Cell Organelles Overview

Lysosomes

• Contain digestive enzymes for breaking down non-usable cellular materials.

Peroxisomes

• Membrane-bound sacs filled with oxidase enzymes.
• Detoxify harmful substances and break down free radicals.
• Replicate by reproducing through binary fission (pinching in half).

Mitochondria

• Known as the "powerhouses" of the cell due to ATP production.
• Continuously change shape.
• Conduct aerobic reactions, using oxygen to convert food into energy.

Cytoskeleton

• Composed of a network of protein structures within the cytoplasm.
• Provides internal support and shape to the cell.
• Consists of three types of filaments:
  • Microfilaments (actin): approximately 2 nm diameter.
  • Intermediate filaments: approximately 10 nm diameter.
  • Microtubules (tubulin): approximately 25 nm diameter.

Centrioles

• Rod-shaped structures made up of microtubules.
• Play a critical role in forming the mitotic spindle during cell division.

Nucleus

• Acts as the control center of the cell, housing genetic material (DNA).
• Composed of three main regions:
  • Nuclear membrane: a double-layered phospholipid barrier with nuclear pores.
  • Nucleolus: site of ribosome production.
  • Nucleoplasm: gel-like substance containing chromatin within the nucleus.

Nuclear Membrane

• Double phospholipid membrane acting as a barrier for the nucleus.
• Contains nuclear pores facilitating material exchange with the cytoplasm.

Nucleoli

• One or more nucleoli are present within the nucleus.
• Responsible for synthesizing ribosomes, which migrate to the cytoplasm through nuclear pores.

Nucleoplasm

• The semi-fluid matrix inside the nucleus, analogous to cytoplasm.
• Contains chromatin, which is a combination of DNA and histone proteins.

Chromatin

• Made of DNA and proteins, dispersed throughout the nucleus.
• Condenses into chromosomes during cell division.

Prokaryote vs. Eukaryote

• Prokaryote:

  • Unicellular organisms without a membrane-bound nucleus; genetic material is located in the nucleoid.
  • Typically smaller in size (1-5 microns) with single, circular DNA.

• Eukaryote:

  • Unicellular or multicellular organisms with a membrane-bound nucleus containing linear, multiple copies of DNA.
  • Generally larger in size (10-100 microns).

This quiz focuses on the essential organelles within a cell, such as lysosomes, peroxisomes, mitochondria, and the cytoskeleton. Test your knowledge on their functions, structures, and importance in cellular processes.