Lesson Worksheet: DNA Replication Biology
In this worksheet, we will practice describing the process of semiconservative DNA replication, including the role of different enzymes, and recalling how errors made during DNA replication can be corrected.
Q1:
When errors in DNA replication occur, the newly formed strand can be proofread and be recognized as not being complementary to the original strand. Which enzyme is responsible for correcting these errors during replication?
- ADNA ligase
- BDNA polymerase
- CDNA helicase
- DDNase
Q2:
Which of the following statements about DNA polymerase is correct?
- ADNA polymerase can only synthesize strands of DNA that are less than 50 nucleotides long.
- BDNA polymerase can only synthesize DNA strands in the to direction.
- CDNA polymerase will not be able to detect any errors made when a DNA strand is being synthesized.
Q3:
What are the products of semiconservative DNA replication?
- ATwo single-stranded molecules of DNA, containing half of the DNA of the original DNA molecule
- BTwo double-stranded molecules of DNA that are identical to each other and to the original DNA molecule
- CFour single-stranded molecules of DNA that are identical to each other and to the original DNA molecule
- DFour double-stranded molecules of DNA that are all genetically unique
Q4:
In semiconservative DNA replication, what is the primary role of DNA ligase?
- ADNA ligase adds nucleotides to a growing DNA chain to synthesize a strand of DNA complementary to the template strand.
- BDNA ligase joins the backbones of fragments formed on a complementary strand during replication.
- CDNA ligase catalyzes the breaking of phosphodiester bonds in the sugar–phosphate backbone, so the DNA can be split into fragments that are ready for replication.
- DDNA ligase breaks the hydrogen bonds between base pairs, separating the two strands of DNA that are ready for replication.
- EDNA ligase joins RNA primers to the end of a single strand of DNA to indicate where replication should begin.
Q5:
Which of the following tables correctly summarizes the enzymes involved in DNA replication and their roles?
- A
Enzyme DNA helicase DNA polymerase DNA ligase Role To join the sugar–phosphate backbones of DNA fragments To break the hydrogen bonds between base pairs in double-stranded DNA To add nucleotides to a growing section of DNA and to form a strand that is complementary to the template - B
Enzyme DNA helicase DNA polymerase DNA ligase Role To break the hydrogen bonds between base pairs in double-stranded DNA To add nucleotides to a growing section of DNA and to form a strand that is complementary to the template To join the sugar–phosphate backbones of DNA fragments - C
Enzyme DNA helicase DNA polymerase DNA ligase Role To add nucleotides to a growing section of DNA and to form a strand that is complementary to the template To break the hydrogen bonds between base pairs in double-stranded DNA To join the sugar–phosphate backbones of DNA fragments - D
Enzyme DNA helicase DNA polymerase DNA ligase Role To break the hydrogen bonds between base pairs in double-stranded DNA To join the sugar–phosphate backbones of DNA fragments To add nucleotides to a growing section of DNA and to form a strand that is complementary to the template
Q6:
In DNA replication, what is the primary role of DNA polymerase?
- ADNA polymerase joins the gaps in the backbone between the fragments formed on a complementary strand.
- BDNA polymerase adds nucleotides to a growing DNA chain to synthesize a strand of DNA complementary to the template strand.
- CDNA polymerase breaks the hydrogen bonds between base pairs, separating the two strands of DNA that are ready for replication.
- DDNA polymerase joins RNA primers to the end of a single strand of DNA to indicate where replication should begin.
- EDNA polymerase catalyzes the breaking of phosphodiester bonds in the sugar-phosphate backbone, so the DNA can be split into fragments that are ready for replication.
Q7:
As it is being replicated, DNA is proofread to prevent errors being made. However, sometimes changes can occur in a DNA base sequence. What are changes in the DNA base sequence called?
- AAlterations
- BAbrasions
- CDisruptions
- DMutations
- ETransformations
Q8:
A single strand of DNA has the following sequence:
Reading from the direction, state the sequence of bases that will form on the complementary strand.
- AATTGGGCCATATA
- BGAACCCTTGAGAG
- CTAACCCGGTATAT
- DTCCAAAGGTCTCT
- ECGGTTTAACGCGC
Q9:
In the process of DNA replication, what is the primary role of DNA helicase?
- ADNA helicase detects and repairs any errors that are made by incorrect base pairings during DNA replication.
- BDNA helicase breaks the hydrogen bonds between base pairs, separating the two strands of DNA.
- CDNA helicase forms phosphodiester bonds between nucleotides to form a strand of DNA.
- DDNA helicase adds nucleotides to a growing DNA chain, synthesizing a strand of DNA complementary to the template strand.
- EDNA helicase joins the gaps in the backbone between newly formed DNA fragments.
Q10:
The stages of DNA replication are shown in the flowchart provided.
What enzyme would correctly replace the gap in statement 2?
- ADNA helicase
- BDNase
- CDNA polymerase
- DDNA ligase
What enzyme would correctly replace the gap in statement 3?
- ADNase
- BDNA helicase
- CDNA polymerase
- DDNA ligase
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