Name and Period:
C
HAPTER3
The Molecules of Cells
Chapter Objectives
Introduction to Organic Compounds
3.1 Explain why carbon is unparalleled in its ability to form large, diverse molecules.
3.1 Define organic compounds, hydrocarbons, a carbon skeleton, and an isomer.
3.2 Describe the properties of and distinguish between the six chemical groups important in the chemistry of life.
3.3 List the four main classes of macromolecules important to life. Explain the relationship between monomers and polymers. Compare the processes of dehydration synthesis and hydrolysis.
Carbohydrates
3.4–3.7 Describe the structures, functions, properties, and types of carbohydrate molecules common in the human diet.
3.6 Explain how and why high-fructose corn syrup is produced.
Lipids
3.8–3.10 Describe the structures, functions, properties, and types of lipid molecules.
3.10 Describe the health risks associated with the use of anabolic steroids.
Proteins
3.11–3.13 Describe the structures, functions, properties, and types of proteins.
3.12 Explain how a protein’s shape determines its functions.
Nucleic Acids
3.14–3.15 Compare the structures and functions of DNA and RNA, noting similarities and differences.
Key Terms
amino
acid-amino
group-anabolic
steroid-
carbohydrate-carbon
skeleton-carbonyl
carboxyl
group-
cellulose-
chitin-
cholesterol-dehydration
reaction-
denaturation-deoxyribonucleic acid
(DNA)-
helix-
enzyme-
fat-functional
group-
gene-
glycogen-
hydrocarbon-
hydrolysis-
hydrophilic-
hydrophobic-hydroxyl
group-
isomers-
lipid-
macromolecule-methyl
monomer-
monosaccharide-nucleic
acid-
nucleotide-organic
compound-peptide
bond-phosphate
group-
phospholipid-
polymer-
polypeptide-
polysaccharide-primary
structure-
protein-quaternary
structure-ribonucleic acid
(RNA)-saturated fatty
structure-
starch-
steroid-tertiary
structure-trans
fat-unsaturated fatty
acid-Lecture Outline
I. Introduction
A.Most of the world’s population cannot digest milk-based foods.
1. These people are lactose intolerant because they lack the enzyme lactase.
2. This illustrates the importance of biological molecules, such as lactase, in the daily functions of living organisms.
II. Introduction to Organic Compounds
A.3.1 Life’s molecular diversity is based on the properties of carbon
1. Diverse molecules found in cells are composed of carbon bonded to
a. b.
2. Organic compounds
-3. By sharing electrons, carbon can
a. b.
4. Methane (CH4) is one of the simplest organic compounds.
b.Each of the four lines in the formula for methane represents a pair of shared electrons.
5. Methane and other compounds composed of only carbon and hydrogen are called
hydrocarbons.
6. Carbon, with attached
hydrogens-7. A carbon skeleton is a chain of carbon atoms that can be
a. branched or
b.unbranched.
8. Isomers
-B. 3.2 A few chemical groups are key to the functioning of biological molecules
1. An organic compound has unique properties that depend upon the
a. size and shape of the molecule and
b.groups of atoms (functional groups) attached to it.
2. A functional group
-3. Compounds containing functional groups
are-4. The functional groups are
a. hydroxylgroup
-b. carbonylgroup
-c. carboxylgroup
-d. aminogroup
-5. An example of similar compounds that differ only in functional groups is sex hormones.
a. Male and female sex hormones differ only in functional groups.
b.The differences cause varied molecular actions.
c. The result is distinguishable features of males and females.
C.3.3 Cells make a huge number of large molecules from a limited set of small molecules
1. There are four classes of molecules important to organisms:
a. b. c. d.
