Chemical Reactions & Enzymes Flashcards by MICHELLE YI

A chemical reaction is a process that changes one set of chemicals into…

another set of chemicals

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Chemical reactions always involve changes in the _______ that join atoms in compounds

chemical bonds

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Some chemical reactions occur ____ or ____

slowly or quickly

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The elements or compounds that enter into a chemical reaction are known as…

reactants

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The elements or compounds produced by a chemical reaction are known as…

products

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Energy is _________ or _________ whenever chemical bonds form or are broken

released or absorbed

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Reversing a reaction requires what to be put in?

energy

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When hydrogen gas reacts with oxygen to produce water vapor, it is an energy-releasing reaction in which…

energy is given off as heat

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Chemical reactions that release energy often occur…

spontaneously (at any time)

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Chemical reactions that absorb energy ______________ a source of energy

will not occur without

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Sometimes chemical reactions that release energy do not always occur spontaneously and

need energy to get started

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Chemists call the the energy that is needed to get a reaction started the…

activation energy

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The lower the activation energy the ______ it is to start a reaction (since it requires less energy to get started)

easier

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Chemical reactions contain an…

energy barrier (a certain amount of energy needed to get them started)

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Some chemical reactions need even MORE help to get started (if their activation energy is too high), made possible by

catalysts

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A catalyst is a substance that…

speeds up the rate of a chemical reaction

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Catalysts work by _________ a reaction’s activation energy

lowering

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ATP (adenosine triphosphate) created by cellular respiration shuttles chemical energy and drives nearly…

all cellular jobs

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ATP is composed of…

one adenine, one ribose (sugar), and three negatively charged phosphates

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The energy in ATP molecule lies in the bonds between what groups?

phosphate groups

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In order to release energy from ATP the weak, energy rich bonds are broken by _____, making ATP become ADP by losing a phosphate molecule

hydrolysis

In ATP, the reaction that releases energy is called?

exergonic

Released energy from an exergonic reaction is used to…

drive all the cellular jobs within the cell (chemical work, mechanical work, and transport work)

Enzymes are proteins that act as…

biological catalysts

Enzymes speed up...

chemical reactions that take place in cells

Enzymes work by _________ the activation energy a reaction needs to get started

lowering

Lowering the activation energy has a dramatic effect on...

how quickly the reaction is completed

Enzymes are very specific, generally catalyzing _______ specific chemical reaction

only one

Part of an enzyme's name is derived from the...

reaction it catalyzes

Enzymes keep getting recycled until...

it's denatured

When a substrate binds to its specific enzyme it forms a structure called an...

enzyme-substrate complex

After the substance binds to an enzyme, the chemical reaction is catalyzed and the substrate is converted into...

products and the products are released

Enzymes provide a site where reactants can be brought together to react with each other, reducing...

the energy needed for the reaction

The reactants of enzyme-catalyzed reactions are known as...

substrates

The enzyme and substrates remain bonded together until the reaction is done and the substrates are...

converted into products

The products of the reaction in an enzyme are released an the enzyme starts...

the process all over again

Enzymes can be affected by...

anything that can change or influence a chemical reaction

Enzymes work best at _____ pH levels

certain

Many enzymes are affected by changes in...

temperature

Cold temperatures _________ enzymes

slow down

Too hot temperature change the shape of an enzyme...

making it ineffective

Cells can regulate the activities of...

enzymes

Most cells contain proteins that help turn key enzymes...

"on" and "off" at critical states in the life of the cell

Enzymes play essential roles in...(list four)

regulating chemical pathways; making material that cells need; releasing energy; transferring information

All enzymes work best within a...

particular temperature range

The lower the temperature of the enzyme...

the slower the enzyme works

The higher the temperature of the enzyme...

the faster enzymes work (up to a certain point)

Above a specific temperature for the enzyme, the enzyme denatures (or changes shape) so it...

can't work as well or not at all

substrate concentraion

when concentration is low, enzymes take longer to find and break down substrates

Enzyme concentration

more enzymes means more substrates that can be broken down

Inhibitors

slow down enzyme activity