Proofreading & Repairing DNA/ Replicating the ends of DNA
100
These scientists came up with the double-helical model of Deoxyribonucleic Acid (DNA). They also proposed that DNA replication follows the semi-conservative model.
Who are Watson & Crick?
100
A polymer of nucleotides, each consisting of a nitrogenous base, a pentose sugar called deoxyribose and a phosphate group.
What is DNA?
100
The type of bond that is found between base pairs in DNA. There are 2 between A&T, and 3 between G&C.
What is a HYDROGEN BOND?
100
A short stretch of DNA with a specific sequence of nucleotides where the process of DNA replication begins. Many of these are found on eukaryotic DNA as compared to prokaryotic DNA which only have one.
What is an ORIGIN OF REPLICATION?
100
A process in which enzymes remove and replace incorrectly paired nucleotides resulting from replication errors.
What is MISMATCH REPAIR?
200
In 1928, he showed that genetic traits can be transferred between different bacterial strains through the process of TRANSFORMATION.
Who is Frederick Griffith?
200
The 4 nitrogenous bases found in DNA.
What are Adenine, Guanine, Cytosine and Thymine?
200
Nitrogenous bases with 2 organic rings in their structure.
What are PURINES?
What are ADENINE & GUANINE?
200
A Y-shaped region where the parental strands of DNA are being unwound.
What is the REPLICATION FORK?
200
A DNA cutting enzyme which cuts out (excises) segments of incorrectly paired nucleotides
What is NUCLEASE?
300
A very accomplished x-ray crystallographer who died at the age of 38 in 1958. This person conducted critical experiments which enabled Watson & Crick to deduce the double-helical structure of DNA.
Who is Rosalind Franklin?
300
A group of viruses that can infect bacteria such as E. coli. Include T2 viruses (composed almost entirely of DNA and proteins)which were used to demonstrate that DNA is the genetic material.
What are bacteriophages or phages?
300
Nitrogenous bases with a single organic ring in their structure.
What are PYRIMIDINES?
What are CYTOSINE & THYMINE?
300
Enzymes that untwist the double helix at the replication forks, separating the 2 parental strands making them available as template strands.
What are HELICASES?
300
The phenomenon in which the lagging strand of eukaryotic DNA cannot be completed at the 5' end once the RNA primer is removed.
What is the "END REPLICATION PROBLEM"?
400
Came up with the rule that can be summarised as: For any given species, A=T, G=C
Who is Erwin Chargaff?
400
A change in phenotype (physical appearance) and genotype (genetic/ hereditary makeup of an individual) due to the assimilation of external DNA by a cell.
What is TRANSFORMATION?
400
The image captured by Rosalind Franklin which allowed James Watson to deduce that DNA had 2 strands in a double-helix formation.
What is an x-ray diffraction photo?
400
Catalyse the synthesis of new DNA by the addition of nucleotides to a pre-existing chain.
What are DNA POLYMERASES?
400
Special nucleotide sequences found at the ends of eukaryotic chromosomal DNA molecules. They do not contain genes but rather are repetitions (100's -1000's) of the 6-nucleotide sequence TTAGGG.
What are TELOMERES?
500
In the late 1950's, these two scientists devised a clever experiment which demonstrated that DNA replication follows a semi-conservative model and NOT the conservative or dispersive models.
Who are Matthew Meselson and Franklin Stahl?
500
The string of alternating phosphates and sugars from which nitrogenous bases project on a DNA strand.
What is a sugar-phosphate backbone?
500
The nitrogenous base which is found in RNA and not in DNA. It base pairs with Adenine.
What is Uracil?
500
Named for its JApanese discoverer, this segment of the lagging strandis joined to other similar segments by the enzyme DNA LIGASE.
What is an OKAZAKI FRAGMENT?
500
A disorder resulting from a hereditary defect in a nucleotide excision repair enzyme.