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Chapter 6 Chemistry in Biology
Section 1: Atoms, Elements, and Compounds
Section 2: Chemical Reactions
Section 3: Water and Solutions
Section 4: The Building Blocks of Life
Atoms
Chemistry is the study of matter.
6.1 Atoms, Elements, and Compounds
Atoms are the building blocks of matter.
Chapter 6 Chemistry in Biology
Neutrons and protons are located at the center of the atom.
Protons are positively charged particles.
Neutrons are particles that have no charge.
Electrons are negatively charged particles that are located outside the nucleus.
Chemistry in Biology
6.1 Atoms, Elements, and CompoundsChapter 6
Elements
Chemistry in Biology
An element is a pure substance that cannot be broken down into other substances by physical or chemical means.
There are over 100 known elements, 92 of which occur naturally.
Each element has a unique name and symbol.
6.1 Atoms, Elements, and CompoundsChapter 6
The Periodic Table of Elements
Chemistry in Biology
Horizontal rows are called periods. Vertical columns are called groups.
6.1 Atoms, Elements, and CompoundsChapter 6
Isotopes
Chemistry in Biology
Atoms of the same element that have the same number of protons and electrons but have a different number of neutrons
6.1 Atoms, Elements, and CompoundsChapter 6
Radioactive Isotopes
Chemistry in Biology
When a nucleus breaks apart, it gives off radiation that can be detected and used for many applications.
6.1 Atoms, Elements, and CompoundsChapter 6
Uses in Biology…
• determine the age of rocks and fossils
• irradiation of food to kill bacteria
• radiation treatment for cancer
• tracers and labels to detect disorders
Compounds
Chemistry in Biology
A pure substance formed when two or more different elements combine
Compounds are always formed from a specific combination of elements in a fixed ratio.
Compounds cannot be broken down into simpler compounds or elements by physical means.
6.1 Atoms, Elements, and CompoundsChapter 6
Chemical Bonds
Chemistry in Biology
Covalent bondsChemical bond that
forms when electrons are shared
A molecule is acompound in which the atoms are held together by covalent bonds.
6.1 Atoms, Elements, and CompoundsChapter 6
Ionic Bonds
Chemistry in Biology
Electrical attraction between two oppositely charged atoms or groups of atoms
6.1 Atoms, Elements, and CompoundsChapter 6
Chemistry in Biology
The elements identified as metals tend to donate electrons.
The elements identified as nonmetals tend to accept electrons.
6.1 Atoms, Elements, and CompoundsChapter 6
Some atoms tend to donate or accept electrons more easily than other atoms.
Most ionic compounds are crystalline at room temperature and have higher melting points than molecular compounds formed by covalent bonds.
Chemistry in Biology
6.1 Atoms, Elements, and CompoundsChapter 6
Chemistry in Biology
van der Waals Forces
When molecules come close together, the attractive forces between slightly positive and negative regions pull on the molecules and hold them together.
The strength of the attraction depends on the size of the molecule, its shape, and its ability to attract electrons.
6.1 Atoms, Elements, and CompoundsChapter 6
This is because atoms of different elements do not have the same ability to attract electrons (ELECTRONEGATIVITY).
• some atoms have a stronger attraction for electrons than others.
• therefore, the sharing of electrons between two atoms in a covalent bond is not always equal.
Reactants and Products A chemical reaction is the
process by which atoms or groups of atoms in substances are reorganized into different substances.
6.2 Chemical Reactions
Clues that a chemical reaction has taken place include the production of heat or light, and formation of a gas, liquid, or solid.
Chemistry in Biology
Chemical reaction
Physical reaction
Chapter 6
Chemical Equations
Chemistry in Biology
Chemical formulas describe the substances in the reaction and arrows indicate the process of change.
Reactants are the starting substances, on the left side of the arrow.
Products are the substances formed during the reaction, on the right side of the arrow.
6.2 Chemical ReactionsChapter 6
• the reaction ALWAYS involves BREAKING bonds in reactants and FORMING new bonds in products resulting in a rearrangement of atoms.
Glucose and oxygen react to form carbon dioxide and water.
Chemistry in Biology
6.2 Chemical ReactionsChapter 6
Chemistry in Biology
Balanced Equations The law of conservation of mass states matter
cannot be created or destroyed.
The number of atoms of each element on the reactant side must equal the number of atoms of the same element on the product side.
