Chemical Reactions & Enzymes Flashcards
A chemical reaction is a process that changes one set of chemicals into…
another set of chemicals
Chemical reactions always involve changes in the _______ that join atoms in compounds
chemical bonds
Some chemical reactions occur ____ or ____
slowly or quickly
The elements or compounds that enter into a chemical reaction are known as…
reactants
The elements or compounds produced by a chemical reaction are known as…
products
Energy is _________ or _________ whenever chemical bonds form or are broken
released or absorbed
Reversing a reaction requires what to be put in?
energy
When hydrogen gas reacts with oxygen to produce water vapor, it is an energy-releasing reaction in which…
energy is given off as heat
Chemical reactions that release energy often occur…
spontaneously (at any time)
Chemical reactions that absorb energy ______________ a source of energy
will not occur without
Sometimes chemical reactions that release energy do not always occur spontaneously and
need energy to get started
Chemists call the the energy that is needed to get a reaction started the…
activation energy
The lower the activation energy the ______ it is to start a reaction (since it requires less energy to get started)
easier
Chemical reactions contain an…
energy barrier (a certain amount of energy needed to get them started)
Some chemical reactions need even MORE help to get started (if their activation energy is too high), made possible by
catalysts
A catalyst is a substance that…
speeds up the rate of a chemical reaction
Catalysts work by _________ a reaction’s activation energy
lowering
ATP (adenosine triphosphate) created by cellular respiration shuttles chemical energy and drives nearly…
all cellular jobs
ATP is composed of…
one adenine, one ribose (sugar), and three negatively charged phosphates
The energy in ATP molecule lies in the bonds between what groups?
phosphate groups
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
