Transcript Section 2-3 - Xavier High School

Interest Grabber
Section 2-1
What’s the Matter?
All of the materials around you are made up of matter. You are made up of
matter, as are the chair you sit on and the air you breathe.
1. Give an example of solid matter.
2. Give an example of liquid matter.
3. Give an example of gaseous matter.
4. Is all matter visible?
5. Does all matter take up space?
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Section:
Answers to What’s the Matter?
1. Sample answers: books, desks, chairs
2. Sample answers: water, milk
3. Sample answers: air, helium in a balloon
4. No
5. Yes
Section Outline
Section 2-1
2–1
The Nature of Matter
A. Atoms
B. Elements and Isotopes
1. Isotopes
2. Radioactive Isotopes
C. Chemical Compounds
D. Chemical Bonds
1. Ionic Bonds
2. Covalent Bonds
3. Van der Waals Forces
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Section:
The Atom
An atom is the basic unit of matter.
It is made up of protons, electrons, and neutrons.
An atom has no charge.
An Atom’s Subatomic Particles
Mass
(amu)
Location
Charge
PROTON
1
(1.0073)
Inside the nucleus
1+
Positive
P and P
NEUTRON
1
(1.0087)
Inside the nucleus
None
(Neutral)
ELECTRON
1/1840
(5.486 x 10-4)
Outside of the nucleus
(Electron cloud)
1Negative
Vocabulary Words
Element – pure substance that consists entirely of one type of atom
Isotopes – atoms of the same element that differ in the number of neutrons; all
isotopes of an element have the same chemical properties because they have
the same number of electrons
Radioactive Isotopes (radioisotopes)– isotopes with unstable nuclei that break
down at a constant rate over time; the radiation they give off can be dangerous,
but radioactive isotopes can also have scientific and practical uses
Examples:
1. Determine the ages of rocks and fossils by analyzing the isotopes found in them
2. Treat cancer
3. Kill bacteria that cause food to spoil
4. Tracers (tagged atoms) to follow the movements of substances within organisms
Radioisotopes
1. Tracers (tagged atoms)-cancer and kidney disorders
2. Tracers with imaging instruments – positron emission tomography (PET
scan)
3. Carbon-14 has been used as a tracer to determine how plants use
carbon dioxide to make sugar (photosynthesis); archaeological carbon
dating
Note: Oxygen-18, a stable isotope, has also been used to study
photosynthesis.
Americium-241 is used in smoke alarms.
Look at the Periodic Table
1. Names and Symbols of the Elements (Note: New elements are
assigned three-letter symbols until they are officially named.)
2. Atomic number – the number of protons (PAN)
3. Atomic mass – the number of protons and neutrons
4. How are the elements arranged in the table?
In order of increasing atomic number
5. What else does the atomic number equal?
The number of electrons because atoms have no charge
6. Which element has seven protons?
Nitrogen
An Element in the Periodic Table
Section 2-1
6
C
Carbon
12.011
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Section:
Figure 2-2 Isotopes of Carbon
Section 2-1
Nonradioactive carbon-12
Nonradioactive carbon-13
6 electrons
6 protons
6 neutrons
6 electrons
6 protons
7 neutrons
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Section:
Radioactive carbon-14
6 electrons
6 protons
8 neutrons
Isotopes of Hydrogen
Common hydrogen – one proton and no neutron
Deuterium – one proton and one neutron
Tritium – one proton and two neutrons
Energy Levels
Level and Maximum Number of Electrons
Level 1
2 electrons
Level 2
8 electrons
Level 3
8 electrons
Draw the carbon atom.
The General Rule
Valence electrons are the electrons that are available to form bonds.
Valence Electrons and Action
1 Lose electrons
2 Lose electrons
3 Lose electrons
4 Share
5 Gain electrons
6 Gain electrons
7 Gain electrons
8 HAPPY!
Chemical Compounds
Chemical compound – substance formed by the chemical combination of
two or more elements in definite proportions; physical and chemical
properties are usually very different from those of the elements from which
it is formed (Example: Hydrogen and oxygen are very different from H2O)
Chemical Formula – a kind of shorthand that shows the composition of
compounds (Note: The number 1 is not written; it is understood.)
