Week 10 - Translation Flashcards
(22 cards)
tRNA (Transfer RNA)
A small RNA molecule that carries an amino acid to the ribosome and matches it to the coded mRNA message using its anticodon.
RNA Polymerase III
An enzyme that transcribes tRNA, 5S rRNA, and some small RNAs.
Ribosome
The molecular machine that synthesizes proteins. It’s made of rRNA and proteins and has two subunits:
-Small subunit: binds to mRNA and decodes it.
-Large subunit: joins amino acids together to form a polypeptide chain.
Anticodon
A set of three nucleotides on the tRNA that is complementary to a codon on mRNA.
Codon
A sequence of three nucleotides on mRNA that codes for a specific amino acid.
Genetic Code
The set of rules by which mRNA codons are translated into amino acids. It’s universal, redundant, and non-overlapping.
Wobble Hypothesis
Explains how some tRNAs can pair with more than one codon, due to flexibility in the third base pairing — this helps explain why fewer tRNAs are needed than there are codons.
Purine
A type of nitrogenous base with two rings. Includes adenine (A) and guanine (G).
Pyrimidine
A nitrogenous base with one ring. Includes cytosine (C), uracil (U) (in RNA), and thymine (T) (in DNA).
Aminoacyl Transferase (aka Aminoacyl-tRNA Synthetase)
The enzyme that attaches the correct amino acid to its tRNA — one for each amino acid.
Start Codon
The first codon of an mRNA that signals the start of translation. Always AUG, which codes for methionine.
Stop Codons
Codons that signal the end of translation. They don’t code for amino acids. The three are: UAA, UAG, and UGA.
Initiation Factors
Proteins that help the ribosome assemble around the mRNA and the first tRNA during the start of translation.
Release Factors
Proteins that recognize stop codons and help end translation by causing the ribosome to release the finished polypeptide.
5’ Cap
A modified guanine nucleotide added to the 5’ end of mRNA during RNA processing. It protects the mRNA and helps with ribosome binding.
rRNA (Ribosomal RNA)
The RNA component of the ribosome. It helps catalyze peptide bond formation and ensures proper alignment of mRNA and tRNA.
Ribosome (Small and Large Subunit)
-Small subunit: reads the mRNA.
-Large subunit: joins amino acids together with peptide bonds.
Peptide Bond
A covalent bond that links amino acids together in a protein, formed between the carboxyl group of one amino acid and the amino group of another.
Exit Site (E Site)
Where the tRNA (now empty) exits the ribosome after its amino acid has been added to the chain.
Aminoacyl Site (A Site)
The entry site for new tRNA carrying an amino acid.
Peptidyl Site (P Site)
Holds the tRNA with the growing polypeptide chain.
RNA Polymerase I
An enzyme that transcribes rRNA genes (except 5S rRNA), mainly in the nucleolus.
