Polynucleotides Flashcards
(15 cards)
What types of covalent bond is formed via in polynucleotides
Phosphodiester linkages
Describe the backbone of polynucletides
Fairly stable, undergoes hydrolysis (accelerated by enzymes)
What makes RNA backbone of polynucleotides unstable?
- In water, RNA lasts for a few years
-In cells, mRNA is degraded in few hours - Hydrolysis accelerated under alkaline conditions or enzymes (RNase)
Linear polymers in polysaccharides don’t contain
branching or crosslinks
What is the direction of the backbone in polynucleotides?
5’ end is different from 3’end
sequence is read from 5 to 3
Complementary and antiparallel
Two bases can hydrogen bond to form a
base pair
For monomers, a large number of base pairs is______, in polynucleotides only a few possibilities _____
possible, exist
Watson-Crick base pairs predominate in _________ ______, what pairs with what?
double-stranded DNA
A pairs with T
C pairs with G
Purine pairs with pyrimidine
The Watson- Crick structure forms what form of DNA
B- form DNA (B-DNA)
What occurs during DNA denturation?
Covalent Bond and Genetic code remain in tact, but the hydrogen bonds are broken, which causes the two strands to separate.
- Based on stacking is lost, and the UV absorbance increases
What causes denturantion in DNA
High temperatures, change in PH
Denaturation may be reversible and this is called
may be reversible and this is called
annealing
What are other functions of nucleotides?: Nucleoside phosphates
Ribonucleotides may have one or two additional phosphates. Hydrolysis of nucleoside triphosphates provides the chemical energy to drive many cellular reactions
Nucleotides can function as coenzyme, examples are
Vitamin B5(Pantothenic acid), Vitamin B3(Nicotinic axid), Vitamin B2(riboflavin)
Nucleotides can also act as Regulatory molecules, examples are
- Adenosine 3’, 5’-cyclic monophosphate (cyclic-AMP; CAMP)
- Guanosine 5’- diphosphate, 3’ diphosphate(guanosine tetraphosphate) ppGpp
-guanosine 3’,5’-cyclic monophosphate (cyclic GMP; cGMP