Examples: C6H12O6 - glucose
1. Name the elements in glucose?
Carbon, hydrogen, and oxygen
2. How many atoms of each element are in the compound?
6 carbon, 12 hydrogen, and 6 oxygen
Structural formula – shows elements and bonding sites in the compound;
see picture (Figure 2-14 on page 46 in text)
Facts to Know about Chemical Bonds
1. Atoms in compounds are held together by chemical bonds.
2. Bond formation involves the electrons that surround each atomic
nucleus.
3. An ionic bond is formed when one or more electrons are transferred
from one atom to another. Since atoms are electrically neutral, an atom
that loses electrons has a positive charge. An atom that gains
electrons, has a negative charge.
4. Charged atoms are called ions. Cations have a positive charge and
anions have a negative charge. (Note: Circle the top of the t in cation
and it looks like a positive sign.)
5. A covalent bond is formed when electrons are shared between atoms.
The smallest unit of this compound is called a molecule.
Covalent Bonds
1. Increases stability of the atom
2. Found in a molecule of water
3. Results in the formation of a molecule
4. Found in most compounds making up living things
Figure 2-3 Ionic Bonding
Section 2-1
Sodium atom (Na)
Chlorine atom (Cl)
Sodium ion (Na+)
Chloride ion (Cl-)
Transfer
of electron
Protons +11
Electrons -11
Charge
0
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Section:
Protons +17
Electrons -17
Charge
0
Protons +11
Electrons -10
Charge
+1
Protons +17
Electrons -18
Charge
-1
Figure 2-3 Ionic Bonding
Section 2-1
Sodium atom (Na)
Chlorine atom (Cl)
Sodium ion (Na+)
Chloride ion (Cl-)
Transfer
of electron
Protons +11
Electrons -11
Charge
0
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Section:
Protons +17
Electrons -17
Charge
0
Protons +11
Electrons -10
Charge
+1
Protons +17
Electrons -18
Charge
-1
Ions are more stable than the neutral atoms
because their outermost levels are filled with
electrons.
Van der Waals Forces
When molecules are close together, a slight attraction can develop
between the oppositely charged regions of nearby molecules. Chemists
call such intermolecular forces Van der Waals forces.
They are not as strong as covalent bonds or ionic bonds, but they can hold
molecules together, especially when the molecules are large. (Example:
geckos can climb up a vertical wall.)
Why can’t a similar technique work for humans?
Even if human toes and fingers had hairlike projections, the surface area
would not be sufficient to generate a combined force that could support a
human’s weight.
Answers to Questions 1-6 on Page 39 in Text
1. Atoms have a nucleus made of protons and neutrons. Electrons are in
constant motion in the space around the nucleus.
2. They have the same number of electrons, but differ in the number of
neutrons.
3. A covalent bond forms when electrons are shared. An ionic bond forms
when electrons are transferred.
4. A compound is a substance formed by the combination of two or more
elements in definite proportions. A molecule is the smallest unit of most
compounds.
5. When the sharing of electrons is unequal, a molecule has regions that
are charged. An attraction can occur between oppositely charged
regions of nearby molecules.
6. In both cases, particles are held together by attractions between
opposite charges, but the attractions are stronger between the ions
than they are between the molecules. (Study Hint: This will be a test
question!)
Interest Grabber
Section 2-2
Water, Water Everywhere
If you have ever seen a photograph of Earth from space, you know that
much of the planet is covered by water. Water makes life on Earth
possible. If life as we know it exists on some other planet, water must be
present to support that life.
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Section:
Interest Grabber continued
Section 2-2
1. Working with a partner, make a list of ten things that have water
in them.
2. Exchange your list for the list of another pair of students. Did your lists contain
some of the same things? Did anything on the other list surprise you?
3. Did either list contain any living things?
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Section:
Interest Grabber
Possible Answers to Water, Water Everywhere
1. Possible answers: bodies of water, rain and snow, soft drinks and other
beverages, juicy foods such as fruits, and so on.
2. Students’ answers will likely be similar, but not exactly alike.
3. Students’ lists may include plants, animals, or other living things.
2–2
Properties of Water
A. The Water Molecule
1. Polarity
2. Hydrogen Bonds
B. Solutions and Suspensions
1. Solutions
2. Suspensions
C. Acids, Bases, and pH
1. The pH Scale
2. Acids
3. Bases
4. Buffers
Properties of Water
Polar – a molecule in which the charges are unevenly distributed
Water is a polar molecule because there is an uneven distribution of
electrons between the hydrogen and oxygen atoms. The negative pole is
near the oxygen atom and the positive pole is between the hydrogen
atoms.
