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Human Biology
Sylvia S. Mader
Michael Windelspecht
Chapter 2
Chemistry of
Life
Lecture Outline
Part 3
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
1
2.5 Lipids
Understanding fats when
reading a nutrition label
• Recommendation for total amount of fat for a
2,000 calorie diet is 65g.
• Be sure to know how many servings there are.
• A % DV of 5% or less is low and 20% or more is
high.
• Try to stay away from trans fats.
• Would you eat the food on the following nutrition
label? Why or why not?
2
2.5 Lipids
Understanding fats when
reading a nutrition label
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Serving Size 1 cup (228g)
Servings Per Container 2
Start here.
Amount Per Serving
Calories 250
Calories from Fat 110
%Daily Value
Total Fat 12g
Limit these
nutrients.
Get enough
of these
nutrients.
Trans Fat 1.5g
Cholesterol 30mg
Sodium 470mg
Total Carbohydrate 31g
Dietary Fiber 0g
Sugars 5g
Protein 5g
Vitamin A
Vitamin C
Calcium
Iron
18%
15%
Saturated Fat 3g
10%
20%
10%
0%
4%
2%
20%
4%
Figure 2.18 Understanding a food label.
3
2.5 Lipids
What is the structure of a
phospholipid?
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• The structure is
similar to a
triglyceride.
• One fatty acid is
replaced by a polar
phosphate group.
• ___________ are the
primary components
of cellular
membranes.
polar
head
inside cell
nonpolar
tails
outside cell
a. Phospholipid structure
b. Membrane structure
Figure 2.19 Structure of a phospholipid.
4
2.5 Lipids
What is a steroid?
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H3C
H3C
• A steroid is a _____.
• The structure is four
fused ___________.
CH3
CH3
CH3
HO
a. Cholesterol
• Examples are
cholesterol and sex
hormones.
OH
OH
CH3
CH3
CH3
O
HO
b. Testosterone
c. Estrogen
b: © Warren Toda/epa/Corbis; c: © Tony Marsh/Reuters/Corbis
Figure 2.20 Examples of steroids.
5
2.6 Proteins
3. What are proteins?
• Made of subunits called ______________
• Important for diverse functions in the body
including hormones, enzymes, antibodies,
and transport
• Can denature: undergo a change in shape
that causes loss of ____________
6
2.6 Proteins
What do amino acids look like?
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H
H
H
H3N+
O
O–
CH
H3C
CH2
valine (val)
(nonpolar)
H
H3N+
C
O–
O–
CH2
CH2
CH2
COO–
N +H 3
glutamic acid (glu)
(ionized, polar)
lysine (lys)
(ionized, polar)
O
C
CH2
H
O–
H3N+ C
O
H
C
CH2
NH
Figure
2.21 The
structure of
a few
amino
acids.
C
CH2
C
CH2
C
C
H3N+ C
O
H3N+ C
O
O–
C
–O
tryptophan (trp)
(nonpolar)
O
aspartic acid (asp)
(ionized, polar)
H3N+
C
CH2
O
C
O–
SH
cysteine (cys)
(polar)
7
2.6 Proteins
What are the 4 levels of protein
organization?
• Primary – the _______ order of amino acids
• Secondary – localized folding into ___________
______ and _________
• Tertiary – the 3-D shape of the entire protein in
space
• Quaternary – combination of more than one
polypeptide
• All proteins have primary, secondary, and
tertiary structure, while only a few have
quaternary structure.
8
2.6 Proteins
What do the levels of organization
look like?
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Primary Structure:
sequence of amino acids
H3N+
amino acid
COO–
peptide bond
Secondary Structure:
Alpha helix or a pleated sheet
hydrogen bond
C
CH
C
N
CH
C
N
CH
R
C
CH
C
CH
N
N
C
C
CH
N
N
R
R
hydrogen bond
C
R
R
CH
N
R
R
CH
 (alpha) helix
Tertiary Structure:
final shape of polypeptide
(beta) sheet =
pleated sheet
disulfide bond
Quaternary Structure:
two or more associated
polypeptides
Figure 2.23 Levels of protein structure.
9
2.7 Nucleic Acids
4. What are nucleic acids?
• Made of _________ subunits
• Function in the cell to make proteins
• Include RNA and DNA
10
2.7 Nucleic Acids
What are the 3 parts of a nucleotide?
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phosphate
C
P
5'
Nucleotide
nitrogencontaining
base
O
S
4'
1'
2'
3'
sugar
11
2.7 Nucleic Acids
What are the 5 bases found in
nucleotides?
• _________ (A) and __________ (G) are
double-ringed purines.
• _________ (C), ________ (T), and _____ (U)
are single-ringed pyrimidines.
• In DNA, A pairs with T and G pairs with C.
12
2.7 Nucleic Acids
What are the 5 bases found in
nucleotides?
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
H
N
Hydrogen bond
N
H
CH3
O
C
N
N
H
bases
N
C
S
N
N
O
G
P
HN
O
Adenine (A)
Thymine (T)
(DNA only)
A
G
T
T
C
A
N
H
O
N
H
CH
N
O
H
Uracil (U)
(RNA only)
C
U
S
P
N
A
S
G
N
P
backbone
H
C
N
C
P
N
CH
U
N
N
H
O
S
H
Guanine (G)
a. DNA structure with base pairs: A with T and G with C
Cytosine (C)
b. RNA structure with bases G, U, A, C
Figure
2.24 The
structure of
DNA and
RNA.
13
2.7 Nucleic Acids
Summary of DNA and RNA
structural differences
• DNA
– Sugar is _________
– Bases include A, T,
C, and G
– Double-stranded
• RNA
– Sugar is _______
– Bases include A, U,
C, and G
– Single-stranded
14
Summary of the macromolecules
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Organic
molecules
Examples
Monomers
Functions
CH2OH
O
H
Carbohydrates
Monosaccharides,
disaccharides,
polysaccharides
OH
Immediate
energy
and stored
energy;
structural
molecules
H
H
HO
OH
H
OH
Glucose
H
Lipids
Fats, oils,
phospholipids,
steroids
H
O
C
OH
H
C
OH
H
C
OH
C
HO
H
H
H
H
H
C
C
C
C
C
H
H
H
H
H
R
Fatty acid
H
Glycerol
Proteins
Structural,
enzymatic,
carrier,
hormonal,
contractile
amino
group
H2N
H
C
acid
group
COOH
R
group
Long-term
energy
storage;
membrane
components
Support,
metabolic,
transport,
regulation,
motion
Amino acid
phosphate
P
Nucleic acids
DNA, RNA
base
C
O
S
Nucleotide
Storage of
genetic
information
15