AP Bio Unit 3

What requires energy?

All living systems

Energy

The ability to cause change in matter

In terms of energy, what do organisms do to maintain homeostasis?

They are constantly transferring and transforming energy

Metabolism

The sum of ALL chemical reactions in an organism

What are metabolic reactions regulated by?

Metaabolic pathways

Purpose of metabolic pathways?

Used to help the cells carefully control many chemical reactions required for life

Enzymes

Proteins that speed up chemical reactions by lowering the activation energy

Where are enzymes used?

Metabolic pathways

Catabolic pathways

Releases energy by breaking down complex molecules to simpler ones

Anabolic pathways

Store energy to build complex molecules from simpler ones

Open system

Exchanges energy and matter with surroundings

Endergonic

A chemical reaction that requires the input of energy in order to proceed. Not spontanous

Exergonic

Chemical reactions that release energy. Spontanous

Example of a catabolic pathway

Cellular respiration

Example of an anabolic pathway

Photosynthesis

energy coupling

the use of an exergonic process to drive an endergonic one

bioenergetics

The study of how energy flows through the metabolic pathways of living systems

What must energy doo in order to maintain cellular processes?

Exceed the energy lost

What can cause the death of an organism?

Loss of order or energy flow

Kinetic energy

The energy of movement/motion in matter

Thermal energy

the energy of random movement of atoms or molecules

Potential energy

The energy matter possesses because of its position or structure

What does matter tend to flow to in terms of potential energy?

Matter tends to move to the lowest state of potential energy

Free energy

The energy available to do work

What does a negative change in free energy mean?

The process in spontaneous

What does positive change in free energy mean?

The process is NOT spontaneous

Metabolic pathways

Sequences of tractions where the product of step becomes the reactant of the next thing

What happens when energy is at an equilibrium?

the forward and reverse reactions occur at the same rate, and there is no further net change in the relative concentration of products and reactants

Thermodynamics

The study of energy transformations

First law of thermodynamics (Conservation of Energy)

The energy of the universe in constant, meaning that energy cannot be created or destroyed, only transformed/transferred

Second law of thermodynamics (Entropy)

As energy changes from one form to another, efficiency decreases, and some energy is lost as heat to the environment and cannot be used to do cellular work

What are the three types of work a cell does?

Chemical, mechanical, and transport work

Chemical work

Endergonic and exergonic reactions to create and break down different chemicals

Transport work

The movement of substances across the cell membrane

Mechanical work

Movement of a cell or cell parts

What's the composition of ATP?

A nucleic acid that contains three phosphate groups, a ribose sugar, and an adenine

What does ATP store between the three phosphate groups?

potential energy in its bonds between the phosphates

How can ATP immediately release energy?

Hydrolysis

Hydrolysis

Removes a phosphate by adding water releases energy, and the energy released can be used to power cellular processes

What does hydrolysis of ATP result in?

adenosine diphosphate (ADP) and an inorganic phosphate (Pi)

What type of reaction is hydrolysis?

Exergonic reaction

Phosphorylation

The addition of a phosphate group to another molecule

How can ATP reform?

Through dehydration synthesis by combining ADP and an inorganic phosphate

What is ATP used for?

Cellular work

Are enzymes resuable?

Yes, they can be used multiple times and don't get consumed

How do enzymes work?

By lowering the activation energy needed for the reaction which allows the reaction to occur at higher rates

Activation energy

The energy needed to start the reaction

In enzymatic reactions, what is the substrate?

The reactant (what goes into the enzymatic reaction)

Where are on the eznyme does the substrate bind to?

The active site

First step in enzyme-substrate binding

The substrate collides with the enzyme in the active site

Second step in enzyme-substrate binding

The substrate binds to the active site and weak bonds hold it in place (hydrogen bonds, ionic bonds, hydrophobic interactions)

Enzyme-substrate complex

A temporary structure formed when an enzyme binds to its substrate molecule(s).

Third step in enzyme-substrate binding

The enzyme wraps itself around the substrate to correctly position it (induced fit model)

Induced fit model

Change in the shape of an enzyme's active site that enhances the fit between the active site and its substrate(s)

Fourth step in enzyme-substrate binding

The enzyme lowers the activation energy by bringing substrates together, straining/bending bonds, or directly participating in the direction

Fifth step in enzyme-substrate binding

The substrate is converted into products, since the products no longer fit in the active site, they are released, and the enzyme is ready for the next substrate

Coupled reactions

Where the products produced from one reaction is needed to fuel the next reaction

Why are coupled reactions used?

