Chapter 5 Flashcards
Reduction reaction involves _____
Gain of electrons
Oxidation reaction involves _____
Loss of electrons
What are catabolic processes?
BReakdown of larger molecules to produce energy
What are anabolic processes
Synthesis of larger molecules from smaller ones
______ consumes sugars less efficiently than respiration in an attempt to produce energy
Anaerobic Fermentation
ATP molecules have 3 phosphate groups, therefore ADP molecules have ____
2 phosphate groups
What does the ADP/AMP to ATP ratio indicate to the cell?
If there is a lot of ADP/AMP in relation to ATP, the cell does not have much energy left to synthesize proteins
What is the function of the kinase AMPK?
Recognizes the ratio of ADP/AMP to ATP, and halts protein synthesis if energy levels are low
Briefly describe the appearance of the mitochondria
HAs an inner and outer membrane, and the inner space is divided into matrix and intermembrane space, Finger-like projections inside the mitochondria are referred to as Cristae.
Why do mitochondria require DNA?
They must synthesize their own proteins
TRUE OR FALSE: Mitochondria are not capable of fusing or splitting
FALSE!! Some cells have multiple mitochondria and therefore they must be able to split to create more
TRUE OR FALSE: Mitochondria are passed down from our mothers
TRUE
How is the lipid (and otherwise) composition of the mitochondrial membrane so significant?
IT is the same lipid composition as bacterial membranes, and contained a bacterial pore-forming protein called “porin”
What is present in the mitochondrial matrix?
Circular DNA molecule, ribosomes, enzymes, sometimes RNA/proteins
What kind of reaction is it when NAD+ is converted to NADH?
Reduction
Glycolysis is the breakdown of 6 carbon Glucose to 3 carbon ______
Pyruvate
After glycolysis, pyruvate is converted to Acetyl CoA. How does this occur?
By release of Co2 (decarboxylation) and a hydrogen (converting NAD+ to NADH)
What happens to Pyruvate in aerobic conditions, anaerobic (muscle) conditions, and anaerobic (bacterial) conditions?
Aerobic - Transported to mitochondrial matrix and oxidized to CO2 and H2O Anaerobic (muscle) - Reduced to lactate in 1 step Anaerobic (bacterial) - Reduced to ethanol in 2 steps (pyruvate > acetaldehyde > ethanol)
What does TCA Cycle stand for?
Tricarboxylic acid cycle
What is generated from TCA cycle? What are the equivalent amounts in ATP?
3 NADH, 1 FADH2, 1 GTP (ATP)
NADH - 3 ATP
FADH2 - 2 ATP
So, 15 ATP x 2!
How is NADH transported to ATP?
Via Oxidative Phosphorylation: NADH transfers its high energy hydrogen molecule to oxygen, creating water. This creates a high energy proton gradient that causes phosphorylation of ADP into ATP
What happens to the one NADH produced during glycolysis?
NADH cannot enter the mitochondria alone, but instead needs a Glycerol phosphate shuttle
How does the Glycerol phosphate shuttle work?
Dihydroxyacetone phosphate takes an H+ from NADH (converting it to NAD+), becoming GLycerol 3 - phosphate. This is the form that can enter the intermembrane space.
Once inside, the H+ from Glycerol-3 -Phosphate is transferred to FAD ( a reaction catalyzed by glyverol 3 - phosphate dehydrogenase), creating FADH2. This dihydroxyacetone phosphate moves back across the outer cel membrane
Describe chemiosmosis
As electrons move through the electron-transport chain, H+ ions are pumped out across the inner membrane, and ATP is formed by H+ ions moving BACK into the mitochondria via the ATP synthase enzyme.
_____ molecules of ATP Are formed from each pair of electrons from NADH. and ____ molecules of ATP are formed from each pair of electrons from FADH2
Three, two
Why is oxygen so necessary for cellular respiration?
Oxygen is the acceptor at the end of the electron transport chain (Forming H2O)
The electron transport chain complexes are _______
Proton pumps.
