2.06 Nucleic Acids Flashcards
Polydeoxyribonucleotide
DNA
DNA is deoxygenated at ___
C-2
Sugar + nitrogen base
Nucleoside
Phosphodiester bond is formed between ____
carbon and oxygen
In nucleoside, nitrogen bases bound to _____ of the sugar
C-1
Bonds containing the -COOC group
Ester bond
Bonds between complementary nitrogen bases
Hydrogen bonding
Cytosine-Guanine has __ H-bonds
3
Adenine-Thymine has __ H-bonds
2
Chargaff’s rule
Determine the percentage of cytosine molecules in a double-stranded DNA given that 32% are adenosine molecules.
18% A=T=32% 100% - (A+T) = 100 - (32% + 32%) = 36% = C+G C+G = 36% Since C=G; then C = 36%/2 = 18%
Polymer of deoxyribonucleoside monophosphates covalently linked by 3’->5’-phosphodiester bonds
DNA
By convention, the bases located along the resulting deoxyribose-phosphate backbone are written in sequence from __ end of the chain to the __ end.
5’; 3’
The end with the free phosphate
5’-end
The end with the free hydroxyl
3’-end
The chains are paired in an _____ manner, 5’-end of one strand is paired with the 3’-end of the other strand
antiparallel
The spatial relationship between the two strands in the helix creates _____ that provide access for the binding of regulatory proteins to their specific recognition sequences along the DNA chain
Major and minor grooves
Disruption of the H-bonds can occur in the laboratory by these treatments
Chemicals
Heat
Decrease in salt concentration
(change in pH of the DNA solution - Lipincotts)
When DNA is heated, the temperature at which one half of the helical structure is lost is defined as the _____
Melting temperature
Loss of helical structure in DNA
Denaturation
Complementary DNA strands can reform the double helix by the process called ______
Renaturation
True/False
In denaturation, phosphodiester bonds are broken by the treatment.
False
H-bonds are broken during denaturation.
True/False
DNA that contains high concentrations of A and T denatures at a lower temperature than G- and C-rich DNA.
True
Because there are three H-bonds between G and C and only two between A and T
3 major structural forms of DNA
B, A, Z form
Right-handed helix with 10 residues per 360deg turn of the helix, and with the planes of the bases are perpendicular to the helical acis
B form
Produced by moderately dehydrating the B form
A right-handed helix with 11 base pairs per turn and the planes of the base pairs are tilted 20deg away from the perpendicular to the helical axis
A form
Left-handed helix that contains 12 base pairs per turn
Deoxyribose-phosphate backbone zigzags
Z form
Structural form of the double helix described by Watson and Crick in 1953
B form
3 major types of RNA that participate in the process of protein synthesis
rRNA, tRNA, mRNA
Found in association with several proteins as components of the ribosomes
rRNA
Smallest of the three major types of RNA molecules
tRNA
The most heterogeneous type of NRA in size and base seqence
mRNA
Polyhydroxyribonucleotide
RNA
Associated with ribosomes
rRNA
70s is present only in _____ while 80s is present only in _____
Prokaryotes
Eukaryotes
Adapter molecule
tRNA
Cloverleaf shape
Each species holds a single amino acid
tRNA
Extensive intrachain base pairing
Contains unusual bases
tRNA
Template in translation
mRNA
Usually found in eukaryotes
sRNA
small RNA
Different subtypes of sRNA
small nuclear RNA (snRNA) micro RNA (miRNA) small interfering RNA (siRNA)
RNA processing
Involved in gene regulation
snRNA
mRNA regulation
Regulates speed of creation of new RNA
Inhibition of gene expression
siRNA
Inhibition of gene expression
miRNA
Introduced when the DNA double helix is twisted
Supercoil
The greater the number of supercoils, the _____ the stress or torsion
Greater
Stabilization of double helix is via
Hydrophobic interaction between stacked nitrogenous bases
Van der waals forces
H-bonds between the nitrogenous base complementary pairing
Composed of a nitrogenous base, a pentose monosaccharide, and one, two or three phosphate gouprs
Nucleotide
Purine bases
Adenine
Guanine
(Para matandaan: PuGA)
Pyrimidine bases
Thymine
Cytosine
Uracil