2. The four classes of biological molecules contain very large molecules.
a. They are often called macromolecules
-b.They are also called polymers
-c. The building blocks of polymers are
called-3. Monomers are linked together to form polymers through dehydration reactions
-4. Polymers are broken apart by hydrolysis
-5. All biological reactions of this sort are mediated by enzymes
-6. A cell makes a large number of polymers from a small group of monomers. For example,
a. proteins are made
from-b.DNA is built from just four kinds
III. Carbohydrates
A.3.4 Monosaccharides are the simplest carbohydrates
1. Carbohydrates
-2. Sugar monomers are monosaccharides
-a. b.
3. Monosaccharides can be hooked together to form
a. b.
4. The carbon skeletons of monosaccharides vary in length.
a. Glucose and fructose are six carbons long.
b.Others have three to seven carbon atoms.
5. Monosaccharides are
a. b.
6. Many monosaccharides form rings.
7. The ring diagram may be
a. abbreviated by not showing the carbon atoms at the corners of the ring and
b.drawn with different thicknesses for the bonds, to indicate that the ring is a relatively flat structure with attached atoms extending above and below it.
B. 3.5 Two monosaccharides are linked to form
a-1. Two monosaccharides (monomers) can bond to form a disaccharide
a. b.
3. The disaccharide maltose is formed from
two-C.3.6 CONNECTION: What is high-fructose corn syrup, and is it to blame for obesity?
1. Sodas or fruit drinks probably contain high-fructose corn syrup (HFCS).
2. Fructose is sweeter than glucose.
3. To make HFCS, glucose atoms are rearranged to make the glucose isomer, fructose.
4. High-fructose corn syrup (HFCS) is
a. used to sweeten many beverages and
b.may be associated with weight gain.
5. Good health is promoted by
a. a diverse diet of proteins, fats, vitamins, minerals, and complex carbohydrates and
b.exercise.
D.3.7 Polysaccharides are long chains of sugar units
1. Polysaccharides are
a. b.
2. Polysaccharides may function as
a. b. 3. Starch is
a. b. c.
a. b. c.
5. Cellulose
a. is a polymer of glucose and
b. 6. Chitin is
a. a polysaccharide and
b.
7. Polysaccharides are usually hydrophilic (water-loving).
8. Bath towels are
a. often made of cotton, which is mostly cellulose, and
b.water absorbent.
IV. Lipids
A.3.8 Fats are lipids that are
mostly-1. Lipids a. b. c. d.
2. Lipids differ from carbohydrates, proteins, and nucleic acids in that they are
a. not huge molecules and
b.not built from monomers.
a. structure and
b.function.
4. We will consider three types of lipids:
a. b. c. 5. A fat
-a. b.
6. A fatty acid can link to glycerol by a dehydration reaction.
a. A fat
contains-b.Fats are often called triglycerides because of their structure.
7. Some fatty acids contain one or more double bonds, forming unsaturatedfatty acids that
a.
b.cause kinks or bends in the carbon chain, and
c. prevent them from packing together tightly
and-8. Fats with the maximum number of hydrogens are
called-9. Unsaturated fats
include-10. Most animal fats
are-11. Hydrogenated vegetable oils are unsaturated fats that have been converted to saturated fats by adding hydrogen.
12. This hydrogenation creates trans fats associated with health risks.
1. Phospholipids are
a. b.
2. Phospholipids are structurally similar to fats.
a. Fats contain three fatty acids attached to glycerol.
b.Phospholipids
contain-3. Phospholipids cluster into a bilayer of phospholipids.
4. The hydrophilic heads are in contact with
a.
b.the internal part of the cell.
5. The hydrophobic tails band in
the-6. Steroids
-7. Cholesterol is a
a. common component in animal
cell-b.starting material for making steroids,
including-C.3.10 CONNECTION: Anabolic steroids pose health risks
1. Anabolic steroids
a. are synthetic variants of testosterone,
b.can cause
a-c. are often prescribed to treat general anemia and some diseases that destroy body muscle.
2. Anabolic steroids are abused by some athletes with serious consequences, including
a.
b.depression,
d.cancer,
e.
f. high blood pressure.
