Tissue: Long, striated fibers, multinucleated, voluntary control, attached to bones.

• Cardiac Muscle Tissue: Branched fibers, involuntary, found in heart walls, contains intercalated discs.

• Smooth Muscle Tissue: Non-striated fibers, involuntary, found in walls of hollow organs like blood vessels and the GI tract.

Excitable Cells

• Neurons and muscle fibers are excitable and exhibit electrical excitability due to specific voltage-gated channels in their plasma membranes.

Tissue Repair

• The process of replacing worn-out, damaged, or dead cells varies across tissue types:

  • Epithelial cells: High rate of regeneration.

  • Connective tissue: Limited capacity for repair.

  • Muscle tissue: Limited repair capabilities.

  • Nervous tissue: Some can perform limited repair, while others cannot.

• Fibrosis: The formation of scar tissue in injured tissues.