Module 5
The carbon atoms of the five-carbon sugar are numbered
1', 2', 3', 4', and 5'
DNA nucleotides that are part of a polynucleotide chain have one phosphate residue_ attached to the hydroxyl group of the ___ carbon of one sugar of one nucleotide and the hydroxyl group of the 3' carbon of the sugar of the next nucleotide, thereby forming a 5'-3' phosphodiester bond.
5'
Individual nucleotides are assembled into a polynucleotide chain by the enzyme DNA polymerase, which catalyzes the formation of a phosphodiester bond between the 3' hydroxyl group of one nucleotide and the
5' phosphate group of an adjacent nucleotide.
DNA nucleotides that are part of a polynucleotide chain have one phosphate residue attached to the hydroxyl group of the 5' carbon of one sugar of one nucleotide and the hydroxyl group of the 3' carbon of the sugar of the next nucleotide, thereby forming a ______ phosphodiester bond.
5'-3'
Watson and Crick also knew of ________ _____, which were a set of observations about the relative amount of each nucleotide that was present in almost any extract of DNA.
Chargaff's Rules
Individual nucleotides are assembled into a polynucleotide chain by the enzyme
DNA polymerase
Each polynucleotide chain has a sugar-phosphate backbone consisting of
alternating sugar and phosphate groups throughout its length
The two strands are _________ in orientation; that is, the 3' end of one strand faces the 5' end of the other strand.
antiparallel
In a reaction catalyzed by DNA polymerase, and using ________ on the template strand, the activated 3' OH of the deoxyguanosine in the growing strand attacks the triphosphate group of the incoming dGTP.
cytosine
In a reaction catalyzed by DNA polymerase, and using cytosine on the template strand , the activated 3' OH of the __________ in the growing strand attacks the triphosphate group of the incoming dGTP.
deoxyguanosine
dNMPs
deoxynucleoside monophosphates
Collectively, dATP, dGTP, dCTP, and dTTP are the
deoxynucleotide triphosphates (dNTPs)
The purines have a double ring structure with a six-membered ring fused to a
five-membered ring
A ________ ____ is formed when a weakly positive hydrogen atom already bonded to one electronegative atom (for example, the oxygen in the water molecule) is attracted to another electronegative atom from another molecule.
hydrogen bond
Base-pair stacking creates two grooves in the double helix, uniformly spaced gaps between the spiraling sugar-phosphate backbone that partially expose the nucleotides. These are known as the
major groove and minor groove
DNA nucleotides that are part of a polynucleotide chain have one phosphate residue attached to the hydroxyl group of the 5' carbon of one sugar of one nucleotide and the hydroxyl group of the 3' carbon of the sugar of the next __________, thereby forming a 5'-3' phosphodiester bond.
nucleotide
Two of the three phosphates of a deoxynucleotide triphosphate (dNTP) are removed (as a pyrophosphate group) during phosphodiester bond formation, leaving the
nucleotides of a polynucleotide chain in their monophosphate form
In other words, hydrogen bonds always include a hydrogen atom in a covalent linkage with a more electronegative atom such as
oxygen and nitrogen
DNA nucleotides that are part of a polynucleotide chain have one ______ _______ attached to the hydroxyl group of the 5' carbon of one sugar of one nucleotide and the hydroxyl group of the 3' carbon of the sugar of the next nucleotide, thereby forming a 5'-3' phosphodiester bond.
phosphate residue
DNA nucleotides that are part of a polynucleotide chain have one phosphate residue attached to the hydroxyl group of the 5' carbon of one sugar of one nucleotide and the hydroxyl group of the 3' carbon of the sugar of the next nucleotide, thereby forming a 5'-3' _______________ bond.
phosphodiester
The nucleotides combine with each other by covalent bonds known as
phosphodiester bonds or linkages
Base pairing takes place between a
purine and pyrimidine
Watson and Crick proposed that DNA is made up of two strands that are twisted around each other to form a
right-handed helix.
Pyrimidines are smaller in size; they have a single
six-membered ring structure.
free reactive DNA nucleotides that are not part of a polynucleotide chain carry a string of ______ ________ __ ____ _____ ____ and are identified as dATP, dGTP, dCTP, and dTTP.
three phosphate groups at the 5' carbon
In a reaction catalyzed by DNA polymerase, and using cytosine on the template strand , the activated 3' OH of the deoxyguanosine in the growing strand attacks the
triphosphate group of the incoming dGTP
