Molecular Genetics

Flashcards from Molecular Genetics lecture notes.

DNA

Contain only four nucleotides and were thought to be repetitive and uninteresting.

Protein

Composed of 20 different amino acids, variable in structure and function, and believed to be sufficiently complex.

Streptococcus pneumoniae

A bacterium that causes pneumonia in mammals; studied by Frederick Griffith.

Smooth strain

A pathogenic strain of Streptococcus pneumoniae (disease-causing).

Rough strain

A non-pathogenic strain of Streptococcus pneumoniae (harmless).

Transformation

The change in the R strain caused by some material from the dead (heat killed) S strain; made it pathogenic.

Oswald Avery

Spent 14 years trying to identify the transforming agent in Griffith’s experiment.

Avery et al. experiment

Experiment where only DNA-destroying enzymes prevented transformation.

DNA

Genetic material (not protein).

Hershey and Chase experiment

An experiment to verify the findings of Avery et al.

E. coli

A bacteria used in the Hershey and Chase experiment.

Bacteriophage

A virus used in the Hershey and Chase experiment (T2 virus).

DNA

Virus injects this into host, not protein.

Alkaptonuria

Disease where people excrete large amount of homogentisic acid.

Metabolic pathways

Each step is a reaction catalyzed by a specific enzyme.

Accumulation of substrate

Disease develops; Garrod hypothesized that people with alkaptonuria accumulate homogentisisc acid because they lack the enzyme that uses it as a substrate.

Garrod

First scientist to connect genotype to a phenotype by identifying the biochemical basis of a genetic disease.

Beadle and Tatum

Scientists who were the first to apply Garrod’s idea to a more complete understanding of what genes do.

Neurospora crasa

A species of bread mold used by Beadle and Tatum to discover what genes do.

One gene-one enzyme hypothesis

Each gene therefore is responsible for a single enzyme.

One gene-one polypeptide hypothesis

Modified to reflect that some proteins are made up of more than one polypeptide, each coded for by a single gene.

Messenger RNA hypothesis

RNA acts as an intermediary between DNA and protein.

Central dogma of molecular biology

Explains the unidirectional flow of information in cells: DNA → RNA → Protein.

Transcription

Synthesis of mRNA under the direction of DNA (occurs in the nucleus).

Translation

Synthesis of protein under the direction of mRNA (occurs in the cytoplasm).