Untitled Flashcards Set

Summary of Key Points from Chapter 4: Cells

1. Origin of Living Cells on Earth

• Life began through four overlapping stages:

  1. Formation of organic molecules (e.g., amino acids, nucleotides).

  2. Formation of organic polymers (e.g., RNA, DNA, proteins).

  3. Enclosure of polymers within membranes (protobionts).

  4. Evolution of cellular characteristics (RNA world to DNA/RNA/protein world).

2. Microscopy

• Types of Microscopes:

  • Light Microscopes: Lower resolution, uses light.

  • Electron Microscopes (TEM & SEM): Higher resolution, uses electron beams.

• Key parameters: Resolution, Contrast, and Magnification.

3. Overview of Cell Structure & Function

• Prokaryotic Cells: Simple, no nucleus, found in bacteria & archaea.

• Eukaryotic Cells: Complex, have nucleus and organelles.

• Cell Size & Shape: Influenced by surface area-to-volume ratio.

4. The Cytosol

• Site of metabolism, protein synthesis, and molecular breakdown.

• Contains cytoskeleton (microtubules, intermediate filaments, actin filaments).

• Motor proteins interact with the cytoskeleton to enable movement.

5. The Nucleus & Endomembrane System

• Nucleus: Stores genetic material (DNA) and controls gene expression.

• Endoplasmic Reticulum (ER):

  • Rough ER: Protein synthesis.

  • Smooth ER: Lipid synthesis and detoxification.

• Golgi Apparatus: Modifies, sorts, and ships proteins.

• Lysosomes: Break down waste and macromolecules.

• Vacuoles: Storage and structural support (large in plants).

• Peroxisomes: Detoxify harmful substances.

6. Semiautonomous Organelles

• Mitochondria: Produce ATP (cellular energy).

• Chloroplasts: Conduct photosynthesis (in plants).

• Endosymbiosis Theory: These organelles originated from ancient bacteria.

7. Protein Sorting

• Cotranslational Sorting: Proteins sorted while being made.

• Post-translational Sorting: Proteins sorted after synthesis.

8. Extracellular Matrix & Cell Walls

• ECM (in animals): Provides structure, support, and signaling.

• Plant Cell Walls: Strong, rigid, provides mechanical support.

9. Systems Biology of Cells

• Bacteria: Simple cells.

• Eukaryotes: Organized into four interacting systems:

  1. Nucleus

  2. Cytosol

  3. Endomembrane system

  4. Semiautonomous organelles