Metabolism:  Energy and Enzymes

Chapter 6

LAB

Thurs 9/17*next week! Be there!Tues 9/22: Unit test: Ch 2,3, & 6 QOD notebook due

Lab 136 http://www.calstatela.edu/univ/ppa/campus_map.pdf

Biological Science buildingroom 136

-13 on mapextra 5 min to get there

Quiz Next Timemacromolecules

http://www.lachsa.net/apps/pages/index.jsp?uREC_ID=383647&type=u&pREC_ID=

507658

MATCHINGa.  carbohydrate     b.  lipidsc.  protein               d.  nucleic acids

1.  contains adenine and thymine2.  lactose3.  chains of amino acids4.  long term energy storage5.  cholesterol6.  chains of fatty acids and glycerol7.  plant cell walls

Energy = the ability to do workKinetic Energy (energy of motion)Potential Energy (stored energy)

First Law of Thermodynamics - the law of conservation of energy (not created or destroyed) Second Law of Thermodynamics - energy cannot be changed without a loss of usable energy (heat)

http://youtube.com/v/Jnj8mc04r9E

QODStaple/tape is the macromolecule graphic organizer as last QOD

Reactants: starting substances, on the left side of the arrow.

Products: substances formed during the reaction, on the right side of the arrow.

Baking soda + vinegar

Reactants Products

water + CO2

Chemical Reaction

What are the reactants and products?

6CO2 + 6H2O C6H12O6

Reactants Products

H2O2 H2O + O2

Reactants Products

http://www.youtube.com/watch?v=Fz9eV-EWtpY

Metabolic ReactionsReactants --> Products 

Exothermic - releases energy 

Endothermic = absorbs energy

Chemistry in Biology

This reaction is exothermic and released heat energy.

Aka: exergonic

The energy of the product is lower than the energy of the reactants.

Chapter 6

Chemistry in Biology

This reaction is endothermic and absorbed heat energy.

Aka: endergonic

The energy of the products is higher than the energy of the reactants.

6.2 Chemical Reactions

Chapter 6

Gibbs free energy change:

Metabolic Pathways & Enzymes (6-3)

Enzyme - protein molecule that functions as an organic catalyst to speed reactions

Substrate - reactants in the enzymatic reaction, this is what an enzyme attaches to

Activation Energy- the energy required to cause the reaction

Chemistry in Biology

activation energy: the minimum amount of energy needed for a reaction.

Enzymes lower the activation energy

Energy of Reactions

Enzymes do not affect the Gibbs free energy change, just the activation energy

Properties of Enzymes:

•Enzymes are made of proteins.

•They speed up chemical reactions inside the cytoplasm.

•They are needed only in small amounts

•They remain unchanged after each reaction and can therefore be reused

•Each enzyme is specific for a substrate

Chemistry in Biology

Substrates: reactants that bind to the enzyme

active site: specific location where a substrate binds on an enzyme

Chapter 6

Lock and Key Model

Each enzyme acts on a specific substrate

Induced Fit Model - substrates and enzymes fit together like a lock and key. 

Degradation vs Synthesis                 breaking down vs building

Factors Affecting Enzymatic Speed1. Substrate concentration2. Temperature & pH *3. Enzyme concentration

Enzymes can be denatured - they change shape so much that they are no longer effective. High temp or pH can cause denaturation. 

Siamese cats have an enzyme that works at lower temperatures only, causing the nose and ears to become a darker color than the rest of the body.

Enzymatic Inhibition - when a substance binds to an enzyme and decreases its activity. (Usually reversible)

Competitive Inhibition vs.

Noncompetitive Inhibition (allosteric site)

**Both are forms of feedback inhibition

http://youtube.com/v/PILzvT3spCQ

Normal

competitive

Non-

competitive

Inhibited:

http://youtube.com/v/PILzvT3spCQ

Some inhibitors are NOT reversible - poisons like cyanide, lead poisoning all affect enzymes

QUESTION: What type of inhibition is pictured below?

