©BRIGHTSTARS EXAM SOLUTIONS
11/16/2024 10:16 AM
CMB 311 Exam 3 Question With Correct
Answers
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+
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, ©BRIGHTSTARS EXAM SOLUTIONS
11/16/2024 10:16 AM
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
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, ©BRIGHTSTARS EXAM SOLUTIONS
11/16/2024 10:16 AM
(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
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