Bio 190 UNLV exam 2, Cellular Respiration and Photosynthesis Overview

What does energy do?

Promote change or do work

Various forms of energy in biological systems

Light, heat, mechanical, potential, Electrical/ion gradient

2 general forms of energy

kinetic and potential

kinetic energy

energy of motion

potential energy

stored energy that results from the position or shape of an object

first law of thermodynamics

Energy can be transferred and transformed, but it cannot be created or destroyed.

chemical energy

A form of potential energy that is stored in chemical bonds between atoms.

second law of thermodynamics

Every energy transfer or transformation increases the entropy (state of disorder) of the universe.

As entropy increases

less energy is available for organisms to use to promote change

total energy

usable energy + unusable energy

unusable energy

entropy

usable energy

free energy/ATP

exergonic reaction

A spontaneous chemical reaction in which there is a net release of free energy. Product energy < Reactants energy

endergonic reaction

A non-spontaneous chemical reaction in which free energy is absorbed from the surroundings. Product energy > Reactants energy

even energetically favorable reactions

will not convert all reactants into products

chemical equilibrium

In a chemical reaction, the state in which the rate of the forward reaction equals the rate of the reverse reaction, so that the relative concentrations of the reactants and products do not change with time.

Keq

[products]/[reactants]. Concentration of products and reactants at state of equilibrium.

Most reactions in cells are

endergonic

Endergonic reactions are often

coupled to an exergonic reaction

coupled reactions

the energy released by an exergonic reaction is used to drive an endergonic reaction

Coupled reactions will be spontaneous if

The products are < the reactants and overall free energy change is negative between both reactions.

Energy released from ATP hydrolysis

is often used to drive other endergonic reactions

Speed of Spontaneous Reactions

Is not necessarily a fast one

catalyst

substance that speeds up the rate of a chemical reaction and is not consumed

Enzymes are

proteins that function as catalysts in living cells that increase the rate of chemical reactions

Enzymes speed up reactions by

lowering the activation energy which makes the process millions of times faster compared to uncatalyzed reactions

activation energy (Ea)

the initial energy needed to start a chemical reaction

Activation energy allows

molecules to get close enough to cause bond rearrangement

transition state

a high-energy intermediate state of the reactants during a chemical reaction that must be achieved for the reaction to proceed

What is the barrier to the formation of products?

The activation energy to achieve the transition state

How do enzymes break the barrier

enzymes lower the activation energy making it easier to reach transition state.

active site

The part of an enzyme or antibody where the chemical reaction occurs.

Substrate

reactant of an enzyme-catalyzed reaction. The before

enzyme specificity

Enzyme specificity is the concept that each enzyme catalyzes only one kind of reaction. However, rarely they can do more than one.

induced fit

The change in shape of the active site of an enzyme so that it binds more snugly to the substrate, induced by entry of the substrate.

induced fit makes

Enzyme-substrate complexes

Where does glycolysis occur?

Cytosol

What are the inputs of glycolysis?

1 Glucose, 2 NAD+, 2 ATP, 4 ADP

What are the outputs of glycolysis?

2 Pyruvate, 2 NADH, 2 ADP, 4 ATP

What is the overall energy transformation in glycolysis?

2 ATP and 2 NADH are made

Where does pyruvate oxidation occur?

Mitochondrial matrix

What are the inputs of pyruvate oxidation?

2 Pyruvate, 2 Coenzyme A, 2 NAD+

What are the outputs of pyruvate oxidation?

2 Acetyl-CoA, 2 CO2, 2 NADH

What is the energy transformation in pyruvate oxidation?

2 NADH are generated

Where does the citric acid cycle occur?

Mitochondrial matrix

What are the inputs of the citric acid cycle?

2 Acetyl-CoA, 6 NAD+, 2 FAD, 2 ADP

What are the outputs of the citric acid cycle?

4 CO2, 6 NADH, 2 FADH2, 2 ATP

Where does the electron transport chain occur?

Mitochondrial inner membrane

What are the inputs of the electron transport chain?

Electrons from 10 NADH, 2 FADH2, Oxygen (O2)

What are the outputs of the electron transport chain?

10 NAD+, 2 FAD, Water (H2O)

What drives ATP synthesis in the electron transport chain?

A hydrogen ion (H+) gradient

What is the function of ATP synthase?

Converts ADP + Pi into ATP

Where does light reaction (linear electron flow) occur?

Thylakoid membrane

What are the inputs of the light reaction (linear electron flow)?

Light, Water (H2O), NADP+, ADP + Pi

What are the outputs of the light reaction (linear electron flow)?

Oxygen (O2), NADPH, ATP

What is the overall energy transformation in the light reaction?

Light energy is converted into chemical energy stored in ATP and NADPH

Where does the Calvin cycle occur?

Stroma

What are the inputs of the Calvin cycle?

ATP, NADPH, CO2

What are the outputs of the Calvin cycle?

ADP + Pi, NADP+, G3P (Glyceraldehyde 3-phosphate)

What is the overall energy transformation in the Calvin cycle?

For every 6 CO2 incorporated, 18 ATP and 12 NADPH must be used