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Section 2.5. Key Concept: Enzymes lower the activation energy for chemical reactions in living things. What Are Enzymes?. Enzymes are a special group of protein molecules which speed up chemical rxns in living cells by lowering the activation energy (E A ). Fun Facts about Enzymes.
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Section 2.5 Key Concept: Enzymes lower the activation energy for chemical reactions in living things
What Are Enzymes? • Enzymes are a special group of protein molecules which speed up chemical rxns in living cells by lowering the activation energy (EA)
Fun Facts about Enzymes • Make rxns go 10 trillion times faster – 1500 yrs vs. 5 seconds • Are not living • Are reusable • There are about 2000 different enzymes in each one of your cells • Names usually end in -ase
How do enzymes work? • Each enzyme has a unique 3-D shape, including a surface groove called an ACTIVE SITE. • One or more molecules called SUBSTRATES chemically bond to the enzyme’s active site. • When joined they are called an ENZYME-SUBSTRATE COMPLEX • Changes in how the atoms are bonded occur resulting in new molecules being made called PRODUCTS . • Products are then released from the active site.
How enzymes make rxns go faster Enzymes work by reducing the amount of energy needed (EA) for the bonds in the substrate molecules to break
Enzyme Enzyme-Substrate Complex The reactant an enzyme acts on is specifically called the _________. Joins Substrate
Enzyme ______ _____ • A specific regionof an enzyme molecule which binds to the substrate. Active Site Substrate
EnzymeAnimation : Gary E. Kaiser http://student.ccbcmd.edu/biotutorials/proteins/enzsub.htmlView : http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_enzymes_work.html
An enzyme flick Let the show begin....
General Types of Enzymes • Amylases – break starch to glucose • Lipases – break lipids to fatty acids and glycerol • Proteases – • break proteins to amino acids • Nucleases – break nucleic acids DNA and RNA to nucleotides
Shape of a Protein • An enzyme fits with its specific substrate like a “lock and key”
DENATURE IT! Means it loses its 3D shape
Factors Affecting Enzyme Activity • Temperature • pH • Cofactors & Coenzymes • Inhibitors
Temperature & pH • Enzymes work best at specific temperatures • This is why very high fevers are so dangerous. They can cook the body’s proteins • Enzymes usually work best between pH 6 - 8
Coenzymes & Cofactors • Molecules that are needed by the enzyme to work properly. • Many are vitamins and mineralsubstances (zinc, iron, copper, vitamins) Image: EnzymeCofactor : Public domain Wiki, Ribbon-diagram showing carbonic anhydrase II. The grey sphere is the zinc cofactor in the active site.
Diseases due to enzyme damaged or missing • Lactose intolerance Phenylketonuria • Lacking lactase
Enzyme Competitive inhibitor Enzyme Inhibitors Chemicals that resemble an enzyme’s normal substrate and compete with it for the active site. Substrate
1. Competitive inhibitors: Resemble an enzyme’s normal substrate and compete with it for the active site. Image: Competitive Inhibition : www-biol.paisley.ac.uk/.../chapter3_2.html
Inhibitors can also attach to another part of the enzyme causing the enzyme to change the shape of its active site. If its shape changes..it no longer works! Noncompetitive Inhibitor Enzyme active site altered Substrate
Enzyme Inhibitors Blocking an bacteria’s enzymes can kill it Many antibiotic drugs are enzyme inhibitors. Enzyme inhibitors are also used as weed and bug killers Images Dead Bug : www.kansas.gov/help_center/user_testing.html Prescription Drugs : www.patentdocs.us/.../08/by-kevin-e-noon.html
Enzymes are ____ ________ in the reactions they catalyze.Think of them as tiny machines in manufacturing. The more machines, the faster the accumulation of _________. Image: Wine Bottling : www.morrison-chs.com/timingscrews/index.html Wine Vats: www.lymebaywinery.co.uk/pages/about_us.htm
Formats for writing a chemical reaction. ( ________ ) _______ + ________ -----------> _________ ( ________ ) __________ -----------> ________ ________
Coenzyme : Vitamin B12 • Example: Most _________ are coenzymes essential in helping move atoms between molecules in the formation of carbohydrates, fats, and proteins. • Exclusively synthesized by ___________ (found primarily in meat, eggs and dairy products). Image: VitaminB12 : NIH, Public Domain www.nlm.nih.gov/.../ency/imagepages/19516.htm
Featured Enzyme #1: Catecholase • Catecholase is present in most ______ and __________. • It is the enzyme that facilitates the ________ of cut or bruised fruits and vegetables by catalyzing the following reaction: (______________) _________ + _____ ----------------- _____________ colorless substrate brown product
Featured Enzyme #1: Catecholase & Noncompetetive Inhibition _________ juice and other acids are used to preserve color in fruit, particularly apples, by lowering the ____ and removing the copper site (cofactor) necessary for the enzyme to function. catecholase catechol + O2 -------------------------- polyphenol colorless substrate brown product
Featured enzyme #2: Bromelain • Pineapple contains enzyme bromelain, which can _______ _________. • Jell-O is made of gelatin, a processed version of a structural protein called _________ that is found in many animals, including humans. • Collagen big, fibrous molecule makes skin, bones, and tendons both strong and elastic. • Gelatin you eat in Jell-O comes from the collagen in cow or pig bones, hooves, and connective tissues. (Yummie!) • Examine 2 containers: a. In one, canned pineapple was used to make jello. b. The other, fresh pineapple was used.
