CR & PH Flashcards
Catabolism vs anabolism
in catabolic reactions, E gets released and the reaction is spontaneous (breakdown reaction)
in anabolic, E has to be invested and the reaction is non-spontaneous (forming bonds)
What is ATP
glucose oxidation efficiency
the universal energy-transfer molecule containing E that gets released from chemical bonds when glucose gets oxidized in CR (only 40% converted to ATP, the rest lost as heat) – it can’t pass through the membrane so it must be synthesized inside each cell
Reduction and oxidation
compare in terms of O2, e-, H+, bonds, E of the yield
coupled processes (one causes the other), e- get relocated from the less to the more electronegative atom and this transfer releases E, the atom that loses e- is oxidized and the one that gains it is reduced
loss/gain, gain/loss, gain/loss, C-H/C-O, higher/lower
How does breaking of covalent bonds release E
they store potential energy because they are made out of electrons which, when transported, release E – in the presence of a strong oxidizing agent (which’ll get reduced), destabilized bonds will easily break
What is the main oxidizing agent in CR and what is the other name for an oxidizing agent?
NAD+, electron/hydrogen carrier (O2 only used during the final step), it’s reduced form is NADH+H+
Why does CR have many steps?
because glucose has to be oxidized gradually in order to get the most energy from it by maximizing the number of NADH+H+ molecules generated (they will release E to form ATP in the final CR step)
Mitochondrion, list components
the location of aerobic respiration, where pyruvate undergoes full oxidation to yield CO2, H2O, and ATP – mitochondrial matrix, inner membrane, outer membrane, cristae, narrow intermembrane space, mDNA
How is mitochondrion structure adapted to its function?
cristae create large SA that is needed for the electron transport chain, narrow intermembrane space allows fast accumulation of protons, the fluid matrix contains enzymes that are involved in the Krebs cycle
Respirometer
device used to measure the rate of cell respiration of a living organism
What happens in anaerobic CR after glycolysis?
happens in the cytoplasm, in humans: lactate (lactic acid) is produced from pyruvate, in yeast: ethanol and CO2 are produced
Four stages of aerobic cell respiration
glycolysis, link reaction, Krebs cycle, and electron transport chain and oxidative phosphorylation
Glycolysis
substeps
draw the process
anaerobic, in the cell cytoplasm, it’s a partial breakdown of glucose into pyruvate
phosphorylation (hexose into hexose biphosphate), lysis (hexose biphosphate into two triose phosphates (TP)), and main oxidative stage (each TP into pyruvate, 2 ATP and 2 NADH+H+ formed)
…
Phosphorylation
substrate level phosphorylation
the phosphate groups added make the molecule less stable and more likely to react and they allow for a stronger interaction between the hexose and the enzyme that catalyzes lysis
when ATP is made by direct transfer of phosphate groups from the substrate to ADP (in the main oxidative state)
Link reaction
what is decarboxylation
in the mitochondrial matrix, 2 pyruvates get decarboxylated into 2 acetyl groups (2 CO2 and 2 NADH+H+ produced) and the CoA (coenzyme A) temporarily joins with the acetyl groups to form acetyl-CoA
when the carboxyl group (COO-) gets removed in the form of CO2
Krebs cycle
aerobic (O2 not directly used), in the mitochondrial matrix – acetyl groups get further decarboxylated to yield 2 CO2 and oxidated to yield 6 NADH+H+ and 2 FADH2 (acetyl-CoA joins with C4 acceptor group and forms citric acid (C6), CoA gets released, C6 undergoes oxidative decarboxylation to form C5 (NADH+H+ and CO2), C5 undergoes oxidative decarboxylation to form C4 (NADH+H+ and CO2), C4 gets regenerated into C4 acceptor group and produces 4 NADH+H+, 2 FADH2 and 2 ATP)
Draw the ATP, NADH+H+ and FADH2 yield for each step of the CR (table)
glycolysis: 2, 2, 0
link reaction: 0, 2, 0
Krebs cycle: 2, 6, 2
total ATP: 4, 103=30, 22=4
Electron transport chain and oxidative phosphorylation
aerobic, along the inner mitochondrial membrane, the main ATP producing pathway of CR – turns each NADH+H+ molecule into 3 ATPs and each FADH2 into 2 ATPs
Describe the etc and op process
an electron transporter oxidates NADH+H+/FADH2, and the 2 e- taken from it get passed on from weaker to stronger e- carrier along the electron transport chain in a series of redox processes until the final and the strongest oxidizing agent, O2 which combines with the 2 e- and H+ released in oxidation of NADH+H+/FADH2 and forms water as a CR byproduct
other H+ released in NADH+H+/FADH2 oxidation are released in the matrix and eventually diffuse into the intermembrane space, once the C are equalized, E released from the e- transport chain is used to further pump H+ and build a C gradient (potential E) and when ATP synthase on the inner membrane opens, protons diffuse through it and release E which is used for reduction of ADP into ATP
Chemiosmosis
oxidative phosphorylation
E released by the passage of H+ down the concentration gradient is used to drive ATP synthesis (mechanism that couples release of E by oxidation to ATP production)
ADP gets phosphorylated using E released in oxidation
Which organisms perform photosynthesis?