The charges on a polar molecule are written in parenthesis (-) or (+) to
show that they are weaker than the charges on ions.
Hydrogen Bonds
The attraction between the hydrogen atom on one water molecule and the
oxygen atom on another water molecule is an example of a hydrogen
bond. (Oxygen is negative and the two hydrogen atoms are positive.)
See Figure 2-7 on page 41 in the text.
Hydrogen bonds are not as strong as ionic or covalent bonds, but they are
the strongest of the bonds that can form between molecules.
A single water molecule can be involved in as many as four hydrogen
bonds at the same time.
Vocabulary Words
Cohesion – an attraction between molecules of the same substance
(Because of hydrogen, water is extremely cohesive)
Adhesion – an attraction between molecules of different substances
(The surface of the water in a graduated cylinder dips slightly in the center
because the adhesion between water molecules and glass molecules is
stronger than the cohesion of water molecules.Adhesion between water
and glass also causes water to rise in a narrow tube against the force of
gravity)
Think! (Study Hint: Test Questions)
1. Why are water molecules attracted to one another?
Water molecules are polar, meaning that they have regions with partial
positive and negative charges.
2. How are cohesion and adhesion similar? Different?
Cohesion and adhesion are similar because they are attractions
between molecules, but cohesion occurs between molecules of the
same substance and adhesion occurs between molecules of different
substances.
3. How does the tarantula’s physical structure help it to stay afloat?
Because of its multiple legs, a tarantula’s mass is distributed over a
large area on the water, which means that the pull of gravity is limited at
any one location on the surface.
Vocabulary Words
Mixture – material composed of two are more elements or compounds
that are physically mixed together but not chemically combined (Salt and
pepper, nut and fruit mix, alphabet grain and marshmallow cereal)
Solutions and suspensions are two types of mixtures.
Solution - all the components are evenly distributed
(Example: If a crystal of table salt is placed in a glass of warm water,
sodium and chloride ions on the surface of the crystal are attracted to the
polar water molecules. Ions break away from the crystal and are
surrounded by the water molecules. The ions gradually become dispersed
in the water. )
Solute – substance that is dissolved (salt)
Solvent substance in which the solute dissolves (Water)
(Memory device: V and W are at the end of the alphabet.)
Suspension – some materials do not dissolve but separate into pieces so
small that they do not settle out (The movement of water molecules keep
the particles suspended.)
Blood is both a solution and a suspension. It is mostly water that contains
many dissolved substances. But it also contains particles that remain in
suspension.
Figure 2-9 NaCI Solution
Section 2-2
ClCl-
Na+
Na+
Water
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Section:
Water
Figure 2-9 NaCI Solution
Section 2-2
ClCl-
Na+
Na+
Water
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Section:
Water
Acids and Bases
H+
OHAcid
Neutral
Base
___________________________________________________________
0
7
14
Strong
Weak
Strong
Know the examples in the next slide. See Figure 2-10 in the text.
pH Scale
Section 2-2
Increasingly Basic
Oven cleaner
Increasingly Acidic
Neutral
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Section:
Bleach
Ammonia solution
Soap
Sea water
Human blood
Pure water
Milk
Normal
rainfall
Acid rain
Tomato
juice
Lemon juice
Stomach acid
Vocabulary
Acid – Any compound that forms hydrogen ions (H+ ) in solution
Hydrochloric acid produced by the stomach to help digest
food is a strong acid (pH 1.5)
Base (Alkaline) – A compound that produces hydroxide ions
(OH-) in solution
pH scale - a measurement system that indicates the concentration of
hydrogen ions in solution; each step represents a factor of 10.
Example: A liter of a solution with a pH of 4 has ten times as many
hydrogen ions as a liter of a solution with a pH of 5.
