Structure of Nucleic Acids Flashcards
Are DNA and RNA referred to as being acidic, basic or neutral molecules and why?
Acidic, due to the high amount of negatively charged phosphate groups.
At physiological pH is DNA/RNA positively or negatively charged?
Negatively due to the phosphate molecules.
Each nucleotide has an alkaline component. What is it?
The nitrogenous base.
What is the difference between uracil and thymine?
Thymine is in DNA, while uracil is in RNA and has a H atom where thymine has a CH3 group.
What is the difference between nucleosides and nucleotides?
Nucleotides have a phosphate group at the at the 5’ carbon.
Which side of DNA is hydrophilic and which is hydrophobic?
Base side is hydrophobic, backbone side is hydrophilic.
Explain the difference between the primary, secondary, tertiary and quaternary structures of DNA.
Primary: linear sequence of nucleotides linked through phosphodiester bonds.
Secondary: complementary base pairing through hydrogen bonds.
Tertiary: Double helix structure
Quaternary: interaction of DNA with other molecules.
What are three other functions of nucleotides?
Energy currency
Coenzymes (e.g. coenzyme A)
Signalling molecules.
What is Hoechst dye used for?
Binds to the minor groove in DNA, becomes rigid and becomes fluorescent.
What is the significance on an azido group?
Replaces OH group of the 3C with an N3 group, preventing polymerisation of nucleotides so the reverse transcriptase cannot make DNA from RNA. Form of HIV treatment. Can be toxic if prevents normal DNA synthesis.
Why is RNA transient?
Want to be able to get rid of it once it completes its function.
What is the size of tRNA?
70-90 bases
What is the size of mRNA?
