CHEMISTRY
Matter and Change
Chapter 23: The Chemistry of Life
CHAPTER
23
Table Of Contents
Section 23.1
Proteins
Section 23.2
Carbohydrates
Section 23.3
Lipids
Section 23.4
Nucleic Acids
Section 23.5
Metabolism
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SECTION
23.1
• Describe the structures
of amino acids and
proteins.
• Explain the roles of
proteins in cells.
Proteins
polymer: large
molecules composed of
many repeating units
called monomers
SECTION
Proteins
23.1
protein
denaturation
amino acid
enzyme
peptide bond
substrate
peptide
active site
Proteins perform essential functions,
including regulation of chemical
reactions, structural support, transport
of materials, and muscle contractions.
SECTION
23.1
Proteins
Protein Structure
• Proteins are organic polymers made of
amino acids linked together in a specific
order, not just random chains of amino
acids.
• Amino acids are organic molecules that
have both an amino group and an acidic
carboxyl group.
SECTION
23.1
Proteins
Protein Structure (Cont.)
• Each amino acid has a central carbon
atom, with four groups arranged around it:
an amino group, carboxyl group, hydrogen
atom, and variable side chain.
SECTION
23.1
Proteins
Protein Structure (Cont.)
SECTION
23.1
Proteins
Protein Structure (Cont.)
• The amino and carboxyl groups provide
bonding sites for linking amino acids
together.
SECTION
23.1
Proteins
Protein Structure (Cont.)
• The amide bond that joins the two amino
acids is called a peptide bond.
SECTION
23.1
Proteins
Protein Structure (Cont.)
• Peptide chains of ten or more amino acids
are called polypeptides.
SECTION
23.1
Proteins
Protein Structure (Cont.)
• When a chain reaches 50 or more amino
acids, it is called a protein.
• Only 20 different amino acids exist.
SECTION
23.1
Proteins
Protein Structure (Cont.)
• Long chains of amino acids fold in unique
shapes determined by the interaction
among amino acids.
• Denaturation is the process in which a
protein’s natural three-dimensional structure
is disrupted.
–Changes in temperature, ionic strength, pH, and
other factors result in the unfolding and uncoiling of
a protein.
SECTION
23.1
Proteins
Protein Structure (Cont.)
SECTION
23.1
Proteins
The Many Functions of Proteins
• An enzyme is a biological catalyst.
• A catalyst lowers the activation energy of a
reaction by stabilizing the transition states.
• A substrate refers to the reactant in an
enzyme-catalyzed reaction.
• The spot to which the substrates bind is
called the active site.
• Substrates must fit the active site in the same
way puzzle pieces fit together.
SECTION
23.1
Proteins
The Many Functions of Proteins (Cont.)
SECTION
23.1
Proteins
The Many Functions of Proteins (Cont.)
• Some proteins are involved in transporting
smaller particles throughout the body.
SECTION
23.1
Proteins
The Many Functions of Proteins (Cont.)
• Certain proteins’ sole function is to form
structures vital to organisms. They are
known as structural proteins.
– The most abundant structural protein in most
animals is collagen, which makes up skin,
ligaments, tendons, and bones.
– Other structural proteins make up feathers, fur,
wool, hooves, fingernails, cocoons and hair.
SECTION
23.1
Proteins
The Many Functions of Proteins (Cont.)
• Some hormones are proteins and are used
as chemical messenger molecules that carry
signals from one part of the body to another.
–Ex. Insulin, made by pancreas cells, when released
into the bloodstream signals the body the blood
sugar is abundant and should be stored.
SECTION
23.1
Section Check
Which best describes a protein?
A. a building block
B. a biological polymer
C. an enzyme
D. a catalyst
SECTION
23.1
Section Check
Amino acids in a protein are linked
together by ____.
A. ionic bonds
B. hydrogen bonds
C. peptide bonds
D. temporary dipole
SECTION
23.2
Carbohydrates
• Describe the structures
of monosaccharides,
disaccharides, and
polysaccharides.
• Explain the functions of
carbohydrates in living
things.
stereoisomers: a class
of isomers whose atoms
are bonded in the same
order but are arranged
differently in space
SECTION
Carbohydrates
23.2
carbohydrate
monosaccharide
disaccharide
polysaccharide
Carbohydrates provide energy and
structural material for living things.
SECTION
23.2
Carbohydrates
Kinds of Carbohydrates
• Carbohydrates are compounds that
contain multiple hydroxyl groups as well as
carbonyl groups.
