The Chemistry of Life Chapter 2 Section 2-3 and 2-4

The Chemistry of Life Chapter 2 Section 2-3 and 2-4

Carbon Compounds Section 2-3
Demonstration of denaturing proteins – cook an egg; bee sting cure by tenderizer

Learning Objectives List characteristics of carbohydrates, lipids, nucleic acids and proteins Describe basic nucleotide structure Explain the special role of nucleic acids in heredity and cellular control Explain why molecular structure and shape is crucial to life – it determines how most molecules recognize and respond to each other

Assignments Read Section 2-3
Complete Chapter 2 Chapter Notes through Section 2-3 Read Section 2-4

Protein – Green atoms are carbon
Protein above is a computer graphic image. It is an example of a large, complex molecule based on carbon, the green atoms. The Chemistry of Carbon

The Chemistry of Carbon
Cells are 70-95% water, the rest consists mostly of carbon-based compounds Proteins, DNA, carbohydrates, and others All composed of carbon atoms bonded to each other and to atoms of other elements These other elements commonly include hydrogen (H), oxygen (O), nitrogen (N), sulfur (S), and phosphorus (P)

“Carbon is a girls best friend”
Depression is a mental illness that is sometimes treated with lithium. Carbon is recycled naturally on Earth in a cycle called the carbon cycle. A substrate is something that forms a base for something else to be put on. Allotrope is any of the forms that an element may come in.

Organic chemistry The study of carbon compounds, focuses on any compound with carbon (organic compounds). The term organic is archaic Though organic compounds implies that these compounds can only come from biological processes, they can be synthesized by non-living reactions

Organic compounds Any compound with carbon is said to be organic CO2 to CH4 to proteins and nucleic acids

History of Organic Chemistry Began with attempts to purify and improve the yield of products from other organisms. First learned to synthesize simple compounds in the laboratory, but they had no success with more complex compounds.

Swedish chemist Berzelius made a distinction between organic compounds that seemed to arise only in living organisms and inorganic compounds from the nonliving world. This led early organic chemists to propose vitalism, the belief in a life outside the limits of physical and chemical laws.

Support for vitalism began to sink as chemists synthesized more complex organic compounds in the laboratory. Early 1800s, German chemist Friedrich Wöhler synthesized urea in lab from totally inorganic starting materials.

Herr Doktor Frederich Wöhler

Milestones in organic chemistry 1856 – an attempt to manufacture anti-malarial drug quinine led to accidental discovery of a carbon-based dye, Perkin’s mauve 1874 – DDT Dichloro-Diphenyl-Trichloroethane (insecticide properties not discovered until later) 1890’s – Aspirin (acetylsalicylic acid) by Bayer AG of Germany

1953, Stanley Miller at the University of Chicago was able to simulate chemical conditions on the primitive Earth to demonstrate the spontaneous synthesis of organic compounds.

Organic chemists finally rejected vitalism and embraced mechanism. all natural phenomena, including the processes of life, are governed by the same physical and chemical laws.

Organic chemistry was redefined as the study of carbon compounds regardless of origin. Still, organisms produce most organic compounds in an amazing diversity and complexity. However, the same rules apply to inorganic and organic compounds alike.

Organic chemistry The term “organic” is an archaic or obsolete term held over from the old days when all chemical compounds were divided into two classes: Inorganic – derived from the nonliving Organic – derived from living For convenience sake, the terms are still used today.

Organic chemistry “Organic chemistry is the chemistry of carbon compounds. Biochemistry is the study of carbon compounds that crawl.” Mike Adams

What is the structure of the carbon atom? With a total of 6 electrons, a carbon atom has 2 in the first shell and 4 in the second shell.

How does carbon’ s structure relate to its chemical behavior? Like any atom, carbon will tend to form chemical bonds with other atoms to fill up its valence shell Like any atom, carbon valence shell has a maximum capacity of eight electrons Therefore, carbon will tend to form chemical bonds with other atoms to “share” their electrons to fill up its valence shell.