Know the chemical equation on the bottom of page 42 in the text.
pH Indicators
pH paper – match color with pH chart
Electronic pH meter – insert probe and read pH
Litmus paper – turns red in the presence of acid and blue in the presence
of bases
Phenolphthalein – pH range of 8-10; colorless for an acid and pink to red in
a base
Bromthymol blue – turns yellow in an acid and blue in a base
Buffers
Buffers are weak acids or bases that can react with strong acids or bases
to prevent sharp, sudden changes in pH.
They are dissolved compounds in the human body.
The pH of the fluids within most cells in the human body must generally be
kept between 6.5 and 7.5
Human blood has a pH of 7.4
If the pH is lower or higher, it affects the chemical reactions that take place
in the cell
Buffers help maintain homeostasis. Carbonic acid-bicarbonate buffering
system is an example.
Answers to Questions 1-5 on page 43 in the Text
1. The hydrogen atoms form covalent bonds with the oxygen atom.
Because of oxygen’s greater attraction for electrons, there is an
unequal distribution of electrons. The oxygen end of the bent water
molecule is negative and the hydrogen end is positive.
2. Per volume, there are more hydrogen ions than hydroxide ions in an
acidic solution and more hydroxide ions than hydrogen ions in a basic
solution.
3. In a solution, all components are easily distributed. In a suspension,
undissolved particles are suspended in the mixture and can settle out
over time.
4. The pH scale measures concentrations of hydrogen ions in a solution.
5. The pH will be less than 7. (Strong acid and neutral water: still acidic)
Interest Grabber
Section 2-3
Life’s Backbone
Most of the compounds that make up living things contain carbon. In fact,
carbon makes up the basic structure, or “backbone,” of these compounds.
Each atom of carbon has four electrons in its outer energy level, which
makes it possible for each carbon atom to form four bonds with other atoms.
As a result, carbon atoms can form long chains. A huge number of different
carbon compounds exist. Each compound has a different structure. For
example, carbon chains can be straight or branching. Also, other kinds of
atoms can be attached to the carbon chain.
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Section:
Interest Grabber continued
Section 2-3
1. On a sheet of paper, make a list of at least ten things that contain
carbon.
2. Working with a partner, review your list. If you think some things on your
list contain only carbon, write “only carbon” next to them.
3. If you know other elements that are in any items on your list, write those
elements next to them.
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Section:
Answers to Life’s Backbone
1. Students will likely know that charcoal and coal contain carbon. They
may also list carbohydrates (starches and sugars), oil, gasoline, wood,
or carbon dioxide.
2. Students will say that charcoal and coal contain only carbon. While
these materials do contain small amounts of other elements, such as
sulfur, they are composed mostly of carbon.
3. Students may know that many carbon compounds also contain oxygen
and/or hydrogen.
Section Outline
Section 2-3
2–3
Carbon Compounds
A.
B.
C.
D.
E.
F.
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Section:
The Chemistry of Carbon
Macromolecules
Carbohydrates
Lipids
Nucleic Acids
Proteins
Carbon
1. Has four valence electrons, so can form four covalent bonds at one
time
2. Carbon atoms bond together in straight chains, branched chains, or
rings
3. Since there are four valence electrons, carbon can form single bonds,
double bonds, and triple bonds.
Vocabulary
Organic compounds – contain carbon and hydrogen, as well as other
elements
Examples: carbohydrates, lipids, proteins, nucleic acids
Inorganic – contains no carbon
Examples – water, mineral elements, acids and bases
Organic chemistry – the study of all compounds that contain bonds
between carbon atoms
Answer to observing (Figure 2-11 on page 44 in text): There are three
covalent bonds between the carbon atoms in acetylene.
