5 Written Questions

1. DNA can be broken by various chemicals and types of radiation. For example UV causes thymine dimers to form causing a kink in the DNA strand. Nucleotide excision repair system recognizes the damage. its enzymes repairs it.
2. Regions at the end of linear chromosomes. There is no way to replace the RNA primer from the lagging strand with DNA. The primer is removed leaving a section of a single stranded DNA (lagging strand) at one end of each new chromosome.
3. DNA replication is very accurate with an average rate error of less than one mistake per billion. DNA polymerase is highly selective in matching complentary bases correctly. Only inserts base once in about 100,000 bases. If mistakes remain, repair enzymes can remove the defective bases and repair them.
4. DNA polymerase requires a primer (consists of a few nucleotides bonded to the template strand.) The Primase synthesizes a short RNA segment that serves as a primer for DNA synthesis.
5. 1 Many proteins responsible for opening and stabilizing double helix. Enzyme helicase catalyzes the breaking of hydrogen bonds between two DNA strands to separate them. Then a single strand of DNA binding proteins attach to the separated strands to prevent from closing
   2 Unwinding the DNA helix creates tension farther down the helix. Enzyme Topoisomerase (cuts and rejoins)

5 Matching Questions

1. Discontinuous replication hypothesis
2. Replication bubble
3. Leading strand
4. Dispersive replication
5. DNA Polymerase

1. a forms in chromosome that is actively being replicated. There are forks at the ends of the bubble.
2. b Once a primase synthesizes an RNA primer on the lagging strand, DNA polymerase might synthesize short fragments of DNA along the lagging strand and these fragments would later be linked together to form a continuous whole. This was tested by Okazaki.
3. c An enzyme that catalyzes the elongation of new DNA at a replication fork by the addition of nucleotides to the existing chain. It's exorgonic because monomers act as subtrates.
   1 Chrosmosome being replicated
   2 bacterial chromosomes have a sine orgin of replication
   3 eukaryotic chromosmes have multiple origins of replication
4. d parent molecules is cut into sections such as the daughter molecules contain old DNA interspected with newly synthesized DNA.
5. e Enzyme's product. Its called this because it deads to replication fork and is syntheiszed continuously in the 5' to 3 ' direction.

5 Multiple Choice Questions

1. Enzymes that add more repeating bases to the end of the lagging strand. (stem cells have telomerase. Most dont have this)
   1. Telomeres
   2. Topoisomerase
   3. Primase
   4. Telomerase
2. removes RNA primer at the begining of each okazaki fragment and fills gaps. The enzyme DNA ligase then joins the Okazaki frapments to form a continuous DNA strand.
   1. DNA Polymerase
   2. DNA ligase
   3. DNA Polymerase I
   4. Topoisomerase
3. Cuts and rejoints DNA downstream of the replication fork to relieve tension.
   1. DNA Polymerase
   2. Telomerase
   3. Primase
   4. Topoisomerase
4. Prevent from closing
   1. SSBPs
   2. Telomeres
   3. Primase
   4. DNA ligase
5. After watson and crick suggested that the existing strands of DNA served as a template biologists proposed 3 alternatives.
   1 Semiconservate replication
   2 conservative replication
   3 dispersive replication
   1. Dispersive replication
   2. How is the leading strand synthesized
   3. Semi-conservative replication
   4. 3 hypothesis of how new DNA strands interacted during replication...

5 True/False Questions

1. Xeroderma Pigmentosum (XP) → rare autosmal recessive disease in humans characterized by the developemtn of skin lesions.
   XP is caused by mutations of one of several nucleotide excision repair systems. These mutations mean that the cells of people with XP cannot repair DNA damaged by ultraviolet radiation.

   True        False

2. Hershey-Chase Experiment → Studied whether genes were made of proteins or DNA. They studied how a T2 virus infects the bacterium e coli. T2 inject its genes into cell. These genes direct production of new virus particles. did this in the presence of 32P and 35S
   Hypothesis: if genes consist of DNA then radiactive DNA found inside the cells while proteins outside of cells. RAdioactive DNA was found in the pellet.

   True        False

3. Enzyme helicase → Enzyme that joins okazaki fragments to form a continous DNA strand

   True        False

4. Conservative Replication → parental molecules serves as a template for sythesis of and entirely different molecule

   True        False

5. Primase → Enzyme that joins okazaki fragments to form a continous DNA strand

   True        False