Misc
DNA Polymerase can only move from the ____' to _____' prime.
5' - 3' prime
What was determined to be the substance responsible for transformation in organisms?
DNA
True or False: Maurice Wilkins and James Watson won the Noble Prize for creating the first accurate models of DNA.
False - James Watson, Francis Crick & Maurice Wilkins won the Nobel Peace Prize.
If a strand reads:
3' A A A T T T C 5'
The complimentary strand would read...
5' T T T A A A G 3'
The starting point for DNA is the _________ and it is built by ___________. It is a short sequence of ______ to signal to DNA Polymerase where to bond.
Primer, Primase, RNA
Who was the scientist who mistakenly observed DNA while trying to find a vaccine for pneumonia?
Frederick Griffith
Describe the structure of a nucleotide.
There are three parts to a nucleotide - a phosphate, a 5-carbon sugar called deoxyribose, and a nitrogenous base (thymine, adenine, cytosine, or guanine).
The enzyme that unwinds the DNA to prepare for replication
Helicase
True or False: DNA Polymerase is only found in young organisms, usually before sexual maturity.
False - Telomorase is only found in young organisms
Who was the scientist who worked at the Rockefeller Institute in New York and used the process of elimination to discover DNA was responsible for transformation?
Oswald Avery
Describe the importance of Rosalind Franklin's discovery.
Rosalind Franklin used x-ray diffraction to study the structure of DNA. She determined that it was a double helix structure and that the center of the model were nitrogenous bases.
Describe the two things DNA polymerase does.
1. Adds free nucleotides to the unzipped DNA
2. Proofreads the new stands being built to avoid mutations or errors
In which strand would you expect to see Okazaki fragments?
The lagging strand
How can radioactive tracers be used to track movement of genetic material?
Hershey & Chase injected radioactive tracers in two parts of bacteriophages - in the DNA and in an area of the bacteriophage made of protein. They examined the bacteria after being infected with the virus to see if they could observe the radioactive tracer. The only bacteria that they were able to find the tracer was the bacteria that was infected by the virus where the DNA was injected with the radioactive materials.
Describe the importance of the DNA strands being anti-parallel.
DNA has to be antiparallel. The antiparallel nature allows two strands to go in opposite direction. The antiparallel arrangement of strands allows them to follow Chargaff's rule of base pairing. In this way, nucleotides of one strand are oriented in the center of the molecule, where they bind with their complementary base.
Describe the difference between prokaryotic DNA replication and Eukaryotic DNA replication.
Prokaryotic DNA replication is much simpler and faster as there is only a single, circular strand of DNA. There will only be two replication forks that develop, that will move in opposite directions to unravel the chromosome. In Eukaryotic DNA replication, the chromosomes are much more plentiful and complex, leading to hundreds of replication forks forming in order to complete the entire replication process.
A virus's DNA contains very small amounts of information. What instructions are in viral DNA?
Seek a host cell, implant in the host, and replicate.
Describe how bacteriophages work.
Bacteriophages are viruses that attack and destroy bacteria. In order to reproduce, a bacteriophage must attach to the surface of the bacterial cell and injects its genetic information into it. The viral genes act to hijack the cells functions and produce many new bacteriophages, which gradually destroy the bacterium. When the cell splits open, hundreds of new viruses burst out, all seeking to replicate this process.
There are two main bonds in a full structure of DNA. Describe them both - what do they bond and discuss their purpose and strength.
Hydrogen Bond is a weak bond found in between the nitrogenous bases. This bond is just strong enough to hold the two strands of DNA together but fairly weak enough to be broken easily during replication.
A covalent bond holds the nucleotides together by bonding together a phosphate and a 5-carbon sugar. This is a strong bond that doesn't allow the strand itself to be broken during replication.
Describe the importance of the enzyme, telomerase.
The tips of chromosomes are known as telomeres. The ends of DNA molecules, located at the telomeres, are particularly difficult to copy. Over time, DNA may actually be lost from telomeres each time a chromosome is replicated. An enzyme called telomerase compensates for this problem by adding short, repeated DNA sequences to telomeres, lengthening the chromosomes slightly and making it less likely that important gene sequences will be lost from the telomeres during replication.