DNA Structure and Nucleotides (sugars, bases, base pairing, and antiparallel strands)

Vocabulary flashcards covering DNA structure, sugars, bases, base pairing rules, and antiparallel strands based on the lecture notes.

Deoxyribonucleic acid (DNA)

The molecule that carries genetic information, composed of a sugar–phosphate backbone with four bases (A, T, C, G) and encoding the sequence that determines proteins and traits.

Ribonucleic acid (RNA)

Nucleic acid with ribose sugar; usually single-stranded; involved in transcription and translation.

Pentose sugar

A five-carbon sugar; in DNA the sugar is deoxyribose, in RNA it is ribose.

Deoxyribose

Five-carbon sugar lacking the 2' hydroxyl group; the sugar found in DNA.

Ribose

Five-carbon sugar with a 2' hydroxyl group; the sugar found in RNA.

Phosphate group

Phosphate group connects sugars to form the backbone of DNA/RNA; negatively charged and involved in forming nucleotide linkages.

Nucleotide

Basic unit of nucleic acids consisting of a sugar (ribose or deoxyribose), a phosphate group, and a nitrogenous base.

Base (nitrogenous base)

Nitrogen-containing component of a nucleotide; purines (A, G) with two rings and pyrimidines (C, T/U) with one ring.

Purines

Bases with two rings: adenine (A) and guanine (G).

Pyrimidines

Bases with one ring: cytosine (C) and thymine (T) in DNA; uracil (U) in RNA.

Adenine

Purine base; pairs with thymine in DNA (two hydrogen bonds) and with uracil in RNA.

Thymine

Pyrimidine base; pairs with adenine via two hydrogen bonds in DNA.

Cytosine

Pyrimidine base; pairs with guanine via three hydrogen bonds.

Guanine

Purine base; pairs with cytosine via three hydrogen bonds.

Hydrogen bond

Weak electrostatic attraction between a slightly positive hydrogen and a slightly negative atom; A–T has two bonds, C–G has three in DNA.

Base pairing (A–T and C–G)

Specific pairing: adenine pairs with thymine (two hydrogen bonds) and cytosine with guanine (three hydrogen bonds) in DNA; RNA uses A–U pairing.

Antiparallel strands

DNA strands run in opposite directions (one 5'→3', the other 3'→5'), enabling proper base pairing.

Adenosine monophosphate (AMP)

A ribonucleotide consisting of ribose, adenine, and one phosphate group; a component of RNA.