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Human BiologySylvia S. Mader
Michael Windelspecht
Chapter 2 Chemistry of
LifeLecture Outline
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
See separate FlexArt PowerPoint slides for all figures and tables pre-inserted into
PowerPoint without notes.
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 4
macromolecules?• How are proteins organized and how is their shape
important to their function?• How are DNA similar and how are they different?
Building blocks from large to small• Matter is anything that has weight 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
Atoms• Atom symbol • Atomic mass• Atomic number
2.1 From atoms to molecules
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
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
20.1819.0016.0014.0112.016.941 9.012 10.81
11 18
Na
22.99
19
39.10
24.31
Mg
12
Ar
39.95
1716151413
Al Si Cl
35.4532.0730.9728.0926.98
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
Subatomic particles of atoms• Neutrons have a neutral charge
• 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
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
0
1
1
1p
hydrogenH
Subatomic Particles
Atomic MassChargeParticle
Proton
Neutron
Electron 0.00055
+1
-1
6p6n
8p8n
7p7n
oxygenO
carbonC
nitrogenN
Isotopes
• Isotopes are atoms that have the same atomic number but a different atomic mass because the number of neutrons differ
• Radioactive isotopes 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
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
a.
b.
larynx
thyroid gland
trachea
missingportionoforgan
a: © Biomed Commun./Custom Medical Stock Photo; b(patient): Courtesy National Institutes of Health; (brain scan):
© Mazzlota et al./Photo Researchers, Inc.
Molecules:
• Are made of atoms that are bonded together
• Can be made of the same atom or different atoms
2.1 From atoms to molecules
Ionic bonds:• Atoms in this type of bond donate or take on electrons• Results in a stable outer shell• Occurs between particles that are charged (ions)
2.1 From atoms to molecules
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
+
Cl
–
Na
sodium atom (Na) chlorine atom (Cl)
Na Cl
sodium ion (Na+)
sodium chloride (NaCl)
chloride ion (Cl–)
b.
Na+ Cl-
a.b: (crystals, shaker)
Covalent bonds:• Atoms in this type of bond share electrons
• Results in a stable outer shell
2.1 From atoms to molecules
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
+
+
b. When two oxygen atoms covalently bond, oxygen gas results.
8p8n
8p8n
8p8n
8p8n
1p
1p
8p8n
1p
1p
oxygenO
2 hydrogen2H
a. When an oxygen and two hydrogen atoms covalently bond, water results.
waterH2O
oxygenO2
oxygen gasO2
oxygenO2
8p8n
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What are the properties of water?• Liquid at room temperature
• Liquid water does not change temperature quickly
• High heat of vaporization
• Frozen water is less dense than liquid water
• Molecules of water cling together
• A solvent for polar molecules
2.2 Water and living things
What bond holds water molecules together?
• Hydrogen bonds occur between a hydrogen in a covalent bond anda negatively charged atom
• These are relatively weak bonds
2.2 Water and living things
HH
Hydrogen bonding between water molecules
O
hydrogenbond
+
+
-
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Acids and bases
• Acids are substances that dissociate and release hydrogen atoms
• Bases are substances that take up hydrogen atoms or release hydroxyl ions
2.2 Water and living things
What is the pH scale?
• A measure of hydrogen ion 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 ions between each whole number is a factor of 10
2.2 Water and living things
Looking at the pH scale2.2 Water and living things
H+ OH–
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
acid
icb
asi
c
stomach acid, lemon juice
vinegar, cola, beer
10
23456789
H+ IonConcentration pH Value Examples
hydrochloric acid
tomatoesblack coffeeurinepure waterseawaterbaking sodaGreat Salt Lakehousehold 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
1413121110
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
How do we build and break down organic molecules?
2.3 Molecules of life
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
subunitsubunit
hydrolysisreaction
subunitsubunit
subunitsubunit
dehydrationreaction
subunitsubunit H
H2O
H2O
b.
a.
OH
OH H
What organic molecules are found in living organisms?
