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Two Major Categories of Cells
- 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
- 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.
- 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).