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GCSE Biology (Combined)

Chapter 1: Cell Biology

1. The Big Idea (30 seconds)

  • All living things are made of cells
  • Cells are the basic building blocks of life
  • Different cells have different structures depending on their job
  • Cells come from pre-existing cells

2. Cell Types

There are two main types of cells:

Animal cells

  • Found in animals (including humans)
  • Do not have a cell wall or chloroplasts

Plant cells

  • Found in plants
  • Have extra structures for support and photosynthesis

3. Animal Cell Structure

  • Nucleus
  • Contains genetic material (DNA)

  • Controls cell activities

  • Cytoplasm

  • Where most chemical reactions happen

  • Cell membrane

  • Controls what enters and leaves the cell

  • Mitochondria

  • Where respiration happens

  • Releases energy

  • Ribosomes

  • Site of protein synthesis

4. Plant Cell Structure

Plant cells contain everything an animal cell has, plus:

  • Cell wall (cellulose)

  • Strengthens the cell

  • Chloroplasts

  • Contain chlorophyll

  • Site of photosynthesis

  • Permanent vacuole

  • Contains cell sap
  • Helps keep the cell rigid

5. Specialised Cells

Cells are adapted to do specific jobs.

Examples:

  • Sperm cell
  • Tail for movement

  • Lots of mitochondria for energy

  • Nerve cell (neurone)

  • Long structure to carry signals

  • Muscle cell

  • Can contract to create movement

  • Root hair cell (plant)

  • Large surface area for absorbing water and minerals

6. Microscopes and Magnification

  • Microscopes allow us to see cells
  • Two types:
  • Light microscope
  • Electron microscope (much higher detail)

Magnification formula:

Magnification = Image size รท Real size

Key idea:

  • Higher magnification does not always mean clearer image (resolution matters)

7. Cell Division (Mitosis)

  • Cells divide to:
  • Grow
  • Repair
  • Replace damaged cells

Process:

  • DNA is copied
  • Cell splits into two identical cells

Key idea:

  • Mitosis produces genetically identical cells

8. Stem Cells

  • Stem cells can turn into different types of cells

Types:

  • Embryonic stem cells

  • Can become any cell type

  • Adult stem cells

  • Limited range of cell types

Uses:

  • Potential to treat diseases (e.g. paralysis, diabetes)

9. Diffusion

  • Movement of particles from high concentration to low concentration

Key idea:

  • Passive process (no energy required)

Example:

  • Oxygen moving into cells from the blood

10. Osmosis

  • Movement of water across a partially permeable membrane
  • From dilute solution to more concentrated solution

Key idea:

  • Only water moves

11. Active Transport

  • Movement of substances from low to high concentration

Key idea:

  • Requires energy

Example:

  • Absorbing minerals from soil into root cells

Check Your Understanding

  • What is the function of the nucleus? (Controls cell activities, contains DNA)
  • Name one structure found only in plant cells (Cell wall / Chloroplast / Vacuole)
  • What is diffusion? (Movement from high to low concentration)
  • Which process requires energy: diffusion or active transport? (Active transport)
  • What does mitosis produce? (Two identical cells)

Watch (Cognito)

  • https://www.youtube.com/watch?v=8IlzKri08kk
  • https://www.youtube.com/watch?v=GZ9G2z0E7ZE
  • https://www.youtube.com/watch?v=J0M2b3Zp2z8