DNA Structure
What are the monomers of DNA?
nucleotides
Which base does adenine bond with?
Thymine/T
True or False: Replication is performed prior to cell division.
True: A cell is able to divide after replication
Where in the eukaryotic cell is DNA found?
Nucleus
What initiates DNA replication?
DNA helicase unwinds a section of DNA to create a replication bubble to expose two template strands
What components make up a DNA nucleotide?
Sugar (Deoxyribose), phosphate, and nitrogenous base (A, T ,G ,C)
How many rings does a pyrimidine have ?
One
What are the short fragments of DNA called on the lagging strands?
Okazaki fragments
Why does DNA replication have to occur?
Growth and repair of cells
What enzyme connects the new nucleotides together and proofreads them?
DNA Polymerase
What bond connects the sugar and phosphate groups of the DNA backbone?
phosphodiester bond
Which type of weak bonds hold the base pairs together ?
hydrogen bonds
True or False: DNA replicates 5’ > 3’ on the leading strand and 3’ > 5’ on the lagging strand.
False: DNA replication is always 5' > 3'
Which two scientists finally stated the shape of the DNA molecule?
Watson and Crick
What is the function of topoisomerase?
It prevents the supercoiling of DNA ahead or behind of the DNA replication bubble
Why is DNA antiparallel?
The sugars in the DNA stands have opposite orientations which results in directionality
What is the difference between a purine and a pyrimidine?
Purines have a two ring structure while pyrimidines have one ring
Why does replication not form leading strands on all sides of the replication bubble?
DNA polymerase can only add nucleotides on the 3' end of a DNA strand
What does Chargaff's Rule state?
Adenine bonds with Thymine and Cytosine bonds with Guanine
Why is primase important?
It places an RNA primer that allows DNA polymerase to place new nucleotides to form the complementary strand
What do the 5' and 3' ends of DNA refer to?
They indicate the specific carbon on the deoxyribose sugar that the DNA strand ends or begins with
Why does adenine only bond with thymine and cytosine only bond with guanine?
Each pairing has a mirrored and opposite chemical configuration allowing favorable conditions for them to form hydrogen bonds together
How is DNA polymerase able to initiate its addition of new nucleotides to a complimentary strand?
Primase places a temporary RNA primer to allow for DNA polymerase to place the first DNA nucleotide on the 3' end of the complimentary strand
What did Meselson and Stahl discover?
The DNA replication occurs semi-conservatively
What is the role of single stranded binding proteins?
They help keep single strands separate during DNA replication