Bio004, College of the Desert

• Two Major Categories of Cells:
• 1. Prokaryotic cells
• 2. Eukaryotic cells

• Prokaryotic Cells:
• a. Smaller of the two cell types.
• b. First appeared 3.5 billion years ago.
• c. Cells do not have a nucleus (DNA in cytoplasm).

• Eukaryotic Cells:
• a. Larger of the two cell types (10X).
• b. First appeared 2.1 billion years ago.
• c. Cell does have a nucleus (DNA in nucleus).

Plasma membrane: regulates traffic of molecules between cells and their surroundings.

• Fluid-mosaic model: concept which describes the structure of the cell membrane.
• i) Fluid: because the molecules can move freely past one another.
• ii) Mosaic: because of the diversity of proteins embedded in the phospholipid bilayer.

Extracellular matrix: non-living material that separates living cells while holding them together; protects & supports.

Cell junctions: structures that connect cells together allowing them to communicate with each other.

• Nucleus: membrane-enclosed organelle that contains DNA.
• ALSO: ball-like mass of granules and fibers that produces components of ribosomes in the nucleus.

Nuclear membrane: surrounds the nucleus; allows the passage of materials between the nucleus and cytoplasm.

Chromatin: long fibers consisting of DNA molecules and associated proteins (spagetti like).

Chromosome: single, long fiber of chromatin material.

Ribosome: site of protein synthesis.

Endoplasmic reticulum (ER) : one of the primary regions within a cell for producing an enormous variety of molecules.

• 2 types of Endoplasmic reticulum:
• 1. Rough ER: studded with ribosomes; synthesizes proteins.
• 2. Smooth ER: – lacks ribosomes; synthesizes lipids (steroids) and detoxifies poisons.

Golgi apparatus: receives, refines, stores, and distributes chemical products of the cell.

Transport vesicles: spheres that distribute chemical products.

Vacuoles: sacs that develop from ER, Golgi apparatus, or plasma membranes, carrying out a variety of functions.

Chloroplasts: organelles that carry out photosynthesis (only in green plants).

Mitochondria: organelles that carry out cellular respiration (in all living organisms).

Endosymbiosis: situation in which one or more organisms reside within another organism.

Cytoplasm: entire region of a cell between the nucleus and plasma membrane (fluid + organelles).

Cytosol: fluid portion of cytoplasm.

• Cytoskeleton: network of protein fibers ex-tending throughout the cytoplasm.
• Functions:
• a. Anchors and reinforces organelles.
• b. Provides shape and support.
• c. Creates movement.

Cilia: short and numerous; provide movement by a coordinated back & forth motion (rowing).

Flagella: long and few; provide movement by an undulating whip-like motion (propeller).