Lesson 2 - DNA and RNA Flashcards
- informational molecules of all living organisms
- long, chain-like polymers assembeld from repeating subunits, nucleotides
nucleic acids
Two types of nucleic acids
- Deoxyribonucleic Acid (DNA)
- Ribonucleic Acid (RNA)
a unit of only the base and sugar without phosphates
nucleoside
nucleosides of DNA
- deoxyadenosine
- deoxyguanosine
- deoxycytidine
- deoxythymidine
nucleosides of RNA
- adenosine
- guanosine
- cytidine
- uridine
Three components of nucleotides
- nitrogenous base
- five-carbon sugar
- phosphate group
two types of nitrogenous bases
- purine
- pyrimidine
six membered ring made up of carbon and nitrogen atoms
pyrimidines
uracil
2,4-dioxypyrimidine
thymine
- 2,4-dioxy-5-methylpyrimidine or
- 5-methyluracil
cytosine
2-oxy-4-aminopyrimidine
six-membered ring fused to a five-memberd ring
purines
adenine
6-aminopurine
guanine
2-amino-6-oxypurine
- reversible change of one DNA base isomer to another
- shift in the location of H atoms and double bonds
tautomeric shift in DNA bases
2 forms of the same molecule differing only in the location of a proton and a double bond
tautomers
in DNA bases, what are the usual forms
- amino (NH2)
- keto (C=O)
in DNA bases, what are the rare forms
- imino (NH)
- enol (C-OH)
links covalently to nitrogenous bases
five-carbon sugar (pentose)
a chain of 1,2, or 3 phosphates linked to the pentose sugar at its 5’ carbon
phosphate group
where is the phosphate group linked to
5’ carbon
bonds between base pairs in the interior of the molecule
numerous hydrogen bonds
- β-N-glycosidic bond (sugar to base)
- phosphodiester bond (nt to nt)
covalent bonds
sugar to base bond
β-N-glycosidic bond
phosphate to sugar base bond
phosphodiester bond
Primary Structure of DNA
- linear sequence of nucleotides
- sugar-phosphate backbone on the outside
Secondary Structure of DNA
- two intertwined antiparellel strands
- major and minor grooves
- right-handed helix
- constant diameter of 20 Å
- base pases are perpendicular to axis
- hydrophobic associations form stable non-polar environment
essential for binding of proteins
major and minor grooves
length between bases
0.34 nm
One complete turn of the double helix
- 3.4 nm long
- 10 base pairs
what is formed between the hydrophobic associations of base pairs
stable non-polar environment
Different DNA conformations
- A DNA
- B DNA
- C DNA
- D DNA
- Z DNA
Why are there different DNA conformations
adapt to stress