a Answer 30 b 20 A bases 20 G bases 40 A and G bases so that means 100 4060 G

A answer 30 b 20 a bases 20 g bases 40 a and g bases

This preview shows page 6 - 9 out of 40 pages.

a.Answer: 30%b.20% A bases 20% G bases = 40% A and G bases so that means 100-40=60% Gand C bases 30% C bases 30% G bases ‘Practice Exam Questions 1.If a strand of DNA is analyzed and contains 30 percent G bases, what percent of thestrand contains C bases? a.Answer: (A) 30%2.The sequence of one strand of DNA is 5’ – GCTTTAG – 3’. The sequence of thecomplementary strand would be: a.3’ – CGAAATC – 5’
Background image
b.Answer: (D) 5’ – CTAAAGC – 3’ 3.Use the replication fork figure to answer this question. The replication fork is movingfrom left to right. The strand labeled ______ is the template for the ______ and is createdfrom _____. Okazaki fragments will be located on strand ____. a.A, leading strand, 5’ to 3’, B b.A, leading strand, 3’ to 5’, B c.B, leading strand, 3’ to 5’, A d.B, leading strand, 5’ to 3’, A e.C, double helix, 5’ to 3’, both A and BLeading strand goes from the 5’ to 3’ direction. Replicationforkis moving left to right so the leading strand has to be going in that direction. Since leading strandgoes from 5’ to 3’ it has be on strand B, so the answer is D. 4.Why is an RNA primer considered essential during DNA synthesis by DNA polymerase? a.The enzyme requires a free 3'-PO4 group. b.The enzyme requires a free 5'-PO4 group. c.The enzyme requires a free 5'-OH group. d.The enzyme requires a free 3'-OH group. e.There is no particular reason; this is simply the observation.Answer: D The primer provides an important 3’ hydroxyl on which to begin synthesis. The nextdeoxyribonucleotide triphosphate enters the binding site of the DNA polymerase and is orientedby the polymerase such that a hydrolysis of the 5’ triphosphate can occur, releasingpyrophosphate and coupling this exergonic reaction to the synthesis of a phosphodiester bondbetween the 5’ phosphate of the incoming nucleotide and the 3’ hydroxyl group of the primer. ---------------------------------------------------------------------------------------------------------------------Lecture 18 Vocabulary Telomeres: a region of repetitive nucleotide sequences at each end of a chromosome,which protects the end of the chromosome from deterioration or from fusion withneighboring chromosomes. A telomere is a repeating DNA sequence (for example, TTAGGG) at the end ofthe body’s chromosomes. Telomeres function by preventing chromosomes fromlosing base pair sequences at their ends. They also stop chromosomes from fusingto each other. However, each time a cell divides, some of the telomere is lost.When the telomere becomes too sort, the chromosome reaches a “critical length”and can no longer replicate. over time, due to each cell division, the telomere ends become shorterTelomerase: an enzyme composed of protein and RNA. Telomerase attaches to the end ofthe chromosome by complementary base pairing between the RNA component oftelomerase and the DNA template
Background image
Telomerase builds telomere DNAThe RNA is used as a complementary strand for the short elongation of itscomplement.
Background image
Image of page 9

You've reached the end of your free preview.

Want to read all 40 pages?

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture