BIOCHEM 2288 EXAM QUESTIONS WITH ACCURATE
ANSWERS RATED A+
DNA - ANSWER carries genetic material, made up of deoxyribose sugar, a nitrogenous
base, and a triphosphate group
mRNA - ANSWER template for producing proteins
rRNA - ANSWER make up much of ribosome, act as template for proteins, catalyze
protein synthesis
tRNA - ANSWER carries amino acids to ribosome, cloverleaf appearance, ~80 bases,
including unconventional bases
ribonucleotides - ANSWER building blocks of RNA, composed of beta-ribose sugar, a
nitrogenous base connected by a glycosidic bond, and a phosphate
phosphate groups - ANSWER negatively charged at cellular pH
nucleoside - ANSWER "RNA" without the monophosphate group
purines - ANSWER adenine/adenosine A, gaunine/guanosine G, join to C1` via N9
pyrimidines - ANSWER cytosine/cytidine C, thymine/thymidine T, uracil/uridine U, join to
C1` via N1
thymine - ANSWER DNA ONLY
,uracil - ANSWER RNA ONLY
polynucleotides - ANSWER sugars joined together via phosphodiester linkage (C3`-C5`)
that are not attached to other monosaccharides
convention - ANSWER written in 5>5 direction, GATC G would have hydroxyl/phosphate
on its 5` carbon and C would have a hydroxyl/phosphate on its 3` carbon
4^n - ANSWER 4 bases to the power of the number of nucleotides in a sequence
DNA double helix constraints - ANSWER chargaff's rule, diffraction pattern, correct
tautomeric forms of bases
Chargaff's Rule - ANSWER [A]=[T] and [G]=[C], they pair up across from one another
forming two strands also called base pairing.
Diffraction pattern - ANSWER suggested double-helix with periodicity of 3.4nm, 10
repeating units
correct tautomeric forms of bases - ANSWER different tautomers have different
hydrogen bonding capabilities
DH B DNA - ANSWER is antiparallel (opposite orientation or chemical polarity),
phosphate are on outside, bases are in center (to minimize repulsion & allow salt
stabilization) and is right-handed (clockwise)
forces stabilizing double helix - ANSWER hydrophobic interactions, base-pairing
hydrophobic interactions - ANSWER planar bases stack (perpendicular to axis), with
van der waals forces, water is excluded and is not sequence-specific
, base-pairing - ANSWER hydrogen bonds between bases, water cannot interfere, is
sequence-specific
watson-crick base-pairing - ANSWER AT contain 2 H bonds, while GC contain 3, the
backbones are always the same distance apart
features of DH B DNA - ANSWER 2nm thick, distance b/w or "rise": 0.34nm, major and
minor grooves because bases are not symmetrically oriented relative to backbone,
longer than RNA, DS, nitrogenous bases are less likely to be modified in DNA, structure
is sequence INDEPENDENT
RNA structure - ANSWER hair-pin, step-loop, cloverlead (tRNA), helices, unpredictable,
sequence DEPENDENT
human genome - ANSWER 3X10^9 bp in length, X2 copies each chromosome per cell,
condensed 10,000-fold to fit inside nucleus
chromatin - ANSWER complex of protein/DNA that is highly organized, must remain
available, with help of special proteins
histones - ANSWER eukaryotic proteins involved in condensing DNA, contain <200 aa,
rich in lysine and guanine with types H1, H2A, H2B, H3, H4
conservative change - ANSWER different aa in a chain yet has a highly similar property
or function
octamers - ANSWER 8 proteins, contain 2 copies of each histone, and DNA DH wraps
around the histone octamer with 146 bp, resembling a spool of thread
nucleosomes - ANSWER the histone core particle + the linker, resembles a string of
beads, 200 bp (146+50 linker)
ANSWERS RATED A+
DNA - ANSWER carries genetic material, made up of deoxyribose sugar, a nitrogenous
base, and a triphosphate group
mRNA - ANSWER template for producing proteins
rRNA - ANSWER make up much of ribosome, act as template for proteins, catalyze
protein synthesis
tRNA - ANSWER carries amino acids to ribosome, cloverleaf appearance, ~80 bases,
including unconventional bases
ribonucleotides - ANSWER building blocks of RNA, composed of beta-ribose sugar, a
nitrogenous base connected by a glycosidic bond, and a phosphate
phosphate groups - ANSWER negatively charged at cellular pH
nucleoside - ANSWER "RNA" without the monophosphate group
purines - ANSWER adenine/adenosine A, gaunine/guanosine G, join to C1` via N9
pyrimidines - ANSWER cytosine/cytidine C, thymine/thymidine T, uracil/uridine U, join to
C1` via N1
thymine - ANSWER DNA ONLY
,uracil - ANSWER RNA ONLY
polynucleotides - ANSWER sugars joined together via phosphodiester linkage (C3`-C5`)
that are not attached to other monosaccharides
convention - ANSWER written in 5>5 direction, GATC G would have hydroxyl/phosphate
on its 5` carbon and C would have a hydroxyl/phosphate on its 3` carbon
4^n - ANSWER 4 bases to the power of the number of nucleotides in a sequence
DNA double helix constraints - ANSWER chargaff's rule, diffraction pattern, correct
tautomeric forms of bases
Chargaff's Rule - ANSWER [A]=[T] and [G]=[C], they pair up across from one another
forming two strands also called base pairing.
Diffraction pattern - ANSWER suggested double-helix with periodicity of 3.4nm, 10
repeating units
correct tautomeric forms of bases - ANSWER different tautomers have different
hydrogen bonding capabilities
DH B DNA - ANSWER is antiparallel (opposite orientation or chemical polarity),
phosphate are on outside, bases are in center (to minimize repulsion & allow salt
stabilization) and is right-handed (clockwise)
forces stabilizing double helix - ANSWER hydrophobic interactions, base-pairing
hydrophobic interactions - ANSWER planar bases stack (perpendicular to axis), with
van der waals forces, water is excluded and is not sequence-specific
, base-pairing - ANSWER hydrogen bonds between bases, water cannot interfere, is
sequence-specific
watson-crick base-pairing - ANSWER AT contain 2 H bonds, while GC contain 3, the
backbones are always the same distance apart
features of DH B DNA - ANSWER 2nm thick, distance b/w or "rise": 0.34nm, major and
minor grooves because bases are not symmetrically oriented relative to backbone,
longer than RNA, DS, nitrogenous bases are less likely to be modified in DNA, structure
is sequence INDEPENDENT
RNA structure - ANSWER hair-pin, step-loop, cloverlead (tRNA), helices, unpredictable,
sequence DEPENDENT
human genome - ANSWER 3X10^9 bp in length, X2 copies each chromosome per cell,
condensed 10,000-fold to fit inside nucleus
chromatin - ANSWER complex of protein/DNA that is highly organized, must remain
available, with help of special proteins
histones - ANSWER eukaryotic proteins involved in condensing DNA, contain <200 aa,
rich in lysine and guanine with types H1, H2A, H2B, H3, H4
conservative change - ANSWER different aa in a chain yet has a highly similar property
or function
octamers - ANSWER 8 proteins, contain 2 copies of each histone, and DNA DH wraps
around the histone octamer with 146 bp, resembling a spool of thread
nucleosomes - ANSWER the histone core particle + the linker, resembles a string of
beads, 200 bp (146+50 linker)
