AP Bio Chapter 16 Review

Thymine makes up 30% of the nucleotides in a sample of DNA from an organism. Approximately what percentage of the nucleotides in this sample will be cytosine? 

• 10%
• 20%
• 30%
• 70%

In an analysis of the nucleotide composition of DNA, which of the following will be found? 

• A = C 
•  A = G and C = T 
• A + C = G + T 
• G + C = T + A

What is meant by the description "antiparallel" regarding the strands that make up DNA? 

• The twisting nature of DNA creates nonparallel strands. 
• The 5' to 3' direction of one strand runs counter to the 5' to 3' direction of the other strand. 
• Base pairings create unequal spacing between the two DNA strands.
• One strand is positively charged and the other is negatively charged. 

An Okazaki fragment has which of the following arrangements? 

• primase, polymerase, ligase 
•  3' RNA nucleotides, DNA nucleotides 5' 
• 5' RNA nucleotides, DNA nucleotides 3' 
• DNA polymerase I, DNA polymerase III 

In E. coli, there is a mutation in a gene called dnaB that alters the helicase that normally acts at the origin. Which of the following would you expect as a result of this mutation? 

•  No proofreading will occur.
• No replication fork will be formed. 
• The DNA will supercoil. 
•  Replication will occur via RNA polymerase alone. 

Tags

NGSS.HS-LS3-2

Which enzyme catalyzes the elongation of a DNA strand in the 5' → 3' directiion?

• primase 
• DNA ligase 
• DNA polymerase III 
• topoisomerase 

The enzyme telomerase solves the problem of replication at the ends of linear chromosomes by which method?

• adding a single 5' cap structure that resists degradation by nucleases

• causing specific double-strand DNA breaks that result in blunt ends on both strands

• causing linear ends of the newly replicated DNA to circularize

• adding numerous short DNA sequences such as TTAGGG

What is the function of ligase?

• to unwind the DNA helix during replicatio

• to seal together the broken ends of DNA strands

• to add nucleotides to the 3' end of a growing DNA strand

• to degrade damaged DNA molecules

The leading and the lagging strands differ in that

• the leading strand is synthesized in the same direction as the movement of the replication fork, and the lagging strand is synthesized in the opposite direction. 
• the leading strand is synthesized by adding nucleotides to the 3' end of the growing strand, and the lagging strand is synthesized by adding nucleotides to the 5' end
•  the lagging strand is synthesized continuously, whereas the leading strand is synthesized in short fragments that are ultimately stitched together. 
• the leading strand is synthesized at twice the rate of the lagging strand.

 A new DNA strand elongates only in the 5' to 3' direction because 

• DNA polymerase begins adding nucleotides at the 5' end of the template. 
• Okazaki fragments prevent elongation in the 3' to 5' direction. 
•  replication must progress toward the replication fork. 
• DNA polymerase can only add nucleotides to the free 3' end.