Lecture Notes: Cell Organelles

Overview

• The human body is composed of trillions of cells.
• Cells are the basic unit of life and consist of organelles.
• Organelles are components within a cell that perform specific functions.

Major Organelles

• Nucleus

  • Acts as the control center of the cell.
  • Contains DNA stored as chromatin, which forms chromosomes during cell division.
  • Enclosed by a nuclear envelope with pores regulated by a pore complex.
  • Nucleolus within the nucleus is where ribosomes are partially assembled.

• Ribosomes

  • Made of proteins and rRNA (ribosomal RNA).
  • Translate messenger RNA (mRNA) into proteins.
  • Found as free ribosomes in the cytoplasm or bound to the endoplasmic reticulum.

• Endoplasmic Reticulum (ER)

  • Rough ER
    • Has ribosomes attached, giving it a rough texture.
    • Continuous with the nuclear membrane.
    • Involved in protein synthesis and folding.
  • Smooth ER
    • Involved in lipid synthesis.
    • Stores calcium ions, which can trigger cellular responses.

• Golgi Body

  • Functions as the cell's warehouse.
  • Modifies, packages, and ships molecules.
  • Consists of folds called cisterna with cis and trans ends.

• Chloroplasts

  • Found only in plant cells.
  • Contain chlorophyll for photosynthesis.
  • Have a double membrane and structures like thylakoids and stroma.

• Mitochondria

  • Convert chemical energy from food into ATP.
  • Have a double membrane with folded inner layers called cristae.
  • Contain their own ribosomes and DNA within the mitochondrial matrix.

• Vacuoles

  • Serve as storage containers.
  • Central vacuole in plant cells stores water and inorganic ions.
  • Animal cells have smaller vacuoles.

• Lysosomes

  • Contain enzymes for digestion.
  • Digest food molecules and dispose of non-functioning organelles.

Conclusion

• This lecture covered the structure and function of the eight major organelles.
• Understanding these organelles is crucial for comprehending cellular operations.

Tips for Further Study

• Review the linked checklist to ensure comprehension of key concepts.
• Utilize resources like videos and discussion forums for additional learning.
• Engage with materials and ask questions to deepen understanding.

Feel free to ask questions or suggest topics for future lectures. Good luck with your studies!