BIOSC 0150 Module 4

Energy in biochemistry is capacity for change in _________ _________.

chemical composition

Chemical bonds and electrical energy are examples of _______ _______

potential energy

Heat, light, mechanical energy are examples of ________ ______.

kinetic energy

_________ reactions are for building something and _________ reactions are for breaking something down.

Anabolic; catabolic

True or false: In catabolic reactions, energy is a reactant.

False

The First Law of Thermodynamics says what?

Energy cannot be created nor destroyed

The Second Law of Thermodynamics states what?

Disorder/entropy tends to increase

_________ energy in a system increases the entropy of the system.

Unusable

Organisms obey the second law of thermodynamics because they are not _______ systems, constantly receiving _______.

closed; energy

The order of an organism is coupled to the generation of ______ by the organism. For example, making 1 kg of soft tissue requires catabolism of 10 kg of food.

disorder

What is Gibbs equation?

Change in free energy = change in enthalpy - (temperature times change in entropy)

Exergonic reactions have a _______ change in free energy, while endergonic reactions have a ________ change in free energy.

negative; positive

• _______ reactions have a negative change in free energy

  • Considered spontaneous, happens naturally

  • Most _______ reactions

  • _______ free energy

Exergonic; catabolic; releases

• _________ reactions have a positive change in free energy

  • Considered ________

  • Does not happen unless energy is put into it

  • Most _______ reactions

Endergonic; nonspontaneous; anabolic

ATP hydrolysis has free energy in the products, which means it’s _________.

exergonic

The _______-______ ________ is when the substrate is bound to the active site.

enzyme-substrate complex

The ________ _______ must be overcome to start a reaction.

Activation energy

True or false: The enzyme stays the same before and after a reaction.

True

Enzymes _____ the activation energy.

lower

What is the shape the enzyme needs to be in to break a substrate?

Transition-state intermediate

How does correct orientation of substrates help enzymes lower activation energy?

It holds the substrates in the right place for them to react, keeping them in one place.

How does placing physical strain on bonds help enzymes lower activation energy?

Helps to break the bonds that need to be broken

How does adding chemical groups help enzymes lower activation energy?

It changes the chemical reactivity of the substrate

____-____ catalysis is when acidic or basic R groups transfer H⁺ to/from a substrate.

Acid-base

________ catalysis is when R groups form a temporary covalent bond w/ the substrate.

Covalent

______ ____ catalysis is when metal ions bound to an enzyme gain/lose electrons from the substrate.

Metal ion

Which model says the substrate fits perfectly into the enzyme w/o the enzyme changing shape?

Lock-and-key model

Which model says that the enzyme fits around the substrate after the substrate binds?

Induced fit model

True or false: All enzymes function independent of other molecules

False

________ groups are part of some enzymes and are organic/made of carbon.

Prosthetic

_______ ________ are part of some enzymes and are metals with various charges.

Inorganic cofactors

________ are an additional inorganic substrate in reactions that help to gain or move something.

Coenzymes

• _______ ______ and _________ _______ are permanently bound to the enzyme

• ________ are only bound to the enzyme during the chemical reaction

Prosthetic groups; inorganic cofactors; coenzymes

True or false: In uncatalyzed reactions, increasing [A] always increases reaction rate.

True

True or false: In catalyzed reactions, increasing [substrate] always increases reaction rate.

False

Reaction rate in catalyzed reactions depend on [substrate] and [______].

enzyme

The _______ ___ is like the enzyme’s capacity for when it can no longer increase reaction rate

maximum rate

The enzyme becomes ________ when there’s too much [substrate] and it can no longer increase reaction rate.

saturated

Enzymes are regulated by ________.

inhibitors

Irreversible inhibitors form a ________ ____ which changes enzyme shape and prevents its function.

covalent bond

A ________ inhibitor binds in the active site, preventing other substrates from binding.

competitive

Name the 3 types of reversible inhibitors

Competitive, uncompetitive, allosteric

________ inhibitors bind to another site on the enzyme, causing a shape change in the enzyme.

Allosteric

An allosteric _______ gives the enzyme its active form which allows it to bond with a substrate.

activator

The ___________ _____ in the metabolic pathway is the reaction that makes the cell committed to finishing the pathway, like the R point.

commitment step

__________ ________ is when the final product acts as an allosteric inhibitor for the commitment step enzyme.

Feedback inhibition

Change in entropy ___ 0 and change in enthalpy ____ 0 = always spontaneous

>, <

Change in entropy ___ 0 and change in enthalpy ___ 0 = Spontaneous at low temperatures

<, <

Change in entropy ___ 0 and change in enthalpy ___ 0 = Spontaneous at high temperatures

>, >

Change in entropy ___ 0 and change in enthalpy ___ 0 = Never spontaneous

<, >

Metabolic pathways are regulated by targeting key _______.

enzymes

What are the two types of metabolic pathway regulation?

Allosteric and hormonal regulation

Hormonal regulation regulates _______ within the cell.

signals

The oxidized compound ______ electrons while the reduced compound ______ electrons.

loses, gains

The reducing agent ______ another molecule and becomes ______.

reduces, oxidized

The oxidizing agent _______ another molecule and becomes ________.

oxidizes, reduced

True or false: Gaining electrons causes a gain in free energy

True

OIL RIG stands for:

• Oxidation Is Loss of e-

• Reduction Is Gain of e-

Methane (CH4) has nonpolar covalent bonds, giving carbon easy access to the electrons, meaning it is in a very ______ state.

reduced

Carbon dioxide (CO2) gives carbon less access to electrons due to the polar oxygen molecules, meaning its in a very _______ state.

oxidized

Molecules in a reduced state have a ______ amount of free energy and its the opposite for molecules in oxidized state.

high

• C₆H₁₂O₆ + 6O₂ —> 6CO₂ + 6H₂O

  • What’s being reduced?

  • What’s being oxidized?

  • Reducing agent?

  • Oxidizing agent?

O₂, glucose, glucose, O₂

The coenzyme ______ is a key electron carrier in a redox reaction as a(n) _______.

NAD+, intermediate

What process of glucose catabolism produces the most ATP and must take place in an aerobic environment?

Cellular respiration

What process of glucose catabolism produces the least ATP and must take place in an anaerobic environment?

Fermentation