B Form DNA and Double Helix Structure

Vocabulary flashcards covering key structural features and terminology of B form DNA and the DNA double helix based on lecture notes.

B form DNA

The most common form of the DNA double helix found inside the cell.

Polynucleotide

A DNA strand made up of many individual units called nucleotides.

Nucleotide

A structural unit of DNA consisting of three components: a five carbon sugar, a phosphate group, and one of four nitrogenous bases.

One prime carbon

The position on the five carbon sugar where the nitrogenous base is always attached.

Deoxyribose

The five carbon sugar in DNA that is missing a hydroxyl group at the two prime carbon position.

Deoxynucleotides

The nucleotides found in DNA, named because their sugar is missing a hydroxyl group at the two prime carbon.

Phosphodiester bonds

Covalent bonds that connect nucleotides together in a DNA strand by binding a phosphate group to the three prime oxygen of the neighboring nucleotide.

DNA backbone

The structural frame of a DNA strand made up of alternating sugars and phosphate groups.

Directionality of the DNA strand

The five prime to three prime orientation determined by the carbon numbering within the sugar molecules.

Watson and Crick

Names sometimes used to refer to the two individual opposite-oriented strands of double stranded DNA.

Base pair

A unit formed when complementary nitrogenous bases on opposite strands interact through non covalent hydrogen bonds.

Pyrimidines

Nitrogenous bases characterized by their single ring structure, which include thymine and cytosine.

Purines

Nitrogenous bases characterized by double rings, which include adenine and guanine.

Thymine and adenine pairing

The specific base pair arrangement where thymine preferentially pairs with adenine through two hydrogen bonds.

Cytosine and guanine pairing

The specific base pair arrangement where cytosine preferentially pairs with guanine through three hydrogen bonds.

Pi pi interactions

Stabilizing forces in the double helix formed when aromatic rings of adjacent bases stack next to each other and share electron probabilities.

Major groove

A repeating space in the DNA double helix that contains base pair specific information for protein binding.

Minor groove

A repeating space in the DNA double helix that is largely base pair nonspecific in its interactions with proteins.

Turn of the helix

A complete rotational structural unit of the double helix measuring approximately 10 base pairs.

GT base pair

An improper base pairing that lacks standard geometry, cannot form strong hydrogen bonds, and disturbs the helix structure.