MCAT HIGH YIELD QUESTIONS WITH
ANSWERS.
carbohydrates are organized by: - Answers-their number of carbon atoms and functional
groups
triose - Answers-3-carbon carbohydrate
tetraose - Answers-4-carbon carbohydrate
aldose - Answers-sugar with aldehyde as their most oxidized group (terminal carbonyl
group)
ketose - Answers-sugar with ketones as their most oxidized functional group (internal
carbonyl group)
D-sugars - Answers-sugars with the highest-numbered chiral carbon with the -OH group
on the right (in a fischer projection)
L-sugars - Answers-sugars with the highest-numbered chiral carbon with the -OH group
on the left (in a fischer projection)
D- and L-forms of the same sugar are: - Answers-enantiomers
diastereomers - Answers-isomers that differ at at least one—but not all—chiral carbons.
non-mirror image stereoisomers. have different chemical and physical properties. type
of configurational isomer
epimer - Answers-isomers that differ at exactly one chiral carbon
anomers - Answers-isomers that differ at the anomeric carbon. a subtype of epimers
cyclization describes the ring formation of carbohydrates from their: - Answers-straight-
chain forms
when a cyclic sugar forms, the anomeric carbon can take on which two conformations?
- Answers-α- or β-conformation
anomeric carbon - Answers-the new chiral center formed in ring closure; it was the
carbon containing the carbonyl in the straight-chain form
α-anomer - Answers-have the -OH on the anomeric carbon trans to the free -CH₂OH
group. points down
,β-anomer - Answers-have the -OH group on the anomeric carbon cis to the free -
CH₂OH group. points up
what happens during mutarotation? - Answers-one anomeric carbon form shifts to
another, with the straight-chain form as an intermediate
D-fructose - Answers-
D-glucose - Answers-
D-galactose - Answers-
D-mannose - Answers-
monosaccharides are single carbohydrate units that can undergo 3 main reactions: -
Answers-1) oxidation-reduction
2) esterification
3) glycoside formation
glycoside formation - Answers-the basis for building complex carbohydrates and
requires the anomeric carbon to link to another sugar
deoxy sugars - Answers-sugars with a -H replacing an -OH
common disaccharides - Answers-include sucrose, lactose, and maltose
what makes up sucrose? - Answers-glucose-α-1,2-fructose
what makes up lactose? - Answers-galactose-β-1,4-glucose
what makes up maltose? - Answers-glucose-α-1,4-glucose
cellulose - Answers-a polysaccharide. the main structural component of plant cell walls;
main source of fiber in the human diet
starches (amylose and amylopectin) - Answers-a polysaccharide. main energy storage
forms for plants
glycogen - Answers-a polysaccharide. the main energy storage form for animals
nucleoside - Answers-contain a 5-carbon sugar bonded to a nitrogenous base
nucleotide - Answers-nucleosides with one to three phosphate groups added
5 different nucleotides - Answers-adenine (A), cytosine (C), guanine (G), thymine (T),
and uracil (U)
,watson-crick model - Answers--the DNA backbone is composed of alternating sugar
and phosphate groups, and is always read 5' to 3'
-there are two strands with antiparallel polarity, wound into a double helix
-purines always pair with pyrimidines. A pairs with T via two hydrogen bonds (in DNA).
A pairs with U via two hydrogen bonds (in RNA) C pairs with G via three hydrogen
bonds
-follows chargaff's rules
purines - Answers-composed of two fused rings. held together by two hydrogen bonds.
include A and G
pyrimidines - Answers-composed of one ring. held together by three hydrogen bonds.
