Chapter 6+7 - Introduction to Metabolism (Enzymes) and Cellular Respiration/Fermentation Flashcards
can't be bothered to split them up now, maybe that can be a weekend project
what is metabolism?
All chemical reactions within a cell that keep the cell and body as a whole alive and healthy
What is a metabolic pathway?
Reactant –> O –> O –> Product
A specific molecule is altered in a series of defined steps, where each step is catalyzed by an enzyme. This makes a product.
What reactions RELEASE energy? (ana or cata bolic)
Catabolic! (like a catastrophe)
What reactions CONSUME energy? (c or a)
Anabolic
What reactions BUILD STUFF?
Anabolic (because exo and endo thermic are for losers who don’t care about entropy, which I should definitely start caring about before AP Chem)
What reactions BREAK stuff?
Catabolic
Is photosynthesis ana or cata bolic?
Anabolic - builds sugars
Is cellular respiration ana or cata bolic?
Catabolic
Do catabolic, anabolic, both, or neither require enzymes to catalyze reactions?
Both
Why do organisms need constant energy?
Power energy requiring reactions like anabolic stuff
What is ΔG?
Gibbs free energy
ΔG = ΔH - ΔS (ΔS is entropy, like choices but honestly I don’t think we need to know so we’re just gonna not)
If ΔG is negative, will the reaction go spontaneously? What is this called?
Yasss - Exergonic - energy exits the system and the reactants are more energetic than the products
If ΔG is positive, will the reaction go spontaneously? What is this reaction called?
Nah bro - Endergonic - energy enters the system and products are more energetic than the reactants
Is photosynthesis exer or ender gonic?
Endergonic - requires energy input (this is the same as endothermic except get rid of the concept of breaking/making - reverse that spit)
Is cellular respiration exer or ender gonic?
Exergonic - releases energy (that’s the whole point)
How do organisms get energy for reactions?
Photosynthesis requires sunlight, we respire, organic products of photosynthesis are used
Label an atp molecule.
OOO-pentose-Adenine
OOO - phosphates held together by phosphoanhydride bonds
Pentose - 5 carbon sugar called Ribose
Adenine - nitrogenous base
When breaking a phosphoanhydride bond, what is the reaction?
Hydrolysis
ATP + H2O –> ADP + Pi + Energy
(adp is adenosine di phosphate, pi is a phosphate)
What is the bond holding together the third phosphate and the rest of the ATP molecule?
Terminal phosphate bond
T or F: When the terminal phosphate bond is broken, energy is absorbed
False. Released. It’s exergonic.
What is Energy Coupling?
Using an exergonic reaction to power an endergonic reaction.
How is ATP reaction coupled?
Energy from catabolism is used to phosphorylate (add phosphate to) ADP, which creates ATP. Then, hydrolysis breaks that ATP down, releasing energy for endergonic processes.
Why is energy coupling advantageous for an organism?
This allows reactions to have a negative net ΔG, allowing the reaction to happen spontaneously.
Describe glutamine reaction coupling.
Glutamic Acid (stable) + ATP –> Phosphorylated Glutamic acid (unstable) –> Glutamine + ADP + Pi
What happens to phosphorylated molecules?
They get unstable and react spontaneously
What is a shared intermediate in reaction coupling?
The product of one reaction that is used as a reactant for another reaction
Why are enzymes considered catalysts?
They speed up biochemical reactions in living organisms without being a reactant
What is activation energy>
The initial energy input to bring molecules to their transition state so they have a higher energy level and can break bonds.
T or F - enzymes decrease Ea required to reach transition state and break bonds
True. Transition state ΔG also decreases.
T or F - Enzyme specificity is a thing for all enzymes
This one will trip you up - yesn’t. Some enzymes have specific active sites that will catalyze the reactions of one specific substrate as they fit together like a lock and key. Other enzymes will mold to the shape of the enzyme (induced fit) and can accept multiple substrates, but they won’t be catalyzing ALL the reactions in the cell, just a couple.
How would a change in the primary structure of an enzyme affect the whole thing?
It could affect the tertiary structure in a way that czuses the enzyme to not function because the active site is no longer complementary to the substrate.
What is an enzyme?
A macromolecule that acts as a catalyst (speeds up reaction, doesn’t get consumed by it)
What is a substrate?
Reactant an enzyme acts on
What is the active site?
The region that binds to the substrate
How does the enzyme hold stuff together?
H or ionic bonds
What are the 4 methods of catalyzing reactions that enzymes use?
- Providing a template for the substrates to come together in the proper orientation
- Stretch substrate molecules towards transition state form, put pressure on critical chemical bonds to break, makes it easier
- Makes microenvironments that work better with specific reactions (like more acidic or neutral)
- May participate in the reaction with brief covalent bonding between the substrate and the side chain of the amino acid of enzyme
How does concentration of substrate (initial) affect rate of enzyme action?
More initial concentration, faster enzyme action (until saturation after which no effect)
How does PH affect rate of enzyme action?
optimal PH yields highest enzyme activity, too acidic or alkali makes it denature, even curve on graph
How does temperature affect rate of enzyme action?