1. Carbohydrates
2. Lipids
3. Proteins
4. Nucleic acids
2.3 Molecules of life
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
• Monosaccharide – 1 carbon ring as found in glucose
• Disaccharide – 2 carbon rings asfound in maltose
What are simple carbohydrates?2.4 Carbohydrates
O H
O H
H
H
H
H
H O
C6H12O6
O H
HO
C
C
C
CC
4
5
6
3 2
1
O HH
H
H
CH2OH
HO O
OHHO
OH
CH2OH
maltose
O O
O
C12H22O11
CH2OHCH2OH
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
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
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
O
H
O
O
OH
HHOH H
starchgranule
cell wall
potato cells
nonbranched
branched
H OHHOHOH H OH H
OO
H O
OH HH
HOH OHH
HOHH H H H O CH2OH CH2OH CH2OH CH2OH
© Jeremy Burgess/SPL/Photo Researchers, Inc.
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
How are fats and oils different?
• Fats• Usually animal origin• Solid at room temperature• Function as long-term energy storage, insulation from
heat loss and cushion for organs
• Oils• Usually plant origin• Liquid at room temperature
2.5 Lipids
What is the structure of fats and oils?
• A glycerol molecule and 3 fatty acid tails
2.5 Lipids
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
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 acidsglycerol fat molecule 3 watermolecules
dehydration reaction
OH
OH
OH
H
H
H
H
H C
C
C
H H H H
HCCCCCO
HO
HO
O
HO
O
HHH
HCCCCC
HHHHH
HHHHHH
HCCCCCC+
H
H
H
H
H H H H
HCCCCCC
HHHHHO
HHHHO
HHHHHO H
HC
C
C
O
O
O
3 H2O
H
Chydrolysis reaction
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 right? Why or why not?
2.5 Lipids
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Start here.
Limit thesenutrients.
Get enoughof thesenutrients.
18%
15%
10%
20%
10%
0%
4%
2%
20%
4%
Calories from Fat 110Calories 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
Saturated Fat 3g
Total Fat 12g
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What are steroids?
• A lipid
• Structure is four fused carbon rings
• Examples are cholesterol and sex hormones
2.5 Lipids
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
OHCH3
a. Cholesterol
b. Testosterone c. Estrogen
CH3
CH3
CH3
CH3
HO
HO
OH
O
CH3
H3C
H3C
b: © Warren Toda/epa/Corbis; c: © Tony Marsh/Reuters/Corbis
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, change in shape, that causes loss of function
2.6 Proteins
What do amino acids look like?2.6 Proteins
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
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 CH2H3N+
SH
HH3N+
CH2
O–
O–
O–
–O
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What are the four 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
What do the levels of organization look like?
2.6 Proteins
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C NR
C
R
C N
C
R
C
N
C
R
N
C
R
N R
N
C
N R
hydrogen bondSecondary Structure:Alpha helix or a pleated sheet
hydrogen bond
(beta) sheet=pleated sheet (alpha) helix
Tertiary Structure:final shape of polypeptide disulfide bond
Quaternary Structure:two or more associatedpolypeptides
CH
CH
CHCH
CH
CHCH
CH
peptide bond
H3N+
Primary Structure:sequence of amino acids
amino acid
COO–
4. What are nucleic acids?
• Made of nucleotide subunits
• Function in the cell to make proteins
• Includes RNA and DNA
2.7 Nucleic acids
What are the 3 parts of a nucleotide?
2.7 Nucleic acids
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
nitrogen-containingbase
sugar
Nucleotide
phosphate P C
5'
4'
3'
1'
2'
S
O
What are the five 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
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
C
O
U
ON
N
NO
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
CA
G
G
C
T
Adenine (A) Thymine (T)(DNA only)
P
S
P
S
P
S
S
P
G
U
A
CN
N
H N
H
O
H
H
H
N
N
N
H
H
N
N
N
NC
NO
H N
CH3
HN CH
CH
O
NH
C
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
Summary of the macromoleculesCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
S
C
O
P
OHH
H
H
HO OH
HO
C
H
H H H
C
H
C
H
C
H
H
C
H
H
RC
O
H O
C O HH
H
C O HH
C O HH
H
H
C
R
Long-termenergystorage;membranecomponents
Immediateenergyand storedenergy;structuralmolecules
Carbohydrates
Lipids
Proteins
Nucleic acidsStorage ofgeneticinformation
Support,metabolic,transport,regulation,motion
Fatty acid
Glycerol
Monosaccharides,disaccharides,polysaccharides
Fats, oils,phospholipids,steroids
Structural,enzymatic,carrier,hormonal,contractile
DNA, RNA
Organicmolecules
Examples Monomers Functions
Nucleotide
basephosphate
aminogroup
acidgroupCOOH
Glucose
Amino acid
group
H2N
CH2OH
OH