Download Enzymes and ATP

Enzymes!
Biology
Intro Video
• https://www.youtube.com/watch?v=XTUm75-PL4
• An enzyme is a protein that functions as a catalyst
to speed up a chemical reaction in the body.
• Continuously recycled over and over again.
• Biological catalyst: speed up rates of reactions
inside the cytoplasm.
• They control the rate of metabolic reactions in the
body.
• They lower activation energy (energy needed to
get a reaction started).
• They weaken chemical bonds so molecules can be
made or broken down by the body.
• Highly specific: catalyze only one chemical reaction
at a time and they have a specific substrate.
Specific Terminology
• Substrate : the reactant in the chemical reaction
that is catalyzed by the enzyme, the substance that
is changed.
• Active Site: the region on the enzyme where the
substrate attaches. The shape of the active site
changes based on the substrate.
• Product: what is created after the chemical
reaction has occurred.
• Many enzymes have an “ase” ending.
• A few popular ones:
– Catalase-> breaks down hydrogen peroxide in eukaryotic
cells
– Sucrose (table sugar) -> sucrase
– Lipids-> lipase
– Proteins-> Proteases
– Amylase-> human saliva, helps break down starch
(amylose)
– Lactose -> Lactase
– DNA helicase-> unzips the double stranded DNA molecule
for replication
– DNA polymerase-> enzymes that create DNA molecules by
assembling nucleotides
Fun Fact!
• Catalase breaks down hydrogen peroxide in
eukaryotic cells.
• It’s estimated that 40 million hydrogen
peroxides go into a catalase enzyme every
second.
• Hydrogen peroxide is toxic to our cells in
large quantities
https://www.youtube.com/watch?v=3Tn7JcZJuQ&ebc=ANyPxKroxLtgDhGJngKVMtc5sx0rTynjTXwGMvf4hSY5G_i7nJkJc9ampYnrF6krm1RzRCN8DzYTBNcZTRYSUG_AquKdc8g&spfrelo
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Enzyme Substrate Complex
• Steps:
– 1. Substrate binds to the enzyme at the active site.
– 2. The substrate is changed by the enzyme and converts
the reactants into products.
– 3. Products are released into the body.
– 4. Once the products are released, the active site is
ready for another molecule (substrate) to bind to.
– 5. The process is ongoing, it never stops.
• This is often referred to as the “Lock and Key
Model” or the “Enzyme Substrate Complex”
• The shape of the active site (“the lock”)
determines which substrate (“the key”) will
“fit” into the enzyme.
• Lowers activation energy so that the product can form
and the chemicals can spontaneously break apart.
• Picture from Biology Holt McDougal text, 2012
Factors that Affect Enzymes
• 1. Temperature:
• As temperature increases, kinetic energy
increases, and molecules move around a lot
more. The more they move around, the higher
the probability that an enzyme and a substrate
will bind together and react.
– Enzymatic reactions increase with an increase in
temperature.
TOO HOT: The
enzyme
denatures / falls
apart.
TOO COLD:
Enzymes work
slowly or not at
all!
Optimal
temperature is
where the enzyme
works best!
98.6 F or 37 C
pH
• Works best at a certain pH.
– Sensitive to changes in pH, especially acidity
– Too low or too high, the enzyme will DENATURE
(fall apart).
https://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ve
d=0ahUKEwjv66SYoJ7LAhXMGR4KHez1CdMQjB0IBg&url=http%3A%2F%2Fwww.rsc.org%2Flearn
-chemistry%2Fresources%2Fchemistry-in-yourcupboard%2Fvanish%2F8&psig=AFQjCNFN6wFjYVL_Vc6UFlcb2Bf7Iu5Ag&ust=1456875515003082
3. Concentration of Enzyme or
Substrate
If enzyme concentration
is low, the reaction is
slow.
• As the enzyme
concentration
increases, the
rate of reaction
increases.
http://www.rsc.org/Education/Teachers/Resou
rces/cfb/enzymes.htm
• As the
substrate
increases, the
reaction
increases, up
to a certain
point (enzyme
is limited).
http://faculty.clintoncc.suny.edu/faculty/micha
el.gregory/files/bio%20101/bio%20101%20lab
oratory/enzymes/enzymes.htm
Activity / Homework
• Complete the Enzyme- Substrate
Manipulation Activity
Enzyme Substrate Complex: Graphing
and Manipulative Lab
Videos
• https://www.youtube.com/watch?v=NdMVRL
4oaUo
• https://vimeo.com/86362472
ATP & Energy
Our main energy currency
•
•
•
•
ATP= Adenosine Triphosphate
Macromolecule: Nucleic Acid
Organelle: Mitochondria
Main Function: Main energy currency in all
living things.
• Comes from: breakdown of glucose
(carbohydrates).
Structure: Made up of adenine,
ribose, and three phosphates
Differences
ATP
 3 phosphates
 High energy
ADP
 2 phosphates
 Low energy
phosphate removed
• Fats store the most energy.
– 80 % of the energy in your body.
– About 146 ATP molecules from a triglyceride.
• Proteins are the least likely to be broken down to
make ATP because they have so many different
functions.
– Amino acids are not usually needed for energy.
– About the same amount of energy as a carbohydrate.
• Carbohydrates are the molecules most commonly
broken down to make ATP.
– Not stored in large amounts.
– Up to 36 ATP is created from one glucose molecule.
Of course it all starts with
photosynthesis, and then organisms
take it in via cellular respiration
• What if there isn’t any sunlight? Where does
the energy come from?
– Chemosynthesis: process by which organisms use
chemical energy to make their food.
– Where does this occur?
• Deep sea hydrothermal vents.
https://www.youtube.com/watch?v=XotF9fzo4
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Review Questions
• 1. Explain in your own words, what is occurring in the ATP / ADP cycle.
• 2. Describe two functions of catalysts in chemical reactions.
• 3. The substrate is also known as the _________________ in a
chemical reaction.
• 4. List three ways in which enzymes can be altered.
• 5. Some organisms live in very hot or very acidic environments. Would
their enzymes function in a person’s cells? Why or why not?
• 6. Suppose that the amino acids that make up an enzyme’s active site
are changed, how might this change affect the enzyme?
• 7. What is the main function of ATP?
• 8. How do we obtain ATP?
• 9. Which organic molecule is used by the body as a good source of long
term energy storage?
• 10. Proteins are composed of chains of ______________________
Label the Diagram