include T, C, and U
chargaff's rules - Answers-purines and pyrimidines are equal in number in a DNA
molecule. the amount of A=the amount of T, and the amount of C=the amount of G
DNA strands can be denatured, meaning: - Answers-they can be pulled apart
DNA strands can be reannealed, meaning: - Answers-they can be brought back
together
number of chromosomes in human cells - Answers-46 chromosomes
DNA is wound around: - Answers-histone proteins
different types of histone proteins - Answers-H1, H2A, H2B, H3, H4
nucleosome - Answers-made of of H2A, H2B, H3, and H4 histone proteins
H1 - Answers-histone protein that helps to stabilize nucleosome
heterochromatin - Answers-dense, transcriptionally silent DNA
euchromatin - Answers-less dense, transcriptionally active DNA
telomeres - Answers-the ends of chromosomes. they contain high GC-content to
prevent DNA unraveling
centromeres - Answers-hold sister chromatids together until they are separated during
anaphase in mitosis. they contain high GC-content
number of origins of replication for prokaryotic cells and eukaryotic cells: - Answers-
prokaryotes: one per chromosome
eukaryotes: multiple per chromsome
, unwinding of DNA double helix by what enzyme in prokaryotic cells and eukaryotic
cells? - Answers-prokaryotes: helicase
eukaryotes: helicase
stabilization of unwound template strands done by what in prokaryotic cells and
eukaryotic cells: - Answers-prokaryotes: single-stranded DNA-binding protein
eukaryotes: single-stranded DNA-binding protein
synthesis of RNA primers done by what enzyme in prokaryotic cells and eukaryotic
cells? - Answers-prokaryotes: primase
eukaryotes: primase
synthesis of DNA by what enzyme in prokaryotic cells and eukaryotic cells? - Answers-
prokaryotes: DNA polymerase III
eukaryotes: DNA polymerase α, δ, ε
removal of RNA primers by what enzyme in prokaryotic cells and eukaryotic cells? -
Answers-prokaryotes: DNA polymerase I (5'→3' exonuclease)
eukaryotes: RNase H (5'→3' exonuclease)
replacement of RNA with DNA by what enzyme in prokaryotic cells and eukaryotic
cells? - Answers-prokaryotes: DNA polymerase I
eukaryotes: DNA polymerase δ
joining of okazaki fragments done by what enzyme in prokaryotic cells and eukaryotic
cells? - Answers-prokaryotes: DNA ligase
eukaryotes: DNA ligase
removal of positive supercoils ahead of advancing replication forks done by what
enzyme in prokaryotic cells and eukaryotic cells? - Answers-prokaryotes: DNA
topoisomerases (DNA gyrase)
eukaryotes: DNA topoisomerases
synthesis of telomeres done by what enzyme in prokaryotic cells and eukaryotic cells? -
Answers-prokaryotes: n/a
eukaryotes: telomerase
DNA replication method is: - Answers-semiconservative
semiconservative replication - Answers-how DNA replicates. one old parent strand and
one new daughter strand is incorporated into each of the two new DNA molecules
DNA polymerase - Answers-synthesizes new DNA strands. reads the template 3'→5'
and synthesizes the new strand 5'→3'
ANSWERS.
carbohydrates are organized by: - Answers-their number of carbon atoms and functional
groups
triose - Answers-3-carbon carbohydrate
tetraose - Answers-4-carbon carbohydrate
aldose - Answers-sugar with aldehyde as their most oxidized group (terminal carbonyl
group)
ketose - Answers-sugar with ketones as their most oxidized functional group (internal
carbonyl group)
D-sugars - Answers-sugars with the highest-numbered chiral carbon with the -OH group
on the right (in a fischer projection)
L-sugars - Answers-sugars with the highest-numbered chiral carbon with the -OH group
on the left (in a fischer projection)
D- and L-forms of the same sugar are: - Answers-enantiomers
diastereomers - Answers-isomers that differ at at least one—but not all—chiral carbons.
non-mirror image stereoisomers. have different chemical and physical properties. type
of configurational isomer
epimer - Answers-isomers that differ at exactly one chiral carbon
anomers - Answers-isomers that differ at the anomeric carbon. a subtype of epimers
cyclization describes the ring formation of carbohydrates from their: - Answers-straight-
chain forms
when a cyclic sugar forms, the anomeric carbon can take on which two conformations?
- Answers-α- or β-conformation
anomeric carbon - Answers-the new chiral center formed in ring closure; it was the
carbon containing the carbonyl in the straight-chain form
α-anomer - Answers-have the -OH on the anomeric carbon trans to the free -CH₂OH
group. points down
,β-anomer - Answers-have the -OH group on the anomeric carbon cis to the free -
CH₂OH group. points up
what happens during mutarotation? - Answers-one anomeric carbon form shifts to
another, with the straight-chain form as an intermediate
D-fructose - Answers-
D-glucose - Answers-
D-galactose - Answers-
D-mannose - Answers-
monosaccharides are single carbohydrate units that can undergo 3 main reactions: -
Answers-1) oxidation-reduction
2) esterification
3) glycoside formation
glycoside formation - Answers-the basis for building complex carbohydrates and
requires the anomeric carbon to link to another sugar
deoxy sugars - Answers-sugars with a -H replacing an -OH
common disaccharides - Answers-include sucrose, lactose, and maltose
what makes up sucrose? - Answers-glucose-α-1,2-fructose
what makes up lactose? - Answers-galactose-β-1,4-glucose
what makes up maltose? - Answers-glucose-α-1,4-glucose
cellulose - Answers-a polysaccharide. the main structural component of plant cell walls;
main source of fiber in the human diet
starches (amylose and amylopectin) - Answers-a polysaccharide. main energy storage
forms for plants
glycogen - Answers-a polysaccharide. the main energy storage form for animals
nucleoside - Answers-contain a 5-carbon sugar bonded to a nitrogenous base
nucleotide - Answers-nucleosides with one to three phosphate groups added
5 different nucleotides - Answers-adenine (A), cytosine (C), guanine (G), thymine (T),
and uracil (U)
,watson-crick model - Answers--the DNA backbone is composed of alternating sugar
and phosphate groups, and is always read 5' to 3'
-there are two strands with antiparallel polarity, wound into a double helix
-purines always pair with pyrimidines. A pairs with T via two hydrogen bonds (in DNA).