Figure 2-11 Carbon Compounds
Section 2-3
Methane
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Section:
Acetylene
Butadiene
Benzene
Isooctane
Concept Map
Section 2-3
Carbon
Compounds
include
Carbohydrates
Lipids
Nucleic acids
Proteins
that consist of
that consist of
that consist of
that consist of
Sugars and
starches
Fats and oils
Nucleotides
Amino Acids
which contain
which contain
Carbon,
hydrogen,
oxygen
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Section:
Carbon,
hydrogen,
oxygen
which contain
which contain
Carbon,hydrogen,
oxygen, nitrogen,
phosphorus
Carbon,
hydrogen,oxygen,
nitrogen,
Organic
Compound
Elements
Building Blocks
Shape/Significant Groups
Carbohydrate
C,H,O
Monosaccharides
Ring
H and O present in same
ration as water 2:1
Lipid
C,H,O
3 Fatty acids and glycerol
Long chains
Protein
C,H,O,N
Amino acids
Amino group and a
carboxyl group
Nucleic Acid
C,H,O,N,P Nucleotides
5-carbon sugar, a phosphate
group, and a nitrogenous
base
Figure 2-13 A Starch
Section 2-3
Starch
Glucose
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Section:
Figure 2-16 Amino Acids
Section 2-3
Amino group
Carboxyl group
General structure
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Section:
Alanine
Serine
Figure 2-16 Amino Acids
Section 2-3
Amino group
Carboxyl group
General structure
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Section:
Alanine
Serine
Figure 2-16 Amino Acids
Section 2-3
Amino group
Carboxyl group
General structure
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Section:
Alanine
Serine
Figure 2-17 A Protein
Section 2-3
Amino
acids
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Section:
Vocabulary
Macromolecule – giant molecules made up of thousands or even
hundreds of thousands of smaller molecules
Polymerization – large compounds are build by joining smaller ones
together; the process in which monomers are joined to form larger units
called polymers
Monomer – each subunit that acts as a building block for a polymer; can
be identical like links on a watch or different like the beads in a
multicolored necklace
Polymer – similar, repeating units; a large compound formed from
combinations of many monomers
Carbohydrates
*Main source of energy for living things
*Plants and some animals also use carbohydrates for structural purposes
*Sugars are stored as starches
*Monomers in starch molecules are sugar molecules
Monosaccharides
One sugar carbohydrate
C6H12O6
Examples: galactose, glucose. fructose
Disaccharides
Two sugars
C12H22O11
Examples: Sucrose (table sugar composed
of glucose and fructose), lactose (milk
sugar), maltose
Polysaccharides
More than two
Can be thousands
Starch (storage form of sugar)
Cellulose (forms cell wall, supporting
material in plants,wood and paper)
Glycogen (animal starch)
*When the level of glucose in your blood runs low, glycogen is released from your liver. The
glycogen stored in your muscles supplies energy for contraction and, thus, for movement.
Isomers- same molecular formula but different structural formula
Example: glucose and fructose
1.
Lipids
Part of cell structures and reserve energy supply: membranes, waterproof coverings
2.
Fats, oils, and waxes (found in fur, skin, leaves, exoskeleton of some insects)
3.
Less O in relation to H
4.
Relatively small, NOT polymers
5.
Long-term energy storage, insulation, protective coating
6.
Furnish about twice as much energy as the same amount of carbohydrates
7. Fats and oils are chemically similar. Unlike fats, however, oils remain liquid at
room temperature
*Note: Steroids (some are chemical messengers) are also lipids.
Vocabulary
Saturated – only single bonds; has the maximum number of hydrogen atoms
(fats with animal origins-milk, beef, butter)
Unsaturated – has at least one carbon-carbon double bond
Has double and triple bonds ( fats with plant origins)
Examples – olive oil, corn oil, fish oil, sunflower oil
Polyunsaturated – more than one double bond
Fats and cholesterol:
LDL- low density lipoproteins
HDL – high density lipoproteins
(H – Happy, good )
Lipid derivatives
Phospholipids : Lecithin (part of cell membrane)
Cephalin (brain nerves, neural tissue)
Nucleic Acids
Store and transmit hereditary, or genetic information
Largest organic molecules
Nucleic Acids – DNA and RNA
Deoxyribonucleic acid (DNA) contains the sugar deoxyribose.
Ribonucleic acid (RNA) contains the sugar ribose.
Know Figure 2-15 on page 47 in text. (Be able to draw and label)
1.
2.
3.
4.
5.
Proteins
Found throughout living organisms - make life possible
Structures are very complex
More than 20 different types of amino acids represent the R (variable) group
There can be more than 3,000 amino acids in a protein
Carbon atoms bond in four places:
A. Amino group (NH2)
B. Carboxyl group (COOH)
C. Hydrogen atom
D. Variable group (R)
This group is a side chain that is different in each amino acid
GLYCINE is the simplest amino acid. Its R group is hydrogen (H).
