Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
77 Cards in this Set
- Front
- Back
autotrophs |
class of organisms that are able to produce their own organic molecules through photosynthesis |
|
heterotrophs |
class of organisms that live on organic compounds produced by other organisms |
|
cellular respiration |
a process used by ALL organisms to extract energy from organic molecules |
|
energy is contained |
within the bonds of molecules |
|
oxidation |
loss of an electron |
|
reduction |
gain of an electron, reduces the positivity of an atom/ion |
|
OIL RIG |
Oxidation Is Loss, Reduction Is Gain |
|
degree of electron sharing
|
some redox reactions do not exchange electrons, they change the degree of electron sharing in covalent bonds
|
|
adding hydrogens |
reduction |
|
removing hydrogens |
oxidation |
|
follow the hydrogens |
to determine/understand where oxidation and reduction has occurred |
|
dehydrogenations |
lost electrons are accompanied by hydrogen ions, therefore what is actually lost is a hydrogen atom (1 electron, 1 proton) |
|
NAD+ |
an electron carrier, accepts 2 electrons and 1 proton to become NADH (reversible reaction) |
|
aerobic respiration
|
final electron receptor is oxygen (O2)
|
|
anaerobic respiration |
final electron receptor is an inorganic molecule (not O2) |
|
fermentation |
final electron receptor is an organic molecule |
|
electron carriers |
soluble, membrane-bound, move within membrane, easily oxidized and reduced |
|
[NAD+] + 2 electrons + 1 proton = |
NADH |
|
substrate-level phosphorylation |
transfer high-energy phosphate group directly to ADP from another molecule |
|
oxidative phosphorylation |
ATP sythase uses energy from a proton (H+) gradient to make ATP |
|
stages of oxidation of glucose |
1. gycolysis 2.pyruvate oxidation 3. krebs cycle 4. electron transport chain 5. chemiosmosis |
|
ATP powers cellular work, 3 main kinds |
mechanical, transport, chemical |
|
ATP hydrolysis drives |
endergonic reactions in cells |
|
APT hydrolysis drives endergonic reactions in cells in two ways |
1. By coupling exergonic reactions with endergonic reactions so over all ⌂G<0 2. By phosphorylating substrates and making them more reactive |
|
energy release |
is always associated with the loss of electrons and so metabolism really is ALL ABOUT THE ELECTRONS |
|
glycolysis |
10-step biochemical pathway that occurs in the cytosol |
|
glycolysis |
6-carbon glucose broken down into two 3-carbon molecules of pyruvate |
|
glycolysis
|
net production of 2 ATP molecules by substrate-level phosphorylation and 2 NADH produced by the reduction of NAD+
|
|
2 phases of glycolysis |
energy investment phase and energy payoff phase |
|
energy investment phase of glycolysis |
two molecules of ATP are consumed, glucose is phosphorylated twice |
|
energy payoff phase of glycolysis |
sugar is split to form 2 pyruvate molecules, 2 molecules of NAD+ are reduced to NADH, four molecules of APT are formed by substrate-level phosphorylation (net gain 2 ATP) |
|
NADH must be recycled to NAD+ by either |
aerobic respiration or fermentation |
|
aerobic respiration |
occurs when oxygen is available as the final electron acceptor |
|
fermentation |
occurs when oxygen is not available and an organic molecule is the final electron acceptor |
|
fate of pyruvate |
depends of oxygen availability |
|
pyruvate + oxygen is present |
pyruvate is oxidized to acetyl-CoA which enters the Krebs cycle |
|
pyruvate + oxygen not present
|
pyruvate is reduced to oxidize NADH back to NAD+ (byproduct is lactate)
|
|
oxidation of pyruvate occurs |
in the mitochondria in eukaryotes, in the plasma membrane in prokaryotes |
|
pyruvate dehydrogenase |
a mutienzyme complex which catalyzes the reaction of pyruvate oxidation |
|
oxidation of one pyruvate molecule yields
|
1 CO2, 1 NADH, 1 Acetyl-CoA (consisting of 2 carbons from pyruvate attached to coenzyme A)... Acetyl-CoA procedes to Krebs cycle
|
|
krebs cycle
|
oxidizes the acetyl group from pyruvate, occurs in the matrix of the mitochondria, 9 steps
|
|
Acetly-CoA + oxaloacetate ----> citrate (2 carbons) (4 carbons) (6 carbons) |
first step of the krebs cycle |
