CMB 311 Exam 3 Guide With
Complete Solution
Photosystems (I and II) in general - ANSWER Light harvesting complex
Reaction center
Light harvesting complex - ANSWER an array of protein and pigment
molecules embedded in the thykaloid membrane of plants which absorb light
and transfer energy
Reaction center - ANSWER has a center chlorophyll a molecule and other
proteins/ electron carriers, accept energy and carry out chemical reactions
Site of photosynthesis - ANSWER Bacteria: in granules bonded to the plasma
membrane
Eukaryotes: in chloroplast
Grana - light dependent
stroma - light independent
Light dependent reactions - ANSWER H2O is oxidized to O2 and NADP+ is
reduced to NADPH
Photophosphorylation: redox reactions coupled to ATP synthesis
Photosystem I - ANSWER generates reducing power in the for of NADPH, but
in the process, becomes electron deficient
Photosystem II - ANSWER oxidizes H2O and transfers the electrons to
,replenish the electrons lost by photosystem I
Product of reaction is O2
Electron transport in photosynthesis - ANSWER Elecetrons travel from PSII to
PSI
Electrons are passed to ferrodoxin then NADP+
Cytochrome b6f generates proton gradient across thykaloid membrane
driving ATP formation
PQ shuttles electrons from PSII
PC shuttles electrons to PSI
Photosynthesis and ATP production - ANSWER Chloroplasts can
phosphorylate ADP in the dark if they have a pH gradient, ADP, Pi
The production of ATP does not require light, proton gradient supplies the
energy
Summary of light-dependent reaction: - ANSWER The proton gradient is
created by:
- splitting H2O which release H+ into thykaloid lumen
- cytochrome b6f pumping H+
- reduction of NADP+ to NADPH by PSI using H+ in the stroma
Light independent reactions - ANSWER Calvin cycle
- fixation
- reduction
,- regeneration
Synthesizes hexose from CO2 and water
Stage 1: Carbon fixation - ANSWER Catalyzed by RuBisCo
- abundant in chloroplast
- most abundant protein in the biosphere
Stage 2: Reduction - ANSWER Goal: Use two of the 3- phosphoglycerate
made by rubisco to make a 6 carbon sugar phosphates
Stage 3: Regeneration - ANSWER Shuffle the carbons to regenerate the
original 5-C ribulose sugar
Nitrogen fixation - ANSWER Reduction of N2 to NH3 and NH4+
Only certain bacteria and archaea are capable of nitrogen fixation and many
form of symbiotic relationships with leguminous plants
Nonpolar side chain amino acids - ANSWER G A V L I P F W M
(gly, ala, val, leu, ile, pro, phe, trp, met)
A, V, L, I, P - ANSWER Contain aliphatic hydrocarbon side chain
M - ANSWER sulfur atom is side chain
W - ANSWER indole ring, aromatic
F - ANSWER aromatic wing
P - ANSWER cyclic structure
Polar uncharged side chains - ANSWER S, T, C, Y, N, Q
(ser, thr, cy, tyr, asn, gln)
, S, T - ANSWER polar hydroxy groups
Y - ANSWER hydroxyl group on aromatic hydrocarbon group
C - ANSWER thiol group
N, Q - ANSWER amide groups
Acidic and basic side chains - ANSWER D, E, K, R, H
(asp, glu, lys, arg, his)
D, E - ANSWER Acidic, negatively charged at neutral pH
K, R - ANSWER basic, positively charged at neutral pH
H - ANSWER Positively charged at neutral pH
Nonstandard amino acid - ANSWER an amino acid that occurs naturally in
cells but do not participate in peptide synthesis
Ornithine, citrulline
Overview of amino acid catabolism - ANSWER Amino acid
NH4+ - biosynthesis of AA, nucleotides, biological amines
Carbamoyl phosphate enters urea cycle, creates urea - excreted out
Carbon skeletons - a keto acids go into TCA cycle oxaloacetate is formed and
used to make glucose
Fate of the amino group - ANSWER Transamination - forming
a-ketoglutaratae and glutamate
