Cells Basics

Cell

The basic unit of life.

Cell theory

1. All living things are made of one or more cells. 2. The cell is the basic unit of life. 3. All cells come from pre-existing cells.

Unicellular organism

An organism made of one cell that carries out all life processes.

Multicellular organism

An organism made of many cells with different cells performing different functions.

Levels of organisation (smallest to largest)

Cells → Tissues → Organs → Organ Systems → Organism.

Cell membrane (plasma membrane)

Controls what enters and leaves the cell. It is selectively permeable.

Selectively permeable

Only allows certain substances to enter or leave the cell.

Cytoplasm

A jelly-like substance where chemical reactions occur and organelles are held in place.

Nucleus

Controls the activities of the cell and contains genetic material (DNA).

Ribosomes

Make proteins needed for growth and repair.

Mitochondria

Release energy through respiration. Known as the "powerhouse" of the cell.

Endoplasmic reticulum (ER)

Transports materials around the cell and helps make proteins and lipids.

Cell wall

Provides support and protection. Found in plant and fungal cells.

Chloroplast

Site of photosynthesis. Contains chlorophyll to absorb light energy.

Chlorophyll

The green pigment that absorbs light energy for photosynthesis.

Vacuole

Stores water, nutrients and waste. Plant cells usually have one large central vacuole.

Plant cell

A cell with a cell membrane, cytoplasm, nucleus, mitochondria, ribosomes, ER, cell wall, chloroplasts and a large vacuole.

Animal cell

A cell with a cell membrane, cytoplasm, nucleus, mitochondria, ribosomes and ER. It has no cell wall or chloroplasts.

Fungal cell

A cell with a cell membrane, cytoplasm, nucleus, mitochondria, ribosomes, ER, cell wall and vacuoles. It has no chloroplasts and cannot photosynthesise.

Plant cell features

Cell wall ✓, Chloroplasts ✓, Large vacuole ✓.

Animal cell features

Cell wall ✗, Chloroplasts ✗, Small vacuoles only.

Fungal cell features

Cell wall ✓, Chloroplasts ✗, Vacuoles ✓.

Photosynthesis

The process plants use to make food using light energy.

Respiration

The process that releases energy from food.

DNA

Genetic material found inside the nucleus that contains the instructions for the cell.

Protein

Molecules made by ribosomes that help cells grow and repair.