Chromosomes
Joe Wolfensohn
Teacher
Recall Questions
This topic requires prior knowledge of the cell nucleus and the role of DNA in controlling cellular function.
Which part of the cell contains the DNA?
Nucleus
What is the role of the nucleus?
To control the activity of the cell
Which type of cell does not contain a nucleus?
A prokaryotic cell
Topic Explainer Video
Check out this @JoeDoesBiology video that explains chromosomes, then read the study notes. Once you’ve gone through them, don’t forget to try the practice questions!
Chromosomes
What Are Chromosomes?
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Chromosomes are long, coiled strands of DNA found in the nucleus.
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They carry genes, which are sections of DNA coding for proteins.
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Each species has a specific number of chromosomes.
Chromosomes in Humans
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Human body cells have 46 chromosomes → 23 pairs.
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One of each pair comes from the mother, and one from the father.
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The 23rd pair are sex chromosomes:
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XX = female
- XY = male
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Role in Cell Division
- Before a cell divides, each chromosome is copied.
- During mitosis, the identical copies are separated into two new nuclei.
- This ensures each daughter cell has the same number of chromosomes as the parent cell.
Key Terms
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Chromosome – coiled DNA found in the nucleus.
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Gene – a section of DNA on a chromosome that codes for a protein.
No answer provided.
Practice Question
Name the chemical that chromosomes are made of. (1 mark)
DNA
More Practice
Try to answer the practice question from the TikTok video on your own, then watch the video to see how well you did!