BIOL2010 DNA replication - Vocabulary Flashcards

Vocabulary flashcards covering DNA composition, structure, base pairing, replication mechanisms, and PCR-related concepts from the notes.

DNA

The molecule that carries genetic information; a double helix made of nucleotides with a sugar–phosphate backbone and bases A, T, C, G.

Nucleotide

The fundamental unit of DNA, consisting of a sugar (deoxyribose), a phosphate, and a nitrogenous base.

Purine

A two-ring nitrogenous base family that includes adenine (A) and guanine (G).

Pyrimidine

A one-ring nitrogenous base family that includes cytosine (C) and thymine (T).

Adenosine

A nucleoside consisting of adenine attached to deoxyribose (DNA) or ribose.

Cytidine

A nucleoside consisting of cytosine attached to deoxyribose.

Guanosine

A nucleoside consisting of guanine attached to deoxyribose.

Thymidine

A nucleoside consisting of thymine attached to deoxyribose.

Phosphate backbone

The sugar–phosphate framework of DNA linked by phosphodiester bonds (outside of the helix).

Deoxyribose

The five-carbon sugar used in DNA, lacking an OH group at the 2' position.

Double helix

The right-handed, two-stranded structure of DNA with bases inside and a sugar–phosphate backbone outside.

Antiparallel

Two DNA strands run in opposite 5'→3' directions.

Major groove

The wider groove of the DNA helix where many proteins interact with bases.

Minor groove

The narrower groove of the DNA helix.

Complementary base pairing

A–T pairs with two hydrogen bonds; G–C pairs with three hydrogen bonds.

Chargaff's rule

In DNA, amounts of A and T are equal, and amounts of C and G are equal.

Base pairs are the same width

AT and GC base pairs maintain the same width to keep the DNA diameter constant.

Hydrogen bonds

Weak bonds between bases: A–T has 2; G–C has 3.

5' to 3' direction

The direction in which DNA polymerases synthesize a new strand by adding nucleotides to the 3' end.

3' OH

The reactive 3' hydroxyl group on the sugar from which a new nucleotide is extended.

Phosphodiester bond

Bond linking the 3' carbon of one sugar to the 5' phosphate of the next nucleotide.

DNA polymerase

Enzyme that catalyzes DNA synthesis by adding dNTPs to the growing strand.

Taq polymerase

Heat-stable DNA polymerase used in PCR (from Thermus aquaticus).

PCR

Polymerase Chain Reaction; a method to amplify DNA through cycles of denaturation, annealing, and extension.

Denaturation

Heating DNA to separate its two strands.

Annealing

Cooling allows primers to bind (anneal) to complementary sequences on the template.

Extension

DNA polymerase extends primers by adding dNTPs to synthesize new DNA.

dNTPs

Deoxynucleoside triphosphates (dATP, dCTP, dGTP, dTTP) used as substrates for DNA synthesis.

Primer

Short DNA sequence that provides a starting point for DNA synthesis.

Template DNA

The strand that serves as the pattern for synthesis of the complementary new strand.

Pyrophosphate (PPi)

Byproduct released when a dNTP is incorporated into a growing DNA strand.

Mg2+

A cofactor essential for DNA polymerase activity and correct nucleotide binding.

Semi-conservative replication

Each new DNA molecule consists of one old (template) strand and one new strand.

Meselson and Stahl

1958 experiment in E. coli that demonstrated semi-conservative DNA replication using isotopes 15N and 14N.

E. coli

A model bacterial organism used to study DNA replication and genetics.

DNA structure – turn and distance

One helical turn equals about 10.5 base pairs (approximately 36 Å); 1 base pair ≈ 3.4 Å.

Watson–Crick base pairing

The model describing specific hydrogen bonding between complementary bases (A–T and G–C) in DNA.

Template strand

The DNA strand used as a guide to synthesize the complementary new strand.

DNA replication vs DNA synthesis

DNA replication is the genome-wide process of copying DNA for cell division; DNA synthesis refers to any creation of DNA, including replication or other DNA repair/ amplification processes.