Strong _____ agents have a high affinity for electrons, strong _____ agents have a low affinity for electrons
Oxidizing, reducing
Electrons associated with either NADH or FADH2 are transferred through specific electron carriers that make up a ______
Electron transport chain
Name and describe the types of electron carriers
Flavoproteins - polypeptides bound to either FAD or FMN
Cytochromes - Contain heme groups bearing Fe or Cu ions
Three copper atoms - Located within a single protein complex and alternate between Cu2+/Cu1+
Ubiquinone - Lipid soluble molecule made of five carbon ispernoid units
Iron-sulfur proteins - Iron-containing proteins in which iron atoms are linked to inorganic sulfide ions
How are iron-sulfur electron carriers arranged
Arranged in order of increasingly positive redox potential. Sequence of carriers determined by use of inhibitors. All electrons flow toward O2 which has the highest electron potential
The lipid-soluble molecule ______ can carry electrons from Iron-sulfur complex I to electron transport complex III in the electron transport chain
Ubiquinone
The water-soluble molecule ______ can carry electrons from electron transport complex III to electron transport complex IV in the electron transport chain
Cytochrome C
Electron transport complexes I, III, and IV all pump H+ protons into _____
the intermembrane space
How did scientists prove that cytochrome oxidase was a proton pump?
Embed cytochrome oxidase into a liposome, measure pH to determine whether pH changes.
Name each of the electron transport chain complexes and describe what they do
Complex I (NADH dehydrogenase) - Catalyzes transfer of electrons from NADH to ubiquinone and transports four H+ per pair
Complex II (succinate dehydrogenase) - Catalyzes transfer of electrons from succinate to FAD to ubiquinone without transport of H+
Complex III (cytochrome bc1) - catalyzes the transfer of electrons from ubiquinone to cytochrome c and transports four H+ per pair
Complex IV (cytochrome c oxidase) - catalyzes transfer of electrons to O2 and transports H+ across the inner membrane (basically adds 4 H+ to O2 to form two H2O)
How does cytochrome oxidase function in the electron transport chain?
Electrons are transferred one at a time. Energy released by O2 presumably induces changes that promote movement of H+ ions through the protein
What are the two components of the proton gradient?
pH gradient created from the concentration gradient
Separation of charge across the membrane creates an electric potential
THIS IS KNOWN AS PROTON MOTIVE FORCE
What is “proton motive force”?
The energy present across the proton gradient (combined pH gradient and electric gradient)
What is meant when one says that Dinitrophenol (DNP) “uncouples” glucose?
Increases the permeability of the inner membrane to H+, thus eliminating the proton gradient.
Dinitrophenol (DNP) is a ________ protein.
Uncoupling
What is the purpose of uncoupling proteins (UCPs)?
By eliminating the proton gradient, UCPs affect metabolic rate, the heat generated in the body (more UCPs, more heat), and the rate at which fat is burned (more UCPs = less ATP = burning fat)
What did coupling factor 1 do under experimental conditions? Why?
Behaved as an ATP synthase. Led to the conclusion that an ionic gradient establishes a proton (K+, N+) gradient to phosphorylate ATP
Briefly describe the structure of ATP synthase
F1 particle is the catalytic subunit, containing 3 catalytic Beta subunits
F0 particle particle attaches to F1 and is embedded in the inner membrane. Contains a channel through which protons are conducted from intermembrane space to the matrix.
What is the binding change mechanism for ATP synthase?
States that movement of protons through ATP synthase changes the conformation and binding affinity. Binding sites can be tight, loose, or open. The ATP synthase stalk (gamma subunit) rotates relative to the head.
How does the F0 portion of ATP synthase help ATP synthesis?
c subunits of the F0 base forms a ring. C ring is bound to gamma subunit. As protons move through the membrane they rotate the ring. Rotation provides the twisting force that drives ATP synthesis. It rotates 30 degrees for each proton. (how many protons are needed to synthesize 1 atp?)
_____ is the most important factor infuencing respiraton rate
ADP
______ are membrane bound vesicles that contain oxidative enzymes. What do they do?
Peroxisomes. Oxidase very-long-chain fatty acids, synthesize “plasmalogens” (type of phospholipid), and make hydrogen peroxide (which is then broken down by catalase).
They form by splitting preexisting organelles, import preformed proteins, engage in oxidative metabolism.
Plants contain a special peroxisome called _____
Glyoxysome.
What happens during aerobic respiration reaction?
Oxidation of sugar into CO2 and Water. You also get ATP.
Glycolysis is the breakdown of ___ into _____
Glucose, pyruvate
IN mitochondria, molecular oxygen is reduced to _____
Water
What are the three conformations of the Beta subunit during ATP synthesis?
Loose, tight, open
The molecule that enters the TCA cycle is called ______. What does it combine with and what is the end product?
Acetyl CoA. Combines with 4 carbon oxaloacetate to form 6 carbon Citrate. This is catalyzed by citrase synthate
