8.2 Structure of DNA

Deoxyribonucleic acid (DNA) is a molecule that encodes the genetic instructions used in the development and functioning of all known living organisms

8.2 Structure of DNA

DNA is well-suited for biological information storage.

8.2 Structure of DNA

DNA is a NUCLEIC ACID

• This is one of the four carbon-based macromolecules– Carbohydrates (quick energy)– Lipids (energy storage)– Protein (body structure)– Nucleic Acid (DNA)

8.2 Structure of DNA

DNA is a DOUBLE HELIX

8.2 Structure of DNA

• DNA is a chain of nucleotides.– Each nucleotide has three parts.

1. a phosphate group

2. a deoxyribose sugar

3. a nitrogen-containing base

phosphate group

deoxyribose (sugar)

nitrogen-containingbase

8.2 Structure of DNA

• There are only FOUR different nucleotides (bases): – T, C, A, & G

DNA alphabet

8.2 Structure of DNA

TAC

G

Nucleotides always pair in the same way.

• The base-pairing rules:– A pairs with T

– C pairs with G

8.2 Structure of DNA

The two strands of DNA run in opposite directions to each other and are therefore anti-parallel

8.2 Structure of DNA

hydrogen bond covalent bond

• The bases are connected by hydrogen bonds.

8.2 Structure of DNA

Within cells, DNA is organized into long structures called chromosomes

8.2 Structure of DNA

chromosomes are duplicated in the process of DNA replication, providing each cell its own complete set of chromosomes

8.2 Structure of DNA

Where is DNA kept?

• Eukaryotes– In the nucleus of each

cell

• Prokaryotes– In the cytoplasm of the

cell