DNA Structure, Replication, and RNA Types: Key Concepts for Biology

Andrew Fire & Craig Melio

Discovered RNA interference

Avery, MacLeod & McCarty

Discovered the transforming principle. Used enzymes in DNA, and RNA

Barbara McClintock

Some DNA is mobile. Discovered transposons in corn

Charles Yanofsky

Noted collinearity between DNA an proteins.

Chromatin

Is the complex of DNA, chromosomal proteins and RNA within a nucleus.

CRISPR RNA (crRNA) Prokaryotic only

Assists destruction of foreign DNA

Erwin Chargaff

Amount of purines = amount of pyrimidines. Discovered based pairing rules.

Features of the Watson and Crick model

Double Stranded
- Antiparallel Strands.
- Complementary Strands (AT 2H bonds ,GC 3H bonds)
- Negative Charge.
- Phosphodiester Bonds join nucleotides together.
- Hydrophobic bonds hold the structure.
- Right handed coil.
- 10 bases per turn.
- Alternating major and minor grooves.

Fredrick Griffith

Observed that transformation occurs. injected mice with smooth and rough strains of Streptococcus pnuemoniae; heat-killed S transformed R into virulent S

Friedrich Miescher

First isolated DNA from white blood cells

Hershey and Chase

DNA is the genetic material in bacteriophages. Used T2 bacteriophages labeled with radioactive sulfur and phosphorous to show DNA enters cells, not protein

James Watson & Francis Crick

Determined the structure of DNA, an built the double-helix model

long noncoding RNA (lncRNA)

variety of functions

Meselson & Stahl

DNA replication is semiconservative. Used density-gradient centrifugation

Messenger RNA (mRNA)

Carries genetic code for the proteins

MicroRNA (miRNA) Eukaryotic only

Inhibits translation of mRNA

Negative Supercoiling

DNA is under-rotated. Negative supercoiling is rotation in the same direction as the DNA helix.

Nirenberg & Matthaei

Deduced the genetic code (triplet binding assay)

Piwi-interacting RNA (piRNA) Eukaryotic only

Suppresses the transcription of the transposable elements in reproductive cells.

Positive Supercoiling

DNA is over-rotated and twist back on itself.

Purine

2 rings, adenine and guanine

Pyrimidine

1 ring, thymine and cytosine

Ribosomal RNA (rRNA)

Structural and functional components of the ribosome

Rosalind Franklin & Maurice Wilkins

DNA is helical and 2nm diameter, 2 regularities (3.4nm & 0.34nm) used X - Ray diffraction

small interfering RNA (siRNA) Eukaryotic only

Triggers degradation of the RNA molecules

small nuclear RNA (snRNA) Eukaryotic only

Processing of pre-mRNA

small nucleolar (snoRNA) Eukaryotic only

Processing and assembly of rRNA

Transfer RNA (tRNA)

helps incorporate amino acids into polypeptide chain