DNA replication, transcription and translation quiz

DNA replication uses one existing strand as a template for the new strand. How is this organization described by biologists?

• Mono-preservative replication

• Semi-preservative replication

• Mono-conservative replication

• Semi-conservative replication

Answer explanation

The process of replication produces a new DNA double helix. One of the strands is from the original DNA molecule which was copied. The new strand is built from nucleotides.

This is semi-conservative replication.

Complementary base pairing occurs in DNA replication and in transcription.

Which bases pair with Adenine (A) in these processes?

• T in replication, and U in transcription.

• T in replication and T in transcription.

• U in replication and U in transcription.

• U in replication and T in transcription.

Answer explanation

DNA replication builds DNA so T pairs with A

Transcription builds mRNA so U pairs with A

What is the name of the enzyme which synthesizes mRNA?

• DNA polymerase

• Helicase

• RNA polymerase

• Ribosome

Answer explanation

RNA polymerase synthesizes mRNA during transcription.

What is the best description of an, "mRNA codon"?

• A complete mRNA molecule, which codes for one protein or one gene.

• One mRNA nucleotide base which codes for an amino acid.

• Three nucleotide bases of mRNA which code for an amino acid.

• The sequence of nucleotide bases on a mRNA molecule corresponding to a protein

Answer explanation

Three bases of mRNA make a single codon which corresponds to an amino acid.

Where is the location of translation in the cell?

• On DNA molecules in the nucleus

• Ribosomes in the nucleus.

• On DNA molecules in the cytoplasm.

• Ribosomes on rER or in the cytoplasm.

Answer explanation

Translation occurs on ribosomes which are not found in the nucleus, they are in the cytoplasm, and on the rER membranes.

What is the role of the helicase enzyme?

• Coils around the DNA and holds the strands together.

• Winds up the DNA and joins the two strands.

• Unwinds DNA and separates the two strands.

• Copies the DNA and makes a double strand.

Answer explanation

Helicase is the enzyme which unwinds the DNA and breaks the hydrogen bonds holding the two DNA strands together.

What is the name and function of the enzyme shown in the diagram below.

• DNA polymerase does DNA replication

• RNA polymerase does Transcription

• DNA polymerase does Transcription

• RNA polymerase does DNA replication

Answer explanation

As the nucleotides being added are DNA nucleotides, it is DNA replication.

The enzyme which does this is called DNA polymerase, more specifically DNA polymerase III

Tags

NGSS.HS-LS1-1

Which enzymes are responsible for DNA replication and the synthesis of mRNA?

• DNA polymerase (DNA replication) and RNA polymerase (mRNA synthesis)

• RNA polymerase (DNA replication) and DNA polymerase (mRNA synthesis)

• DNA replicase (DNA replication) and RNA synthase (mRNA synthesis)

• DNA polymerase (DNA replication) and RNA synthase (mRNA synthesis)

Answer explanation

This is logical, DNA polymerase builds a DNA polymer, and RNA polymerase builds an RNA polymer.

Where does the synthesis of polypeptides from mRNA and tRNA molecules take place?

• On DNA molecules

• In the nucleus

• On RNA polymerase molecules

• On ribosomes

Answer explanation

The synthesis of polypeptides takes place on ribosomes and involves mRNA molecules and tRNA.

If an mRNA molecule were to code for a polypeptide with 50 amino acids, how many bases of mRNA would be required to provide for the codons which correspond to the amino acids. (Do not count the stop codon)

• 100

• 50

• 500

• 150

Answer explanation

Each codon has three mRNA nucleotide bases, so to code for 50 amino acids would be 150 bases.