Complete Solution
Photosystems (I and II) in general - ANSWER Light harvesting complex
Reaction center
Light harvesting complex - ANSWER an array of protein and pigment
molecules embedded in the thykaloid membrane of plants which absorb light
and transfer energy
Reaction center - ANSWER has a center chlorophyll a molecule and other
proteins/ electron carriers, accept energy and carry out chemical reactions
Site of photosynthesis - ANSWER Bacteria: in granules bonded to the plasma
membrane
Eukaryotes: in chloroplast
Grana - light dependent
stroma - light independent
Light dependent reactions - ANSWER H2O is oxidized to O2 and NADP+ is
reduced to NADPH
Photophosphorylation: redox reactions coupled to ATP synthesis
Photosystem I - ANSWER generates reducing power in the for of NADPH, but
in the process, becomes electron deficient
Photosystem II - ANSWER oxidizes H2O and transfers the electrons to
,replenish the electrons lost by photosystem I
Product of reaction is O2
Electron transport in photosynthesis - ANSWER Elecetrons travel from PSII to
PSI
Electrons are passed to ferrodoxin then NADP+
Cytochrome b6f generates proton gradient across thykaloid membrane
driving ATP formation
PQ shuttles electrons from PSII
PC shuttles electrons to PSI
Photosynthesis and ATP production - ANSWER Chloroplasts can
phosphorylate ADP in the dark if they have a pH gradient, ADP, Pi
The production of ATP does not require light, proton gradient supplies the
energy
Summary of light-dependent reaction: - ANSWER The proton gradient is
created by:
- splitting H2O which release H+ into thykaloid lumen
- cytochrome b6f pumping H+
- reduction of NADP+ to NADPH by PSI using H+ in the stroma
Light independent reactions - ANSWER Calvin cycle
- fixation
- reduction
,- regeneration
Synthesizes hexose from CO2 and water
Stage 1: Carbon fixation - ANSWER Catalyzed by RuBisCo
- abundant in chloroplast
- most abundant protein in the biosphere
Stage 2: Reduction - ANSWER Goal: Use two of the 3- phosphoglycerate
made by rubisco to make a 6 carbon sugar phosphates
Stage 3: Regeneration - ANSWER Shuffle the carbons to regenerate the
original 5-C ribulose sugar
Nitrogen fixation - ANSWER Reduction of N2 to NH3 and NH4+
Only certain bacteria and archaea are capable of nitrogen fixation and many
form of symbiotic relationships with leguminous plants
Nonpolar side chain amino acids - ANSWER G A V L I P F W M
(gly, ala, val, leu, ile, pro, phe, trp, met)
A, V, L, I, P - ANSWER Contain aliphatic hydrocarbon side chain
M - ANSWER sulfur atom is side chain
W - ANSWER indole ring, aromatic
F - ANSWER aromatic wing
P - ANSWER cyclic structure
Polar uncharged side chains - ANSWER S, T, C, Y, N, Q
(ser, thr, cy, tyr, asn, gln)
, S, T - ANSWER polar hydroxy groups
Y - ANSWER hydroxyl group on aromatic hydrocarbon group
C - ANSWER thiol group
N, Q - ANSWER amide groups
Acidic and basic side chains - ANSWER D, E, K, R, H
(asp, glu, lys, arg, his)
D, E - ANSWER Acidic, negatively charged at neutral pH
K, R - ANSWER basic, positively charged at neutral pH
H - ANSWER Positively charged at neutral pH
Nonstandard amino acid - ANSWER an amino acid that occurs naturally in
cells but do not participate in peptide synthesis
Ornithine, citrulline
Overview of amino acid catabolism - ANSWER Amino acid
NH4+ - biosynthesis of AA, nucleotides, biological amines
Carbamoyl phosphate enters urea cycle, creates urea - excreted out
Carbon skeletons - a keto acids go into TCA cycle oxaloacetate is formed and
used to make glucose
Fate of the amino group - ANSWER Transamination - forming
a-ketoglutaratae and glutamate
