GCSE · Biology · Edexcel · Spec 1BI0

Animal cell sub-cellular structures and functions

Inside your cells, tiny structures split the work between them. Learn who does which job, and the cell stops being a mystery.

Biology · Cell structure

The model animal cell

Showing 2 layers: Cell, Labels

Explore

tap a part of the cell

This is a model: a simple drawing of the structures that animal cells have in common. Tap a part to meet its job.

Five structures, five jobs. Tap any part of the cell, or use the buttons, to see what it does.

Predict, then check

Time to test the model you just explored.

A red blood cell is an animal cell. Does a red blood cell have a nucleus?

The cell membrane

Reason it through

Why does it matter that the cell membrane is partially permeable?

Link 1 of 3

First link · your turn

The membrane is partially permeable. What does that let it do?

Locked — reveal the link above first

Mitochondria and energy

What really happens to energy in a mitochondrion?

You're checking a friend's revision notes. Next to the mitochondria, they've written a sentence about energy, and you're not sure it's right.

Which of these is closest to what you think right now?

Mitochondria make energy for the cell.The energy released in the mitochondria stays inside the mitochondria.Aerobic respiration happens in the cytoplasm, and the mitochondria just hold the energy.Mitochondria are where respiration releases energy, which is then transferred to other processes in the cell.

How sure are you?

I'm sureI think soI'm guessing

Mitochondria make energy for the cell.

This is a common misconception

This is the one to lose, and lots of people hold it. Energy is not created in respiration. Mitochondria are where respiration releases energy: the energy isn't new, it's transferred so the cell can use it. Swap 'make' for 'release' (or 'transfer') and the sentence is fixed.

The energy released in the mitochondria stays inside the mitochondria.

This is a common misconception

Releasing energy would be pointless if it stayed put. After respiration releases energy in the mitochondria, that energy is transferred to other processes in the cell, the jobs that need it.

Aerobic respiration happens in the cytoplasm, and the mitochondria just hold the energy.

This is a common misconception

It's an easy mix-up, because many of the cell's chemical reactions do happen in the cytoplasm. But aerobic respiration takes place in the mitochondria. They contain the enzymes for respiration, and they're where most of the energy is released.

Mitochondria are where respiration releases energy, which is then transferred to other processes in the cell.

This matches the evidence

Spot on. Respiration in the mitochondria releases (transfers) energy, and that energy is then passed on to other processes in the cell. Nothing is created: the energy is released and moved on.

Energy is released, never created. Respiration in the mitochondria transfers energy, which then goes to other processes in the cell.

Biology · Animal cell

Whose job is it?

Which sub-cellular structure does each clue describe?

Still to sort

Nucleus (0)

Cell membrane (0)

Cytoplasm (0)

Mitochondria (0)

Ribosomes (0)

10 of 10 still to sort.

Every clue belongs to exactly one structure. Sort them all, then check the reason for each.

Your turn to write

Mitochondria and ribosomes, in your own words

Describe the function of the mitochondria and the function of the ribosomes in an animal cell. [3 marks]

Your answer

0 words · your answer stays on this page and is not sent anywhere.

The mark scheme

Mitochondria are the site of (aerobic) respiration. (1 mark)
Respiration in the mitochondria releases or transfers energy. Don't give yourself this one for 'makes' or 'creates' energy. (1 mark)
Ribosomes are where proteins are made (protein synthesis). (1 mark)

Model answer

Mitochondria are where aerobic respiration takes place, and respiration there releases energy for the cell to use. Ribosomes are the site of protein synthesis, so they're where the cell's proteins are made.

Two verbs to get right: mitochondria release energy; ribosomes make proteins.

WHAT YOU'VE LEARNED

A quick recap of today's lesson.

Five structures, five jobs, and why the textbook cell is only a model.

