Flashcards in Lecture 1 - Nucleotides and DNA Deck (79)
What are the 3 parts of a nucleotide?
1. Purine or pyrimidine base
2. Pentose sugar
3. Phosphate group
What forms the backbone of DNA?
Phosphoester linkages between phosphate groups and sugars
Order of DNA?
5' => 3'
How to differentiate between purines and pyrimidines?
Longer name = smaller structure
2. Thymine (DNA)
3. Uracil (RNA)
On what part of nucleotides do mutations happen most often on?
What is a nucleoside?
Base + sugar
What is a nucleotide?
Base + sugar + phosphate
What are deoxyribonucleotides?
Nucleotides with β-2′-deoxy-D-ribofuranose (without a 2' (-OH) group)
What are deoxyribonucleotides used for?
What are ribonucleotides used for?
Order of DNA synthesis?
5' => 3'
How many H bonds between A and T?
How many H bonds between C and G?
Why is the antiparallel structure of DNA more thermodynamically favorable/stable?
Because it orients the H bonds in a linear manner, in which they are the strongest
How was the DNA structure discovered?
By X-ray showing the diffraction pattern of DNA: spots forming a cross in the center denote a helical structure and heavy bands at the left and right arise from the recurring bases
Periodicity of the helical structure? What does it represent?
34 angstroms (36 in solution) = periodicity of the stacking of the bases
Which noncovalent bond is the strongest in the presence of water?
Van der Waals
If the H bonds contribute so significantly to the stability of DNA, then what must be true about the interior of the helix?
Water is excluded
What does the 5' end of DNA/RNA lack?
A nucleotide at the 5′ position
What does the 3' end of DNA/RNA lack?
A nucleotide at the 3′ position
Is the backbone of DNA/RNA polar?
What is the sugar of RNA? How does it exist in solution?
β-D-ribofuranose: the straight-chain (aldehyde) and ring (β-furanose) forms of free ribose are in equilibrium (99% ring form)
What happens to DNA when put in solution?
B to A form
What is semi-conservation replication of DNA?
The preexisting or "parent" strands become separated, and each is the template for biosynthesis of a complementary "daughter" strand
What are the 3 forms of DNA? Most common one? Least common one?
2. B (most common)
3. Z (least common)
Helical sense of A form DNA?
Helical sense of B form DNA?