Biochem Lecture 12a

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In what direction is the genetic code written?

From middle to both ends

3' to 5'

5' to 3' (correct)

Random direction

Which base in a codon is less crucial in binding to tRNA?

All bases are equally crucial

Second base

Third base (correct)

First base

How many termination codons are there in the genetic code?

1

3 (correct)

2

4

Which codon acts as both an initiation codon and a Methionine codon?

AUG Signup and view all the answers

What is the primary reason for the resistance of the genetic code to mutations?

Degeneracy of the code Signup and view all the answers

Which amino acids have more than one codon in the genetic code?

All except Methionine and Tryptophan Signup and view all the answers

'Codon bias' in the genetic code refers to which of the following?

Preference for certain codons over others that specify the same amino acid Signup and view all the answers

What is the role of UGA in the genetic code of vertebrate mitochondrial DNA?

Encodes Trp Signup and view all the answers

In vertebrate mitochondrial DNA, what does AGA/AGG encode?

STOP Signup and view all the answers

How many tRNAs are used by mitochondria compared to the standard genetic code?

22 Signup and view all the answers

What is the significance of the 'wobble' hypothesis in the genetic code?

Permits rapid dissociation of mRNA from tRNA Signup and view all the answers

Which nucleotide can form weak hydrogen bonds with A, U, and C in some tRNAs?

Inosinate (I) Signup and view all the answers

What determines the number of codons recognized by a tRNA?

The first base of the anticodon Signup and view all the answers

What percentage of the chemical energy of a cell can protein synthesis use up?

90% Signup and view all the answers

What is the role of tRNA in protein synthesis?

Acting as an 'adapter' to translate mRNA into protein Signup and view all the answers

What keeps pace with protein synthesis?

Degradation Signup and view all the answers

What effect does codon bias have on minimizing the effect of mutations in the genetic code?

Minimizes the effect of mutations Signup and view all the answers

How does a mutation in the first base of a codon typically affect the amino acid sequence?

Frequently results in a conservative substitution Signup and view all the answers

What is the role of translational frameshifting in protein synthesis?

Allows for translation of completely different proteins Signup and view all the answers

How is translational frameshifting described in relation to ribosomes?

Ribosomes hiccup to change the reading frame Signup and view all the answers

How does a slippery sequence influence translational frameshifting?

Facilitates ribosome shifting in reading frame Signup and view all the answers

How does RNA secondary structure contribute to translational frameshifting?

Induces ribosome pausing, affecting reading frame Signup and view all the answers

What is the role of guide RNAs in RNA editing?

Act as templates for the editing process Signup and view all the answers

Which proteins are essential for reverse transcriptase in HIV1 replication?

Gag and pol proteins Signup and view all the answers

In which genomes is RNA editing common?

Mitochondrial and chloroplast genomes Signup and view all the answers

What is the result of inserting four U residues in post-transcriptional editing?

Revises the reading frame Signup and view all the answers

What is the role of the editosome in RNA editing?

Multienzymatic complex for editing Signup and view all the answers

Which organism's mitochondrial genome provides an example of RNA editing in the Cytochrome Oxidase subunit II gene?

Trypanosoma brucei Signup and view all the answers

What do guide RNAs do in the editing process?