Unknown Material Exam Three Flashcards
What are the forms of energy?
- Chemical energy - stored in bonds
- Heat energy - transfer due to temp difference
- Electrical energy - separation of charges
- Light energy - electromagnetic radiation stored as photons
- Mechanical - energy of motion
What are the laws of thermodynamics?
in biology, they are a set of laws that help us understand how cells harvest and transform energy to sustain life
What is the difference between potential and kinetic energy?
- Potential energy - stored energy (chemical bonds, concentration gradient, or an imbalance in charges)
- Kinetic energy - energy of movement
What is the second law of thermodynamics?
when energy is converted from one form to another, some of that energy becomes unavailable to do work i.e no energy transformation is 100% efficient, some energy is lost to disorder (entropy)
What is free energy?
it is the usable energy that can do work unit is (G)
How is a change in energy measured?
it is measured in calories or joules, delta symbol (triangle) means (a change in)
formula for change in free energy goes as follows:
∆ G = ∆H - T∆S
What does a -∆G mean?
when the change in energy is negative, energy is released
What does +∆G mean?
when the change in energy is positive, energy is required
What is meant by coupling reactions?
When the free energy RELEASED from one reaction (exergonic) and is used for/ coupled with another reaction that REQUIRES (endergonic) OR when one molecule is reduced SO THAT another can be oxidized.
What are the two characteristics of ATP that allow so much energy to be released?
- phosphate groups have negative charges and repel each other - the energy that is needed to get them close is in the P-O bond
- The free energy of the P-O bond is much higher in ATP than is the O-H bond that forms after hydrolysis on the ADP
How do enzymes do what they do?
enzymes lower the energy barrier E(a) AKA activation energy AKA the amount of ΔG needed to jumpstart the reaction
When activation energy is lowered, the reactions speed up
What do enzymes not do?
enzymes do not make a reaction happen that could not already happen
enzymes do not change the difference in Δ G between the reactants and the products i.e the final equilibrium
What are transition state intermediates?
are unstable substates/reactants with higher free energy, any substate with a +ΔG
What are substrates?
are the reactants or molecules that the enzyme exerts its catalytic function i.e lowering the activation energy.
What are the three mechanisms of enzyme action?
- Chemical change - enzymes can temporarily add chemical groups to itself
- Orientation - enzymes can align/position the substrate so they can react
- Physical strain - enzymes can induce strain by stretching substrate, and by consequence make the bonds of the substrate more reactive
What are the two ways enzymes can be regulated?
- Regulation of gene expression - how many enzyme molecules are made (works slowly)
- Regulation by the enzyme itself - enzyme shape may change (adding phosphate group/enzyme inhibitor may close/open the active site)
What is a competitive inhibitor?
reversible inhibitor that directly COMPETES with natural substrate for the active site / binding site.
the degree of the inhibition depend on what type of substrate and what type of inhibitor
What is an uncompetitive inhibitor?
reversible inhibitor that binds to the enzyme substrate complex (when the enzyme has substrate bound to it) and prevents the substrates release, freezes the reaction of substrates
UN = eNzyme sUbstrate
What is a competitive inhibitor?
a reversible inhibitor that binds to the enzyme at site that isn’t the active (allosteric site)
this changes the shape of the shape of the enzyme and alters the active site (allostery)
What is allosteric regulation?
when an effector (non competitive inhibitor) binds an enzyme at the allosteric site (different from the active site), changing the shape
active form - can bind substrate = product
inactive form - can’t bind substrate = no product
What is feedback inhibition?
when the final product acts as a noncompetitive inhibitor of the first enzyme, which shuts down the pathway.
this makes sure we don’t make too much of something or waste energy/materials making something in excess
what is the transition state?
it is the reactive status of the substrate/reactant, after there has been a good enough input of energy to start the reaction.
What are the principles of metabolic pathways?
- Complex transformations occur in a series of separate reactions
- Each reaction is catalyzed by a specific enzyme
- Many metabolic pathways are similar in all organisms
- In Eukaryotes are compartmentalized in specific organelles
- Key enzymes can be inhibited or activated to alter the rate of the pathway
The transfer of electrons is often associated with?
the transfer of hydrogen ions
a hydrogen atom is H+ ion plus a negatively charged electron
When a molecule loses H atoms what does it mean?
it becomes more oxidized
less hydrogens = more oxidized = less free energy
What is the oxidized form of NADH, and how many electrons / protons does the molecule transfer?
the oxidized form is NAD+ and it transfers 2 electrons and one proton (H+)
When NADH loses an electron to O2, which is oxidized and which is reduced? Is this exergonic or endergonic?
{NADH + (H+) + (.5)O2 –> (NAD+) + H2O}
The oxygen is reduced and the NADH is oxidized.
This reaction is exergonic because the NADH loses an electron and therefore releases energy.
What are the five energy-yielding metabolic pathways?
- Glycolysis
- Pyruvate Oxidation
- Fermentation
- Krebs Cycle
- ETC and Chemiosmosis (Oxidative Phosphorylation)
Where does glycolysis occur and does it occur when oxygen is present or in the absence?
glycolysis occurs in the cytoplasm (cytosol) of the cell outside the mitochondria
glycolysis is anaerobic (it does not require oxygen), but functions the same even if oxygen is available
Where does fermentation occur and does it function with or without the presence of oxygen?
fermentation occurs in the cytoplasm
it occurs in the absence of oxygen
Where does pyruvate oxidation occur and does it function with or without the presence of oxygen?
it occurs in the mitochondrial matrix
it ONLY functions in the presence of oxygen.
Where does the citric acid cycle occur and does it function with or without the presence of oxygen?
it occurs in the mitochondrial matrix
it ONLY functions in the presence of oxygen
