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Chapter 6, The Cell

1. Prokaryotic vs. Eukaryotic Cells

  • Comparison: Prokaryotic cells are smaller, simpler, lack a nucleus and membrane-bound organelles. Eukaryotic cells are larger, more complex, and contain a nucleus and other membrane-bound organelles.

2. The Nucleus

  • Structure: The nucleus is the control center, housing the cell's genetic material (DNA).

  • Function: It regulates protein synthesis by transcribing DNA to mRNA, which moves to the cytoplasm for translation into proteins.

3. Ribosomes

  • Structure: Composed of RNA and proteins.

  • Function: Sites of protein synthesis where mRNA is translated into polypeptides (proteins).

4. Endomembrane System

  • Components: Includes the nuclear envelope, endoplasmic reticulum (ER), Golgi apparatus, lysosomes, and plasma membrane.

  • Functions: Modifies, packages, and transports lipids and proteins.

    • Relationships: The ER synthesizes proteins and lipids, while the Golgi apparatus modifies and sorts these for distribution.

5. Mitochondria

  • Structure: Double membrane; smooth outer membrane and folded inner membrane (cristae).

  • Function: Produces ATP through aerobic respiration, serving as the cell's powerhouse.

6. Chloroplasts

  • Structure: Double-membraned with thylakoids and stroma.

  • Function: Conducts photosynthesis, converting sunlight, water, and carbon dioxide into glucose and oxygen.

7. Cytoskeleton

  • Function: Provides structural support, facilitates intracellular transport, and enables cell movement.

  • Components: Composed of microtubules, actin microfilaments, and intermediate filaments, each with distinct roles.

8. Cytoskeletal Components

  • Microtubules: Hollow tubes providing rigidity and transport tracks for organelles.

  • Actin Microfilaments: Thin fibers involved in muscle contraction and cell shape alteration.

  • Intermediate Filaments: Provide mechanical support and stabilize cell structures.

9. Plant Cell Walls vs. Extracellular Matrix (ECM) of Animal Cells

  • Plant Cell Walls: Rigid, composed mainly of cellulose; provide structural support and define cell shape.

  • Extracellular Matrix: Flexible network of proteins and polysaccharides in animal cells; supports cellular functions, communication, and attachment.

10. Intercellular Junctions

  • Plant Cells: Plasmodesmata allow substance transport between cells.

  • Animal Cells: Have tight junctions, anchoring junctions, and gap junctions for communication, adhesion, and transport between neighboring cells.