Concepts in Biochemistry, Chapter 11

1. DNA replication results in:
A.Protein production
B.Heavy DNA
C.Two new daughter strands
D.Induced mutations
E.mRNA transcripts


2. DNA replication is semiconservative. Why do you think this is?
A.Requires less energy
B.Only one DNA strand can be copied at a time.
C.RNA primer limitations
D.DNA replication starts at specific sites only.
E.Increased fidelity


3. Why does lagging strand synthesis consist of discontinuous Okazaki fragments?
A.There is a shortage of dNTPs for lagging strand synthesis.
B.DNA is synthesized 5' to 3'. Replication can only proceed from the unwound portion of DNA outward.
C.Lagging strand DNA polymerase can only handle a few nucleotides at a time.
D.Okazaki fragments are riddled with mistakes; proofreading enzymes chop up the nucleotide into short fragments.


4. Single-stranded binding proteins (SSB) bind to the outer backbone of DNA during replication. What would you predict about SSBs?
A.Sequence-specific binding
B.They hydrolyze phosphodiester bonds.
C.They contain arginine and lysine residues.
D.They form covalent bonds to sugars.


5. Which of the following statements is NOT true of telomerase?
A.Telomerase contains a ribozyme.
B.Telomerase activity decreases as the cell ages.
C.Telomerase adds a repeating sequence to the 5' end of DNA.
D.Telomerase adds a repeating sequence to the 3' end of DNA.
E.Telomerase is found only in eukaryotes.


6. DNA replication is not perfect; a mistake is made for every 104 to 105 nucleotides added. However, there are proofreading enzymes that excise incorrect bases and insert the correct one. Which of the following enzymes proofread DNA?
A.DNA ligase
B.DNA gyrase
C.DNA Polymerase I and II
D.DNA Polymerase III


7. Enter the letter of the mutagen (A-F) next to its corresponding effect.

A. OH

B.

C.


D. HNO2

E.


F. UV light

___ Thymine-dimer formation
___ DNA strand breaks
___ Methylation of guanine
___ Replaces thymine
___ Intercalates in DNA
___ Deaminates cytosine to form uracil

Answer:


8. Rearrange and enter the following terms to properly fit into the paragraph below:
template, RNA polymerase, RNA primer, 3'-5', RNA, coding strand

Transcription is the synthesis of __________ directed by a DNA template by the enzyme __________. The DNA strand is read in the __________ direction. This DNA strand is called the __________. The RNA transcript is synthesized in the 5'-3' direction, and it has the same sequence as the 5'-3' strand of DNA, which is called the __________. Unlike DNA replication, no __________ is required to initiate transcription.

Answer:


9. All of the following are true of RNA polymerase except:
A.It binds to most regions of DNA.
B.It binds best to promoter regions.
C.It unwinds DNA.
D.It produces transient RNA-DNA hybrids.
E.It has proofreading capability.
F.It requires r to terminate transcription.g) It produces hairpin structures in mRNA.
G.It is inhibited by rifampicin.


10. RNA replicase synthesizes RNA from an RNA template. RNA replicase differs from RNA polymerase in that:
A.It requires ATP.
B.It is found in viruses.
C.It has proofreading capability.
D.The synthesis of RNA proceeds in the 3'-5' direction.


11. All three forms of RNA are post-transcriptionally modified into their final form. Enter the type of RNA (mRNA, tRNA, and rRNA) that matches the modification described in each line. (More than one type of RNA may be entered per line.)
__________ Trimming of 5' end by phosphodiester bond cleavage
__________ Intron removal
__________ Addition of CCA sequence to 3' end
__________ Heterocyclic base modification
__________ Methylation of bases
__________ Addition of 7'-methylguanosine to the 5' end of the RNA molecule
__________ Addition of poly-A tail to the 3' end of the RNA molecule

Answer:


12. In DNA sequencing reactions, which of the following molecules is responsible for the chain termination reaction that results in DNA fragments?
A.dNTPs
B.DNA primer
C.ddNTPs
D.Denaturing agent
E.32P-dATP



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