10 questions🇬🇧English
🧬 DNA & Protein Synthesis – A-level
Biology · A-level — practises DNA replication, transcription, translation and the genetic code
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Questions
What is the role of DNA helicase during DNA replication?
Joins nucleotides with phosphodiester bonds
Attaches free nucleotides to the template
Breaks hydrogen bonds between complementary bases
Seals gaps between Okazaki fragments
20s
DNA replication is described as semi-conservative. What does this mean?
One new molecule keeps both original strands
Only half of the DNA in a cell is replicated
Each strand is a mix of old and new sections
Each new molecule has one original and one new strand
20s
During transcription, which enzyme joins nucleotides together to form a pre-mRNA molecule?
DNA polymerase
RNA polymerase
DNA ligase
Reverse transcriptase
20s
The genetic code is described as degenerate. What does this mean?
Most amino acids are coded for by more than one codon
Each codon codes for more than one amino acid
Neighbouring codons share some of their bases
Codons code for different amino acids in each species
30s
In which direction does DNA polymerase build a new DNA strand?
3′ to 5′
5′ to 3′
In both directions equally
It depends on leading or lagging strand
30s
In eukaryotes, which sections are removed from pre-mRNA during splicing?
Introns
Anticodons
Start codons
Exons
20s
During translation, how are adjacent amino acids joined at the ribosome?
Condensation reaction forming a glycosidic bond
Condensation reaction forming a peptide bond
Hydrolysis reaction forming a peptide bond
Hydrolysis reaction forming a phosphodiester bond
30s
Meselson and Stahl grew bacteria in ¹⁵N, then moved them to ¹⁴N. After two generations in ¹⁴N, what DNA bands were seen?
One heavy band and one light band
One intermediate band and one light band
One heavy, one intermediate and one light band
One intermediate band only
30s
A DNA template strand contains the base triplet TAC. What is the anticodon of the tRNA that binds to the resulting codon?
UAC
AUG
ATG
TAC
30s
A mature mRNA has 459 bases from the start codon to the stop codon inclusive. How many amino acids are in the polypeptide?
153
152
151
459
60s