Transcript chapt02_HumanBiology14e_lecture

Chapter 02
Lecture Outline
See separate PowerPoint slides for all figures and tables preinserted into PowerPoint without notes.
Copyright © 2016 McGraw-Hill Education. Permission required for reproduction or display.
1
Chemistry of Life
2
Points to ponder
• How are living things organized from atoms to
molecules?
• What is pH and how is it important to living
organisms?
• What are the four macromolecules found in living
organisms?
• What are the structure (subunits) and function of
these four macromolecules?
• How are proteins organized and how is their shape
important to their function?
• How are DNA and RNA similar and how are they
different?
3
2.1 From Atoms to Molecules
Building blocks from large to small
• Matter is anything that has mass and takes up
space.
• Elements are the basic building blocks of matter
that cannot be broken down by chemical means.
• Atoms are the smallest units of an element that
retain the element’s physical and chemical
properties. These bond together to form
molecules.
4
2.1 From Atoms to Molecules
• Atomic symbol
• Atomic mass
• Atomic number
Periods
1
2
3
4
Figure 2.1 A portion of the
periodic table of elements.
Elements
I
VIII
1
atomic number
H
atomic symbol
2
atomic mass
He
1.008
II
III
IV
V
VI
VII
4.003
3
4
5
6
7
8
9
10
Li
Be
B
C
N
O
F
Ne
6.941
9.012
10.81
12.01
14.01
16.00
19.00
20.18
11
12
13
14
15
16
17
18
Na
Mg
Al
Si
P
S
Cl
Ar
22.99
24.31
26.98
28.09
30.97
32.07
35.45
39.95
19
20
31
32
33
34
35
36
K
Ca
Ga
Ge
As
Se
Br
Kr
39.10
40.08
69.72
72.59
74.92
78.96
79.90
83.60
Groups
5
2.1 From Atoms to Molecules
Subatomic particles of atoms
• Neutrons are neutral (uncharged).
• Protons are positively charged.
• Neutrons and protons make up the nucleus.
• Electrons are negatively charged and orbit
around the nucleus.
6
2.1 From Atoms to Molecules
Subatomic particles of atoms
Subatomic Particles
Particle
Charge
Atomic Mass Unit
(AMU)
Proton
+1
1
Neutron
0
1
Electron
–1
0
1p
hydrogen
H
Figure 2.2 The
atomic structure
of select
elements.
6p
6n
7p
7n
8p
8n
carbon
C
nitrogen
N
oxygen
O
2.1 From Atoms to Molecules
Isotopes
• Isotopes are atoms that have the same atomic
number but a different atomic mass because the
number of neutrons differ.
• Radioisotopes are useful in dating old objects,
imaging body organs and tissues through X-rays,
and killing cancer cells.
• Radiation can be harmful by damaging cells and
DNA and/or causing cancer.
8
2.1 From Atoms to Molecules
Isotopes
missing
portion
of organ
larynx
thyroid gland
trachea
a.
b.
2.3a: © Biomed Commun./Custom Medical Stock Photo; 2.3b(patient): © National Institutes of Health; 2.3b(scan):
© Mazzlota et al./Science Source
Figure 2.3 Medical uses for
low-level radiation.
2.1 From Atoms to Molecules
Molecules
• Made of atoms that are bonded together
• Can be made of the same atom or
different atoms
10
2.1 From Atoms to Molecules
Ionic bonds
• Atoms in this type of bond donate or take on
electrons
• Result in a stable outer shell
• Occur between particles that are charged
(ions)
11
2.1 From Atoms to Molecules
Ionic bonds
Figure 2.5 Formation of an ionic bond.
12
2.1 From Atoms to Molecules
Covalent bonds
• Atoms in this type of bond share electrons
• Result in a stable outer shell
13
2.1 From Atoms to Molecules
Covalent bonds
1p
8p
8n
1p
+
8p
8n
1p
oxygen
O
2 hydrogen
2H
1p
water
H2O
a. When an oxygen and two hydrogen atoms covalently bond, water results.