V. Proteins
A.3.11 Proteins are made from amino acids linked by peptide bonds
1. Proteins are
a. involved in nearly
every-b.very diverse, with ten of thousands of different proteins, each with a
specific-2. Proteins are composed of differing arrangements of a common set of
-3. Aminoacids have
a. b.
4. Also bonded to the central carbon is
a. a hydrogen atom and
b.a chemical group symbolized by
R-5. Amino acids are classified as either
a. hydrophobic or
b.hydrophilic.
6. Amino acid monomers are linked together
a. in
a-b.joining carboxyl group of one amino acid to the amino group of the next amino acid, and
c. creating a peptidebond.
B. 3.12 A protein’s specific shape determines its function
1. Probably the most important role for proteins is
as-a. serve as
metabolic-b.regulate
the-2. Other proteins are also important.
a. Structural-b. Contractile-c. Defensive
-d. Signal
-e. Receptor
-f. Transport proteins
carry-g. Storage proteins serve as a source of amino acids for developing embryos.
3. A polypeptide chain contains of hundreds or thousands of amino
acids-4. The amino acid sequence causes the polypeptide to assume
a-5. The shape of a protein determines
its-6. If a protein’s shape is altered, it can
no-7. In the process of denaturation, a polypeptide chain
a. b. c.
8. Proteins can be denatured by changes
in-C.3.13 A protein’s shape depends on four levels of structure
1. A protein can have four levels of structure:
b. c. d.
2. The primary structure of a protein is its unique amino acid sequence.
a. The correct amino acid sequence is determined by the
cell’s-b.The slightest change in this sequence may affect the
protein’s-3. Protein secondary structure results from coiling or folding of the polypeptide.
a. Coiling results in
a-b.A certain kind of folding leads to a structure called a pleated sheet, which dominates some fibrous proteins such as those used in spider webs.
c. Coiling and folding are maintained by regularly spaced hydrogen bonds between hydrogen atoms and oxygen atoms along the backbone of the polypeptide chain.
4. The overall three-dimensional shape of a polypeptide is called
its-a. Tertiary structure generally results from interactions between the R groups of the various amino acids.
b.Disulfide bridges may further
strengthen-5. Two or more polypeptide chains (subunits) associate
providing-a. Collagen is an example of a
protein-b.Collagen’s triple helix gives great strength to connective tissue, bone, tendons, and liga-ments.
VI. Nucleic Acids
A.3.14 DNA and RNA are the two types of nucleic acids
1. The amino acid sequence of a polypeptide is programmed by a discrete unit of inheritance known as
of-4. DNA provides directions for its own replication.
5. DNA programs a cell’s activities by directing
the-6. DNA does not build proteins directly.
7. DNA works through an
intermediary-a. b.
B. 3.15 Nucleic acids are polymers of nucleotides
1. DNA (deoxyribonucleic acid) and RNA (ribonucleic acid) are composed of monomers
called-2. Nucleotides have three parts:
a. b. c.
3. DNA nitrogenous bases are
a. b. c. d. 4. RNA
a. also
has-b.but instead of T, it
has-5. A nucleic acid polymer, a polynucleotide, forms
a. from the nucleotide monomers,
b.when the phosphate of one nucleotide bonds to the sugar of the next nucleotide,
d.by producing a repeating sugar-phosphate backbone with protruding nitrogenous bases.
6. Two polynucleotide strands wrap around each other to form a
DNA-a. The two strands are associated because particular bases always hydrogen bond to one an-other.
b.
7. RNA is usually
a-C.3.16 EVOLUTION CONNECTION: Lactose tolerance is a recent event in human evolution
1. The majority of people
a. stop producing the enzyme lactase in early childhood and
b.do not easily digest the milk sugar lactose.
2. Lactose tolerance represents a
a. relatively recent mutation in the human genome and
b.survival advantage for human cultures with milk and dairy products available year-round.
3. Researchers identified three mutations that keep the lactase gene permanently turned on.
4. The mutations appear to have occurred
a. about 7,000 years ago and