• Monosaccharides are the simple sugars,
composed of five or six carbon atoms.
SECTION
23.2
Carbohydrates
Kinds of Carbohydrates (Cont.)
• Glucose is a six-carbon sugar that is
present in high concentration in blood.
• Glucose is a major source of immediate
energy for the body.
SECTION
23.2
Carbohydrates
Kinds of Carbohydrates (Cont.)
• Disaccharides are formed when two
monosaccharides are bonded together.
SECTION
23.2
Carbohydrates
Kinds of Carbohydrates (Cont.)
• Polysaccharides are polymers of simple
sugars made up of 12 or more monomers.
• Glycogen is an important polysaccharide
found in animals that is used to store energy.
• Starch and cellulose are also important
polysaccharides found in starch.
SECTION
23.2
Section Check
Carbohydrates contain which two
functional groups?
A. amine and hydroxyl
B. carbonyl and amide
C. carbonyl and aldehyde
D. hydroxyl and carbonyl
SECTION
23.2
Section Check
Which of the following is considered a
monosaccharide?
A. glucose
B. glycogen
C. starch
D. cellulose
SECTION
23.3
Lipids
• Describe the structures of fatty acids, triglycerides,
phospholipids, and steroids.
• Explain the functions of lipids in living organisms.
• Identify some reactions that fatty acids undergo.
• Relate the structure and function of cell membranes.
nonpolar: without separate positive and negative
areas or dipoles
SECTION
Lipids
23.3
lipid
phospholipid
fatty acid
wax
triglyceride
steroid
saponification
Lipids make cell membranes, store
energy, and regulate cellular
processes.
SECTION
23.3
Lipids
What is a lipid?
• A lipid is a large, nonpolar biological molecule.
• Fatty acids, the building blocks of lipids, are
long-chain carboxylic acids.
• Fatty acids are placed in two groups: saturated
and unsaturated.
SECTION
23.3
Lipids
What is a lipid? (cont.)
• Saturated fats contain only single bonds.
• Unsaturated fats contain one or more double
bonds.
SECTION
23.3
Lipids
What is a lipid? (cont.)
• Triglycerides are formed when three fatty
acids are bonded to a glycerol backbone.
• Triglycerides can be solids or liquids at room
temperature.
SECTION
23.3
Lipids
What is a lipid? (cont.)
• Saponification is the hydrolysis of a
triglyceride using an aqueous solution of a
strong base to form carboxylate salts and
glycerol.
• Saponification is used to make soaps.
SECTION
23.3
Lipids
What is a lipid? (cont.)
• Phospholipids are triglycerides in which
one fatty acid is replaced by a polar
phosphate group.
• Cell membranes are made up of a double
layer of phospholipids, called a lipid bilayer.
SECTION
23.3
Lipids
What is a lipid? (cont.)
• Waxes are lipids formed by combining a
fatty acid with a long-chain alcohol.
• Both plants and animals make waxes.
• Steroids are lipids that have multiple cyclic
rings in their structures.
SECTION
23.3
Section Check
A triglyceride in which a fatty acid is
replaced by a phosphate group is a ____.
A. wax
B. phospholipid
C. steroid
D. fatty acid
SECTION
23.3
Section Check
Fatty acids, the building blocks of lipids,
are composed of what?
A. triglycerides
B. steroids
C. amides
D. long-chain carboxylic acids
SECTION
23.4
Nucleic Acids
• Identify the structural
components of nucleic
acids.
• Relate the function of
DNA to its structure.
genetic information: an
inherited sequence of
RNA or DNA that causes
traits or characteristics to
pass from one generation
to the next
• Describe the structure
and function of RNA.
nucleic acid
nucleotide
Nucleic acids store and transmit
genetic information.
SECTION
23.4
Nucleic Acids
Structure of Nucleic Acids
• A nucleic acid is a nitrogen-containing
biological polymer that is involved in the
storage and transmission of genetic
information.
• The monomer that makes up a nucleic acid is
called a nucleotide.
SECTION
Nucleic Acids
23.4
Structure of Nucleic Acids (Cont.)
• Each nucleotide has three parts:
− Inorganic phosphate group
− Five-carbon monosaccharide
− Nitrogenous base
SECTION
23.4
Nucleic Acids
DNA: The Double Helix
• DNA consists of two long
chains of nucleotides wound
together to form a spiral
structure.
• The spiral structure is
known as a double helix.
SECTION
Nucleic Acids
23.4
DNA: The Double Helix (Cont.)
• DNA contains four different nitrogenous
bases.
