Biology Translation Flashcards

Questions and Answers

What is translation and where does it occur?

Translation is the process by which an mRNA is translated into protein. This process occurs in the cytoplasm.

What are the stop codons?

UAA, UAG, UGA

How many codons can encode an amino acid?

An amino acid may be encoded by multiple codons.

Compare the nuclear and mitochondrial genetic codes.

The nuclear and mitochondrial genetic codes are similar but not identical. Signup and view all the answers

What are tRNAs?

Transfer RNAs are involved in the translation of the genetic code, linking mRNA to the amino acid sequence of proteins. Signup and view all the answers

What adds the sequence CCA to the 3' end of all tRNAs?

Nucleotidyl transferase Signup and view all the answers

What do tRNAs contain?

Specific anticodons of three bases that are complementary and anti-parallel to an mRNA codon. Signup and view all the answers

How many codons do tRNAs recognize and what is wobble base pairing?

Many tRNAs can recognize more than one codon due to wobble base pairing. Signup and view all the answers

What is the function of ribosomes in translation?

Ribosomes are the site of protein synthesis. Signup and view all the answers

Describe the structure of a ribosome.

Ribosomes consist of two subunits, the large 60S and the small 40S subunit, composed of ribosomal proteins and rRNAs. Signup and view all the answers

What do ribosomes act as?

Ribosomes act as ribozymes, catalyzing the peptidyl transferase reaction. Signup and view all the answers

Describe the steps of protein synthesis: attachment of amino acids to tRNAs.

Amino acids are attached to the CCA sequence of tRNAs by specific aminoacyl-tRNA synthetases, requiring ATP. Signup and view all the answers

Describe the two adaptors that act one after another to translate the genetic code.

<ol> <li>Aminoacyl-tRNA synthetase: Couples a particular amino acid to its corresponding tRNA. 2. tRNA molecule: Anticodon forms base pairs with appropriate mRNA codon.</li> </ol> Signup and view all the answers

What complex is involved for the initiation of protein synthesis, and what does this complex do?

Initiation involves a complex including Met-tRNA, initiation factors, GTP, and the 40S ribosome, which scans mRNA for the first AUG codon. Signup and view all the answers

What is the result of the complex finding the AUG codon?

Association of the 60S ribosomal subunit and the generation of the 80S initiation complex. Signup and view all the answers

Describe the initiation and elongation of protein synthesis.

Initiation assembles a complex that scans for AUG. Elongation involves a second charged tRNA binding, peptide bond formation, and translocation to the next codon until a termination codon is reached. Signup and view all the answers

Describe the termination of protein synthesis.

When a termination codon is reached, protein synthesis stops. Signup and view all the answers

Study Notes

Translation Process

Translation converts mRNA into protein in the cytoplasm.
Ribosomes are the site of protein synthesis.

Codons and tRNAs

Stop codons: UAA, UAG, UGA signify the end of translation.
Each amino acid can be encoded by multiple codons; however, a specific codon uniquely encodes a single amino acid.
tRNAs act as adapters between mRNA codons and amino acids, containing anticodons complementary to mRNA.

Genetic Code

Nuclear and mitochondrial genetic codes share similarities but differ in specifics.
Wobble base pairing allows a tRNA to recognize multiple codons due to fewer tRNAs (about 50 in humans) than codons.

tRNA Structure

tRNAs possess conserved secondary/tertiary structures and modified nucleotides.
Anticodons of tRNAs are anti-parallel and complementary to the mRNA codons (e.g., for 5'−AUG−3', the tRNA anticodon is 3'−UAC−5').

Ribosome Structure

Ribosomes are large complexes of rRNAs and proteins, with eukaryotic ribosomes being 80S (60S large subunit and 40S small subunit).
The 60S subunit includes about 50 proteins and several rRNAs (28S, 5.8S, 5S), while the 40S contains around 30 proteins and 18S rRNA.
Ribosomes function as ribozymes, with RNA catalyzing the peptidyl transferase reaction.

Protein Synthesis

Amino acids are attached to tRNAs at the CCA sequence via aminoacyl-tRNA synthetases, requiring ATP.
Two adaptors operate sequentially: aminoacyl-tRNA synthetase (charging the tRNA) and the tRNA itself (pairing with mRNA codons).

Initiation of Protein Synthesis

Initiation complex includes Met-tRNA, several initiation factors, GTP, and the 40S ribosome, scanning for the first AUG codon.
Finding the AUG codon triggers the association of the 60S subunit to form the 80S initiation complex, starting protein synthesis.

Elongation Phase

A second charged tRNA binds to the next mRNA codon, involving elongation factors and GTP.
The ribozyme catalyzes peptide bond formation between amino acids.
Ribosome translocates to the next codon, requiring GTP hydrolysis and the translocase enzyme (EF2), continuing until a termination codon is reached.

Termination of Protein Synthesis

Protein synthesis concludes upon encountering a termination codon, completing the translation process.

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Description

Test your knowledge on the translation process in biology with these flashcards. Explore essential concepts such as codons, stop codons, and the role of mRNA in protein synthesis. Perfect for students needing a refresher on molecular biology topics.