6.2 Chemical ReactionsChapter 6
Chemistry in Biology
The activation energy is the minimum amount of energy needed for reactants to form products in a chemical reaction.
Energy of Reactions
6.2 Chemical ReactionsChapter 6
• Exothermic (exit): reactions which release energy and occur spontaneously (without the additional input of energy).
Chemistry in Biology
This reaction is exothermic and released heat energy.
The energy of the product is lower than the energy of the reactants.
6.2 Chemical ReactionsChapter 6
Chemistry in Biology
This reaction is endothermic and absorbed heat energy.
The energy of the products is higher than the energy of the reactants.
6.2 Chemical ReactionsChapter 6
• Many biochemical reactions take place so slowly or have such high activation energies that they would not occur in a timely manner without “help”.
Chemistry in Biology
A catalyst is a substance that lowers the activation energy needed to start a chemical reaction.
Enzymes are biological catalysts.
It does not increase howmuch product is made and it does not get used up in the reaction.
Enzymes
6.2 Chemical ReactionsChapter 6
• ENZYMES are proteins that act as biological catalysts.
• Enzymes end with –ase and are named after the molecule they act upon (Ex. Lipase – lipids).
• They are very specific and will only catalyze one reaction.
Chemistry in Biology
The reactants that bind to the enzyme are called substrates.
The specific location where a substrate binds on an enzyme is called the active site.
6.2 Chemical ReactionsChapter 6
Chemistry in Biology
Factors such as pH, temperature, and other substances affect enzyme activity.
6.2 Chemical ReactionsChapter 6
The active site changes shape and forms the enzyme-substrate complex, which helps chemical bonds in the reactants to be broken and new bonds to form.
Water’s Polarity
6.3 Water and SolutionsChemistry in Biology
Molecules that have an unequal distribution of charges are called polar molecules.
Polarity is the property of having two opposite poles.
A hydrogen bond is a weak interaction involving a hydrogen atom and a fluorine, oxygen, or nitrogen atom.
Chapter 6
Properties of Water
1) Water is a POLAR MOLECULE: the H end is (+) and the O end is (-) because O is more electronegative than H.
1)Because water is polar it forms HYDROGEN BONDS with oppositely charged parts of other molecules. Each water molecule can form 4 of these bonds.
* These two properties give rise to the other properties of water
1)COHESION – the attraction of water molecules to EACH OTHER.
2)ADHESION – the attraction of water molecules to OTHER SUBSTANCES. *Importance to living organisms: 3 & 4 explain how water travels against gravity from roots to shoots in tall plants such as trees (CAPILLARY ACTION)
1)Water has a high SPECIFIC HEAT – the amount of energy it takes to raise or lower the temperature of water 1 C. The value is high because of hydrogen bonding.
Importance to living organisms:• Keeps Earth’s temperature suitable for life.• Coastal regions have more moderate
temperatures than inland regions. • Keeps the temperature of the oceans stable.
1.Water has a high HEAT OF VAPORIZATION – the amount of energy needed to convert liquid water into a gas. The value is high due to hydrogen bonding.
Importance to living organisms:• EVAPORATIVE COOLING – cools surfaces
as it evaporates (sweating) • Keeps plants and animals from overheating • Moderates the Earth’s climate • Stabilizes aquatic environments
1)Water EXPANDS when it freezes and becomes LESS dense. * Water is MOST dense at 4° C, yet it freezes at O° C. * As bonds FORM, heat is RELEASED, as bonds BREAK heat is ABSORBED (requires energy)
Importance to living things:
• Seasonal changes are less abrupt
• Deep bodies of water don’t freeze solid and freeze from the top down.
1)Water is a versatile SOLVENT (due to polarity).
*Because of its polarity water can dissolve SOLUTES (other polar molecules) into SOLUTION.
• HYDROPHILLIC – water LOVING, polar molecules
• HYDROPHOBIC – water FEARING, non polar molecules.
• SUSPENSION – mixture of water and undissolved substances (Ex. Blood)
Chemistry in Biology
Homogenous Mixtures
A mixture that has a uniform composition throughout
A solvent is a substance in which another substance is dissolved.
A solute is the substance that is dissolved in the solvent. Food coloring dissolved in
water forms a homogenous mixture.
6.3 Water and SolutionsChapter 6
Chemistry in Biology
Heterogeneous Mixtures
In a heterogeneous mixture, the components remain distinct.
