DNA: structure and function

DNA

• Deoxyribonucleic acid• 1. Nuclear DNA– In nucleus of cell• + proteins, form a chromosome

– A set of DNA molecules is called a genome.

• 2. Mitochondrial DNA– In mitochondria• Cytoplasmic organelle

– Inherited from mother only

DNA structure

• Double helix• Basic building block is the nucleotide– phosphate group + deoxyribose + base

• Purines: adenine, guanine• Pyrimidines: thymine, cytosine• Complementary base pairs: A-T; G-C

DNA function1. replication

Long, thin moleculesAll the DNA in a humanindividual: c. 200 timesthe distance from the Earth to the sun.

Figure 3.10 The Steps of DNA ReplicationOur Origins, 2nd Edition

Copyright © 2011 W.W. Norton & Company

Figure 3.14a The Steps of Mitosis in HumansOur Origins, 2nd Edition

Copyright © 2011 W.W. Norton & Company

Figure 3.15 MeiosisOur Origins, 2nd Edition

Copyright © 2011 W.W. Norton & Company