AP Biology / Unit 6: Gene Expression and Regulation
6.1 DNA and RNA Structure
Notes
- DNA is the genetic material in all cells. Prokaryotes have circular chromosomes and often plasmids; eukaryotes have linear chromosomes.
- Purines (A, G) have two rings; pyrimidines (C, T, U) have one. A purine always pairs with a pyrimidine.
Practice
Which is a purine?
A and G are purines.
If a DNA sample is 30% adenine, it is what percent guanine?
A=T=30%, so C+G=40%, G=20%.
Plasmids are:
Extra DNA, often with useful genes.
Ready for more? Take the Unit 6 test.