DNA chemical structure Flashcards
What will you learn about nucleic acids by the end of this session?
Principles that underpin the structure of nucleic acids and forces that contribute to their stability.
What are the four bases in DNA?
- Adenine (A)
- Guanine (G)
- Thymine (T)
- Cytosine (C)
What is the difference between DNA and RNA in terms of nucleobases?
RNA contains Uracil (U) instead of Thymine (T).
What components make up a nucleotide?
- Base
- Sugar
- Phosphate(s)
Define nucleoside.
A nucleoside consists of a base and a sugar.
What is the nomenclature for 5’-mononucleotides?
- Deoxyadenosine 5’-monophosphate (5’-dAMP)
- Deoxyguanosine 5’-monophosphate (5’-dGMP)
- Deoxythymidine 5’-monophosphate (5’-dTMP)
- Deoxycytidine 5’-monophosphate (5’-dCMP)
- Uridine 5’-monophosphate (5’-UMP)
What is the sugar pucker in DNA?
2’-deoxyribose.
What characterizes the B-form helix of DNA?
Right-handed helix with planes of bases nearly perpendicular to the helix axis.
What is the helical twist in B-DNA?
Average of 36º (10.4 bases per helix turn).
What is the helical pitch of B-DNA?
35.4 Å (/turn).
What are the major and minor grooves in B-form double helix?
- Major groove: Wide and deep
- Minor groove: Narrow and deep
What distinguishes A-DNA from B-DNA?
A-DNA has tilted planes of bases and a different sugar pucker conformation.
What is a Z-form double helix?
Left-handed helix with alternating purines and pyrimidines at high salt.
What is Hoogsteen pairing?
A triad structure found in triplex DNA.
What is a G-quadruplex?
A tetrad or quartet structure found in many gene regulatory regions.
What interactions stabilize DNA?
- Hydrophobic interactions
- Stacking interactions
- Hydrogen bonding
What causes destabilization in DNA?
Electrostatic interactions due to negative phosphates.
What is the melting temperature (Tm) of DNA?
The temperature at which the DNA sample is denatured.
What factors affect the melting temperature (Tm) of DNA?
- GC content
- Presence of intercalating agents
- Salt concentration
- pH
- Length
How many pairs of chromosomes do humans have?
23 chromosome pairs (46 chromosomes total).
What are zoonotic RNA viruses known for?
Rapid mutation rates, short generation times, and large population sizes.
Fill in the blank: The nucleic acid biopolymer can be synthesized either chemically, a combination of chemical and biological starting materials, or completely _______ by living organisms.
[biosynthesized]