− Adenine
− Thymine
− Cytosine
− Guanine
SECTION
23.4
Nucleic Acids
DNA: The Double Helix (Cont.)
• The side-by-side base pairs are close
enough to form hydrogen bonds.
• Guanine always bonds to cytosine, and
thymine always bonds to adenine.
SECTION
23.4
Nucleic Acids
DNA: The Double Helix (Cont.)
• Watson and Crick used their model to
predict how DNA’s chemical structure
enables it to function.
• DNA stores genetic information of a cell in the
cell’s nucleus.
• The two chains of a DNA helix are
complementary. This complementary pairing
provides a mechanism by which genetic
material of a cell is copied.
SECTION
Nucleic Acids
23.4
RNA
• RNA is also a nucleic acid.
• The structure of RNA differs from DNA in
three ways.
− RNA contains adenine, cytosine, guanine, and
uracil (but never thymine).
− RNA contains sugar ribose instead of sugar
deoxyribose.
− DNA is a double helix while RNA is a single strand.
SECTION
23.4
Nucleic Acids
RNA (cont.)
• RNA allows cells to use genetic information
found in DNA.
SECTION
23.4
Section Check
Which is NOT part of a nucleotide?
A. nitrogenous base
B. lipid
C. phosphate group
D. sugar
SECTION
23.4
Section Check
Which is NOT a difference between RNA
and DNA?
A. DNA is a double helix; RNA a single strand.
B. DNA is a nucleic acid; RNA is not.
C. DNA has thymine; RNA has uracil.
D. DNA contains deoxyribose sugar; RNA contains
ribose sugar.
SECTION
23.5
Metabolism
• Distinguish between
anabolism and
catabolism.
• Describe the role of ATP
in metabolism.
• Compare and contrast
the processes of
photosynthesis, cellular
respiration, and
fermentation.
redox process: a
chemical reaction in
which electrons are
transferred from one
atom to another
SECTION
23.5
Metabolism
metabolism
photosynthesis
catabolism
cellular respiration
anabolism
fermentation
ATP
Metabolism involves many thousands
of reactions in living cells.
SECTION
23.5
Metabolism
Anabolism and Catabolism
• The set of chemical reactions carried out
within an organism is its metabolism.
• Catabolism refers to the metabolic
processes that break down complex
biological molecules such as proteins,
polysaccharides, triglycerides, and nucleic
acids for the purpose of forming smaller
building blocks and extracting energy.
SECTION
23.5
Metabolism
Anabolism and Catabolism (Cont.)
• Anabolism refers to the metabolic
reactions that use energy and small
building blocks to synthesize complex
molecules needed by an organism.
• Catabolism and anabolism are linked by
common building blocks that catabolic
reactions produce and anabolic reactions
use.
SECTION
23.5
Metabolism
Anabolism and Catabolism (Cont.)
SECTION
23.5
Metabolism
Anabolism and Catabolism (Cont.)
• ATP is a nucleotide that functions as the
universal energy-storage molecule in living
cells.
SECTION
23.5
Metabolism
Photosynthesis
• The process that converts energy from
sunlight to chemical energy in the bonds of
carbohydrates is called photosynthesis.
• Photosynthesis results in the reduction of
carbon atoms in carbon dioxide as glucose is
formed.
SECTION
23.5
Metabolism
Cellular Respiration
• Oxygen produced during photosynthesis is
used by living things during cellular
respiration, the process in which glucose
is broken down to form carbon dioxide,
water, and large amounts of energy.
• Cellular respiration is the major energyproducing process in living organisms.
SECTION
23.5
Metabolism
Fermentation
• Cells can extract energy from glucose in
the absence of oxygen.
• Cellular respiration produces 38 mol of ATP
per 1 mol glucose.
• Fermentation produces 2 mol ATP per 1 mol
of glucose.
SECTION
23.5
Metabolism
Fermentation (cont.)
• Fermentation is the process by which
glucose is broken down in the absence of
oxygen.
• There two common kinds of fermentation:
alcoholic and lactic acid fermentation.
SECTION
23.5
Metabolism
Fermentation (cont.)
• In alcoholic fermentation, yeast and some
bacteria can ferment glucose to produce
ethanol.
• Alcoholic fermentation is used to make bread,
form tofu, and produce ethanol in alcoholic
beverages.
SECTION
23.5
Metabolism
Fermentation (cont.)
• In lactic acid fermentation, when the
oxygen supply is depleted, cellular
respiration stops.
