Thẻ ghi nhớ: BIOL201 Final UBC | Quizlet

Turnover number or kcat

number of substrate molecules converted to the product in a given unit of time by a single enzyme molecule at saturation (100% active site filling) is referred to as...

steady state

a state in which inputs equal outputs, so that the system is not changing over time

Human example of steady state

Humans maintain a nearly constant level of hemoglobin by continually synthesizing and degrading it

Units of kcat

s^-1

What is the unit for Km?

M

To calculate the kcat (turnover number) of an enzyme, you need to know...

To calculate the kcat (turnover number) of an enzyme, you need to know

Lambert-Beer Law is used to...

convert absorbance value into concentration value of the light‑absorbing solute using spectrophotometry measurements

The benefit of measuring the initial rate of a reaction V0 is that at the beginning of a reaction:

A) [ES] can be measured accurately.

B) changes in [S] are negligible, so [S] can be treated as a constant.

C) changes in Km are negligible, so Km can be treated as a constant.

D) V0 = Vmax.

E) varying [S] has no effect on V0.

B) changes in [S] are negligible, so [S] can be treated as a constant.

For the reaction A —> B, the K'eq is 10^4.

If a reaction mixture originally contains 1 mmol of A and no B, which of the following is true?

- The reaction requires coupling to an exergonic reaction in order to proceed.

- The rate of the reaction is very slow.

- At equilibrium, there will be far more B than A.

- The reaction will proceed toward B at a very high rate.

- Δ𝐺′∘ for the reaction will be large and positive

At equilibrium, there will be far more B than A.

Competitive inhibitor: structure

Transition state analog; resembles substrate structure

Competitive inhibitor: reaction rate

Competitive inhibitor does not alter the maximum reaction rate

Competitive inhibitor: Km value

Competitive inhibitor will increase Km value; amount of S needed is more with competitive inhibitor

noncompetitive inhibitor ________ ________ of enzyme

Distorts shape

Non-competitive inhibitor: mechanism

Non-competitive inhibitor binds non-covalently at site other than active site

What do cells use energy for?

- active transport

- cellular movement

- biosynthesis of more complex molecules

Both chemical and biochemical standard state

- temperature is 298 K

- initial concentration of reactants and products is 1M

- pressure is 1 atm

chemical standard state

- Δ𝐺°

- pH 0

biochemical standard state

- Δ𝐺°′ or Δ𝐺′°

- [H+] = 10−7 M (pH = 7)

- change in [H2O] is assumed to be insignificant.

- constant value for [Mg2+]

What kind of inhibitors are suicide in activators usually classified as?

Irreversible inhibitors

The MM line for irreversible inhibitors look like which type of reversible inhibitor?

Non-Competitive inhibitor

Glycolysis is the process by which energy is harvested from glucose by living things. Several of the reactions of glycolysis are thermodynamically unfavorable (nonspontaneous), but proceed when they are coupled with other reactions.

Reaction A: Pi + glucose ⟶ glucose-6-phosphate + H2O Δ𝐺=13.8 kJ/mol

Reaction B: Pi + fructose-6-phosphate ⟶ fructose-1,6-bisphosphate + H2O Δ𝐺=16.3 kJ/mol

Reaction C: ATP + H2O ⟶ ADP + Pi Δ𝐺=−30.5 kJ/mol

Select every unfavorable reaction

Reaction A, Reaction B

T or F: a chemical system at equilibrium can be used to do work.

False

T or F: At equilibrium, the rate of the forward reaction is the same as the backward reaction.

true

T or F: a chemical system at equilibrium cannot be used to do work.

True

T or F: Equilibrium is the condition of maximum thermodynamic stability for a chemical system.

True

Complete the definition of oxidative phosphorylation.

Oxidative phosphorylation is the process in which ___ is generated from ___ and ___ using the energy generated by the oxidation reactions of the electron transport chain.

ATP; ADP; Pi

What happens to two molecules engaged in an oxidation‑reduction reaction?

- A proton transfers from the reducing agent to the oxidizing agent.

- Electrons transfer from the reducing agent to the oxidizing agent.

- A proton transfers from the oxidizing agent to the reducing agent.

- Electrons transfer from the oxidizing agent to the reducing agent.

