View
5
Download
0
Category
Preview:
Citation preview
1
Chapter 02
Lecture Outline
See separate PowerPoint slides for all figures and tables pre-
inserted into PowerPoint without notes.
Copyright © 2016 McGraw-Hill Education. Permission required for reproduction or display.
2
Chemistry of Life
3
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?
4
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.
2.1 From Atoms to Molecules
5
Elements • Atomic symbol
• Atomic mass
• Atomic number
2.1 From Atoms to Molecules
Figure 2.1 A portion of the
periodic table of elements.
I
1
H
2
V
3 4 5
B
6
C
7
N
8
O
9
F
P S
K
atomic number
atomic symbol atomic mass
1.008
Li Ne
He
4.003
VIII
II III IV VI VII
10
Be
20.18 19.00 16.00 14.01 12.01 6.941 9.012 10.81
11 18
Na
22.99
19
39.10
24.31
Mg
12
Ar
39.95
17 16 15 14 13
Al Si Cl
35.45 32.07 30.97 28.09 26.98
20 31 32 33 34 35 36
83.60
Kr
79.90
Br
78.96
Se
74.92
As
72.59
Ge
69.72
Ga
40.08
Ca
Peri
od
s
1
2
3
4
Groups
6
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.
2.1 From Atoms to Molecules
2.1 From Atoms to Molecules
Figure 2.2 The
atomic structure
of select
elements.
Subatomic particles of atoms
0
1
1
1p
hydrogen
H
Subatomic Particles
Atomic Mass Unit
(AMU)
Charge Particle
Proton
Neutron
Electron 0
+1
–1
6p
6n
8p
8n
7p
7n
oxygen
O
carbon
C
nitrogen
N
8
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.
2.1 From Atoms to Molecules
Isotopes 2.1 From Atoms to Molecules
Figure 2.3 Medical uses for
low-level radiation.
a.
larynx
thyroid gland
trachea
missing
portion
of organ
2.3a: © Biomed Commun./Custom Medical Stock Photo; 2.3b(patient): © National Institutes of Health; 2.3b(scan):
© Mazzlota et al./Science Source
b.
10
Molecules
• Made of atoms that are bonded together
• Can be made of the same atom or
different atoms
2.1 From Atoms to Molecules
11
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)
2.1 From Atoms to Molecules
12
2.1 From Atoms to Molecules
Figure 2.5 Formation of an ionic bond.
Ionic bonds
13
• Atoms in this type of bond share electrons
• Result in a stable outer shell
2.1 From Atoms to Molecules
Covalent bonds
14
2.1 From Atoms to Molecules
+
+
b. When two oxygen atoms covalently bond, oxygen gas results.
8p
8n
8p
8n
8p
8n
8p
8n
1p
1p
8p
8n
1p
1p
oxygen
O
2 hydrogen
2H
a. When an oxygen and two hydrogen atoms covalently bond, water results.
water
H2O
oxygen
O2
oxygen gas
O2
oxygen
O2
8p
8n
Figure 2.6 Covalent bonds.
Covalent bonds
15
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.
2.2 Water and Life
16
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.
2.2 Water and Life
H H
Hydrogen bonding between water molecules
O
hydrogen
bond
+
+ -
Figure 2.7b Hydrogen bonds and water molecules.
17
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-).
2.2 Water and Life
18
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
2.2 Water and Life
19
Looking at the pH scale 2.2 Water and Life
H+ OH–
ac
idic
b
as
ic
stomach acid, lemon juice
vinegar, cola, beer
1
0
2
3
4
5
6
7
8
9
H+ Ion
Concentration pH Value Examples
hydrochloric acid
tomatoes
black coffee
urine
pure water
seawater
baking soda
Great Salt Lake
household ammonia
household bleach
sodium hydroxide
10-1 100
10-3
10-4
10-5
10-6
10-7
10-8
10-9
10-10
10-11
10-12
10-13
10-14
10-2
14
13
12
11
10
Figure 2.10
The pH scale.
