Chapter 6 Flashcards

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1
Q

What is an enzyme? What do they do and how do they work?

A

A biomolecule, most are proteins, although evidence indicates some enzymes are actually RNA molecules.

Enzymes lower activation energy of reactions.

3-D shape of enzymes allow them to stabilize a temporary association between substrates.

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2
Q

If you place table sugar (sucrose) into water, what happens? if you then add sucrose to the sugar water, how will this change the reaction?

A

The water and sucrose will not break into glucose and fructose because it does not have enough activation energy.

Adding sucrose will speed up the break down of carbs/starches (sugar) from polymers into monomers.

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3
Q

What is meant by activation energy (Ea) What do enzymes do to the Ea of a reaction?

A

Extra energy needed to de-stabilize existing chemical bonds to lower activation energy needed to initiate reactions.

Enzymes lower the activation energy of the reaction.

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4
Q

What is meant by the Delta-G of a reaction? Imagine the Delta-G of a chemical reaction is -40kcal/mol. if you add the appropriate enzyme to the chemical reaction, what will happen to the Delta-G (increase, decrease, or no change)?

A

The difference between the energy available to do work at the beginning and the end of a reaction.

Reactants have more energy than the products when delta-G is positive. Energy is released, you do not need to add an enzyme the reaction will proceed on its own.

Adding enzyme would speed up the reverse reaction where Delta-G is negative, but have no effect when Delta-G is positive.

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5
Q

Describe the factors that can alter enzyme activity

A
Temperature
Hyrophobic/Hydrophillic environments
Cofactors (elements like zinc, magnesium, organic molecules)
pH
Salt
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6
Q

What is the difference between competitive inhibition and noncompetitive inhibition?

A

Competitive - binds at active site, competing with substrate for the same active site, occupying active site prevents the substrate from binding

Noncompetitive- binds away from the active site, makes active site less effective; changes the shape of the active site, making it unable to bind to the substrate - most bind to an allosteric site.

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7
Q

Statins are a type of drug. You might know someone who takes a type of statin for the treatment of cardiovascular disease. Look up information on statins and describe their mechanism of action (hint: what enzyme do they target and why?)

A

Statins - medicine used to lower blood cholesterol levels

Drugs are able to block the action of a chemical in the liver that is necessary for making cholesterol
-inhibit an enzyme (HMG-CoA reductase) which controls cholesterol production in the liver, decreases cholesterol production and body responds by increasing production of LDL receptors.

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8
Q

What is an activated Carrier?

A

A molecule that can store energy for easy release (cofactor)

Non-protein chemical compound that is bound to a protein and is required for the proteins biological activity

“helper molecules” that assist in biochemical transformations

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9
Q

How does the structure of ATP allow it to store energy?

A

Electron configuration - 3 phosphate groups have a total of 4 negative charges in a small area that repel each other making potential energy of the molecule very high.

ATP undergoes hydrolysis - ADP + P are stabilized because electrons are distributed between them.

The H+ from H2O surrounds the phosphate to reduce the charge. ATP Hydrolysis is exergonic and can do work on its surroundings. Uses free energy to phosphorylate (add phosphates to) molecules.

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10
Q

Look up 5 examples of how ATP is used in a cell.

A

Transport work - moving substances across cell membranes

Mechanical work - supplying the energy needed for muscle movements

Chemical work - supplying the needed energy to synthesize the multi-thousands of types of macromolecules that the cell needs to exsist

On/Off switch to control chemical reactions and send messages

Bond to one part of a protein molecule

Supplies energy to the heart muscle

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