BIOCHEM Flashcards
(28 cards)
are the chemical basis of heredity.
Nucleic Acids
_______ is organized into genes, the fundamental unit of genetic information.
DNA
directs the synthesis of RNA.
DNA
directs and regulates protein synthesis
RNA
DNA contains four distinct deoxynucleotides, what are these?
- Deoxyadenylate (A)
- Deoxyguanylate (G)
- Deoxycytidylate (C)
- Deoxythymidylate (T)
These monomeric units of DNA are held in polymeric form
by____________________ constituting a single strand.
3′,5′-phosphodiester bonds
The polymer possesses a polarity: one end has a 5′-
_________ or ________________ while the other has a 3′-
________________ or ___________________
hydroxyl, phosphate terminus, phosphate, hydroxyl terminus.
The two strands of this double-stranded helix are held in
register by both ______________ between the purine and pyrimidine bases of the respective linear molecules and by_______________ and ________________ between the stacked adjacent base pairs.
hydrogen bonds (H-bonds), van der Waals, hydrophobic interactions
This common form of DNA is said to be _______________
because as one looks down the double helix, the base
residues form a spiral in a clockwise direction.
right-handed
A-T and G-C base pairs are often referred to as ____________________
Watson- Crick base pairs.
The two strands of the double-helical molecule, each of
which possesses a polarity, are _________________; that is, one
strand runs in the 5′ to 3′ direction and the other in the 3′
to 5′ direction.
antiparallel
This is the strand of DNA that is copied, or
transcribed, during ribonucleic acid (RNA)
synthesis.
Template Strand
the template strand is also referred to as _____________
non coding strand
A single turn of B-form DNA about the long axis of the
molecule contains _______
The distance spanned by one turn of B-DNA is__________________
10 bp, 3.4 nm (34 Å).
______________ hold the deoxyguanosine
nucleotide to the deoxycytidine nucleotide.
By contrast, the other canonical base pair, the A- T pair, is held together by _______________
Three H-bonds, two H-bonds.
The midpoint of the measured DNA denaturation
is called the __________________, or _____.
melting temperature, Tm
is often referred to as renaturation or hybridization.
Reannealing
are formed
when the molecule is twisted in
the direction opposite from the
clockwise turns of the right-
handed double helix found in B-
DNA.
Negative Supercoils
Enzymes that catalyze topologic changes of DNA are
called ____________________
topoisomerases.
can relax or insert supercoils,
using ATP as an energy source.
topoisomerases.
In RNA, the sugar moiety to which the phosphates and purine and pyrimidine bases are
attached is _____________ rather than the 2′-deoxyribose
of DNA.
ribose
This class is the most heterogeneous in
abundance, size, and stability;
Messenger RNA
serve as adapters
for the translation of the information in
the sequence of nucleotides of the
mRNA into specific amino acids.
The tRNA molecules
DNA rich in _________ melts at a higher temperature than
DNA rich in________, due to differences in hydrogen bond
content and base stacking.
G-C pairs, A-T pairs
