Which statement about tRNAs is false?

They have an anticodon at their 5? end and an amino acid attachment site at their 3? end.
They interact with mRNA.
ATP is required for the charging of tRNAs with amino acids.
They interact with ribosomes.
Specific enzymes bind amino acids to their corresponding tRNAs.

They have an anticodon at their 5? end and an amino acid attachment site at their 3? end.
Which component of transcribed RNA in eukaryotes is present in the primary transcript but is removed before translation occurs?

5? cap
Intron
Exon
Poly A tail
Ribosome binding site

Intron
Put the following four steps of eukaryotic gene expression in order, from beginning to end.
(1) Pre-mRNA is processed to make mRNA.
(2) Ribosomes translate the mRNA sequence to make proteins.
(3) mRNA is transported to the cytoplasm.
(4) DNA is used as a template to make pre-mRNA.

1; 2; 4; 3
4; 1; 2; 3
1; 4; 3; 2
4; 3; 1; 2
4; 1; 3; 2

4; 1; 3; 2
Which component is not involved in the elongation step of translation?

RNA polymerase
Charged tRNA
Ribosomes
The amino acid site
Peptidyl transferase

RNA polymerase
Which statement about pre-mRNA splicing is false?

It is directed by consensus sequences.
It removes introns.
It shortens the RNA molecule.
It is performed by small nuclear ribonucleoprotein particles (snRNPs).
It is common in prokaryotes.

It is common in prokaryotes.
Sickle-cell disease and hemoglobin C disease are both caused by point mutations, resulting in glutamic acid at position 6 in the ?-globin being replaced by _______ and _______, respectively.

lysine; arginine
serine; cysteine
serine; a stop codon
valine; lysine
valine; glycine

valine; lysine
At the initiation complex of translation in eukaryotes,

the anticodon of tRNA charged with methionine binds to mRNA associated with the small ribosomal subunit.
the large ribosomal subunit binds to mRNA, causing the release of the small subunit.
the poly A tail of mRNA is directly involved.
the complex of mRNA and the large ribosomal subunit are formed.
the large ribosomal subunit binds to the complex before the methionine-charged tRNA.

the anticodon of tRNA charged with methionine binds to mRNA associated with the small ribosomal subunit
Which single-base substitution in the template strand of DNA would result in the premature termination of translation (sequences are written 5? to 3?)?

CCT to CCC
TTG to TTA
CTG to CTT
GAG to TAG
CAA to CAG

TTG to TTA
Ribosomes

carry out translation.
are not found in prokaryotes.
have no role in the fidelity of mRNA and tRNA interactions.
carry genetic information.
contain RNA only.

carry out translation.
RNA polymerases differ from DNA polymerases in that

DNA polymerases use ribonucleoside triphosphates as substrates.
RNA polymerases are less effective at proofreading than DNA polymerases.
only DNA polymerases are processive.
RNA polymerases do not require a template.
RNA polymerases use deoxyribonucleoside triphosphates as substrates.

RNA polymerases are less effective at proofreading than DNA polymerases.
In the elongation stage of translation,

peptidyl transferase activity is catalyzed by a ribosomal protein.
the polypeptide chain grows from the Trp to the Met direction.
rRNA is catalytically active.
rRNA plays a passive role.
the codons are read in the 3?-to-5? direction.

rRNA is catalytically active.
Why did the original “one-gene, one-enzyme” hypothesis have to be modified?

Some enzymes are made up of more than one polypeptide.
All genes code for multiple enzymes.
Not all proteins are coded by genes.
Some RNAs have catalytic activity.
Not all enzymes are coded for by genes.

Some enzymes are made up of more than one polypeptide.
In eukaryotes, the first amino acid in a growing polypeptide chain is always _______ because the only codon for this amino acid is also the _______ codon.

methionine; start
alanine; start
alanine; stop
tryptophan; start
tryptophan; stop

methionine; start
What are the intracellular destinations of the following proteins: DNA polymerase; pyruvate kinase; rubisco; citrate synthase?

Cytoplasm; chloroplast; mitochondrion; nucleus
Nucleus; cytoplasm; chloroplast; mitochondrion
Nucleus; mitochondrion; chloroplast; cytoplasm
Cytoplasm; chloroplast; nucleus; mitochondrion
Mitochondrion; chloroplast; nucleus; cytoplasm

Nucleus; cytoplasm; chloroplast; mitochondrion
A protein destined for a lysosome carries a signal peptide for the

rough ER.
lysosome.
nucleus.
mitochondria.
plasma membrane.

rough ER.
UAU and UAC both code for tyrosine. A change from UAU to UAC would thus be a _______ mutation; a change from UAU to UAG would be a _______ mutation.

frame-shift; missense
silent; missense
nonsense; silent
nonsense; frame-shift
silent; nonsense

silent; nonsense
Posttranslational alterations of proteins

do not include the cleavage of signal sequences.
may include the addition of polysaccharides to proteins.
do not include the addition of polysaccharides to proteins.
do not include the addition of phosphate groups.
do not affect the activity of an enzyme.

may include the addition of polysaccharides to proteins.
The mRNA codon for leucine is 5?-UUG-3?, and the tRNA anticodon is

5?-AAC-3?.
5?-CAA-3?.
5?-UUG-3?.
5?-TTC-3?.
5?-GUU-3?.

5?-CAA-3?
Which component is required for the initiation of transcription?

Promoter DNA sequence
Ribonucleoside triphosphates
The start codon AUG
DNA polymerase
Terminator DNA sequence

Promoter DNA sequence
During protein synthesis, ribosomes

translate mRNA into polypeptides.
transcribe mRNA to proteins.
translate mRNA into DNA.
transcribe DNA into mRNA.
translate mRNA into tRNA.

translate mRNA into polypeptides.
x

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