DNA Structure and Replication

Flashcards covering key concepts related to DNA structure and replication.

DNA

A chemical substance that controls all chemical changes in cells, present in the nucleus of all living organisms.

Nucleotide

The subunit of DNA made up of a sugar (deoxyribose), a phosphate group, and an organic base.

Deoxyribose

A sugar molecule similar to ribose but lacking one oxygen atom.

Purine

A type of nitrogenous base with two carbon-nitrogen rings.

Pyrimidine

A type of nitrogenous base with a single carbon-nitrogen ring.

Chargaff’s Rule

A rule stating that in DNA, the amount of adenine (A) equals thymine (T) and the amount of guanine (G) equals cytosine (C).

Double helix

The structure of DNA, resembling a twisted ladder, where the sides are sugar and phosphate and the rungs are base pairs.

Antiparallel strands

Refers to the opposite orientation of the two strands in a DNA double helix.

DNA replication

The process by which DNA makes a copy of itself before cell division.

Semiconservative replication

The model of DNA replication where each new DNA molecule consists of one original strand and one new strand.

Okazaki fragments

Short sequences of DNA synthesized on the lagging strand during DNA replication.

DNA Polymerase III

An enzyme that synthesizes new DNA strands by adding complementary bases during DNA replication.

Hershey-Chase experiment

An experiment that demonstrated DNA is the hereditary material, not protein.

X-ray diffraction

A technique used by Rosalind Franklin to produce images of DNA structure.

Leading strand

The DNA strand that is synthesized continuously in the direction of the replication fork.

Lagging strand

The DNA strand that is synthesized in short fragments and must be pieced together during replication.