Cell Organelles Overview

Lysosomes

• Contain enzymes responsible for digesting non-usable cellular materials.

Peroxisomes

• Membranous sacs filled with oxidase enzymes.
• Detoxify harmful substances and dismantle free radicals.
• Replicate by pinching in half.

Mitochondria

• Known as the "powerhouses" of the cell.
• Continuously change shape.
• Perform oxygen-dependent reactions to break down food.
• Generate ATP, the primary energy currency of the cell.

Cytoskeleton

• Composed of a network of protein structures throughout the cytoplasm.
• Functions as the internal framework of the cell.
• Consists of three types of filaments:
  • Microfilaments (2mm) made of actin subunits.
  • Intermediate filaments (10m) with fibrous subunits.
  • Microtubules (25mm) formed from tubulin subunits.

Centrioles

• Rod-shaped structures made of microtubules.
• Play a crucial role in directing the formation of the mitotic spindle during cell division.

Nucleus

• Acts as the control center of the cell.
• Houses genetic material (DNA) and consists of three main regions:
  • Nuclear membrane.
  • Nucleolus.
  • Nucleoplasm.

Nuclear Membrane

• A double phospholipid membrane that serves as a barrier for the nucleus.
• Contains nuclear pores for material exchange with the cytoplasm.

Nucleoli

• The nucleus contains one or more nucleoli, essential for ribosome production.
• Ribosomes migrate to the cytoplasm through the nuclear pores.

Nucleoplasm

• Surrounds the nucleus, embedding chromatin which is a folded form of DNA and histones.

Chromatin

• Comprises DNA and proteins scattered within the nucleus.
• Condenses into chromosomes during cell division.

Prokaryote vs. Eukaryote

• Prokaryote (unicellular):

  • Lacks a membrane-bound nucleus; genetic material is in a nucleotide region.
  • Unicellular and smaller than eukaryotes, averaging 1-5 microns in size.
  • DNA is single and circular.

• Eukaryote (multicellular):

  • Has a membrane-bound nucleus enclosing genetic material.
  • DNA is linear and present in multiple copies within the nucleus.
  • Typically larger, with an average size of ~10-100 microns.

This quiz covers the essential functions and characteristics of various cell organelles, including lysosomes, peroxisomes, mitochondria, and the cytoskeleton. Gain insights into how these organelles contribute to cellular structure and energy production. Perfect for biology students learning about cell biology.