Cell Biology Notes

Cells

• Cells are the basic units of all forms of life.
• They can be eukaryotic or prokaryotic.

Eukaryotic Cells

• Eukaryotic cells have a nucleus (e.g., animal and plant cells).

Animal Cell

• Contains a nucleus, cell membrane, cytoplasm, mitochondria, and ribosomes.

Plant Cell

• Contains all the components of an animal cell, plus a cell wall, chloroplasts, and a permanent vacuole.

Eukaryotic Cell Parts and Functions

• Nucleus: Controls all cell activity and contains the DNA.
• Cytoplasm: A liquid gel where most chemical reactions take place.
• Cell membrane: Controls the movement of substances into and out of the cell.
• Mitochondria: The site of respiration; releases energy for the cell to use.
• Ribosomes: Protein synthesis - they make proteins.
• Cell wall: (Plant cells only) Strengthens the cell; made of cellulose.
• Chloroplasts: (Plant cells only) Where photosynthesis takes place; traps sunlight's energy using chlorophyll.
• Permanent vacuole: (Plant cells only) Filled with cell sap; helps keep the cell turgid (swollen and rigid) to support the plant.

Prokaryotic Cells

• Prokaryotic cells are smaller and do not have a nucleus.
• Their genetic material (DNA) is free and forms a single loop.
• All bacteria are prokaryotes.

Bacterial Cell

• Contains cell wall, cell membrane, cytoplasm, genetic material, plasmids, flagella, and slime capsule.

Prokaryotic Cell Parts and Function

• Plasmids: Small rings of extra bacterial DNA.
• Slime capsule: For protection and to stop the bacterial cell drying out.
• Flagella: A tail-like protein strand that lashes about, allowing the bacterial cell to move around. (Not all bacteria have this.)