Cell Biology Overview

Study Notes

Cell Biology

Definition: Study of the structure, function, and behavior of cells.
Cell Types:
- Prokaryotic Cells:
  - No nucleus or membrane-bound organelles.
  - DNA is circular and located in nucleoid region.
  - Examples: Bacteria and Archaea.
- Eukaryotic Cells:
  - Have a nucleus and membrane-bound organelles.
  - DNA is linear and associated with histones.
  - Examples: Plant and animal cells.
Cell Structure:
- Plasma Membrane:
  - Semi-permeable barrier controlling entry/exit of substances.
- Cytoplasm:
  - Gel-like substance where organelles are suspended.
- Organelles:
  - Mitochondria: Energy production (ATP synthesis).
  - Ribosomes: Protein synthesis.
  - Endoplasmic Reticulum:
    - Rough ER: Protein synthesis and folding.
    - Smooth ER: Lipid synthesis and detoxification.
  - Golgi Apparatus: Modifies, sorts, and packages proteins.
  - Lysosomes: Digestion of macromolecules.
  - Chloroplasts (in plants): Photosynthesis.
Cell Membrane Structure:
- Phospholipid bilayer with embedded proteins.
- Fluid mosaic model: Describes the dynamic nature of the membrane.

Cell Division

Purpose: To allow growth, development, and repair of tissues.
Types of Cell Division:
- Mitosis:
  - Produces two genetically identical daughter cells.
  - Involves one cell division.
  - Stages:
    1. Prophase: Chromatin condenses into chromosomes.
    2. Metaphase: Chromosomes align at the cell equator.
    3. Anaphase: Sister chromatids separate to opposite poles.
    4. Telophase: Nuclear membranes reform; chromosomes decondense.
    5. Cytokinesis: Division of cytoplasm.
- Meiosis:
  - Produces four genetically diverse daughter cells (gametes).
  - Involves two rounds of cell division (Meiosis I and II).
  - Key Features:
    - Reduction in chromosome number by half.
    - Genetic recombination through crossing over during Prophase I.
    - Stages:
      1. Meiosis I: Homologous chromosomes separate.
      2. Meiosis II: Sister chromatids separate.
Regulation of Cell Division:
- Cell cycle checkpoints: Ensure proper division and prevent errors.
- Cyclins and cyclin-dependent kinases (CDKs): Proteins that regulate the cell cycle.
Significance of Cell Division:
- Essential for growth, tissue repair, and reproduction (in the case of meiosis).
- Errors in cell division can lead to cancer and genetic disorders.

Cell Biology

Study of cell structure, function, and behavior.
Cell Types:
- Prokaryotic Cells: Lack a nucleus and membrane-bound organelles; DNA is circular and found in nucleoid; examples include bacteria and archaea.
- Eukaryotic Cells: Possess a nucleus and membrane-bound organelles; DNA is linear and associates with histones; includes plant and animal cells.
Cell Structure:
- Plasma Membrane: Acts as a semi-permeable barrier regulating substance entry and exit.
- Cytoplasm: Gel-like substance housing organelles.
- Organelles:
  - Mitochondria: ATP synthesis, the powerhouse of the cell.
  - Ribosomes: Sites for protein synthesis.
  - Endoplasmic Reticulum (ER):
    - Rough ER: Involved in protein synthesis and folding.
    - Smooth ER: Responsible for lipid synthesis and detoxification processes.
  - Golgi Apparatus: Modifies, sorts, and packages proteins for secretion or use within the cell.
  - Lysosomes: Contain enzymes for digesting macromolecules.
  - Chloroplasts (in plants): Sites for photosynthesis.
Cell Membrane Structure:
- Composed of a phospholipid bilayer integrated with proteins; described by the fluid mosaic model representing its dynamic nature.

Cell Division

Purpose: Facilitates growth, development, and tissue repair.
Types of Cell Division:
- Mitosis: Results in two genetically identical daughter cells; single cell division.
  - Stages include:
    - Prophase: Chromatin condenses into distinct chromosomes.
    - Metaphase: Chromosomes align at the equatorial plate.
    - Anaphase: Sister chromatids are pulled apart to opposite ends.
    - Telophase: Nuclear membranes reform; chromosomes decondense.
    - Cytokinesis: Complete division of the cytoplasm.
- Meiosis: Produces four genetically diverse gametes; involves two rounds of division.
  - Key features:
    - Reduces chromosome number by half, essential for sexual reproduction.
    - Genetic recombination occurs via crossing-over in Prophase I.
    - Stages include:
      - Meiosis I: Homologous chromosomes separate.
      - Meiosis II: Sister chromatids segregate.
Regulation of Cell Division:
- Checkpoints in the cell cycle ensure accurate division and minimize errors.
- Cyclins and cyclin-dependent kinases (CDKs) are vital proteins that control progression through the cell cycle.
Significance of Cell Division:
- Critical for organismal growth, tissue repair, and sexual reproduction; errors can lead to cancer and genetic disorders.

Description

This quiz explores key concepts in cell biology, including the definitions and differences between prokaryotic and eukaryotic cells. It also covers essential cell structures and their functions, such as the plasma membrane, cytoplasm, and various organelles. Test your knowledge of how cells operate and their importance in biological systems.