Exam1 Protein Synthesis

Protein synthesis

Making a protein using genetic instructions: DNA → RNA → protein.

Protein-coding gene

A section of DNA with instructions used to make a protein.

Amino acids

The building blocks joined together to make proteins. Cells use 20 standard amino acids.

Transcription

Copying DNA instructions into RNA. For nuclear genes, this happens in the nucleus.

RNA polymerase

The enzyme that opens DNA locally and builds a complementary RNA copy.

DNA template → RNA pairing

DNA A → RNA U; DNA T → RNA A; DNA C → RNA G; DNA G → RNA C.

Pre-mRNA

The first RNA copy of a protein-coding gene, before processing is complete.

Introns

Sections removed from pre-mRNA in the nucleus.

Exons

Sections kept and joined together in mature mRNA.

Spliceosome

The machinery that removes introns and joins exons.

Translation

Reading mRNA at a ribosome and joining amino acids into a protein chain.

mRNA

Messenger RNA. Carries the genetic message that the ribosome reads.

tRNA

Transfer RNA. Brings an amino acid to the ribosome and uses an anticodon to match an mRNA codon.

Codon

A group of 3 bases on mRNA. There are 64 possible codons.

Anticodon

A group of 3 bases on tRNA that pairs with a matching mRNA codon.

Start codon

AUG. Signals the start of translation and codes for methionine.

Stop codons

UAA, UAG and UGA. End translation; they do not add an amino acid or receive a normal tRNA.

Class example: DNA template TAC-CGC-ACT

Transcribes to mRNA AUG-GCG-UGA. This produces methionine-alanine, then stops.