Enzymes! Biology Intro Video https://www.youtube.com/watch?v=XTUm- - - PowerPoint PPT Presentation

Enzymes!

Biology

Intro Video

• https://www.youtube.com/watch?v=XTUm-

75-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.

• 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.

Specific Terminology

• 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=3Tn- 7JcZJuQ&ebc=ANyPxKroxLtgDhGJngKVMtc5s- x0rTynj- TXwGMvf4hSY5G_i7nJkJc9ampYnrF6krm- 1RzRCN8DzYTBNcZTRYSUG_AquKdc8g&spfrelo ad=10

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.

• 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-your-

cupboard%2Fvanish%2F8&psig=AFQjCNFN6wFjYVL_Vc6UFl- cb2Bf7Iu5Ag&ust=1456875515003082

• 3. Concentration of Enzyme or

Substrate

• As the enzyme

concentration increases, the rate of reaction increases.

If enzyme concentration is low, the reaction is slow.

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

• ratory/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 ADP

 3 phosphates  High energy  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 Vo

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