A salad is a heterogeneous mixture.
6.3 Water and SolutionsChapter 6
Chemistry in Biology
Substances that release hydrogen ions (H+) when dissolved in water are called acids.
Substances that release hydroxide ions (OH–) when dissolved in water are called bases.
Acids and Bases
6.3 Water and SolutionsChapter 6
Chemistry in Biology
The measure of concentration of H+ in a solution is called pH.
Acidic solutions have pH values lower than 7. Basic solutions have pH values higher than 7.
pH and Buffers
6.3 Water and SolutionsChapter 6
Chemistry in Biology
Buffers are mixtures that can react with acids or bases to keep the pH within a particular range.
6.3 Water and SolutionsChapter 6
Organic Chemistry
The element carbon is a component of almost all biological molecules.
6.4 The Building Blocks of LifeChemistry in BiologyChapter 6
Carbon has four electrons in its outermost energy level.
One carbon atom can form four covalent bonds with other atoms.
Chemistry in Biology
Carbon compounds can be in the shape of straight chains, branched chains, and rings.
6.4 The Building Blocks of LifeChapter 6
Macromolecules
Chemistry in Biology
Carbon atoms can be joined to form carbon molecules.
Macromolecules are large molecules formed by joining smaller organic molecules together.
Polymers are molecules made from repeating units of identical or nearly identical compounds linked together by a series of covalent bonds.
6.4 The Building Blocks of LifeChapter 6
* POLYMERS are formed by a condensation reaction, also called dehydration synthesis. Remove a water, make a bond.
Chemistry in BiologyChapter 6
• During this process, a water molecule is lost and 2 smaller molecules (monomers) are bonded together.
Chemistry in BiologyChapter 6
• Polymers are usually broken down in a process called hydrolysis. This is the opposite of condensation. Add a water, break a bond.
Chapter 6 Chemistry in Biology
Chemistry in Biology
Carbohydrates Compounds composed of carbon, hydrogen, and
oxygen in a ratio of one oxygen and two hydrogen atoms for each carbon atom—(CH2O)n
6.4 The Building Blocks of LifeChapter 6
Their names almost always end in –ose. Example: fructose, sucrose, maltose, ribose.
Chemistry in BiologyChapter 6
Chemistry in Biology
Two monosaccharides joined together form a disaccharide.
Longer carbohydrate molecules are called polysaccharides.
6.4 The Building Blocks of LifeChapter 6
Values of n ranging from three to seven are called simple sugars, or monosaccharides.
Chemistry in Biology
6.4 The Building Blocks of LifeChapter 6
Functions of Carbohydrates:• Primary source of short-term energy (glucose,
sugars). Stored by animals as glycogen and by plants as starch.
• Structural support (plant cell walls are mostly cellulose, the exoskeletons of insects are composed of the carbohydrate chitin).
Chemistry in Biology
Lipids
Molecules made mostly of carbon and hydrogen
A triglyceride is a fat if it is solid at room temperature (butter) and an oil if it is liquid at room temperature (olive oil).
6.4 The Building Blocks of LifeChapter 6
• Lipids are composed of 3 fatty acid tails and a glycerol molecule. Fats are hydrophobic (think salad dressing).
Chapter 6 Chemistry in Biology
Chemistry in Biology
Lipids that have tail chains with only single bonds between the carbon atoms are called saturated fats.
Lipids that have at least one double bond between carbon atoms in the tail chain are called unsaturated fats.
Fats with more than one double bond in the tail are called polyunsaturated fats.
6.4 The Building Blocks of LifeChapter 6
Functions of Lipids
• Long-term energy storage• Cell membranes (lipid bilayer)• Waterproof seal on aquatic animals• Cushioning to protect kidneys and other
organs. • Insulation for marine mammals like
whales.
Chapter 6 Chemistry in Biology
Chemistry in Biology
Proteins
Made of monomers called amino acids which are held together by peptide bonds
Amino acids are small compounds that are made of carbon, nitrogen, oxygen, hydrogen, and sometimes sulfur.
6.4 The Building Blocks of LifeChapter 6
Chemistry in Biology
Amino acids have a central carbon atom.
One of the four carbon bonds is with hydrogen.
The other three bonds are with an amino group (–NH2), a carboxyl group (–COOH), and a variable group (–R).
6.4 The Building Blocks of LifeChapter 6
Chemistry in Biology
The number and the order in which the amino acids are joined define the protein’s primary structure.