Proteins form peptide bonds- a bond between C in the carboxyl group of one
amino acid and N in the amino group of the next amino acid
dipeptide bond – two amino acids linked together by a peptide bond
polypeptide chain – a large number of amino acids linked by peptide bonds
Polypeptides combine to form proteins.
Some proteins control the rate of reactions and regulate cell processes.
Some are used to form bones and muscles.
Other proteins transport substances into and out of the cells or help to fight
disease.
Types of Proteins
Type
Function
Examples
Hormonal
Chemical messengers
Glucagon, insulin
Transport
Transport of other
substances
Hemoglobin,
carrier proteins
Structural
Physical support
Collagen
Contractile
Movement
Actin, myosin
Antibodies
Defense
Immunoglobulins,
Interferons
Enzymes
Biological catalysts
Amylase, lipase, ATPase
Glucagon- secreted by pancreas, helps change glycogen (a polysaccharide that is a
major storage product in animals) to glucose (a sugar)
Insulin – secreted by pancreas, helps convert glucose to glycogen
Hemoglobin – an iron-containing protein compound that helps transport O and CO2
(gives blood red color)
Collagen – part of connective tissue (supports, binds tissue and organs together)
Actin – thin filaments found in microfilaments used for cell movement and
contraction of muscle cells
Myosin – thick filaments found in muscles
Interferons – produced by living cells that have been entered by a virus
Interest Grabber
Section 2-4
Matter and Energy
Have you ever sat around a campfire or watched flames flicker in a
fireplace? The burning of wood is a chemical reaction—a process that
changes one set of chemicals into another set of chemicals. A chemical
reaction always involves changes in chemical bonds that join atoms in
compounds. The elements or compounds that enter into a chemical
reaction are called reactants. The elements or compounds produced by a
chemical reaction are called products. As wood burns, molecules of
cellulose are broken down and combine with oxygen to form carbon
dioxide and water vapor, and energy is released.
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Section:
Interest Grabber continued
Section 2-4
1. What are the reactants when wood burns?
2. What are the products when wood burns?
3. What kinds of energy are given off when wood burns?
4. Wood doesn’t burn all by itself. What must you do to start a fire? What
does this mean in terms of energy?
5. Once the fire gets started, it keeps burning. Why don’t you need to
keep restarting the fire?
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Section:
Answers to Matter and Energy
1. Reactants are oxygen and cellulose.
2. Products are carbon dioxide and water.
3. Light and heat are given off. Some students may also mention sound
(the crackling of a fire).
4. To start a fire, you must light it with a match and kindling. You are giving
the wood some energy in the form of heat.
5. Once the fire gets going, it gives off enough heat to start more of the
wood burning.
Section Outline
Section 2-4
2–4
Chemical Reactions and Enzymes
A. Chemical Reactions
B. Energy in Reactions
1. Energy Changes
2. Activation Energy
C. Enzymes
D. Enzyme Action
1. The Enzyme-Substrate Complex
2. Regulation of Enzyme Activity
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Section:
Vocabulary
Chemical reactions – process that changes one set of chemicals into
another set of chemicals
They always involve the breaking of bonds in reactants and the formation
of new bonds in products.
Example: oxygen and iron form rust
Reactants – elements or compounds that enter into a chemical reaction
Products – elements or compounds produced by a chemical reaction
Example: Carbon dioxide, which is not very soluble in water, reacts with
water in your blood to form a soluble compound called carbonic acid. This
enables the bloodstream to carry carbon dioxide into your lungs. In the
lungs, the reaction is reversed. This produces carbon dioxide gas, which
is released as you exhale. (Equations on bottom of page 49 in text.)
Energy in Reactions
Chemical reactions that release energy often occur spontaneously.
Example: Hydrogen gas burning, or reacting with oxygen to produce water
vapor..Energy is released in the form of heat…and when hydrogen gas
explodes – light and sound
Chemical reactions that absorb energy will not occur without a source of
energy.
Example: Water generally doesn’t change into hydrogen and oxygen gas
without requiring energy, such as an electric current.
Cellulose (paper) burns in the presence of oxygen, but only if you apply a
lit match.
Activation energy – the energy that is needed for a reaction to begin
Answers to Analyzing Data on Page 51 in Text
1. Time is plotted on the x-axis and pressure of oxygen on the y-axis.
2. The rate was very rapid at first and then dropped off dramatically after
about 40 seconds.