To power energy-requiring reactions by linking them to energy-releasing reactions so the overall process can occur faster

How is energy coupling organized?

Enzyme controlled pathways, ATP hydrolysis, electron carriers carry an electron charge from one place to another (NADH and FADH)

What does it mean that enzymes are highly specific?

They are very selective on what substrates will bind to them and the reactions the enzyme will catalyze (Meaning 2 different enzymes cannot bind to the same substrate)

What is the active site made out of?

Specific amino acids with specific properties that interact with the substrate molecule

What do the molecular properties and the structure of the active site determine?

The type of substrate that will bind there (meaning that the active site and the substrate are complementary towards each other

What is it important to remember about enzymatic reactions?

The reactants and products REMAIN THE SAME

Enzymes DON'T change the reaction spontaneity

What do most enzymes end in?

-ase

What can enzymes change regarding the active site?

The pH or polarity of the active site

How does induced fit affect an enzyme?

The tighter of an enzyme speeds up efficiency

How are enzyme named?

Off the enzymes they act upon

What happens as the amount of substrate increases for an enzyme?

efficiency of the enzyme will increase until a certain point in which the enzyme becomes saturated with the substrate which causes it to not work anymore

Are enzymes anabolic or catabolic?

They are both however they are always called catalysts

How does increasing the temperature affect an enzyme?

It increase the rate of the enzymatic reaction until it exceeds the enzyme's optimal temperature, and then the enzyme denatures

Optimal temperature

The temperature that an enzyme works best at

What are the two factors, that if exceeds the enzyme optimal conditions, will cause denaturation of the enzyme?

pH and temperature

Denaturation

When an enzyme changes shape which can impact the enzyme's ability to function

What structure of the enzyme are affected if it becomes denaturated?

Secondary, tertiary, and quartnery

Why doesn't denaturation affect the enzyme's primary structure?

Because the peptide bonds that hold the amino acids together are too strong to break

What is the optimal temperatures for humans?

37 celsius

Why does high temperatures disrupt enzymatic reactions?

Because the high temperature disrupts the hydrogen bonds that hold the enzyme in its functional shape

Do all organisms have the same optimal temperature?

No, different organisms have different optimal temperatures

Optimal pH

The pH that an enzyme works best at

How does pH affect the enzyme?

By altering it shape/structure resulting in an increase or decrease of its function

What happens to an enzyme outside it optimal pH range?

The enzyme will denature

Why is it important that enzymes work right when they are supposed to?

So they catalyze reactions in the right part of the body

What's maximum velocity in terms of enzyme substrate reactions?

The maximum amount of substrate and enzyme can hold

What does it mean when maximum velocity is reached?

The environment is saturated with substrate

Cofactor

The nonprotein activator molecule

Coenzymes

When the cofactor is organic (contains carbon)

Inhibitors

A molecule that binds to an enzyme, decreasing or stopping its activity, which regulates metabolic pathways and cell signaling

Competitive inhibitors

Molecules that resemble the substrate and bind to the active site of an enzyme

What happens to the enzyme when the competitive inhibitors binds to the active site?

The activity of the enzyme reduces and the substrate is blocked from binding there

Are inhibitors binding to the enzyme reversible?

Sometimes

Noncompetitive inhibitors

Molecules that DO NOT bind to the active site and bind to another place on the enzyme called the allosteric site

What happens when noncompetitive inhibtors bind to an enzyme?

The shape of the enzyme can change making the enzyme less efficient at catalyzing the reaction

Selective inhibition

When a substance blocks a specific enzyme without affecting other enzymes

How does selective inhibition work?

An inhibitor binds to a certain part of the enzyme, ONLY that enzyme's reaction is slowed or stopped, other enzymes continue to function normally

What is the importance of selective inhibition?

It allows control of biochemical pathways and many antibiotics work by selectively inhibiting bacterial enzymes without harming human cells

Feedback inhibition

When the final product of a metabolic pathway inhibits/slows an earlier enzyme in the pathway

Metabolic pathway example

Enzyme 1 ➡ Enzyme 2 ➡ Enzyme 3 ➡ Final product

(Each step in the metabolic pathway depends on each other) (Its a linear progression, meaning the final product does not circle back to enzyme 1)

How feedback ihibition works?

A pathway produces its final product, when enough product builds up, the product binds (typically to the allosteric site) to an enzyme, this stops or slows the metabolic pathway from continuing

Importance of feedback inhibition?

This prevents overproduction, conserves energy and resources, maintains homeostasis

Summary of feedback inhibition

The metabolic pathway continues, however the product of the final enzyme circles back to enzyme 1 preventing it from working