After an amino acid chain is formed, it folds into a unique three-dimensional shape, which is the protein’s secondary structure, such as a helix or a pleat.
6.4 The Building Blocks of LifeChapter 6
4 Levels
• Tertiary structure occurs with “contortions” of the secondary structure. Think gymnastics.
Chemistry in BiologyChapter 6
• Quaternary structure – when more than one protein molecule combine.
Chapter 6 Chemistry in Biology
Functions of Proteins
• Some are enzymes which control the rate of chemical reactions and regulate cell processes
• Some serve as transport molecules to move substances into or out of cells
Chapter 6 Chemistry in Biology
Functions of Proteins (continued)• Some act as parts of the immune system• Some help transport substances
throughout the body (hemoglobin carries oxygen)
• Some form bones and muscles
Chapter 6 Chemistry in Biology
Chemistry in Biology
Nucleic acids are complex macromolecules that store and transmit genetic information.
Nucleic acids are made of monomers called nucleotides, composed of C, N, O, P and H.
6.4 The Building Blocks of LifeChapter 6
1. A2. B3. C4. D
CDQ 1
A. electronB. isotopeC. neutronD. proton
Which of the following particles is negatively charged?
Chemistry in Biology
Chapter Diagnostic Questions
Chapter 6
1. A2. B3. C4. D
CDQ 2
Chemistry in Biology
Chapter Diagnostic Questions
Chapter 6
A. electronsB. neutronsC. protonsD. ions
Isotopes are created by a change in the number of what particle of an atom?
1. A2. B3. C4. D
CDQ 3
Chemistry in Biology
Chapter Diagnostic Questions
Chapter 6
A. substratesB. enzymesC. ionsD. reactants
Identify the proteins that speed up the rate of chemical reactions.
1. A2. B3. C
FQ 1
Chemistry in BiologyChapter 6
A. neutrons and electronsB. protons and electronsC. protons and neutrons
What particles are in an atom’s nucleus?
6.1 Formative Questions
1. A2. B3. C
FQ 2
Chemistry in BiologyChapter 6
6.1 Formative Questions
A. an equal number of protons and neutrons
B. an equal number of protons and electrons
C. an equal number of neutrons and electrons
What causes the overall charge of an atom to be zero?
1. A2. B3. C4. D
FQ 3
Chemistry in BiologyChapter 6
6.1 Formative Questions
A. a compoundB. an elementC. an isotopeD. a mixture
What type of substance is water?
1. A2. B3. C4. D
FQ 4
Chemistry in BiologyChapter 6
6.1 Formative Questions
A. chemical bondsB. ionic compoundsC. radioactive isotopesD. van der Waals forces
What provides the energy for all living processes?
1. A2. B3. C4. D
FQ 5
Chemistry in BiologyChapter 6
6.2 Formative Questions
A. a match burningB. salt dissolvingC. water boilingD. gasoline evaporating
Which is a chemical reaction?
1. A2. B
FQ 6
Chemistry in BiologyChapter 6
6.2 Formative Questions
Which chemical reaction is endothermic?A.
A.
1. A2. B3. C4. D
FQ 7
Chemistry in BiologyChapter 6
6.2 Formative Questions
A. It acts as a reactant.B. It reduces the amount
of heat produced.C. It increases the
amount of product.D. It lowers the activation
energy.
How does an enzyme increase the rate of a chemical reaction?
1. A2. B3. C4. D
FQ 8
Chemistry in BiologyChapter 6
6.2 Formative Questions
What occurs at the active site in the enzyme substrate complex?
A. An exothermic chemical reaction takes place.
B. Chemical bonds are broken and new bonds are formed.
C. The enzyme gets used up in the reaction.
D. The substrates provide energy for the enzyme.
1. A2. B3. C4. D
FQ 9
Chemistry in BiologyChapter 6
6.3 Formative Questions
A. It acts as a catalyst.B. Its pH is neutral.C. It is a polar molecule.D. It is an ionic compound.
Why is water able to dissolve a wide variety of solutes?
1. A2. B3. C4. D
FQ 10
Chemistry in BiologyChapter 6
6.3 Formative Questions
A. covalent bondsB. double bondsC. hydrogen bondsD. ionic bonds
What type of bonds attracts water molecules to each other and to other substances?
