Biology Module 1: Cells as the Basis of Life

What are Cells?

• Cells serve as the fundamental unit of life and reproduction.

Cell Theory

• Composed entirely of cells or derived from them, including viruses.
• All cells arise from pre-existing cells.
• Cell discoveries are attributed to advanced microscopy technology.

Size of Cells

• Plant cells range between 20-100 micrometers (μm).
• Animal cells measure 5-20 μm.
• Bacteria cells are the smallest, measuring 0.1-5.0 μm.

Prokaryotic Cells

• Lack a nucleus and membrane-bound organelles; DNA resides in the cytoplasm.
• Generally smaller and more ancient than eukaryotic cells.
• Exist predominantly as unicellular organisms.
• Major groups include bacteria and archaea.

Cell Shapes

• Bacillus: Rod-shaped (example: Lactobacillus).
• Coccus: Spherical or round (example: Streptococcus).
• Spirillum: Curved or corkscrew shaped.
• Vibrio: Straight rods with a single rigid curve.

Cell Wall Composition and Antibiotics

• Stiff cell walls stem from proteins and acids.
• Bacterial cell walls typically contain peptidoglycan, while archaea use pseudomurein.
• Antibiotics can disrupt cell wall formation, leading to cell destruction.

Eukaryotic Cells

• Distinguished by a true nucleus containing genetic material (DNA/chromosomes).
• Encompass organelles, which are membrane-bound structures.
• Evolved from prokaryotic cells supporting the endosymbiotic theory, evidenced by mitochondria and chloroplasts having their own DNA.

Cell Organelles and Their Functions

• Chloroplasts: Convert light energy into chemical energy via photosynthesis (found in plants).
• Mitochondria: Conduct cellular respiration to produce ATP energy (found in both plant and animal cells).
• Cell Wall: Provides structural support, made from cellulose (found in plants and fungi).
• Cell Membrane: Regulates substance movement and acts as a barrier to the external environment (found in both).
• Cytoplasm: Jelly-like substance that suspends organelles (found in both).
• Cytoskeleton: Maintains organelle positions and cell shape (found in both).
• Centrioles: Assist in cell division by organizing chromosomes (found in both).
• Vacuole: Storage structures; larger and permanent in plant cells, small and temporary in animal cells.
• Nucleus: Stores genetic information necessary for cell function (found in both).
• Nucleolus: Produces and assembles ribosomes (found in both).
• Ribosomes: Synthesize proteins based on genetic information (found in both).
• Endoplasmic Reticulum (ER): Transports substances; has smooth (lipid production) and rough (protein processing) types (found in both).
• Golgi Body: Modifies, processes, and packages cellular products (found in both).
• Lysosomes: Digest waste and foreign materials using enzymes (found in animals).
• Pili and Flagella: Appendages aiding movement in prokaryotic cells and some fungi.

Microscopy Technologies

• Light Microscope: Utilizes visible light and lenses for magnification, crucial for developing cell understanding.
• Electron Microscope: Uses electron beams for high-resolution imaging; operates under vacuum conditions.
  • Transmission Electron Microscope (TEM): Provides internal images by slicing specimens thinly.
  • Scanning Electron Microscope (SEM): Scans surfaces to produce external images.

Advanced Microscopy

• Confocal Microscope: Employs focused lasers for high-quality imaging and creates 3D images through computer enhancement.

Comparing Microscopes

• Light microscopes use light for magnification, while electron microscopes use electrons for higher resolution imagery.

Explore the fundamental concepts of cells, their differentiation, and the cell theory in this quiz based on Biology Module 1. Understand the sizes of various cell types and the technological advances that allow us to study them effectively. Test your knowledge of what distinguishes different cells and their role as the building blocks of life.