The Nucleus
The nucleus stores DNA and directs cell activity.
About this topic
The nucleus is the cell's control centre. It is surrounded by a double nuclear envelope with pores, and contains DNA packaged with proteins as chromatin, which condenses into chromosomes during division. The nucleolus makes ribosomal RNA and assembles ribosomes.
The nucleus stores genetic information and controls the cell by deciding which genes are transcribed into mRNA, which exits through the pores to make proteins. Red blood cells lose their nucleus to carry more oxygen, while some muscle cells have many.
If a cell is a factory, the nucleus is the head office that stores the master plans. DNA is never removed from the nucleus; instead, a working copy called mRNA is made and sent out through the nuclear pores to the ribosomes. This protects the precious original from damage in the busy cytoplasm. During division the chromatin coils tightly into the X-shaped chromosomes you see in diagrams.
Nuclei are central to many technologies, such as cloning, where the nucleus from an adult body cell is transferred into an egg to create Dolly the sheep. Mature red blood cells lose their nucleus to make room for haemoglobin, which is why they cannot divide. A classic confusion is between the nucleus and the nucleolus: the nucleolus is a dense spot inside the nucleus that builds ribosome parts.
Key ideas
- Nuclear envelope with pores
- Nucleolus makes ribosomes
- Chromatin condenses into chromosomes
Quick check
Use cases: where The Nucleus helps
- Homework: review the key idea behind The Nucleus before you start a problem set.
- Exam revision: use the quick check to test whether you can recall The Nucleus without notes.
- Visual learning: play with the interactive lab to see how The Nucleus changes when you adjust its inputs.
- Teaching a friend: explain The Nucleus in your own words, then compare your version with the key ideas.
Biology underpins medicine, farming, conservation and biotechnology.
Frequently asked questions
What is The Nucleus?
The nucleus stores DNA and directs cell activity.
What will I learn in The Nucleus?
Nuclear envelope with pores. Nucleolus makes ribosomes. Chromatin condenses into chromosomes.
Is The Nucleus part of Biology?
Yes. It is one of 150 Biology topics on LearnViz HighSchoolEdu, with 3 key ideas, a live animation and a quick check.
Does the The Nucleus lab work on a phone or tablet?
Yes. The animation resizes to fit your screen and supports touch, so you can drag, tap and slide with your finger.
How should I study The Nucleus?
Read the summary and key ideas first, play with the interactive lab to see the idea in motion, then answer the quick check. If you get a question wrong, go back to the key idea it tests.
Do I need an account, and is my progress saved?
No account is needed. Marking a topic as learned is saved in your own browser, so it stays on that device and is not sent to a server.