DNA: the double helix
Label a model of DNA, from a chromosome down to the bases, discover the base-pairing rules, and see what a gene is.
Core concept
DNA is a double helix of two sugar-phosphate backbones joined by base pairs (A with T, G with C); a gene is a stretch of DNA that codes for a trait, and DNA is coiled into chromosomes
Topic: Cells and heredity
The nucleus of every cell: The tiny building block that every living thing is made of. All key words holds chromosomes, and each chromosome is one very long molecule of DNA tightly coiled up. DNA is shaped like a twisted ladder, a double helix. The two sides of the ladder are backbones made of sugar and phosphate. The rungs are pairs of bases, held together by weak hydrogen bonds. There are four bases: adenine (A), thymine (T), guanine (G) and cytosine (C), and they always pair the same way: A with T and G with C. The order of the bases is a code. A gene is a stretch of DNA whose code tells the cell how to make a particular protein: A nutrient for growth and repair, found in beans, eggs, milk and meat. All key words, which in turn produces a trait such as eye colour.
What you will learn
- Label the parts of a DNA molecule.
- State the base-pairing rules.
- Explain how chromosomes, DNA and genes are related.
Before you start
- Know that the nucleus controls the cell and contains chromosomes.
Materials
- A DNA model kit or paper model
Equipment
- None for the virtual lab
Procedure
- Choose a card, find out what it is or what it pairs with, and place it on the matching letter.