S4.2.1 For the adult
DNA, genes and chromosomes
Children look like their parents. What exactly is handed down from one to the other?
What this chapter teaches
Instructions for a living thing are written in DNA. DNA is coiled into chromosomes inside the nucleus, and a gene is a section of it that codes for one protein. Most human cells have 46 chromosomes in 23 pairs.
Three questions to ask
There is no one right wording. Listen for the idea.
- What is the difference between a gene and a chromosome?
- Why does a long molecule of DNA fit inside a tiny nucleus?
- Does a living thing with more chromosomes have to be more complex? Why not?
After the chapter, the learner can
- Put DNA, gene, chromosome, nucleus and cell in order of size
- Explain that a gene is a code for making a protein
What they copy into their notebook
A cell has a nucleus. The nucleus holds chromosomes. A chromosome is one coiled DNA molecule. A gene is a section of DNA that codes for one protein. Humans: 46 chromosomes, 23 pairs.