cell biology (1.1)

What are the two types of cells?

• Eukaryotic cells: Have a nucleus (e.g., animal & plant cells).

• Prokaryotic cells: No nucleus, DNA in a loop and plasmids (e.g., bacterial cells).

What structures are found in prokaryotic cells?

• Cell membrane: Controls entry/exit of substances.

• Cytoplasm: Site of chemical reactions.

• Cell wall: Provides support (not made of cellulose in bacteria).

• Plasmids: Small rings of DNA.

• Single circular DNA strand: Not enclosed in a nucleus.

What are the key structures of eukaryotic cells?

• Animal cells: Nucleus, cytoplasm, cell membrane, mitochondria, ribosomes.

• Plant cells (in addition to the above): Cell wall, chloroplasts, permanent vacuole.

How do you calculate magnification?

Magnification = Image size ÷ Real size

Units?

• mm → µm (×1000)

• µm → nm (×1000)

What is the function of chromosomes?

• Chromosomes are DNA molecules that carry genetic information.

• Human body cells have 46 chromosomes (23 pairs).

What are the stages of the cell cycle?

1. Growth phase: Cell grows and duplicates organelles.

2. DNA replication: Chromosomes are copied.

3. Mitosis: Cell divides into two identical daughter cells.

Why is mitosis important?

Growth, repair, and asexual reproduction.

What are stem cells?

• Embryonic stem cells: Can differentiate into any cell type.

• Adult stem cells: Found in bone marrow, can only differentiate into a few cell types.

• Plant meristems: Can differentiate into any plant cell.

What are the uses & risks of stem cells?

• Uses: Treat diabetes, paralysis.

• Risks: Ethical concerns, risk of infection.

What is diffusion?

The movement of particles from high to low concentration.

Factors that affect diffusion !

• Temperature (higher = faster).

• Surface area (larger = faster).

• Concentration gradient (steeper = faster).

What is osmosis?

• Diffusion of water across a partially permeable membrane from dilute to concentrated solution.

What is active transport?

• Movement against a concentration gradient, requiring energy from respiration.

Examples of diffusion . . .

• Root hair cells absorbing minerals from soil.

• Glucose absorption in the intestine