• Animal cells produce lactic acid and a small
amount of energy from lactic acid
fermentation of glucose.
• Build-up of lactic acid is what results in
burning pain in the muscles during strenuous
exercise.
SECTION
23.5
Section Check
Which process is the major energyproducing process in living organisms?
A. photosynthesis
B. cellular respiration
C. alcoholic fermentation
D. lactic acid fermentation
SECTION
23.5
Section Check
What process breaks down glucose in the
absence of oxygen?
A. anabolism
B. catabolism
C. cellular respiration
D. fermentation
CHAPTER
The Chemistry of Life
23
Resources
Chemistry Online
Study Guide
Chapter Assessment
Standardized Test Practice
SECTION
Proteins
23.1
Study Guide
Key Concepts
• Proteins are biological polymers made of amino
acids that are linked by peptide bonds.
• Protein chains fold into intricate three-dimensional
structures.
• Proteins have many functions in the human body,
including functions within cells, functions between cells,
and functions of structural support.
SECTION
Carbohydrates
23.2
Study Guide
Key Concepts
• Carbohydrates are compounds that contain multiple
hydroxyl groups (–OH) and a carbonyl functional group
(C=O).
• Carbohydrates range in size from single monomers to
polymers composed of hundreds or thousands of
monomers.
• Monosaccharides in aqueous solution exist in both
open-chain and cyclic structures.
SECTION
Lipids
23.3
Study Guide
Key Concepts
• Fatty acids are long-chain carboxylic acids that
usually have between 12 and 24 carbon atoms.
• Saturated fatty acids have no double bonds;
unsaturated fatty acids have one or more double
bonds.
• Fatty acids can be linked to glycerol backbones to form
triglycerides.
• Steroids are lipids that have multiple-ring structures.
SECTION
Nucleic Acids
23.4
Study Guide
Key Concepts
• Nucleic acids are polymers of nucleotides, which
consist of a nitrogen base, a phosphate group, and a
sugar.
• DNA and RNA are the information-storage molecules of
a cell.
• DNA is double stranded, and RNA is single stranded.
SECTION
Metabolism
23.5
Study Guide
Key Concepts
• Living organisms undergo catabolism and
anabolism.
• Photosynthesis directly or indirectly provides all living
things with energy.
• The net equation for cellular respiration is the reverse
of the net equation for photosynthesis.
CHAPTER
23
The Chemistry of Life
Chapter Assessment
What are biological polymers made of amino
acid monomers called?
A. enzymes
B. peptides
C. nucleotides
D. proteins
CHAPTER
23
The Chemistry of Life
Chapter Assessment
Carbonyl and hydroxyl groups are found in
which group?
A. lipids
B. fatty acids
C. carbohydrates
D. proteins
CHAPTER
23
The Chemistry of Life
Chapter Assessment
Cell membranes are usually made of what?
A. fatty acids
B. cellulose
C. triglycerides
D. phospholipids
CHAPTER
23
The Chemistry of Life
Chapter Assessment
Nucleotides are the monomers of what
biological polymer?
A. nucleic acid
B. nitrogenous bases
C. polysaccharides
D. polypeptides
CHAPTER
23
The Chemistry of Life
Chapter Assessment
Energy from sunlight is harnessed by which
process?
A. alcoholic fermentation
B. cellular respiration
C. photosynthesis
D. catabolism
CHAPTER
23
The Chemistry of Life
Standardized Test Practice
Which of the following is NOT true about
cellulose?
A. It is a polysaccharide.
B. It is easily digestible by humans.
C. It is produced by plants.
D. It is a carbohydrate.
CHAPTER
23
The Chemistry of Life
Standardized Test Practice
Which of the following is NOT true about DNA?
A. DNA contains the nitrogenous base thymine.
B. DNA is usually double stranded.
C. DNA contains the nitrogenous base uracil.
D. DNA contains deoxyribose sugar.
CHAPTER
23
The Chemistry of Life
Standardized Test Practice
What is the condensed structural formula of 1pentanol?
A. CH3(CH2)4OH
B. CH3(CH2)3COOH
C. CH3(CH2)3CH=O
D. CH2-O-(CH2)3CH3
CHAPTER
23
The Chemistry of Life
Standardized Test Practice
What is the oxidation number of Zn in Zn(NO3)2?
A. +2
B. +3
C. +5
D. +6
CHAPTER
23
The Chemistry of Life
Standardized Test Practice
Glucose is considered a ____.
A. simple sugar
B. polysaccharide
C. fatty acid
D. nucleotide
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