Overview of Cell Biology Concepts

Jan 5, 2025

Cell Biology Lecture Notes

Basic Characteristics of Cells

  • Cells: Smallest living units of an organism.
  • Common features of all cells:
    • Cell Membrane: Separates cell interior from the environment.
    • Cytoplasm: Jelly-like fluid inside the cell.
    • DNA: Genetic material of the cell.

Categories of Cells

  1. Eukaryotic Cells
    • Have organelles, including a nucleus.
    • More advanced and complex; found in plants and animals.
  2. Prokaryotic Cells
    • No nucleus or membrane-enclosed organelles.
    • Genetic material exists freely; unicellular organisms like bacteria.

Organelles and Their Functions

  • Organelles: Specialized cell parts with unique functions.
    • Nucleus: Control center containing DNA.
      • DNA dictates cell function and behavior.
      • Chromatin: Spread-out form of DNA inside nuclear membrane.
      • Chromosomes: Condensed DNA during cell division.
      • Nucleolus: Site where ribosomes are made.
    • Ribosomes: Synthesize proteins.
      • Can be free in the cytoplasm or attached to the endoplasmic reticulum (ER).
    • Endoplasmic Reticulum (ER):
      • Rough ER: Has ribosomes; involved in protein synthesis.
      • Smooth ER: Lacks ribosomes; involved in lipid synthesis.
    • Golgi Apparatus: Processes and packages proteins.
      • Modifies proteins into usable forms with added lipids or carbohydrates.
    • Vacuoles: Storage sacs for materials.
      • Central vacuole in plant cells stores water.
    • Lysosomes: Break down cellular debris with enzymes.
    • Mitochondria: Powerhouse of the cell, produces energy (ATP) via cellular respiration.
    • Chloroplasts: Site of photosynthesis in plant cells, contains chlorophyll.
    • Cytoskeleton: Maintains cell shape, includes microfilaments and microtubules.

Unique Cell Structures

  • Cell Wall: Provides shape, support, and protection in plant cells (absent in animal cells).
  • Cilia: Hair-like structures in respiratory tract cells, trap particles and assist movement.
  • Flagella: Tail-like structures for cell movement, present in some bacteria and sperm cells.

Summary

  • Eukaryotic vs. Prokaryotic Cells:
    • Eukaryotic: Plants and animals, nucleus present.
    • Prokaryotic: Unicellular, no nucleus.
  • Commonality: All cells have cell membrane, cytoplasm, and DNA.
  • Plant cells uniquely have chloroplasts; both plant and animal cells have mitochondria.