How does carbon’ s structure relate to its chemical behavior? Carbon usually completes its valence shell by sharing electrons with other atoms in four covalent bonds. This tetravalence by carbon makes large, complex molecules possible. Carbon has little tendency to form ionic bonds by loosing or gaining 4 electrons.

Carbon’ s structure makes it themost versatile building blocks of molecules. C

The electron configuration of carbon Gives it covalent compatibility with many different elements H O N C Hydrogen (valence = 1) Oxygen (valence = 2) Nitrogen (valence = 3) Carbon (valence = 4)

Inorganic compounds are not based on carbon: A “C” will not be part of their molecular formula Salts, water, phosphates, sulfates, etc. NaCl, H2SO4, HCl, etc Yet organic living things get needed elements in the form of inorganic compounds.

From one organism to the next No real difference in the overall percentages of the major elements of life (C, H, O, N, P, and S). Yet because of carbon, the diversity of molecules is not limited

Key part of carbon compound diversity is the formation of carbon chains Carbon atom covalently bonding to carbon atom covalently bonding to carbon atom… Carbon chains form the carbon skeletons of most organic molecules. Vary in length and may be straight, branched, or arranged in closed rings. May also include double bonds.

Ring Structure Carbon skeletons Double bond

Naming carbon ring structures (just kidding!)

Macromolecules Cells join smaller organic molecules together to form larger molecules, known as Macromolecules, may be composed of thousands of atoms and weigh over 100,000 daltons

Macromolecules Daltons
Dalton is unit of measurement equivalent to atomic mass units One dalton = one atomic mass unit (amu) Periodic table displays the atomic mass of the atoms of the elements in amu

Macromolecules Three of the four classes of macromolecules form chainlike molecules called polymers. Polymers consist of many similar or identical building blocks linked by covalent bonds. The repeated units are small molecules called monomers. Some monomers have other functions of their own.

How are links in a chain like monomers?

Macromolecules Figure 2-13
When small molecules called monomers join together, they form polymers, or large molecules.

Macromolecules We shall explore the structure and function of the four major classes of macromolecules which are: Carbohydrates Lipids Proteins Nucleic acids

Carbohydrates Carbon, hydrogen and oxygen atoms in a 1:2:1 ratio
Food molecule – source of energy Energy is stored when chemical bonds are formed – some bonds store more than others Energy released when chemical bonds break Digestion of carbohydrates, such as pasta and bread, break these bonds are release the energy Also used as a structural molecule

Carbohydrates Each six sided shape is a glucose molecule.
Glucose is the monomer - monosaccharide in a starch polymer - polysaccharide

Carbohydrates Hydrogen bonds between OH groups of carbons 3 and 6

Carbohydrates Cellulose is difficult to digest
Cows have microbes in their stomachs to facilitate this process

Chitin – important structural polysaccharide
used in the exoskeletons of arthropods (including insects, spiders, and crustaceans). similar to cellulose, except that it contains a nitrogen-containing appendage on each glucose. Pure chitin is leathery, but the addition of calcium carbonate hardens the chitin. Used to make strong, flexible surgical thread that decomposes after the wound heals. Chitin also forms the structural support for the cell walls of many fungi.

Lipids Not generally soluble in water
Mostly carbon and hydrogen atoms; also oxygen Fats, oils and waxes, plus some steroids (hormones) The job of a lipid is to: Store energy Give structure to cell membranes As steroids, function as a chemical messenger

Lipids Glycerol Fatty Acid

The three fatty acids in a fat can be the same or different.
Fatty acids may vary in length (number of carbons) and in the number and locations of double bonds. If there are no carbon-carbon double bonds, then the molecule is a saturated fatty acid - a hydrogen at every possible position.

If there are one or more carbon-carbon double bonds, then the molecule is an unsaturated fatty acid - formed by the removal of hydrogen atoms from the carbon skeleton. Saturated fatty acids are straight chains, but unsaturated fatty acids have a kink wherever there is a double bond. Fig. 5.11b

Lipids Fats with saturated fatty acids are saturated fats.
Most animal fats are saturated. Saturated fats are solid at room temperature. A diet rich in saturated fats may contribute to cardiovascular disease (atherosclerosis) through plaque deposits.

