Genetic Code and Translation Flashcards

Flashcards about the genetic code and translation

Genetic Code

A set of rules for determining how genetic information in the form of a nucleotide sequence is converted to an amino acid sequence of a protein.

Codon

Sequences of three bases used to code for an amino acid.

Start Codon

AUG, codes for methionine and signals the start of translation.

Stop Codons

UAA, UAG, UGA: signal the termination of translation.

Redundant Genetic Code

More than one codon can code for the same amino acid.

Continuous Genetic Code

The code is read as a series of three-letter codons.

Universal Genetic Code

Almost all organisms build proteins with the same genetic code.

Translation

The second stage of gene expression, involves translating the nucleic acid code of mRNA into the amino acid code of a protein.

tRNA (Transfer RNA)

Folded RNA molecule with an anticodon loop, complementary to the mRNA codon. Carries the corresponding amino acid.

Anticodon Loop

A sequence of three nucleotides on tRNA that is complementary to an mRNA codon.

Acceptor Stem

A single-stranded region on tRNA where an amino acid is attached.

Aminoacyl-tRNA Synthetase

Enzymes that attach the correct amino acid to a tRNA.

Ribosome

A complex of protein combined with ribosomal RNA (rRNA) where translation occurs.

P Site (Peptidyl Site)

Holds the tRNA with the growing chain of amino acids.

A Site (Aminoacyl Site)

Receives the tRNA with the next amino acid to be added to the chain.

E Site (Exit Site)

Releases the used tRNA back into the cytoplasm.

Initiation (Translation)

Ribosome binds to a specific sequence on the mRNA.

Elongation (Translation)

The ribosome moves along the mRNA, tRNA delivers the appropriate amino acid, and the polypeptide is elongated.

Termination (Translation)

The ribosome reaches a stop signal; the ribosome falls off the mRNA, and the polypeptide chain is released.

Translocation

The ribosome moves 3 nucleotides (one codon) along the mRNA.

Uncharged tRNA

tRNA that has been used to make the polypeptide chain.

Release Factor

A protein that cleaves the polypeptide from the last tRNA during termination.

Polysome/Polyribosome

One mRNA can be bound simultaneously to more than one ribosome.