3. Hydrogen peroxide was used up OR the reaction is reversible.
4. With added base, the rate of reaction slowed down.
With added acid, there is almost no reaction.
5. A base inhibits the enzyme so that it is less effective.
An acid may deactivate the enzyme so that the reaction cannot take
place.
6. Because vinegar is an acid, it would inhibit and possible destroy the
catalyst
Enzymes
Catalyst-substance that speeds up the rate of a chemical reaction (lowers
the activation energy
Enzymes – proteins that act as catalysts
Cells use enzymes to speed up chemical reactions that take place in cells.
A reaction can take place as much as ten billion times faster.
Very specific
Name derived from the reaction it catalyzes
Lock and key fit (perfect fit)
Enzymes at Work
Carbonic anhydrase – catalyzes the reaction that removes water
from carbonic acid
Hexokinase – converts glucose and ATP into glucose-6-phosphate
and ADP (stored energy and released energy)
Catalase – one of the fastest acting enzymes; breaks down
hydrogen peroxide (poisonous byproduct of most chemical
reactions in human cells) into water and oxygen
Commercial Uses of Enzymes
Some enzymes split proteins so they are used in laundry detergents.
Papain, found in papaya, is used in meat tenderizer.
Vocabulary
Substrate – material acted upon by an enzyme; the reactants
Active site – where enzyme and substrate join
Products – substances liberated during the reaction
Coenzyme – non-protein molecule that assists enzyme; vitamins
Denaturation – active sites of enzymes altered; life-threatening
Inhibitor-disables enzyme by joining with it without itself being changed
Competitive inhibitor – fake substances (antibiotics)
Non-competitive inhibitor – attaches to OR changes the shape of an
active site (lead, mercury, cyanide)
Effect of Enzymes
Section 2-4
Reaction pathway
without enzyme
Activation energy
without enzyme
Reactants
Reaction pathway
with enzyme
Activation
energy
with enzyme
Products
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Section:
Figure 2-19 Chemical Reactions
Section 2-4
Energy-Absorbing Reaction
Energy-Releasing Reaction
Activation
energy
Products
Activation energy
Reactants
Reactants
Products
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Section:
Figure 2-19 Chemical Reactions
Section 2-4
Energy-Absorbing Reaction
Energy-Releasing Reaction
Activation
energy
Products
Activation energy
Reactants
Reactants
Products
Go to
Section:
Figure 2-21 Enzyme Action
Section 2-4
Enzyme
(hexokinase)
Glucose
Substrates
Products
ADP
Glucose-6phosphate
Products
are released
ATP
Active site
Enzyme-substrate
complex
Substrates
are converted
into products
Go to
Section:
Substrates
bind to
enzyme
Figure 2-21 Enzyme Action
Section 2-4
Enzyme
(hexokinase)
Glucose
Substrates
Products
ADP
Glucose-6phosphate
Products
are released
ATP
Active site
Enzyme-substrate
complex
Substrates
are converted
into products
Go to
Section:
Substrates
bind to
enzyme
Figure 2-21 Enzyme Action
Section 2-4
Enzyme
(hexokinase)
Glucose
Substrates
Products
ADP
Glucose-6phosphate
Products
are released
ATP
Active site
Enzyme-substrate
complex
Substrates
are converted
into products
Go to
Section:
Substrates
bind to
enzyme
Figure 2-21 Enzyme Action
Section 2-4
Enzyme
(hexokinase)
Glucose
Substrates
Products
ADP
Glucose-6phosphate
Products
are released
ATP
Active site
Enzyme-substrate
complex
Substrates
are converted
into products
Go to
Section:
Substrates
bind to
enzyme
Factors Affecting Enzyme Action
1. pH – Pepsin (stomach) works best at a pH of 1.5-2.2
Trypsin (small intestine) works best at a pH of 7.9-9.0
2. Temperature – most at body temperature (37
Factors Affecting Enzyme Action
1. pH – Pepsin (stomach) works best at a pH of 1.5-2.2
Trypsin (small intestine) works best at a pH of 7.9-9.0
2. Temperature – most at body temperature (37 degrees Celsius)
3. Relative amounts of enzyme and substrate
4. Most cells contain proteins that turn key enzymes “on and off” during
critical stages in the life of the cell.