Animal and plant cells (AQA GCSE Biology): Revision Notes
Animal and plant cells
What are animal and plant cells?
Animal and plant cells are the basic building blocks of living things. Both types contain smaller parts called structures that do different jobs to keep the cell alive and working properly.
Understanding cell structures is essential for learning how living organisms function. Each structure has a specific role that contributes to the cell's survival.
Structures found in animal cells
Cell membrane
The cell membrane acts like a security guard for the cell. It controls what can enter and leave the cell. Important substances like oxygen, carbon dioxide and glucose can pass through the membrane.
Nucleus
The nucleus is the control centre of the cell. It's a large structure that contains genes - these are like instruction manuals that tell the cell what to do and how to behave.
Cytoplasm
Cytoplasm is a jelly-like liquid that fills up the space inside the cell. Many important chemical reactions happen in the cytoplasm to keep the cell working.
Mitochondria
Mitochondria are tiny power stations inside the cell. This is where respiration happens - the process that releases energy from food so the cell can do its work.
Ribosomes
Ribosomes are the cell's protein factories. They make proteins that the cell needs to function properly. This process is called protein synthesis.
Extra structures found in plant cells
Plant cells have all the same structures as animal cells, plus three extra ones:
Cell wall
The cell wall is a tough outer layer made from a material called cellulose. It makes the plant cell stronger and helps it keep its shape.
Permanent vacuole
The permanent vacuole is a large storage space filled with cell sap (a watery liquid). It helps keep the plant cell firm and rigid, like blowing up a balloon.
Chloroplasts
Chloroplasts are green structures that contain a substance called chlorophyll. This is where photosynthesis happens - the process that makes food for the plant using sunlight.
Key Difference: Plant cells can make their own food through photosynthesis, while animal cells cannot. This is why plants have chloroplasts but animals don't.
Key differences between animal and plant cells
Animal cells:
- Have a flexible cell membrane only
- Are usually round or irregular in shape
- Do not make their own food
Plant cells:
- Have both a cell membrane AND a tough cell wall
- Are usually rectangular in shape
- Can make their own food through photosynthesis
- Are usually larger than animal cells
Important facts to remember
Different types of cells have specialised features to help them do their specific jobs:
- Muscle cells contain lots of mitochondria because they need extra energy to contract and move
- Root cells don't usually have chloroplasts because they're underground and don't get sunlight
- Both animal and plant cells need mitochondria for respiration
Don't confuse the cell wall with the cell membrane - they're different structures! The cell membrane is found in both animal and plant cells, while the cell wall is only found in plant cells.
Key Points to Remember:
- Animal and plant cells both have: cell membrane, nucleus, cytoplasm, mitochondria, and ribosomes
- Only plant cells have: cell wall (made of cellulose), permanent vacuole, and chloroplasts
- Each structure has a specific job that helps the cell survive
- Plant cells can make their own food, but animal cells cannot
- The number of mitochondria in a cell depends on how much energy it needs