Lipids Fats with unsaturated fatty acids are unsaturated fats.
Plant and fish fats, known as oils, are liquid are room temperature. The kinks provided by the double bonds prevent the molecules from packing tightly together.

Lipids Major function of fats is energy storage.
One gram of fat stores more than twice as much energy as a gram of a polysaccharide. Humans and other mammals store fats as long-term energy reserves in adipose cells. Plants use starch for energy storage when mobility is not a concern but use oils when dispersal and packing is important, as in seeds.

Lipids Fat also functions to: Cushion vital organs.
Insulate the organism against the environment. This subcutaneous layer is especially thick in whales, seals, and most other marine mammals

Nucleic Acids Contain carbon (C), hydrogen (H), oxygen (O), nitrogen (N) and phosphorus (P) Function as the hereditary molecule Two forms RNA – ribonucleic acid DNA – deoxyribonucleic acid Individual monomers are called nucleotides

Nucleic Acids Five carbon sugar molecule (gray)
Nitrogenous base (green) Phosphate group (blue) Thousands of these monomers may be linked by covalent bonds to create DNA or RNA

RNA vs DNA Key difference in structure RNA contains the sugar ribose
DNA contains the sugar deoxyribose Do you see the difference?

Nucleic Acids How nucleic acids function to store and transmit heredity information will be covered later in the year.

Activity Building Model of DNA Double Helix
STUDENT Activity Building Model of DNA Double Helix Students will build a model of the DNA double helix using the Kinex model system One of the most spectacular chemistry demonstrations is also one of the simplest. It's the dehydration of sugar (sucrose) with sulfuric acid. Basically, all you do to perform this demonstration is put ordinary table sugar in a glass beaker and stir in some concentrated sulfuric acid (you can dampen the sugar with a small volume of water before adding the sulfuric acid). The sulfuric acid removes water from the sugar in a highly exothermic reaction, releasing heat, steam, and sulfur oxide fumes. Aside from the sulfurous odor, the reaction smells a lot like caramel. The white sugar turns into a black carbonized tube that pushes itself out of the beaker. Here's a nice youtube video for you, if you'd like to see what to expect.

Proteins Proteins may Control the rate of chemical reactions
Form muscles and bone Others transport materials in and out of cells Still others fight disease

Proteins Structural proteins – support
Storage proteins – storage of amino acids Transport proteins – transport of other substances Hormonal proteins – coordination of activities Receptor proteins – response of cell to chemical stimuli

Proteins Contractile proteins – movement
Defensive proteins – immune response (antibodies) Enzymatic proteins – selective acceleration of chemical reactions

Proteins

Proteins Polypeptides Are polymers of amino acids A protein
Consists of one or more polypeptides An amino acid Is only a monomer; a single molecule It is not protein

Proteins Amino acids Are organic molecules possessing both carboxyl and amino groups Differ in their chemical properties due to differing side chains, called R groups

Proteins

20 different amino acids make up proteins
Amino Acid Monomers 20 different amino acids make up proteins O O– H H3N+ C CH3 CH CH2 NH H2C H2N Nonpolar Glycine (Gly) Alanine (Ala) Valine (Val) Leucine (Leu) Isoleucine (Ile) Methionine (Met) Phenylalanine (Phe) Tryptophan (Trp) Proline (Pro) H3C S

Amino Acid Monomers Polar Electrically charged Serine (Ser)
OH CH2 C H H3N+ O CH3 CH SH NH2 Polar Electrically charged –O NH3+ NH2+ NH+ NH Serine (Ser) Threonine (Thr) Cysteine (Cys) Tyrosine (Tyr) Asparagine (Asn) Glutamine (Gln) Acidic Basic Aspartic acid (Asp) Glutamic acid (Glu) Lysine (Lys) Arginine (Arg) Histidine (His)

Proteins There are 20 amino acid monomers that put together polypeptides. Because the amino acids have different R groups, they can have different chemical properties. Polar vs. nonpolar

Proteins R groups, assembled in a polypeptide, will interact with each other – attracted or repelled. R group interactions determine the polypeptide 3D shape. Protein shape makes protein function possible Shape follows function!

