Essential Biology Facts: DNA, RNA, and Protein Synthesis

Biology Study Notes

Enzymes and Molecules

• Enzymes are organic molecules that function to start and regulate chemical reactions.
• The largest molecules in our bodies are nucleic acids.
• The human body is primarily composed of oxygen, nitrogen, hydrogen, and carbon.

Genetics and DNA Structure

• A genome is an organism’s complete set of DNA, containing all the information needed to build and maintain that organism.
• DNA molecules exist in the shape of a double helix.
• There are about 3 billion chemical base pairs in human DNA, with approximately 1%–2% coding for a gene.
• A gene is essentially a sequence of many codons in a DNA molecule.
• Portions of DNA molecules that do not contain codes for proteins are called introns.
• The DNA code is shared by all living things.
• Hydrogen bonds form between complementary base pairs.

Protein Synthesis and Transcription

• Amino acids are the building blocks of proteins; there are 20 different kinds.
• Proteins are produced in the ribosomes.
• A cell builds its proteins from instructions encoded in its genome.
• At the beginning of protein synthesis, a section of a DNA molecule unwinds and unzips.
• Messenger RNA (mRNA) is a short-lived molecule that carries encoded information transcribed from DNA.
• Transcription occurs before translation and is the synthesis of RNA from a DNA template.
• RNA polymerase performs template-directed synthesis in the 5’ to 3’ direction.
• Researchers employed X-ray crystallography to view the structure of RNA polymerase.
• Transcription begins when RNA polymerase binds to a sigma factor to create a holoenzyme, which guides the polymerase to specific start locations.

Replication and Codons

• In DNA replication, one DNA molecule becomes two identical ones.
• A DNA codon consists of three nucleotides.
• Each tRNA anticodon has three bases; these combinations code for specific amino acids.
• Not all codons specify amino acid components to be included in a protein.