Competency Appraisal 501

Study Notes

Robert Hooke discovered cells in cork in 1665 and introduced the term "cell" (Latin: cellulae), meaning small room.
Robert Brown identified the cell nucleus in 1831.
Cytology is defined as the study of cells.
Cells are comprised entirely of chemical substances.

Prokaryotic Cells:
- Do not have a nucleus.
- DNA is located in a specific region called the nucleoid.
Eukaryotic Cells:
- Possess a true nucleus and membrane-bound organelles.

Ribosomes:
- Function as protein factories.
- Free ribosomes produce proteins for use in the cytosol.
- Bound ribosomes produce proteins for membrane integration and export.
Endoplasmic Reticulum (ER):
- Acts as a biosynthetic factory with folded membranes for material transport.
- Rough ER contains ribosomes; Smooth ER lacks ribosomes.
Golgi Apparatus:
- Serves as a shipping and receiving center, processing and packaging macromolecules.
Mitochondria:
- Known as the powerhouse of the cell, converting food into energy (ATP).
Nucleus:
- Largest organelle in animal cells, containing the majority of genes (DNA).
Plasma Membrane:
- Functions as a selective barrier (semipermeable) between the cell's interior and external environment.

Cytoplasm:
- Gel-like substance within the cell where organelles reside.
Lysosomes:
- Act as digestive compartments or "suicidal bags" which digest bacteria, foreign substances, and damaged organ parts.
Chloroplasts:
- Found only in plants, chloroplasts capture light energy and are sites of photosynthesis, containing chlorophyll.
Cell Wall:
- A protective layer located outside the plasma membrane, providing structural support to plant cells.