Cell Structure and Function Notes

Cell Basics

• Cells are the basic structural unit of an organism.
• Eukaryotic cells have a nucleus and are usually microscopic.
• Some cells, like paramecium, may live independently.

Cell Membrane

• Functions include protecting the cell, controlling entry/exit of substances, and responding to environmental changes.

Cytoplasm

• Contains all cell contents except the nucleus and cell membrane.
• The cytosol is the fluid within the cytoplasm.

Nucleus

• Houses DNA and regulates cellular activities.

Ribosomes

• Protein synthesis occurs here.
• Free ribosomes produce proteins for internal use, while attached ribosomes (on the rough endoplasmic reticulum) produce proteins for export.

Endoplasmic Reticulum (ER)

• Rough ER synthesizes proteins; Smooth ER synthesizes lipids.

Golgi Apparatus

• Packages proteins and lipids into vesicles for secretion.

Lysosomes

• Contain enzymes for digesting cellular waste.

Mitochondria

• Site of energy production (ATP synthesis).

Cytoskeleton

• Composed of microfilaments and microtubules, it provides structural support and aids in transport.

Cell Membrane Structures

• Microvilli: Increase surface area for absorption/secretion.
• Flagella: Aid in locomotion (found in sperm cells).
• Cilia: Move materials across cell surfaces; found in the respiratory tract and reproductive tubes.

Next Study Focus:

• Definition of tissue.
• Four types of tissues in the body and examples of each.