What you need to know

The model animal cell shows five sub-cellular structures common to animal cells: the nucleus, cell membrane, cytoplasm, mitochondria and ribosomes.
Nucleus: controls the activities of the cell and contains the genetic material, DNA, which carries the genetic code for making proteins.
Cell membrane: the partially permeable outer boundary. It lets some substances through but not others, so it controls what moves into and out of the cell.
Cytoplasm: a jelly-like substance containing dissolved nutrients and salts. It surrounds the other structures and is where many of the cell's chemical reactions take place.
Mitochondria: the site of aerobic respiration. They contain the enzymes for respiration, and most of the energy in respiration is released there.
Ribosomes: very small structures (the smallest in the cell) where protein synthesis takes place, which means where proteins are made.

The big picture

The model animal cell shows five sub-cellular structures that animal cells have in common: the nucleus, the cell membrane, the cytoplasm, mitochondria and ribosomes. The nucleus controls the cell and contains DNA. The partially permeable cell membrane controls what enters and leaves. The jelly-like cytoplasm is where many chemical reactions take place. Mitochondria are the site of aerobic respiration, where most of the energy is released, and ribosomes are where proteins are made. Respiration releases (transfers) energy and never creates it. The model is a simplification: real animal cells are three-dimensional and vary, and a red blood cell has no nucleus.

Key points

1Respiration releases (transfers) energy. Energy is never created in respiration.

2Energy released in the mitochondria is then transferred to other processes in the cell.

3A cell usually has many mitochondria.

4The membrane's control over what enters and leaves helps keep conditions inside the cell relatively constant.

5The model animal cell is a simplification: real animal cells are three-dimensional, and many don't have the model's shape or all of its structures.

6Red blood cells are animal cells with no nucleus, but real animal cells still contain similar sub-cellular structures.

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Worked example

Problem

A student writes: 'The nucleus makes the cell's proteins, and aerobic respiration takes place in the cytoplasm.' Find the two mistakes and write a corrected version.

⚠ Watch out

Writing that mitochondria 'make' or 'create' energy. Respiration in the mitochondria releases (transfers) energy. Energy is never created.

🧠

Memory hook

Picture the cell as a workshop. Nucleus: the manager, in charge and keeping the DNA instructions. Membrane: security on the door. Cytoplasm: the workshop floor. Mitochondria: release the energy. Ribosomes: tiny builders making proteins.

✓

Check yourself

Cover the page. Name the five structures in the model animal cell and give each one's job. Then explain how a red blood cell shows that the model is only a model.

Flashcards

(14)

Name the five sub-cellular structures in the model animal cell.

Nucleus, cell membrane, cytoplasm, mitochondria and ribosomes.

What does the nucleus do?

It controls the activities of the cell, and it contains the genetic material (DNA).

What does the DNA in the nucleus carry?

The genetic code for making proteins.

What does 'partially permeable' mean?

It lets some substances through, but not others.

What does the cell membrane control?

The movement of substances into and out of the cell.

How does the cell membrane help the inside of the cell?

By controlling what enters and leaves, it helps keep conditions inside the cell relatively constant.

What is the cytoplasm, and what happens there?

A jelly-like substance with dissolved nutrients and salts, surrounding the other structures. Many of the cell's chemical reactions take place there.

What do mitochondria contain that lets respiration happen there?

The enzymes for respiration.

Is energy created in respiration?

No. Respiration releases (transfers) energy. Energy is never created.

What happens to the energy released in the mitochondria?

It is transferred to other processes in the cell.

How many mitochondria does a cell usually have?

Usually many.

What takes place at the ribosomes?

Protein synthesis: this is where proteins are made.

Which is the smallest structure in the animal cell?

The ribosomes.

Why is the model animal cell called a simplification?

Real animal cells are three-dimensional, and many don't have its shape or all of its structures. A red blood cell, for example, has no nucleus.

Tap any card to flip it, or use Study as deck to go through them one at a time. In the full lesson these run as a spaced-repetition deck — you rate each card Hard, Good or Easy and the tricky ones keep coming back until they stick.

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What really happens to energy in a mitochondrion?

Whose job is it?

Mitochondria and ribosomes, in your own words

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