Chapter 11:
Nucleic Acids
Supplemental Instruction
IowaStateUniversity / Leader: / Adam
Course: / Biology 211
Instructor: / Emeka Kemdirim
Date:

Describe the three possible models of DNA-Replication

  • Semi- Conservative Mechanism:
  • Conservative Mechanism:
  • Dispersive Mechanism:

In DNA replication, newly made stands are called what?

In DNA replication, original strands are called what?

Meselson and Stahl Experiment

  1. Which two isotopes were used in this experiment and which isotope corresponded to “light” and which to “heavy”?
  1. E-coli were first grown on a medium of (light,heavy) N isotope, then transferred to a medium with (light, heavy) N isotope.
  1. By transferring the E-coli to different mediums, they were able to tell that the (parent,daughter) strand were heavy, and that the (parent, daughter) strand were light.
  1. The E-Coli cells were allowed to go through three generations (1 sample from each) then centrifuged to divide the DNA based on density and then put on a salt gradient in a test tube. What would be observed if DNA was heavy, light, and both if you had each in a tube.
  1. Results:

After round one of replication, the DNA was?

These results were consistent with which theories?

Based on these results which theory could be thrown out?

After the second round of DNA replication, what was observed?

Disproving which theory and proving which theory?

DNA REPLICATION

  1. The Origin of Replication of DNA initiates in multiply spots along the DNA strand in regions where the double helix separate called what?
  1. T or F: Replication proceeds in a bidirectional fashion.
  1. Bacteria have (one, multiple) orgin(s) of replication and eukaryotes have (one, multiple) orgin(s) of replications.
  1. Which enzyme separates the two strands of DNA as it moves outward from the origin of replication? This enzyme moves in which directionality?
  1. Energy for this process comes from what?
  1. Which enzyme alleviates coiling ahead of the replication fork?
  1. What coats the two newly broken DNA strands to prevent them from re-attaching together?
  1. Which enzyme links nucleotides together to form a double stranded DNA (one parent, one daughter strand)?
  1. DNA polymerase can only elongate pre-existing strands of DNA, so what allows polymerase to copy a bare template?
  1. The RNA primers are removed and filled in with DNA by which enzyme?
  1. The (leading,lagging) strand is synthesized continuously while the other is not.
  1. The (leading,lagging) strand is made as small fragments in the direction (toward,away) the replication fork that are eventually connected to each other. These small fragments are given the name ______in name of the person who had discovered them.
  1. Which enzyme attaches these fragments together?
  1. What covalently bonds the parent and daughter strand together?