1. A2. B3. C4. D
FQ 11
Chemistry in BiologyChapter 6
6.3 Formative Questions
A. Cl– B. OH–
C. H+
D. Na+
Which ion, when released in water, causes a solution to be basic?
1. A2. B3. C4. D
FQ 12
Chemistry in BiologyChapter 6
6.3 Formative Questions
A. alkaliB. antacidC. bufferD. neutralizer
What is the name for a substance that keeps the pH in cells within the 6.5 to 7.5 pH range?
1. A2. B3. C4. D
FQ 13
Chemistry in BiologyChapter 6
6.4 Formative Questions
A. carbonB. nitrogenC. phosphorusD. sodium
Which element do almost all biological molecules contain?
1. A2. B3. C4. D
FQ 14
Chemistry in BiologyChapter 6
6.4 Formative Questions
A. 1B. 2C. 4D. 8
How many covalent bonds can carbon form with other atoms?
1. A2. B3. C4. D
FQ 15
Chemistry in BiologyChapter 6
6.4 Formative Questions
A. hormoneB. nucleic acidC. proteinD. steroid
What type of biological molecule is an enzyme?
1. A2. B3. C4. D
FQ 16
Chemistry in BiologyChapter 6
6.4 Formative Questions
A. lipidsB. nucleotidesC. polypeptidesD. sugars
What are fats, oils, and waxes composed of?
1. A2. B3. C4. D
FQ 17
Chemistry in BiologyChapter 6
6.4 Formative Questions
A. amino acidsB. fatty acidsC. glycerolsD. nucleotides
What are the monomers that make up proteins?
1. A2. B3. C4. D
FQ 18
Chemistry in BiologyChapter 6
A. carbohydrateB. lipidC. nucleic acidD. protein
Which biological molecule transports substances between cells?
6.4 Formative Questions
1. A2. B3. C4. D
CAQ 1
Chemistry in BiologyChapter 6
A. activation energyB. reactantsC. productsD. enzymes
Look at the following figure. Determine what the upward curve represents.
Chapter Assessment Questions
?
1. A2. B3. C4. D
CAQ 2
Chemistry in BiologyChapter 6
Chapter Assessment Questions
A. 2B. 4C. 6D. 8
Look at the energy levels in the atom. What is the maximum number of electrons energy level two can hold?
Explain why chemical equations must be balanced.
Chemistry in Biology
Answer: Chemical reactions require balanceof mass. Therefore, the number of atoms of each element on the reactant side must equal the number of atoms of the same element on the product side.
Chapter Assessment Questions
Chapter 6
CAQ 3
1. A2. B3. C4. D
STP 1
Chemistry in BiologyChapter 6
A. atoms sharing electrons
B. table salt dissolving in water
C. ionic compounds forming crystals
D. water molecules forming droplets
Which is a result of van der Waals forces?
Standardized Test Practice
1. A2. B3. C4. D
STP 2
Chemistry in BiologyChapter 6
What is true of this chemical reaction?
A. Energy is not needed to start the chemical reaction.
B. Heat and/or light energy are released in this reaction.
C. The activation energy is greater than the energy released.
D. The energy of the products and the reactants is the same.
Standardized Test Practice
1. A2. B3. C4. D
STP 3
Chemistry in BiologyChapter 6
Standardized Test Practice
A. tomatoesB. bananas
Which fruit contains a higher concentration of hydrogen ions?
1. A2. B3. C4. D
STP 4
Chemistry in BiologyChapter 6
Standardized Test Practice
What do cellulose and chitin have in common?
A. They are energy- storing polymers.
B. They are found in the cells of animals.
C. They are structural polysaccharides.
D. They are composed of repeating sucrose units.
1. A2. B3. C4. D
STP 5
Chemistry in BiologyChapter 6
Standardized Test Practice
A. glutenB. glycogenC. starchD. sucrolose
Which polysaccharide stores energy in muscle and liver tissue?
1. A2. B3. C4. D
STP 6
Chemistry in BiologyChapter 6
Standardized Test Practice
What is the function of this biological macromolecule?A. communicate signals
between cellsB. produce vitamins
and hormonesC. provide support
and protectionD. store and transmit
genetic information
1. A2. B3. C4. D
STP 7
Chemistry in BiologyChapter 6
Standardized Test Practice
Which is a characteristic of all lipids?
A. They are saturated triglycerides.
B. They do not dissolve in water.
C. They are liquid at room temperature.
D. They store less energy than carbohydrates.