A pairs with U via two hydrogen bonds (in RNA) C pairs with G via three hydrogen
bonds
-follows chargaff's rules
purines - Answers-composed of two fused rings. held together by two hydrogen bonds.
include A and G
pyrimidines - Answers-composed of one ring. held together by three hydrogen bonds.
include T, C, and U
chargaff's rules - Answers-purines and pyrimidines are equal in number in a DNA
molecule. the amount of A=the amount of T, and the amount of C=the amount of G
DNA strands can be denatured, meaning: - Answers-they can be pulled apart
DNA strands can be reannealed, meaning: - Answers-they can be brought back
together
number of chromosomes in human cells - Answers-46 chromosomes
DNA is wound around: - Answers-histone proteins
different types of histone proteins - Answers-H1, H2A, H2B, H3, H4
nucleosome - Answers-made of of H2A, H2B, H3, and H4 histone proteins
H1 - Answers-histone protein that helps to stabilize nucleosome
heterochromatin - Answers-dense, transcriptionally silent DNA
euchromatin - Answers-less dense, transcriptionally active DNA
telomeres - Answers-the ends of chromosomes. they contain high GC-content to
prevent DNA unraveling
centromeres - Answers-hold sister chromatids together until they are separated during
anaphase in mitosis. they contain high GC-content
number of origins of replication for prokaryotic cells and eukaryotic cells: - Answers-
prokaryotes: one per chromosome
eukaryotes: multiple per chromsome
, unwinding of DNA double helix by what enzyme in prokaryotic cells and eukaryotic
cells? - Answers-prokaryotes: helicase
eukaryotes: helicase
stabilization of unwound template strands done by what in prokaryotic cells and
eukaryotic cells: - Answers-prokaryotes: single-stranded DNA-binding protein
eukaryotes: single-stranded DNA-binding protein
synthesis of RNA primers done by what enzyme in prokaryotic cells and eukaryotic
cells? - Answers-prokaryotes: primase
eukaryotes: primase
synthesis of DNA by what enzyme in prokaryotic cells and eukaryotic cells? - Answers-
prokaryotes: DNA polymerase III
eukaryotes: DNA polymerase α, δ, ε
removal of RNA primers by what enzyme in prokaryotic cells and eukaryotic cells? -
Answers-prokaryotes: DNA polymerase I (5'→3' exonuclease)
eukaryotes: RNase H (5'→3' exonuclease)
replacement of RNA with DNA by what enzyme in prokaryotic cells and eukaryotic
cells? - Answers-prokaryotes: DNA polymerase I
eukaryotes: DNA polymerase δ
joining of okazaki fragments done by what enzyme in prokaryotic cells and eukaryotic
cells? - Answers-prokaryotes: DNA ligase
eukaryotes: DNA ligase
removal of positive supercoils ahead of advancing replication forks done by what
enzyme in prokaryotic cells and eukaryotic cells? - Answers-prokaryotes: DNA
topoisomerases (DNA gyrase)
eukaryotes: DNA topoisomerases
synthesis of telomeres done by what enzyme in prokaryotic cells and eukaryotic cells? -
Answers-prokaryotes: n/a
eukaryotes: telomerase
DNA replication method is: - Answers-semiconservative
semiconservative replication - Answers-how DNA replicates. one old parent strand and
one new daughter strand is incorporated into each of the two new DNA molecules
DNA polymerase - Answers-synthesizes new DNA strands. reads the template 3'→5'
and synthesizes the new strand 5'→3'