8p
8n
oxygen
O2
+
8p
8n
oxygen
O2
8p
8n
8p
8n
oxygen gas
O2
b. When two oxygen atoms covalently bond, oxygen gas results.
Figure 2.6 Covalent bonds.
14
2.2 Water and Life
What are the properties of water?
• Water is liquid at room temperature.
• Liquid water does not change temperature
quickly.
• Water has a high heat of evaporation.
• Frozen water is less dense than liquid water.
• Molecules of water cling together.
• Water is a solvent for polar molecules.
15
2.2 Water and Life
What bond holds water molecules
together?
• Hydrogen bonds
occur between a
hydrogen in a
covalent bond and
a negatively charged
atom.
• These are relatively
weak bonds.
+
H
O
hydrogen
bond
H
+
Hydrogen bonding between water molecules
Figure 2.7b Hydrogen bonds and water molecules.
16
2.2 Water and Life
Acids and bases
• Acids are substances that dissociate and
release hydrogen ions (H+).
• Bases are substances that take up
hydrogen ions (H+) or release hydroxide
ions (OH-).
17
2.2 Water and Life
What is the pH scale?
• A measure of hydrogen ion (H+) concentration
• Working scale is between 0 and 14 with 7 being
neutral
• A pH below 7 is acidic and above 7 is basic
• The concentration of hydrogen ions between
each whole number changes by a factor of 10
18
2.2 Water and Life
Looking at the pH scale
basic
acidic
H+ Ion
Concentration
Figure 2.10
The pH scale.
100
10-1
10-2
10-3
10-4
10-5
10-6
10-7
10-8
10-9
10-10
10-11
10-12
-13
+
10H
10-14
pH Value
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
Examples
hydrochloric acid
stomach acid, lemon juice
vinegar, cola, beer
tomatoes
black coffee
urine
pure water
seawater
baking soda
Great Salt Lake
household ammonia
household bleach
OH–
sodium hydroxide
19
2.3 Molecules of Life
Making and breaking down
organic molecules
• Dehydration reaction – the removal of water
that allows subunits to link together into
larger molecules
• Hydrolysis reaction – the addition of water
that breaks larger molecules into their
subunits
20
2.3 Molecules of Life
How do we build and break down
organic molecules?
subunit
OH
H
dehydration
reaction
subunit
H2O
subunit
subunit
a.
subunit
hydrolysis
reaction
Figure 2.11 The
breakdown and synthesis
of macromolecules.
subunit
b.
OH
H
subunit
H2O
subunit
21
2.3 Molecules of Life
What organic molecules are
found in living organisms?
1. Carbohydrates
2. Lipids
3. Proteins
4. Nucleic acids
22
2.4 Carbohydrates
1. What are carbohydrates?
• Made of subunits called monosaccharides
• Made of C, H, and O in which the H and O
atoms are in a 2:1 ratio
• Function as short- and long-term energy
storage
• Found as simple and complex forms
23
2.4 Carbohydrates
What are simple carbohydrates?
• Monosaccharide –
1 carbon ring as
found in glucose
CH2OH
6
H
CH2OH
O
5 C
H
C
4
H O
C
O H
H
C
C
3
O
H
H
1
OH
O H
O
H
H
HO
OH
2
H
O H
H
O H
C6H12O6
• Disaccharide –
2 carbon rings as
found in maltose
CH2OH
CH2OH
O
O
O
maltose
Figure 2.12 The synthesis and breakdown of a disaccharide.
C12H22O11
24
2.4 Carbohydrates
What are complex carbohydrates?
• Polysaccharides are
made of many carbon
rings.
• Glycogen is the
storage form in
animals.
CH2OH
O
H
O
H
OH
H
H
OH
H H
O
CH2OH
O
H
OH
H
H
OH
CH2OH
H
O
H
O
H
OH
H
H
OH
H
H
O
CH2OH
O
H
OH
H
H
H
O
OH
branched
nonbranched
• Starch is the storage
form in plants.
starch
granule
cell wall
potato cells
© Jeremy Burgess/SPL/Science Source
Figure 2.13 Starch is a plant complex carbohydrate.