photoautotrophic organisms, e.g. cyanobacteria, algae, plants
Chloroplast structure
double membrane, stroma (thick fluid containing starch grains, lipid droplets, 70S ribosomes, cDNA), and thylakoids (made out of thylakoid membranes and arranged in grana) which contain chlorophyll and other pigments
Wavelengths of visible (white) light
from 400 to 700 nm
Pigments
the most important example
substances that absorb visible light
chlorophyll (a and b), its structure allows it to absorb other colors better than green so it reflects (appears) green, there are also red, brown, and yellow pigments
Absorption spectrum and action spectrum
a diagram that shows the absorption of different wavelengths by a certain pigment
a diagram that shows the rate of photosynthesis at different wavelengths (effectiveness of each wavelength)
NADPH
photosystems
a molecule that temporarily stores energized electrons and protons (H+), produced during the LDS and is a substrate for LIDS
a light-harvesting unit located in the thylakoid membrane (PS I and PS II absorb light best at slightly different wavelengths) consisting of antenna pigment molecules, reaction center, and primary e- acceptor
Light-dependent stage function and process
using solar power to generate ATP and NADPH to provide chemical E and reduce power in the light-independent stage (Calvin cycle)
photon energizes one pigment molecule in PSII, its lost e- goes from one antenna pigment molecule to another until it reaches the reaction center and the primary e- acceptor from where it is transferred along the e- transport chain until it reaches PSI where it goes through the same process, at the end of the second electron transport chain it reduces NADP+ into NADPH (H+ from water – photon used for photolysis, O2 byproduct)
H+ from water diffuse from stroma into thylakoid space, E released in e- transport chains is used to further pump protons into the thylakoid space after C have been equalized to create a C gradient, ATPase in the thylakoid membrane opens, protons diffuse through it, and E is released which is used to reduce ADP into ATP, the e- gets back to PSII to stabilize the energized pigment molecule
Photophosphorylation
the production of ATP using E from an excited e- from a photosystem
Light-independent stage function and process
forms carbohydrates by taking H from NADPH, E from ATP, and C from CO2, in the stroma – CO2 combines with ribulose bisphosphate (RuBP – 5C sugar) to create glycerate-3-P (G3P) through carbon fixation, G3P then gets reduced to triose phosphate (TP) and NADPH+H+ and ATP are oxidized to provide E, H+, and high energy e- (TP is a substrate for a variety of organic molecules), only one out of 6 produced TP is turned into glucose-phosphate (GP), the other five are used to regenerate RuBP to allow more CO2 to be fixed – RuBP is both produced and consumed in LIDS
Factors affecting the rate of photosynthesis
light intensity (proportional, saturation point), CO2 levels (proportional, saturation point), temperature (optimal temperature for enzymes involved in photosynthesis)
Limiting factor
the factor that determines the rate as the one that is the furthest from its optimum (growth is controlled by the scarcest resource)
