Proteins Slides
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Transcript of Proteins Slides
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PROTEINS
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ProteinsA protein is made of monomers called amino acids
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ProteinProtein structure is determined by the number and order of amino acids
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Protein StructureThe structure of proteins are important because
1. Proteins make up what our cells look like
2. Proteins carry out important functions in the cell
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Special Proteins
Proteins that catalyze reactions (which means speed up reactions) are called enzymes
Examples of enzymes picture
Tyrosinase Hydrolase Lactase
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Four Levels of Protein Structure
Primary Structure (1o structure)
The order and number of amino acids strung together aka a polypeptide chain.
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Four Levels of Protein Structure
Secondary Structure (2o structure)
Common shapes found in all proteins made from hydrogen bonds such as alpha helices and beta pleated sheets
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Four Levels of Protein Structure
Tertiary Structure (3o structure)
The three dimensional (3-D) structure of amino acids
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Four Levels of Protein Structure
Quaternary Structure (4o structure)
2 or more polypeptides that are folded in a 3D shape and combined together
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Warm-up* Check bacteria paintings in incubator
What are special proteins that speed up reactions called?
Study Guide Questions
#2 What is the general equation for photosynthesis
#7 What are the 3 differences between mRNA and DNA
#10 What is mRNA and tRNA? What is their structure and function in the cell?
Announcements:
Participation Pts announcement
Honors HW due Tomorrow
9 Days until Exam
Lab Notebooks
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Protein Function• Made by all living things to perform these
functions:o Structural: Hair and muscleso Immunity: Antibodieso Signaling and communication:
Neurotransmitters and hormones.o Transport: Ion channelso Enzymes: Catalyze (speed up) biochemical
reactions
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Enzymes in our daily lives:
PROTEASE
HYDROLASE LACTASE
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Enzymes are the ConstructionWorkers of the Cell…
Enzymes help BUILD UP or BREAK DOWN
molecular structures
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Catalysts• Catalysts speed up chemical reactions by lowering the
activation energy and are not used up in the reaction.
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How do catalytic enzymes work?• Substrate binds a region of the enzyme called the active
site (a pocket formed by the folding of the protein enzyme that is highly specific for the substrate).
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Enzymes are usually named with the suffix –ase added to the name of the substrate or reaction
Inhibitorsslow downenzymes!
Paperclipase Toothpickase
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Changing how enzymes work
We can change the enzymes ability to catalyze (speed up) a reaction in two ways:
1. Denaturation – protein unfolding into the 1o structure
2. Inhibition – preventing an enzyme from functioning 1. Competitive inhibitors – block the active site so that the substrate
can not bind
2. Non-competitive inhibitors - bind to the enzyme and make them unable to bind the substrate
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Why care about enzymes?• Enzyme that helps muscle cells communicate with the
nervous system.• Nerve Gas inhibits acetylcholinesterase
o Enzyme is used to break down the neurotransmitter acetylcholine. o When it is inhibited, paralysis and death follow.
http://ucsdnews.ucsd.edu/newsrel/health/nihgrants06.asp
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Why care about enzymes?Myasthenia Gravis is an autoimmune disease that causes an individual to suffer from severe muscle weakness. This weakness is caused by a decreased amount of nicotinic acetylcholine receptors in the neuromuscular junction. These receptors normally are activated by the neurotransmitter acetylcholine, which is also deactivated by an enzyme called acetylcholinesterase. By inhibiting acetylcholinesterase, more acetylcholine is available to the receptors and a normal ratio of receptors to neurotransmitters is established and the muscles can function normally. In this video a myasthenic dog, who normally has trouble walking, is treated with an acetylcholinesterase inhibitor and can walk and even run normally until the inhibition wears off.
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ENZYME LAB
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Objective
To extract the enzyme Tyrosinase from a Portobello mushroom in order to test the reaction rate of the enzyme in normal conditions and compare it to conditions where the enzyme is exposed to inhibitors, increased temperature, or changes in pH.
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The Enzyme Tyrosinase
Tyrosinase is an enzyme that causes pigmentation in apples, skin, hair, etc.
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The Enzyme Tyrosinase
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The Enzyme Tyrosinase
Albinism
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Heat-Sensitive Tyrosinase
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The Reaction
General Enzyme-Substrate Reaction
Enzyme + Substrate = Product + Enzyme
General Tyrosinase ReactionTyrosinase + L-DOPA = Dopachrome + Tyrosinase
+=
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The Lab
3 Main Parts of the Tyrosinase Enzyme Lab1. Enzyme Extraction
2. Control Reaction
3. Experimental Reaction
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The Lab – Enzyme Extraction
1a. Break open the cell to free Tyrosinase
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The Lab – Enzyme Extraction
1b. Filter out the solid chunks of mushroom
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The Lab – Control Reaction
4 roles (demo):
- Mixer - Reader
- Timer - Recorder
Tyrosinase + L-DOPA = Dopachrome + Tyrosinase
+=
0.1 mlENZ CTL CTL
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Tyrosinase + L-DOPA = Dopachrome (pigment)
Measure Product
Enzyme Substrate Product+ =
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The Lab – Experimental Trials3 Different Experimental Trials
- pH
- Inhibitor
- Temperature
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The Lab – Experimental Trial
pH
Tyrosinase + L-DOPA = Dopachrome + Tyrosinase
+=
0.1 ml
- Test the pH of L-DOPA- Test the pH of L-DOPA after you add HCl- Start the reaction
HCl
?ENZ EXP EXP
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Tyrosinase + L-DOPA + HCl = Dopachrome (pigment)
Measure Product
Enzyme Substrate Product+ =
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The Lab – Experimental Trial
Inhibitor
- Add Inhibitor
- Start the reaction
Tyrosinase + L-DOPA = Dopachrome + Tyrosinase
+=
0.1 ml
Inhibitor
?EXP EXPENZ
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Tyrosinase + L-DOPA + INH = Dopachrome (pigment)
Measure Product
Enzyme Substrate Product+ =
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The Lab – Experimental TrialTemperature
-Heat 0.1 ml of L-DOPA in EXP tube for 1 min. in water
- Add L-DOPA and start the experiment
0.1 ml Tyrosinase
L-DOPA
=
?
EXP EXP
EXP
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Tyrosinase + L-DOPA + Heat = Dopachrome (pigment)
Measure Product
Enzyme Substrate Product+ =
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Graphing!X = time in seconds
Y = mM of Dopachrome
10 30 50 80 120
160
240
360
0
0.5
1
1.5
2
2.5
Sample Control Enzyme Reaction
Control Enzyme Reaction