SAS 2: Levels of Organization

Overview of Cells

• Cells are the fundamental unit of life, forming the basic building blocks of all living organisms.
• Composed of tissues and organs, each specialized for specific functions.
• Organisms can be unicellular (single-celled) or multicellular.

Types of Organisms

• Prokaryotes:

  • Simple, unicellular organisms without a defined nucleus or membrane-bound organelles (e.g., bacteria, archaebacteria).
  • Likely the first living organisms on Earth.

• Eukaryotes:

  • More complex organisms with a defined nucleus and membrane-bound organelles.
  • Can be unicellular (e.g., protozoans) or multicellular (e.g., plants, animals, fungi).

Key Cell Components

• Nucleoplasm:

  • Fluid inside the nucleus that suspends chromosomes.

• Nucleolus:

  • Specialized regions within chromosomes, containing multiple copies of genes.

• Nucleus:

  • Contains the cell's genetic information; the most prominent organelle.

• Lysosome:

  • Organelle responsible for breaking down foreign materials and waste within the cell.

• Smooth Endoplasmic Reticulum (Smooth ER):

  • Involved in lipid synthesis and detoxification of harmful substances.

• Golgi Complex:

  • Modifies, packages, and stores products from the rough endoplasmic reticulum.

• Rough Endoplasmic Reticulum (Rough ER):

  • Site of most protein synthesis within the cell.

• Ribosomes:

  • Cellular structures responsible for translating RNA into proteins.

• Cytoplasm:

  • Jelly-like fluid holding all cell contents, providing a medium for cellular processes.

• Plasma Membrane:

  • Selectively permeable membrane that encases the cell, controlling the movement of substances in and out.

• Mitochondria:

  • Powerhouse of the cell, producing ATP (adenosine triphosphate), the energy currency of cells.

Genetic Similarities

• Both prokaryotes and eukaryotes share DNA and use the same genetic code, indicating a common ancestor.