|
remaining steps of Krebs cycle |
release 2 molecules of CO2, reduce 3 NAD+ to 3 NADH, reduce 1 FAD to FADH2, produce 1 ATP, regenerate oxaloacitate |
|
Kreb cycle has to run _______ for each glucose |
twice |
|
feedback inhibition for Krebs cycle |
Krebs cycle can be turned off at multiple points based on the abundance or scarcity of ATP and NADH |
|
ATP and NADH in abundance |
Krebs cycle slows |
|
ATP and NADH are scarce |
Krebs cycle speeds up |
|
glycolysis-->pyruvate oxidation-->Krebs cycle= |
glucose has been oxidized to 6 CO2, 4 ATP, 10 NADH, and 2 FADH (these electron carriers proceed to the electron transport chain) |
|
electron transport chain (ETC) |
a series of membrane-bound electron carriers embedded in the inner mitochondrial membrane |
|
energy lost with each transfer in the ETC |
used to pump protons (H+) across the membrane from the matrix to the inner membrane space of the mitochondria |
|
protein gradient |
between the intermembrane space and the matrix of the mitochondria, makes up the ETC |
|
NADH produces _____ ATP |
three |
|
FADH2 produces _____ ATP |
two |
|
FADH2 produces less ATP |
because electrons enter ETC later and pump only two protons into the intermembrane space |
|
chemiosmosis |
higher negative charge in matrix attracts the protons (H+) back from the intermembrane space to the matrix, and so the accumulation of protons in the intermembrane space drives protons into the matrix via diffusion |
|
during chemiosmosis, most protons move back to the matrix through ____________ |
ATP synthase |
|
ATP synthase |
a membrane-bound enzyme that uses the energy of the proton gradient to synthesize ATP from ADP - Pi |
|
ATP synthase structure
|
an enzyme complex consisting of ATPase "knob" component and a membrane-bound, proton-transporting base component, connected by a "stalk"
|
|
ATP synthase function |
protons flow through transport protein and cause the stalk to spin, as the knob spins with the stalk, it's subunits change shape in a way that catalyzes the phosphorylation of ADP to ATP |
|
actual yield per glucose for eukaryotes |
30 ATP per glucose |
|
theoretical yield per glucose for eukaryotes |
38 ATP per glucose |
|
reduced yield of ATP due to
|
"leaky" inner membrane (some protons enter outside of ATP sythase), use of the proton gradient for purposes other than ATP sythesis (pyruvate transport)
|
|
___% of available energy from glucose is harvested by the cell |
32 |
|
regulation of respiration |
occurs by feedback inhibition, when a step with in glycolysis is allosterically inhibited by ATP and citrate |
|
high levels of NADH inhibit ______ ______________ |
pyruvate dehydrogenase |
|
high levels of ATP inhibit ________ _________
|
citrate synthase
|
|
anaerobic respiration |
use of inorganic molecules (other than O2) as final electron acceptor- many prokaryotes use sulfur, nitrate, carbon dioxide or even inorganic metals |
|
fermentation |
use of organic molecules as final electron acceptor |
|
methanogens |
CO2 is reduced to CH4 (methane), found in diverse organisms including bacteria that live in cows- anaerobic |
|
sulfur bacteria |
inorganic sulphate (SO4) is reduced to hydrogen sulfide (H2S), early sufate reducers set the stage for evolution of photosynthesis |
|
fermentation |
(2 kinds) reduces organic molecules in order to regenerate NAD+ |
|
ethanol fermentation |
occurs in yeast, CO2, ethanol and NAD+ are produced |
|
lactic acid fermentation |
occurs in animal cells (esp muscles), electrons are transferred from NADH to pyruvate to produce lactic acid |
|
catabolism of protein |
amino acids undergo deamination to remove the amino group, remainder of amino acid is converted to a molecule that enters glycolysis or the Krebs cycle, where high energy electrons are removed and used to make ATP |
|
examples of catabolism of protein |
alanine is converted to pyruvate, aspartate is converted to oxaloacetate |
|
catabolism of fat |
fats are broken down to fatty acids and glycerol, fatty acids are converted to acetyl groups by beta oxidation- oxygen dependent process |
|
respiration of 6 carbon fatty acid yields ____ more energy than 6-carbon glucose |
20% |