Cell Organelles Functions to Know for General Biology I

Cell organelles are essential components that perform specific functions to keep cells alive and functioning. Understanding these organelles helps us grasp how cells operate, which is crucial in Cell Biology and General Biology, laying the foundation for more complex biological concepts.

1. Nucleus: Stores and protects genetic material, controls cellular activities

   • Contains the cell's DNA, organized into chromosomes.
   • Surrounded by a double membrane called the nuclear envelope.
   • Regulates gene expression and mediates the replication of DNA during the cell cycle.

2. Mitochondria: Energy production through cellular respiration

   • Known as the powerhouse of the cell, converting nutrients into ATP (adenosine triphosphate).
   • Contains its own DNA and ribosomes, suggesting an evolutionary origin.
   • Involved in regulating metabolic processes and apoptosis (programmed cell death).

3. Endoplasmic Reticulum: Protein and lipid synthesis, transport

   • Composed of rough (with ribosomes) and smooth (without ribosomes) regions.
   • Rough ER synthesizes proteins for secretion or membrane incorporation.
   • Smooth ER is involved in lipid synthesis and detoxification processes.

4. Golgi Apparatus: Modification, packaging, and distribution of proteins

   • Consists of flattened membrane-bound sacs called cisternae.
   • Modifies proteins received from the ER by adding carbohydrate groups (glycosylation).
   • Packages proteins into vesicles for transport to their final destinations.

5. Ribosomes: Protein synthesis

   • Composed of ribosomal RNA (rRNA) and proteins, found free in the cytoplasm or attached to the ER.
   • Translate messenger RNA (mRNA) into polypeptide chains (proteins).
   • Essential for cellular function and growth, as proteins perform most cellular tasks.

6. Lysosomes: Breakdown of cellular waste and foreign materials

   • Contain hydrolytic enzymes that digest macromolecules, old cell parts, and pathogens.
   • Maintain an acidic environment optimal for enzyme activity.
   • Play a key role in autophagy, recycling cellular components.

7. Chloroplasts: Photosynthesis in plant cells

   • Contain chlorophyll, the pigment responsible for capturing light energy.
   • Convert light energy into chemical energy through photosynthesis, producing glucose and oxygen.
   • Have a double membrane and their own DNA, similar to mitochondria.

8. Cell Membrane: Selective barrier, cellular communication

   • Composed of a phospholipid bilayer with embedded proteins.
   • Regulates the movement of substances in and out of the cell.
   • Facilitates communication between cells through receptor proteins.

9. Vacuoles: Storage of water, nutrients, and waste

   • Large central vacuole in plant cells stores water, maintaining turgor pressure.
   • Can store nutrients, waste products, and help in cellular metabolism.
   • Involved in the degradation of complex molecules.

10. Cytoskeleton: Cell structure, shape, and movement

    • Composed of microfilaments, intermediate filaments, and microtubules.
    • Provides structural support and maintains cell shape.
    • Facilitates intracellular transport and cell division.