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Enzymes

metabolism, ATP intro, and
by

Jean Battinieri

on 20 January 2016

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Transcript of Enzymes

The living cell is a chemical industry in miniature, where thousands of reactions occur within a microscopic space.
Introduction to Metabolism
interactions between molecules within the orderly environment of the cell
the ability to do work
Energy
Entropy often takes the form of increasing amount of heat
Two laws of Thermodynamics
Energy and Metabolism
without enzymes metabolism could not occur as we know it
Enzymes
Enzymes :more
Effects of pH and Temperature
Metabolism
all chemical reactions that occur in an organism
enzymes accelerate the steps of the process
manages the material and energy resources of the cell
when there is a break down of complex molecules into simpler ones
Catabolic Pathway
when bonds break between molecules energy is released
energy that was stored in organic molecules becomes available to work in the cell
Anabolic Pathways
these use energy to build complicated molecules from simpler ones
need to have a catabolic reaction take place that provides the energy for the anabolic reaction - this is called a "coupled" reaction
to move matter against opposing forces such as gravity and friction
Law of conservation of Matter
AKA
1st Law of Thermodynamics
Kinetic Energy
energy of motion - anything that is in motion has this
Potential Energy
the energy that matter possesses due to its location or structure -
stored energy
ex.
Hydropower
Electricity
Light
Heat/Thermal
ex. chemical energy
very important to biology due to the energy stored in molecules as a result of the arrangement of atoms
chemical energy
tapped for use when chemical reactions rearrange the atoms of molecules and potential energy stored in molecules is converted to kinetic energy
Thermodynamics=
the study of the energy transformations that occur in a collection of matter
1st law of thermodynamics
AKA principle of conservation of energy
Matter cannot be created or destroyed it can be transformed and re-arranged.
2nd law of thermodynamics
Every energy transfer or transformation increases entropy of the universe.
Every energy transfer makes the universe more disordered.
ENTROPY is a measure of this disorder or randomness
Organisms are open systems that exchange energy and materials with their surroundings.
They create ordered structures from less organized starting materials.
exergonic reactions
energy is released
energy outward
downhill
endergonic reactions
energy is absorbed from the surroundings
energy inward
uphill
energy coupling
the use of an exergonic process to drive an endergonic one = usually use ATP
ATP - Adenosine Triphosphate
powers cellular work
Cells do 3 main types of work
mechanical work
ex. beating of cilia, contraction of muscle cells, and movement of chromosomes during reproduction
transport work
ex. pumping substances across membranes against the direction of spontaneous movement
Chemical work
ex. synthesis of polymers from monomers
ATP
related to one type of nucleotide
nitrogen base - adenine
5 carbon sugar - ribose
has a chain of 3 phosphates attached to ribose
bonds broken by hydrolysis
between 2nd and 3rd phosphate group
energy is released
the enzyme ATPase helps in the breaking of this bond
Adenosine Triphosphate
The enzyme ATPase helps to break the bond
bond breaks between the 2nd and 3rd phosphate group
the enyzme ATP synthase helps the bond form
bond forms when a free phosphate is added to the 2nd phosphate group = phosphorylation
An organism at work uses ATP continuously.
Nearly all cellular work depends on ATP's energizing of other molecules by transferring phosphate groups.
The ATP cycle
ATP is a renewable resource that can be regenerated by the addition of phosphate to ADP. (ADP + P --> ATP)
The bonds between the phosphate groups of the ATP can be broken by hydrolysis - when the bond is broken a P group is released and energy is released. (ATP ----> ADP + P)
a catalyst is a chemical agent that changes the rate of a reaction without being consumed by the reaction
enzymes are proteins
enzymes are catalysts
every chemical reaction involves bond breaking and bond forming
whenever a reaction re-arranges the atoms of molecules, existing bonds in the reactants must be broken and the new bonds of the products formed
The energy needed to break the bonds in the reactant molecules is known as ACTIVATION ENERGY
enzymes reduce the amount of activation energy needed to get a reaction started
enzymes speed up a chemical reaction
enzymes reduce the amount of activation energy needed
the REACTANT an enzyme acts on is referred to as the enzyme's SUBSTRATE
an enzyme bonds to a substrate (or substrates) and converts the substrate to the product (or products)
most enzyme names have an ase ending
each enzyme catalyzes a particular reaction - it is specific to its substrate
the active site is a region of the enzyme where the substrate binds to it
when they are joined together it is an enzyme substrate complex
often compared to a lock and key
substrate is converted into NEW products and they leave the enzyme
the enzyme is UNCHANGED and can be RE-USED
a single enzyme can work on about a thousand substrates per second
most enzymes can catalyze both the forward and the reverse reactions
the enzyme catalyzes the reaction in the direction of equilibrium
adding more substrate can increase the number of reactions
however eventually every enzyme will be working at full capacity
temperature and pH are environmental factors for optimal enzyme activity
as a protein enzymes have conditions under which it works optimally
up to a point
, the velocity of an enzymatic reaction increases with increasing temperature due to the increased movement of the molecules
optimal temperature allows for the greatest number of reactions without denaturing the enzyme
enzymes also have optimal pH ranges where the enzyme is most active
pepsin is an enzyme in the stomach - optimal pH 2
pepsin is a stomach enzyme - optimal pH is 2
trypsin is an enzyme in the intestine where it is more basic - optimal pH of 8
when the enzymes are out of their normal range either a pH or a temperature that is too high or to low they will denature
denaturation causes a change in shape to the enzyme
remember shape determines function
change in shape = change in ability to do its job
substrate can no longer "fit"
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