25
2.5 Lipids
2. What are lipids?
• Molecules that do not dissolve in water
• Used as energy molecules
• Found in cell membranes
• Found as fats and oils, phospholipids, and
steroids
26
2.5 Lipids
How are fats and oils different?
• Fats
• Usually animal origin
• Solid at room temperature
• Function for long-term energy storage,
insulation from heat loss, and cushion for
organs
• Oils
• Usually plant origin
• Liquid at room temperature
27
2.5 Lipids
What is the structure of fats and
oils?
• A glycerol molecule and 3 fatty acid tails
H
H
H
C
C
O
OH
OH
C
HO
+
O
HO
C
H
H
H
H
C
C
C
C
H
H
H
H
H
H
H
H
C
C
C
C
H
H
H
H
H
C
C
H
H
H
H
H
H
H
H
H
H
C C
C
C
C
C
H
H
H
C
O
dehydration reaction
H
H
C
O
H
C
OH
H
H
H
H
H
H
C
C
C
C
C
H
H
H
H
O
H
H
H
H
H
H
C
C
C
C
C
C
C
H
H
H
H
H
H
O
H
H
H
H
H
C
C
C
C
C
C
hydrolysis reaction
O
HO
O
H
C
H
O
H
H
H
H
+
3 H2O
H
H
H
glycerol
3 fatty acids
fat molecule
3 water
molecules
Figure 2.16 Structure of a triglyceride.
28
2.5 Lipids
Understanding fats when
reading a nutrition label
• The 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?
29
2.5 Lipids
Understanding fats when
reading a nutrition label
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.
30
2.5 Lipids
What is the structure of a
phospholipid?
• The structure is
similar to a
triglyceride.
• One fatty acid is
replaced by a polar
phosphate group.
• Phospholipids 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.
31
2.5 Lipids
What is a steroid?
H3C
H3C
• A steroid is a lipid.
• The structure is four
fused carbon rings.
CH3
CH3
CH3
HO
a. Cholesterol
• Examples are
cholesterol and sex
hormones.
OH
OH
CH3
CH3
CH3
O
HO
b. Testosterone
c. Estrogen
© Purestock/Superstock RF
Figure 2.20 Examples of steroids.
32
2.6 Proteins
3. What are proteins?
• Made of subunits called amino acids
• Important for diverse functions in the body
including hormones, enzymes, antibodies,
and transport
• Can denature, undergo a change in shape
that causes loss of function
33
2.6 Proteins
What do amino acids look like?
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)
34
2.6 Proteins
What are the 4 levels of protein
organization?
• Primary – the linear order of amino acids
• Secondary – localized folding into pleated
sheets and helices
• 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.
35
2.6 Proteins
What do the levels of organization
look like?
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.
36
2.7 Nucleic Acids
4. What are nucleic acids?
• Made of nucleotide subunits
• Function in the cell to make proteins
• Include RNA and DNA
37
2.7 Nucleic Acids
What are the 3 parts of a nucleotide?
phosphate
C
P
5'
Nucleotide
nitrogencontaining
base
O
S
4'
1'
2'
3'
sugar
38
2.7 Nucleic Acids
What are the 5 bases found in
nucleotides?
• Adenine (A) and guanine (G) are doubleringed purines.
• Cytosine (C), thymine (T), and uracil (U) are
single-ringed pyrimidines.
• In DNA, A pairs with T and G pairs with C.
39
2.7 Nucleic Acids
What are the 5 bases found in
nucleotides?
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.
40
2.7 Nucleic Acids
Summary of DNA and RNA
structural differences
• DNA
– Sugar is deoxyribose
– Bases include A, T,
C, and G
– Double-stranded
• RNA
– Sugar is ribose
– Bases include A, U,
C, and G
– Single-stranded
41
Summary of the macromolecules
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
42