Genetics and DNA Structure Vocabulary Flashcards

Vocabulary flashcards covering key definitions, fundamental historical experiments, and structural features of nucleic acids from the genetics lecture notes.

Genetics

The scientific study of how living organisms determine and inherit physical characteristics.

DNA

Deoxyribonucleic acid; the material used to determine inheritance and expression of physical characteristics in living organisms.

Nucleotide

A monomer (building block, basic structural unit) within a DNA polymer, composed of a five-carbon sugar, a phosphate group, and a nitrogen-containing base.

Gene

A segment of DNA that directs the production of one polypeptide.

Genome

The complete set of genetic material in one living organism.

Genetic Code

The association between nucleotides and corresponding amino acids of peptides.

Transforming Principle (Griffith, 1928)

The phenomenon demonstrated using smooth and rough strains of Strep. pneumoniae where heat-killed S strain combined with live R strain transformed the harmless R strain into deadly live S strain bacteria.

Transformation Agent Identification (Avery, McCarty, MacCleod, 1944)

The discovery that DNA is the transforming factor, proven by using DNAase, RNAase, and Proteinase on heat-killed S strain bacteria and observing that transformation fails only when DNA is inactivated.

Hershey-Chase Experiment (1952)

An experiment using T2 Phage labeled with radioactive isotopes ($^{32}\text{P}$ for DNA and $^{35}\text{S}$ for protein) that demonstrated DNA is the genetic material passed on to host cells and progeny.

Nucleoside

A chemical unit consisting of a sugar combined with a nitrogenous base.

Purines

Double-ring nitrogenous bases, specifically Adenine and Guanine.

Pyrimidines

Single-ring nitrogenous bases, specifically Cytosine, Thymine, and Uracil (found in RNA).

Chargaff's Rule

In double-stranded DNA (dsDNA), the total number of purines is equal to the total number of pyrimidines.

Base Hydrogen Bonding

The pairing mechanism in DNA where Adenine forms a double hydrogen bond with Thymine, and Cytosine forms a triple hydrogen bond with Guanine.

X-Ray Crystallography (Franklin & Wilkins)

The imaging technique used to determine that the overall shape of DNA is helical with individual nucleotides positioned perpendicular to the axis of the molecule.

Double Helix (Watson & Crick, 1953)

The molecular structure model of DNA featuring two linear polynucleotide anti-parallel strands held by phosphodiester bonds and nitrogenous base hydrogen bonds, coiling at $10$ nucleotides ($34\,\text{angstrom}$) per revolution.

Forms of DNA

The three distinct structural conformations of DNA: A-DNA, B-DNA, and Z-DNA.