Year 1 · Organs and cells · Section 2.4
Cells
Animal cells
Animal cells contain cytoplasm, a jelly-like material containing water, dissolved substances and cell structures. A cell membrane, made mainly of lipids and proteins, surrounds the cytoplasm.
The membrane separates the cell from its surroundings and controls which substances enter and leave, partly through membrane proteins.
The nucleus lies within the cell and is surrounded by a nuclear envelope. It contains nucleoplasm and genetic material, and helps control the cell's activities.
Plant cells
Typical plant cells share basic structures with animal cells: cytoplasm, a cell membrane and a nucleus. They also have additional structures:
- Cell wall: A strong layer outside the cell membrane that provides support. It lies outside the living contents of the cell.
- Vacuole: Usually a large central, fluid-filled compartment that stores substances and helps keep the cell firm.
- Plastids: Structures with different functions. Chloroplasts carry out photosynthesis; chromoplasts contain pigments that colour flowers and fruits; amyloplasts store starch.
Some plastids can change into another type, for example as a fruit ripens.
Organelles
Organelles are cell structures with particular functions. Examples include the nucleus, vacuole and plastids. Both animal and plant cells contain several types of organelles.
Glossary
- Chloroplasts
- Plastids in which photosynthesis takes place.
- Nucleus
- The cell structure containing genetic material that helps control cell activities.
- Cell membrane
- The thin boundary around the cytoplasm that controls the entry and exit of substances.
- Organelles
- Cell structures with particular functions, such as the nucleus, vacuole and plastids.
- Cell wall
- A strong layer outside a plant cell's membrane, providing support and protection.
- Cytoplasm
- Jelly-like material containing water, dissolved substances and cell structures.
- Chromoplasts
- Plastids containing pigments that colour many flowers and fruits.
- Nuclear envelope
- The membrane boundary separating the contents of the nucleus from the cytoplasm.
- Nucleoplasm
- The material inside the nucleus.
- Plastids
- Structures in plant cells with functions such as photosynthesis, colour production or storage.
- Vacuole
- A fluid-filled compartment used for storage and, in plant cells, support.
- Amyloplasts
- Plastids that store starch in starch grains.
Frequently asked questions
What does cytoplasm do?
Cytoplasm contains dissolved substances and cell structures. Many of the cell's processes take place there.
Does an animal cell have a cell wall?
No. An animal cell has a cell membrane but no cell wall. A plant cell has a strong cell wall outside its membrane.
Does an animal cell have a vacuole?
In the usual school model, an animal cell does not have a large central vacuole. A typical mature plant cell does have one, used for storage and support.