Proteins Just 20 amino acid building blocks? Even that few can create incredible diversity. Just do the math. How many polypeptides 4 amino acids long can be made from 20 amino acids? 204 or 20 x 20 x 20 x 20 = 160,000

Proteins Amino acids Are linked by covalent peptide bonds OH
DESMOSOMES OH CH2 C N H O Peptide bond SH Side chains H2O Amino end (N-terminus) Backbone (a) (b) Carboxyl end (C-terminus) Amino acids Are linked by covalent peptide bonds

Animation – Protein Synthesis

Proteins Proteins have four levels of organization
Primary – the linear sequence of amino acids Secondary – the amino acid chain twists and folds upon itself Tertiary – two or more protein chains link to each other by van der Waals weak bonds Quaternary – highest level; two or more tertiary units form weak bonds with each other

Four Levels of Protein Structure
– Amino acid subunits +H3N Amino end o Carboxyl end c Gly Pro Thr Glu Seu Lys Cys Leu Met Val Asp Ala Arg Ser lle Phe His Asn Tyr Trp Lle Primary structure Is the unique sequence of amino acids in a polypeptide

Secondary structure Is the folding or coiling of the polypeptide into a repeating configuration Relies on hydrogen bonds

Tertiary structure Overall 3-D shape of a polypeptide Results from interactions between amino acids and R groups CH2 CH O H O C HO NH3+ -O S CH3 H3C Hydrophobic interactions and van der Waals interactions Polypeptide backbone Hyrdogen bond Ionic bond Disulfide bridge

Quaternary structure Is the overall protein structure that results from the aggregation of two or more polypeptide subunits Polypeptide chain Collagen  Chains  Chains Hemoglobin Iron Heme

Summation of the four levels of protein structure.

Proteins Why is understanding these four levels of organization important? Shape is critical to protein functions! Lose the quaternary level means losing their shape – conformation – which means losing function Now think of bee sting venom and powered meat tenderizer…

Macromolecules You will now work together to learn what they are, what they do and how they are built.

Instructions Divide class into 4 person teams with one person for each macromolecule. Position teams in room corners. Each “macromolecule” will complete the worksheet column for their macromolecule. Macromolecules will then meet together; proteins with proteins, nucleic acids with nucleic acids, … These macromolecule groups share information to improve their work. Macromolecule groups will break up and return to original groups. Now all four will share their facts so that everyone completes the worksheet. Completed worksheets are collected (or completed at home). Preparation is completion of reading and chapter notes. Precede activity with PowerPoint review of content. Classes will be divided into eight person teams with two-persons paired for each macromolecule. Position pairs in room thusly, with pairs facing each other across desk: Carbs Nucleic Acids Carbs Nucleic Acids Proteins Lipds Proteins Lipids Each student pair will work together to complete the worksheet column for their macromolecule. Then within each team, the pairs will circulate. Lipids meet with Nucleic Acids and review their column with each other, one to one, recording the information on their own worksheet. Carboydrates meet with Proteins and review their column with each other, one to one, recording the information on their own worksheet. Then the pairs work to fill up the remaining columns. Completed worksheets are collected (or completed at home).

Summation List characteristics of carbohydrates, lipids, nucleic acids and proteins Describe basic nucleotide structure Explain the special role of nucleic acids in heredity and cellular control Explain why molecular structure and shape is crucial to life – it determines how most molecules recognize and respond to each other

Assignments Read Section 2-3
Complete Chapter 2 Chapter Notes through Section 2-3. Complete the Worksheet Section 2-3 / Due next class Read Section 2-4

Cornell Notes Using your Cornell Notes, you will now:
compare notes with a partner for one minute. write reflection in bottom space. possible open-notes quiz. Cornell Notes must be turned in on day of chapter test; they will be graded.

