Exam 3 Flashcards

Translation

The process in the cytosol where mRNA sequence is translated into an amino acid sequence.

Codon

A sequence of three nucleotides on mRNA that specifies a particular amino acid or a start/stop signal.

tRNA (transfer RNA)

Molecule that serves as the link between codons on mRNA and amino acids.

Aminoacyl Synthetase

Enzyme that attaches the appropriate amino acid to its corresponding tRNA.

Polycistronic mRNA

Bacterial mRNA that can encode multiple proteins.

Stop Codons

Nucleotide sequences (UAA, UAG, UGA) that signal the termination of protein synthesis.

Hydrolytic Editing

The process by which incorrect amino acids are removed from tRNA during protein synthesis.

Ribosome

Large ribonucleoprotein complex responsible for protein synthesis, composed of two subunits.

Eukaryotic Initiation Factors (eIFs)

Proteins involved in the initiation of translation in eukaryotes.

Molecular Chaperones

Proteins that assist in the proper folding of other proteins and can repair minor defects.

Quality Control in Protein Synthesis

Process of ensuring only correctly folded proteins are produced, with mis-folded proteins targeted for degradation.

Ubiquitin

A small protein that tags mis-folded proteins for degradation by proteasomes.

Peptide Bond

The bond formed between amino acids during protein synthesis.

Cytosol

The aqueous component of the cytoplasm where translation occurs.

AUG

The start codon that initiates translation and codes for Methionine.

Polyribosomes

Structures composed of multiple ribosomes translating a single mRNA strand simultaneously.

What does mRNA stand for?

mRNA stands for messenger RNA, which carries genetic information from the DNA to the ribosome for protein synthesis.

What is the role of ribosomes in protein synthesis?

Ribosomes are responsible for translating mRNA into a polypeptide chain, assembling amino acids in the order specified by the mRNA.

What is the function of tRNA?

tRNA (transfer RNA) carries specific amino acids to the ribosome corresponding to the codons on the mRNA.

What is a peptide bond?

A peptide bond is a covalent bond that links amino acids together in a protein.

What is the significance of the start codon AUG?

AUG is the start codon that initiates translation and codes for the amino acid Methionine.

What are stop codons?

Stop codons are nucleotide sequences (UAA, UAG, UGA) that signal the termination of protein synthesis.

What is the role of aminoacyl synthetase?

Aminoacyl synthetase is an enzyme that attaches the correct amino acid to its corresponding tRNA.

What are polycistronic mRNA molecules?

Polycistronic mRNA molecules are bacterial mRNA that encode multiple proteins within a single transcript.

Define molecular chaperones. What is their function?

Molecular chaperones are proteins that assist in the correct folding of other proteins and can help repair misfolded proteins.

What is quality control in protein synthesis?

Quality control is the process that ensures only correctly folded proteins are produced, with mis-folded proteins targeted for degradation.

Fill in the blank: The ________ is the molecule that links codons on mRNA to specific amino acids during protein synthesis.

tRNA (transfer RNA)

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