Both cofactors and coenzymes help to complete the structure of a conjugated enzyme

CO-ENZYME is a small organic non-protein MOLECULE that carries chemical groups between enzymes

ex: iron, magnesium or zinc.

CO-FACTOR is a non-protein CHEMICAL COMPOUND that is bound tightly to an enzyme and is required for catalysis.

ex: NAD+, NADP+ and FAD+

Enzyme Animation (Tutorial) 

http://www.stolaf.edu/people/giannini/flashanimat/enzymes/prox-orien.swf

Enzyme Quiz

http://www.sciencegeek.net/Biology/review/U2Enzymes.htm

Enzyme Lab

  2H2O2 ----> 2H2O + O2

Hydrogen Peroxide is broken down by the enzyme catalase within cells.   

Potatoes hold the enzyme catalase, which will speed up the breakdown of hydrogen peroxide

Proteins have four shapes1. Primary Structure - sequence of amino acids that form the polypeptide chain2. Secondary Structure - Parts of the polypeptide fold into local patterns (alpha helix or pleated sheet)3. Tertiary Structure - the overall 3D shape (globular or fibrous)4. Quaternary Structure - consists of two or more polypeptide chains or subunits

Factors Affecting Enzymatic Speed1. Substrate concentration2. Temperature & pH *3. Enzyme concentration

Enzymes can be denatured - they change shape so much that they are no longer effective. High temp or pH can cause denaturation. 

The activity of catalase can be seen by the bubbling of oxygen during the reaction

Generally speaking, catalase reactions occur faster at warmer temperatures.

If temperature is too hot (boiling) then the enzyme becomes denatured

Virtual Labs with Enzymes

McGraw Hill LabBio 114  EnzymesLab Bench Enzyme Catalysis

ADP

ATP

Ribose (sugar)

rele

ase

ener

gy

Ad

d

ener

gy

Diphosphate

Energy stored in ATP is released by breaking the bond between the 2nd and 3rd phosphates.

Copyright Pearson Prentice Hall

ATP

Energy stored in ATP is released by breaking the bond between the 2nd and 3rd phosphates.

P

ADP

2 Phosphate groups

ATP - the energy currency of cells (adenosine triphosphate) 

Functions:1. CHEMICAL WORK - Supplies energy needed to make macromolecules that make up the cell (and organism)2. TRANSPORT WORK - Supplies energy needed to pump substances across the cell membrane3. MECHANICAL WORK - supplies energy needed to make muscles contract and other cellular parts to move (flagella)

How do cells make ATP?

• Cellular respiration• Photosynthesis• Electron transport chain

Chemiosmosis= production of ATP due to hydrogen ion gradient across a membrane

ATP

redox reaction: oxidation-reduction reaction

oxidized loses electrons, releasing energya molecule that is reduced gains electrons, storing energy

ADP + P ATP NAD+ + 2e- + H+ NADP

https://www.khanacademy.org/science/biology/cellular-molecular-biology/cellular-respiration/v/oxidation-and-reduction-from-biological-view

Review videos

https://www.youtube.com/watch?v=ok9esggzN18 https://www.youtube.com/watch?v=5GMLIMIVUvo

FRQ: free response question- there are long and short versions- I have to be able to read your writing- they often ask for interpretation of data

Interpreting graphs:

QOD: write at least a sentence per graph, interpreting the data in graph

FRQ example: An experiment was conducted to measure the reaction rate of the human salivary enzyme α-amylase. Ten mL of a concentrated starch solution and 1.0 mL of α-amylase solution were placed in a test tube. The test tube was inverted several times to mix the solution and then incubated at 25°C. The amount of product (maltose) present was measured every 10 minutes for an hour. The results are given in the table below.

(c) Draw and label another line on the graph to predict the results if the concentration of α-amylase was doubled. Explain your predicted results. (d) Identify TWO environmental factors that can change the rate of an enzyme-mediated reaction. Discuss how each of those two factors would affect the reaction rate of an enzyme.

(a) Graph the data on the axes provided and calculate the rate of the reaction for the time period 0 to 30 minutes. (b) Explain why a change in the reaction rate was observed after 30 minutes.

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