No collisions happen when too cold, increases to optimal temperature, too hot and it denatures - higher temp = higher rate of reaction until denature
T or F - All enzymes are proteins
F - most are but some aren’t (answer questions like they are? not sure)
Why does denaturing make enzymes not work?
They can’t catalyse reactions if the substrate is like nah
What are some examples of competitive inhibitors?
They mimic the substrate and compete for the active site and hog it up
What are some examples of allosteric inhibitors
aka noncompetitive
They bind to another site and change the shape - some will just cover up the active site, others will make a circle turn into a square or somthing
What is allosteric regulation?
any case in which a protein’s function on one side is affected by (increased or decreased - NOT THE SAME as feedback inhibition) the binding of a regulatory molecule of a separate site
What are allosteric inhibitors and activators?
Activator - freezes enzyme in active form
Inhibitor - freezes enzyme in inactive form
Otherwise the enzyme will just be a wobbly man
Sometimes it will open it up
What is feedback inhibition / negative feedback / allosteric inhibition?
A metabolic pathway is halted by the inhibitory binding of its end product to an enzyme that acts early in the pathway (like a reaction where substrate A forms B then B acts as an inhibitor when there’s enough B to stop enzymes from making more)
Fermentation vs Cellular respiration
Fermentation –> partial degradation of sugars or other organic fuels without using oxygen. Cellular respiration is technically used for both aerobic and anaerobic respiration but it usually refers to aerobic respiration which needs oxygen
What’s another name for catabolic degradation of glucose?
cellular respiration
what is the cellular respiration equation?
C6H12O6 + 6O2 –> 6CO2 + 6H2O + Energy as atp and heat
T or F - when compounds lose electrons, they lose energy
True
What is the main electron carrier in cellular respiration?
GLUCOSE which turns into pyruvate but still starts out as glucose so there
What is the function of the ETC in cellular respiration? (without chemiosmosis)
It allows electrons deposited by NADH and FADH2 to move down the ETC to more and more electronegative acceptors and eventually get accepted by water. Energy is released from these redox reactions, which is used to pump out protons to make a concentration gradient.
4 stages of cellular respiration
Glycolysis, pyruvate oxidation, krebs cycle, oxidative phosphorylation
What is substrate level phostphorylation?
phosphorylation of atp in glycolysis and the krebs cycle - the substrate gives a phosphate to ADP and an enzyme makes it ATP
How is ATP formed in oxidative phosphorylation>
As protons are pumped out of the matrix, a concentration gradient is formed. Protons flow back in through ATP synthase, and that energy turns a rotor that turns a rod that turns a knob that sticks a phosphate onto ADP and makes ATP
What does glycolysis really mean?
Sugar splitting
During glycolysis, what is produced?
One glucose makes 2 pyruvate, 2H2O, 2 net atp, 2 NADH, and 2H+
Where in the cell does glycolysis occur?
Cytoplasm
Does glycolysis need oxygen
no
How does glucose enter a cell?
active transport
What happens during pyruvate oxidation?
CO2 Removed from pyruvate and 2 carbon fragment is oxidized, electrom forms NADH from NAD+, COA is added (presumably) and acetyl COA is formed
How many times does the citric acid cycle occur for each glucose molecule?
2 - once for each acetyl COA
During the citric acid/krebs cycle, what is formed?
3 NADH 2 CO2 1 FADH 1ATP (for one acetyl coa - double it for glucose)
T or F - After going through the ETC, electrons end up at oxygen, which has the least free energy but most electronegativity.
True
Why is oxygen the ultimate electron acceptor?
It picks up 2 electrons and 2H+ ions and forms H2O, so it’s the ultimate final electron acceptor and gradient maintainer
What are the 2 electron carrier molecujles that feed electrons into the electron transport system>
NADH and FADH2
What is chemiosmosis?
The process where a concentration gradient’s energy is used to do work
T or F - when H+ ions are pumped out of the matrix, they also leave the cell.
False. They’re in the IMS.
What is the proton motive force?
Concentration gradient with H+ ions (in oxidative phosphorylation it’s between the IMS and the Matrix)
How much ATP is formed during oxidative phosphorylation?
30 - 32 - from substrate level phosphorylation, a lot from oxidative phosphorylation.
Would pain medications use allosteric or competitive inhibition?
Competitive (do we have to know this? idk)
What is the difference between anaerobic respiration and fermentation?
Anaerobic still goes through all the motions of aerobic respiration, but it makes less ATP and uses SO4 as the final electron acceptor, whereas fermentation doesn’t ever enter the mitochondria and stays in the cytoplasm
Would poison use allosteric or competitive inhibition?
Allosteric (I still don’t think we have to know this but whatever)
If increasing the substrate concentration decreases the impact of the inhibitor, what kind of inhibitor is it?
Competitive (more collisions with the enzymes)
If increasing the substrate concentration doesn’t decrease the impact of the inhibitor, what kind of inhibitor is it?
Allosteric (doesn’t matter how many collisions there are if the enzymes are broken)
T or F: Competitive inhibitors will stay on the enzyme indefinitely
False - they might bump another molecule or change the shape (don’t think about it too hard I beg) and fall off