Cornell Notes Tonight Reread your Cornell Notes in the right column.
Review the ideas in the left column. Study your summary/reflection.

Chemical Reactions and Enzymes Section 2-4

Learning Objectives Given a chemical reaction, identify the reactants and products, and the coefficients. Distinguish between energy absorbing and energy releasing chemical reactions. Explain the concept of activation energy.

Learning Objectives Explain why molecular structure and shape is crucial to life – it determines how most molecules recognize and respond to each other. Explain why chemical reactions do not create new matter. Explain the relationship between concentration and the rate of reaction. Explain the importance of enzymes to biochemical reactions.

Assignments Complete Chapter 2 Chapter Notes through Section 2-4.
Complete the Worksheet Section 2-4 / Due next class

Chemical Reactions Chemical property – ability of a substance to undergo a specific chemical change Example – rust is a chemical reaction between iron and oxygen to create iron oxide Composition of matter always changes

Chemical Reactions No new matter is created or destroyed during a chemical reaction If you weighed all the matter of the reactants, and did the same for the products, their masses would be the same The number of atoms on both sides would be exactly the same The reactions must be “balanced.”

Chemical Reactions

Chemical Reactions Some chemical reactions go to completion; that is, all the reactants are converted to products Most chemical reactions are reversible, the products in the forward reaction becoming the reactants for the reverse reaction

Chemical Reactions Example: 3H2 + N2 <=> 2NH3
Hydrogen and nitrogen molecules combine to form ammonia, but ammonia can decompose to hydrogen and nitrogen molecules Initially, when reactant concentrations are high, they frequently collide to create products As products accumulate, they collide to reform reactants

Chemical Reactions How do we know a chemical reaction happened?
Clues one can sense Change in color Change in temperature / heat energy Gas production Formation of a precipitate

Demonstration: Chemical Reactions
TEACHER Polyurethane Foam Rainbow colors Mystery nylon polymer

Chemical Reactions Chemical reactions always require the breaking and forming of chemical bonds. Break bonds of reactants. Form new bonds in products.

Rust is a chemical reaction – Iron and oxygen reactants combine to form iron oxide product.

Photosynthesis: a solar-powered rearrangement of matter – Light energy
6CO2 + 6H2O -> C6H12O6 + 6O2 Photosynthesis is an important chemical reaction. Green plants combine carbon dioxide (CO2) from the air and water (H2O) from the soil to create sugar molecules and molecular oxygen (O2), a byproduct. This chemical reaction is powered by sunlight. Humans and other animals depend on photosynthesis for food and oxygen. The overall process of photosynthesis is 6CO2 + 6H2O -> C6H12O6 + 6O2 This process occurs in a sequence of individual chemical reactions.

Energy in Reactions Energy involved in any chemical reactions.
Break bonds, release energy. Form bonds, absorb energy.

Energy in Reactions Energy Capacity of a physical system to do work.
A system can have energy in a variety of forms, for example: kinetic energy due to its motion, potential energy due to the positions of the components, chemical energy stored in chemicals that can undergo a reaction.

Energy in Reactions Energy in biochemistry is:
stored when chemical bonds are formed. Released when chemical bonds are broken. Though biochemical systems always lost some energy as heat. The trick in biology is to set up systems that recapture, store and release energy in controlled circumstances.

Energy in Reactions Certain biochemical processes
unleash the energy stored in sugar molecules, recapture it with other molecules, and then use it to (re)build yet more molecules needed by the cell. Organisms take in energy from their surrounding – light energy or chemical energy from food molecules – and then release energy as heat or in waste molecules, such as carbon dioxide.

Energy Changes Energy Changes
Chemical reactions either release energy or absorb energy Reactions releasing energy often occur spontaneously. Reactions absorbing energy do not go until provided with source of energy.

The relationship of energy to stability, work capacity, and spontaneous change
There is a tendency of all things to seek their lowest state of energy. The molecule at far right has high-energy chemical bonds that are not stable, so it has a tendency to split apart and release that energy.