20
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
2.3 Molecules of Life
21
How do we build and break down
organic molecules?
2.3 Molecules of Life
subunit subunit
hydrolysis
reaction
subunit subunit
subunit subunit
dehydration
reaction
subunit subunit H
H2O
H2O
b.
a.
OH
OH H
Figure 2.11 The
breakdown and synthesis
of macromolecules.
22
What organic molecules are
found in living organisms?
1. Carbohydrates
2. Lipids
3. Proteins
4. Nucleic acids
2.3 Molecules of Life
23
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
2.4 Carbohydrates
24
• Monosaccharide –
1 carbon ring as
found in glucose
• Disaccharide –
2 carbon rings as found in maltose
What are simple carbohydrates? 2.4 Carbohydrates
O H
O H
H
H
H
H
H O
C6H12O6
O H
H O
C
C
C
C C
4
5
6
3 2
1
O H H
H
H
CH2OH
H O O
OH HO
OH
CH2OH
maltose
O O
O
C12H22O11
CH2OH CH2OH
Figure 2.12 The synthesis and breakdown of a disaccharide.
25
What are complex carbohydrates?
• Polysaccharides are made of many carbon rings.
• Glycogen is the storage form in animals.
• Starch is the storage form in plants.
2.4 Carbohydrates
O
H
O
O
O H
H
H O H H
starch
granule
cell wall
potato cells
nonbranched
branched
H OH H OH OH H OH H
O O
H O
OH H H
H OH OH H
H O
H H H H H O
CH2OH CH2OH CH2OH CH2OH
© Jeremy Burgess/SPL/Science Source
Figure 2.13 Starch is a plant complex carbohydrate.
26
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
2.5 Lipids
27
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
2.5 Lipids
28
What is the structure of fats and
oils? • A glycerol molecule and 3 fatty acid tails
2.5 Lipids
C
C
H H H H H H
C
H H H
C C C
H
C
C
H
C
H
H H H H
C
H H
C
H
C
+
C
H
H
3 fatty acids glycerol fat molecule 3 water
molecules
dehydration reaction
OH
OH
OH
H
H
H
H
H C
C
C
H H H H
H C C C C C O
HO
HO
O
HO
O
H H H
H C C C C C
H H H H H
H H H H H H
H C C C C C C +
H
H
H
H
H H H H
H C C C C C C
H H H H H O
H H H H O
H H H H H O H
H C
C
C
O
O
O
3 H2O
H
C
hydrolysis reaction
Figure 2.16 Structure of a triglyceride.
29
• 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?
2.5 Lipids
Understanding fats when
reading a nutrition label
30
Understanding fats when
reading a nutrition label
2.5 Lipids
Saturated Fat 3g
Start here.
Limit these
nutrients.
Get enough
of these
nutrients.
18%
15%
10%
20%
10%
0%
4%
2%
20%
4%
Calories from Fat 110 Calories 250
Amount Per Serving
Serving Size 1 cup (228g) Servings Per Container 2
%Daily Value
Iron
Calcium
Vitamin C
Vitamin A
Protein 5g
Sugars 5g
Dietary Fiber 0g
Total Carbohydrate 31g
Sodium 470mg
Cholesterol 30mg
Trans Fat 1.5g
Total Fat 12g
Figure 2.18 Understanding a food label.
31
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.
2.5 Lipids
Figure 2.19 Structure of a phospholipid.
inside cell
outside cell
b. Membrane structure a. Phospholipid structure
nonpolar
tails
polar
head
32
What is a steroid?
• A steroid is a lipid.
• The structure is four
fused carbon rings.
• Examples are
cholesterol and sex
hormones.
2.5 Lipids
Figure 2.20 Examples of steroids.