- Electrons transfer from the reducing agent to the oxidizing agent.

Determine whether each molecular transformation corresponds to oxidation or reduction.

Oxidation:

- FADH2 ⟶ FAD

- CH4 ⟶ CO2

- N2H4 ⟶ N2

Reduction:

- NO−2 ⟶ NH3

- NAD+ ⟶ NADH

- CH3CHO ⟶ CH3CH2OH

- Ag+ ⟶ Ag

- CH3OH ⟶ CH4

C6H12O6 -> CO2

oxidation

C2H6O —> C2H4O

Oxidation

Cu to Cu2+

oxidation

Ubiquitous (ketone) —> ubiquinol (alcohol)

Reduction

2 Ag+ —> 2 Ag

Reduction

Fe3+ —> Fe2+

reduction

CH3CH2OH —> CH3CH3

Reduction

NO3- —> NO2-

reduction

At equilibrium...

- forward and reverse reaction occur at equal rates

- concentration of products and reactants remain constant

When not at equilibrium...

The concentration of reactants slowly decreases

May or may not be at equilibrium...

- the concentration of reactants is equal to the concentration of products

- forward reaction occurs at a very slow rate

- concentration of products is greater than the concentration of reactants

ATP is a source of free energy that drives unfavorable reactions.

Which of the processes are coupled to the dephosphorylation of ATP?

- membrane transport that maintains Na+ levels in cells

- myosin action during muscle contraction

- de novo (from scratch) anabolism of nucleotides

One reason that ATP is a source of energy is that the products of ATP hydrolysis have less free energy than the reactants. Why?

hydrogen bonding between free phosphate and water

Resonance: resonance stabilization of free phosphate

Charges: electrostatic repulsion in ATP

Which of these statements accurately describes the conditions of chemical equilibrium?

- The concentrations of the reactants and products are equal.

- A forward and reverse reaction occur at the same rate.

- The reaction fully consumes one of the reactants.

- The forward reaction is thermodynamically unfavorable

- A forward and reverse reaction occur at the same rate.

The immediate electron acceptor from complex II is...

Q

Compare the pH of the mitochondrial matrix and the intermembrane space.

- The pH is lower in the inter membrane space.

- The comparison of the pH varies from moment to moment depending on energy needs of the cell.

- The pH is lower in the matrix.

- The pH in both regions is the same.

- The pH is lower in the inter membrane space.

The standard free‑energy changes for the reactions below are given.

Phosphocreatine ⟶ creatine + Pi

Δ𝐺′∘ = −43.0 kJ/mol

ATP ⟶ ADP + Pi

Δ𝐺′∘ = −30.5 kJ/mol

What is the overall Δ𝐺′∘ for the following reaction?

Phosphocreatine + ADP ⟶ creatine + ATP

A) − 12.5 kJ/mol

B) + 12.5 kJ/mol

C) Δ𝐺′∘ cannot be calculated without 𝐾′eq.

D) − 73.5 kJ/mol

E) + 73.5 kJ/mol

− 12.5 kJ/mol

Complex I

- electron transfer from NADHG to ubiquinone (coenzyme Q)

- NADH dehydrogenase complex

Complex II

- electron transfer from succincte to ubiquinone (coenzyme A)

- succincte dehydrogenase complex

Complex III

- electron transfer from ubiquinol (QH2, or reduced CoQ) to cytochrome c

- cytochrome bc1 complex (CoQ-cytochrome c reductase)

Complex IV

- electron transfer from cytochrome c to O2

- cytochrome oxidase

How many protons are translocated across the membrane by Complex I for every pair of electrons that are passed from NADH to Q?

4

How many protons are translocated across the inner mitochondrial membrane by Complex II for every pair of electrons that are passed from Succinate to Q?

The given statements concern the relationship between mitochondrial hydrogen ion concentration and energy storage as ATP during oxidative phosphorylation. Classify each statement as either accurate or inaccurate.

Accurate statements:

- Hydrogen ions cannot freely pass through the inner mitochondrial membrane.

- H+ concentration is higher in the intermembrane space than in the mitochondrial matrix.

- Oxidative phosphorylation relies on the H+ gradient generated by the electron transport chain.

Inaccurate statements:

- The pH in the intermembrane space is higher than the pH in the mitochondrial matrix.