Energy-releasing chemical reaction between hydrogen and oxygen
Ignite with a flame or spark, inputting energy. In chemical reactions, chemical bonds are broken and reformed, leading to new arrangements of atoms. The starting molecules in the process are called reactants and the end molecules are called products. In a chemical reaction, all of the atoms in the reactants must be accounted for in the products. The reactions must be “balanced.” For example, we can recombine the covalent bonds of H2 and O2 to form the new bonds of H2O. In this reaction, two molecules of H2 combine with one molecule of O2 to form two molecules of H2O. The ratios of molecules are indicated by coefficients. Some chemical reactions go to completion; that is, all the reactants are converted to products. The amount of energy on the reactant side will equal the amount of energy on the products side (remember some energy always lost as heat energy

Energy changes in energy-releasing and energy-absorbing reactions

Energy Sources Energy is stored in chemical bonds of molecules.

Activation Energy Activation energy – The peak in the curve is the amount of energy required to get the reaction going. Strike at match and you’ll see an example of activation energy. The match starts burning only because another chemical reaction provided the activation energy.

Activation Energy Essential controlling feature of biochemical systems. Life could not exist by relying on spontaneous reactions. Activation energy functions as a control or brake on reactions. Biology links energy-releasing reactions to get the activation energy for energy-absorbing reactions.

Demonstration: Decomposition of Sugar
TEACHER Demonstration: Decomposition of Sugar Students will observe the decomposition of sugar by a strong acid – a chemical reaction Dehydration of water – removal of water from sucrose which is also an exothermic reaction. One of the most spectacular chemistry demonstrations is also one of the simplest. It's the dehydration of sugar (sucrose) with sulfuric acid. Basically, all you do to perform this demonstration is put ordinary table sugar in a glass beaker and stir in some concentrated sulfuric acid (you can dampen the sugar with a small volume of water before adding the sulfuric acid). The sulfuric acid removes water from the sugar in a highly exothermic reaction, releasing heat, steam, and sulfur oxide fumes. Aside from the sulfurous odor, the reaction smells a lot like caramel. The white sugar turns into a black carbonized tube that pushes itself out of the beaker. Here's a nice youtube video for you, if you'd like to see what to expect.

Demonstration: Energy Held in Bonds of a Carbohydrate
TEACHER Demonstration: Energy Held in Bonds of a Carbohydrate Students will observe the decomposition of sugar by a strong oxidizer – potassium chlorate – a chemical reaction Highly exothermic requiring we go outside. Chemical bond energy turned into heat energy and light energy.

Enzymes Some biochemical reactions just will not work well, or at all, without help. Perhaps their activation energy is too high. Perhaps the reactant concentration is always too low.

Enzymes The help comes in the form of a catalyst:
Substance that speeds up the rate of a chemical reaction. Are not changed due to the chemical reaction. Catalysts lower a reaction’s activation energy.

Enzymes lower a reaction’s activation energy
Easier to get the red line reaction going, isn’t it?

Enzymes So what is an enzyme exactly?
Protein molecules of a very specific shape (conformation). Shape is specific for the reactant(s). Reactant is now called a substrate.

Enzymes Enzymes may put two reactants together to form a new molecule, or Enzymes may take a large molecule and break it into smaller molecules. Enzymes capture the reactants, thereby bringing them close together. Enzymes work only when they are at their highest level of organization – quanternary structure.

Breaking up isn’t hard to do…
Enzyme hexokinase converts the reactants (substates) glucose and ATP into glucose-6-phosphate and ADP

Enzyme sucrase breaks down sucrose into two smaller sugars, fructose and glucose

Generally speaking… One enzyme for one chemical reaction.
So enzyme names come from the reaction is catalyzes. Look for the –ase suffix to recognize an enzyme’s name. Carbonic anhydrase catalyzes reaction that removes water from carbonic acid.

Enzymes It’s all about breaking existing bonds and forming new bonds.
Enzymes provide a site where reactants can be brought together, thereby reducing activation energy.

