17/03 Lecture 10 - DNA Structure

Nucleoside

This is the portion of a nucleotide that has no phosphate groups bonded to it

Pyrimidine

This is a nitrogenous base consisting of one six-membered ring of carbon and nitrogen. Classifies cytosine, thymine, and uracil

Purines

This is a nitrogenous base consisting of one six-membered ring bonded to a five-membered ring, all containing carbon and nitrogen. Classifies adenine and guanine

Phosphodiester linkage

This is the chemical link that covalently bonds a phosphate group to the (deoxy)ribose sugars in a phosphate-sugar backbone

5’ end

This is the end of the polynucleotide with a terminal phosphate group

3’ end

This is the end of the polynucleotide with a terminal -OH group

Antiparallel

This describes the structure of two sugar-phosphate backbones in a DNA molecules running in opposite 5’-3’ directions

Chargaff’s rules

This describes two rules: that DNA base composition varies between species, and that the percentages of A/T and C/G will be relatively equal to each other

Semiconservative replication

This is the process by which both daughter cells would contain one strand of DNA from the parents cells’ double helix

Conservative replication model

This is the proposed process by which both parental DNA strands would reunite after DNA replication

Dispersive replication model

This is the proposed process by which each strand of DNA in a daughter cell would contain a mixture of both new and parent DNA

DNA polymerase

This is the protein that adds lone DNA nucleotides to a polynucleotide