- Energy is generated as a result of the difference in hydrogen ion concentration between the intermembrane space and the cytoplasm.

- ATP synthase uses energy from ATP to move H+ into the mitochondrial matrix.

A lipid‑soluble cofactor of the electron transport chain, that can diffuse freely in the inner mitochondrial membrane and carry electrons across the membrane is _______.

Ubiquinone (Q)

Select the true statements about the electron transport chain.

- Coenzyme A is a component of the electron transport chain.

- In the electron transport chain, a series of reactions moves electrons through carriers.

- The electron transport chain is a series of oxidation-reduction reactions that occurs in the inner mitochondrial membrane.

- The products of the electron transport chain are H2O and either NAD+ or FAD.

- The electron transport chain is an anaerobic process.

- In the electron transport chain, a series of reactions moves electrons through carriers.

- The electron transport chain is a series of oxidation-reduction reactions that occurs in the inner mitochondrial membrane.

- The products of the electron transport chain are H2O and either NAD+ or FAD.

In the mitochondria ____, ______, and ______ are the electron donors, while ______ is the terminal electron acceptor.

NADH & H+; succinate; glycerol-3-phosphate (L-3-P)

Oxygen

Which of the following statements about the chemiosmotic theory is correct?

- The synthesis of ATP can occur in the presence of uncoupling agents in the mitochondria.

- Electron transfer in mitochondria is accompanied by an asymmetric release of protons on one side of the inner mitochondrial membrane.

- The ATP synthase carries out phosphorylation independent of the electron transport chain.

- It predicts that oxidative phosphorylation occurs in the absence of an intact inner mitochondrial membrance.

- Electron transfer in mitochondria is accompanied by an asymmetric release of protons on one side of the outer mitochondrial membrane

Electron transfer in mitochondria is accompanied by an asymmetric release of protons on one side of the inner mitochondrial membrane.

The electron transport chain (ETC), or respiratory chain, is linked to proton movement and ATP synthesis.

Select the statements that accurately describe the electron transport chain.

- Electron transfer in the ETC is coupled to proton transfer from the matrix to the intermembrane space.

- Prosthetic groups, such as iron-sulfur centers, are directly involved with electron transfer.

- The reactions of the ETC take place in the inner membrane of mitochondria.

- Electron carriers in the mitochondrial matrix include ubiquinone (coenzyme Q), FMN, and cytochrome c.

- The inner membrane of mitochondria is readily permeable to small molecules and hydrogen ions.

- Electron carriers are organized into four complexes of proteins and prosthetic groups.

- Electrons generated by the citric acid cycle in the mitochondrial matrix enter the ETC

- Electron transfer in the ETC is coupled to proton transfer from the matrix to the intermembrane space.

- Prosthetic groups, such as iron-sulfur centers, are directly involved with electron transfer.

- The reactions of the ETC take place in the inner membrane of mitochondria.

- Electron carriers are organized into four complexes of proteins and prosthetic groups.

- Electrons generated by the citric acid cycle in the mitochondrial matrix enter the ETC

Oxioreductase

catalyze oxidation-reduction reactions

Dehydrogenase

(Subtype of oxioreductase); catalyzes redox reaction involving NADH/NADPH/FMN/FAD

Transferase

Catalyzes the transfer of functional groups between molecules

Kinase

Subtype of transferase; catalyzes the transfer of a Pi (phosphate) group between two molecules, only of which is ATP

Hydrolyse

Catalyzes the transfer of a functional group to H2O

Eg) XY + H2O —> XOH + YH

Lyase

Catalyzes splitting of 1 molecule into 2, with nothing else lost or gained

Synthase

Joins 2 molécules to make 1, without ATP

Isomerase

Catalyzes internal rearrangement/isomerization

Synthetase/Ligase

Catalyzes the joining of 2 molecules requiring ATP

Decarboxylase

catalyzes non-oxidative decarboxylation reactions

Alkaloid

chemical produced by plants that contains nitrogen

Terpenes

built from multiple isoprene units

Polyketones

Contains alternating 2 carbon groups, with the second being ketone groups

Phenolics

Contains phenol groups: aromatic ring with -OH group (hydroxyl group)

Cyanogens

contain cyanide (CN-) or SCN