Enzymes Enzymes are built for specific substrates
Specificity comes from ability to form weak bonds between active site and substrate Wrong substrate may not be able to form these bonds Weak bonds hold the substrate to the active site

The reactant binds to the enzymes active site

Metaphor for the enzyme-substrate complex
Enzymes are very specific for substrates, much like a lock is very specific for a key.

Regulation of Enzyme Activity
Enzymes work if the conditions are right. Enzymes will not work if temperature, pH or other factors disrupt the shape of the enzyme molecule. Denaturation – weak bonds that hold an enzyme together break; loss of shape and function.

Regulation of Enzyme Activity
Cells also regulate enzymes by using protein messengers that bind to enzymes to turn them off or turn them on.

Demonstration: Denaturation
TEACHER Fry an egg in class.

Analyzing Data Read the chart. What do you see?
Catalase is an enzyme that helps decompose the toxic hydrogen peroxide that is produced during normal cell activities. (You can use hydrogen peroxide bought from a store as an antiseptic.) The products of this reaction are water and oxygen gas. The pressure of the oxygen gas in a closed container increases as more oxygen is produced. Any increase in the [catalase-hydrogen peroxide] reaction will increase the pressure of oxygen. What variable is plotted on the x-axis? – time in seconds What variable is plotted on the y-axis – pressure of oxygen How did the rate of reaction change over time in the controlled reaction? – purple line, just before 40 seconds the rate of reaction bottomed out. Suggest an explanation for the change in the control reaction at about 40 seconds. – The catalase/hydrogen peroxide reaction stopped. The simplest explanation is that all the substrate – hydrogen peroxide – was changed into water and oxygen. What effect do acids and bases have on the enzyme catalase? – Acids seem to inhibit the reaction the most, as shown by the little (if any) production of oxygen – the reaction is not happening. Likely the conformation or shape of the enzyme was disrupted by the increases hydrogen ion content. Bases seem to effect the enzyme less so, allowing the reaction to continue to a certain point. Would it be valid to conclude that if a base were added, the rate of the reaction would slow down? - Yes, since even with a base the reaction rate is much lower than the control. Predict what would happen if vinegar were added to a water solution of hydrogen peroxide and catalase. - Acetic acid would slow the reaction down significantly.

Summation Given a chemical reaction, identify the reactants and products, and the coefficients. Distinguish between energy absorbing and energy releasing chemical reactions. Explain the concept of activation energy.

Summation Explain why molecular structure and shape is crucial to life – it determines how most molecules recognize and respond to each other. Explain why chemical reactions do not create new matter. Explain the relationship between concentration and the rate of reaction. Explain the importance of enzymes to biochemical reactions.

Assignments Complete Chapter 2 Chapter Notes through Section 2-4.
Complete Chapter 2 Chapter Review Problems (graded) Complete the Chapter 2 Chapter Notes to end Check FirstClass for test dates

Cornell Notes Using your Cornell Notes, you will now:
compare notes with a partner for one minute. write reflection in bottom space. possible open-notes quiz. Cornell Notes must be turned in on day of chapter test; they will be graded.

Cornell Notes Tonight Reread your Cornell Notes in the right column.
Review the ideas in the left column. Study your summary/reflection.

Lab Effect of Temperature on Enzyme Activity
STUDENT Lab Effect of Temperature on Enzyme Activity Distribute lab instructions, Tootpick-ase: An Introduction to Enzymes Simulation of how substrate concentration and temperature affect enzyme function.

Lab Effect of Temperature on Enzyme Activity
STUDENT Lab Effect of Temperature on Enzyme Activity Distribute lab instructions, Effect of Temperature on Enzyme (Catalase) Activity Conduct lab, Effect of Temperature on Enzyme (Catalase) Activity Students must read and complete the Pre-Lab activity

Lab Conduct lab, Effect of Temperature on Enzyme (Catalase) Activity
Students must have read and completed the Pre-Lab activity

Test, Chapter 2 Following the acid/base lab. Tentative date:

The Chemistry of Life Chapter 2 Section 2-3 and 2-4

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