OH CH3
a. Cholesterol
b. Testosterone c. Estrogen
CH3
CH3
CH3
CH3
HO
HO
OH
O
CH3
H3C
H3C
© Purestock/Superstock RF
33
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
2.6 Proteins
34
What do amino acids look like? 2.6 Proteins
C
O
C C
C C
C C
H O
C
O
C C
O
cysteine (cys)
(polar)
aspartic acid (asp)
(ionized, polar)
tryptophan (trp)
(nonpolar)
valine (val)
(nonpolar)
lysine (lys)
(ionized, polar)
glutamic acid (glu)
(ionized, polar)
N+H3
CH2
CH2
CH2
H3N+
O
O–
H
CH2
CH2
COO– CH2
CH
H3C
H3N+
H
C C
O
O–
H3N+
H O
O–
H3N+
H
C
CH2
NH CH2 H3N
+
SH
H H3N+
CH2
O–
O–
O–
–O
Figure
2.21 The
structure of
a few
amino
acids.
35
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.
2.6 Proteins
36
What do the levels of organization
look like?
2.6 Proteins
Figure 2.23 Levels of protein structure.
hydrogen bond Secondary Structure:
Alpha helix or a pleated sheet
(beta) sheet =
pleated sheet (alpha) helix
Tertiary Structure:
final shape of polypeptide disulfide bond
Quaternary Structure:
two or more associated
polypeptides
peptide bond
H3N+
Primary Structure:
sequence of amino acids
amino acid
COO–
C N
C H
R
C
C H
R
C N
C
C H
R
C
N
C
C H
R
N
C
C H
R
N
C H
R
N
C
N
C H
R
C H
hydrogen bond
37
4. What are nucleic acids?
• Made of nucleotide subunits
• Function in the cell to make proteins
• Include RNA and DNA
2.7 Nucleic Acids
38
What are the 3 parts of a nucleotide?
2.7 Nucleic Acids
nitrogen-
containing
base
sugar
Nucleotide
phosphate P C
5'
4'
3'
1'
2'
S
O
39
What are the 5 bases found in
nucleotides?
• Adenine (A) and guanine (G) are double-ringed purines.
• Cytosine (C), thymine (T), and uracil (U) are single-ringed pyrimidines.
• In DNA, A pairs with T and G pairs with C.
2.7 Nucleic Acids
40
2.7 Nucleic Acids
Figure
2.24 The
structure of
DNA and
RNA.
What are the 5 bases found in
nucleotides?
C
O
U
O N
N
N O
a. DNA structure with base pairs: A with T and G with C b. RNA structure with bases G, U, A, C
Uracil (U) (RNA only)
bases
backbone
Hydrogen bond
Cytosine (C) Guanine (G)
A
T
C
A
G
G
C
T
Adenine (A) Thymine (T)
(DNA only)
P
S
P
S
P
S
S
P
G
U
A
C N
N
H N
H
O
H
H
H
N
N
N
H
H
N
N
N
N
C
N
O
H N
CH3
HN CH
CH
O
N H
C
41
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
2.7 Nucleic Acids
42
Summary of the macromolecules
S
C
O
P
O H H
H
H
H O O H
H O
C
H
H H H
C
H
C
H
C
H
H
C
H
H
R C
O
H O
C O H H
H
C O H H
C O H H
H
H
C
R
Long-term
energy
storage;
membrane
components
Immediate
energy
and stored
energy;
structural
molecules
Carbohydrates
Lipids
Proteins
Nucleic acids Storage of
genetic
information
Support,
metabolic,
transport,
regulation,
motion
Fatty acid
Glycerol
Monosaccharides,
disaccharides,
polysaccharides
Fats, oils,
phospholipids,
steroids
Structural,
enzymatic,
carrier,
hormonal,
contractile
DNA, RNA
Organic
molecules Examples Monomers Functions
Nucleotide
base phosphate
amino
group
acid
group
COOH
Glucose
Amino acid
group
H2N
CH2OH
OH
Recommended