Download Water C

Water and
Macromolecules
Water can IONIZE transiently
H 2O
Today s Topics
•  More about Water
•  pH
H+
H
H
H
H
H
Hydronium
ion (H3O+)
•  Carbohydrates
+
H
H
Macromolecules
–  monomers and polymers
–  Condensation and hydrolysis
H
Hydroxide
ion (OH–)
Only a tiny fraction
is ionized at any
moment
•  Lipids
–  Fats and oils
–  Phospholipids
–  How soap works
Sept 2, 2016
pH Scale
0
Acidic
Increasingly Acidic
[H+] > [OH–]
1
2
3
4
5
6
Neutral
[H+] = [OH–]
Battery acid
Digestive (stomach)
juice, lemon juice
Vinegar, beer, wine,
cola
Tomato juice
Increasingly Basic
[H+] < [OH–]
Definition: A mole
Low pH
H+ high
-OH low
Black coffee
Rainwater
Urine
Human blood
9
10
11
12
13
Seawater
Milk of magnesia
Household ammonia
Household bleach
Oven cleaner
(or mol )
–  Represents an exact number of molecules
–  One mole is 6.02x1023 molecules
Molarity
7 Pure water
8
Basic
OH-
High pH
H+ low
-OH high
•  Number of molecules per liter of solution
Mass units
•  Hydrogen atom =1g/mole
•  Oxygen atom= 16 g/mole
•  Water (H2O)= 18g/mole
14
How big is a mol?
6.02 x 1023
Buffers resist changes in pH
•  1017 seconds
since the big
bang.
14 billion years x
31,557,600 seconds per year
•  That is less than
one millionth of a
mole of seconds!
HA <--> A- + H+
1
C-C bonds are very stable-can make very long chains
Carbon
Helium
2He
Hydrogen
1H
First
shell
Second
shell
Lithium
3Li
Beryllium
4Be
Boron
3B
Sodium Magnesium Aluminum
13Al
11Na
12Mg
Third
shell
Carbon
6C
Nitrogen
7N
Silicon
14Si
Phosphorus
15P
Oxygen
8O
Fluorine
9F
Neon
10Ne
Sulfur
16S
Chlorine
17Cl
Argon
18Ar
H3C
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH3
•  Hydrocarbons contain only C and H
Carbon forms the backbone of
most biological molecules
Carbon can form covalent bonds
with many different elements
First
shell
Second
shell
Can form chains or
branched chains or
rings
Third
shell
Helium
2He
Hydrogen
1H
Lithium
3Li
Beryllium
4Be
Boron
3B
Sodium Magnesium Aluminum
13Al
11Na
12Mg
Carbon
6C
Nitrogen
7N
Silicon
14Si
Phosphorus
15P
Oxygen
8O
Fluorine
9F
Neon
10Ne
Sulfur
16S
Chlorine
17Cl
Argon
18Ar
Fig. 4-9
Functional Groups determine the
biological properties
Types of Functional Groups
Hydrophobic
Estradiol
Testosterone
Hydrophilic
–  Straight-chain
•  Polar things
hydrocarbons
–  Alcohols (hydroxl)
–  Branched-chain ,
es
–  Sulfhydryls
hydrocarbons
shap
d
n
a
e double
–  Aldehydes
– y Hydrocarbons
izes ese arwith
s
h
Man bonds
–  Ketones
of t s
l
l
a
n
but–  Hydrocarbon
arbo
rings
c
o
r
hy– d Aromatic rings
•  Polar Ionizable Things
–  Carboxylic Acids
–  Bases (amines)
–  Phosphate
2
Know the functional groups in Fig. 2.7, page 25
•  R-OH
•  R-SH
•  R-C=O
•  R-COOH
•  R-NH2
•  R-PO4
Some Functional Groups can form Ions
hydroxyl
sulfhydryl
aldehyde
keto
carboxyl
amino
phosphate
• 
• 
• 
• 
• 
• 
What determines whether acids &
bases are ionized?
H+ concentration (or pH)
R-COO-
hydroxyl
sulfhydryl
aldehyde, keto
carboxyl
amino
phosphate
Each has a
balance point
Ionizable Functional Groups
Acids
Bases
Carboxylic acid
R-COOH
R-COOH
R-OH
R-SH
R-C=O
R-COOR-NH3+
R-PO4--
H+
Each has a
balance point
Amine
R-CH2N-H
pKa
H
Most
organic
Acids
3 to 5
R-COO-
HOH
pKb
H+
H
+
R-CH2N-H
Most
organic
Bases
8 to 11
-OH
H
Understand the concept, but don’t memorize this
What happens when
Ionizable Functional Groups pH = 7.0 ?
Acids
Carboxylic acid
R-COOH
Amine
R-CH2N-H
pKa
Most
organic
Acids
H
3-to-5
R-COO-
Oily Amines in fish
Bases
H+
H
+
R-CH2N-H
H
Understand the concept, but don’t memorize this
cadaverine
HOH
pKb
Most
organic
Acids
8-to-11
-OH
putrescine
High pH
•  Little H+
•  NH2 molecular form
•  insoluble
Low pH
•  Lots of H+
•  NH3+, ionized
•  soluble
3
Macromolecules
Macromolecules
Macromolecules
•  Carbohydrates
•  Lipids
•  Proteins
•  Nucleic Acids
Carbohydrates
(polysaccharides)
H
Hydrolysis
OH
H
H 2O
H
Lipids
Ions and
small molecules
Monomer
OH
Nucleic
acids
Wat
er
Condensation
H
Proteins
OH
OH
H 2O
H
H
OH
OH
H
H 2O
H 2O
H
Monosaccharides
OH
H
OH
OH
H
OH
Simple sugars can be coupled together by
Condensation
CH2OH
O H
1
OH
Glucose
Formation of
linkage
CH2OH
O
2
H
HO
CH2OH
Fructose
CH2OH
O H
1
CH2OH
O
2
O
H 2O
CH2OH
Sucrose
Sucrose is a common
disaccharide;
Glucose+Fructose
4
Cellulose, a polysaccharide
Other common disaccharides
10 µm
0.5 µm
Cellulose
molecules
Do not
memorize
β  Glucose
monomer
H
O
CH2OH
O
H
OH
H
H
OH
O
H
H
H
OH
OH
H
H
H
CH2OH
O
H
O
O
CH2OH
O
H
OH
H
H
OH
H
H
H
OH
OH
H
H
Lipids (fats and oils)
H
O
O
CH2OH
Cellulose is an unbranched polymer of glucose
H
O
CH2OH
O H
H
OH
H
H
OH O
CH2OH
CH2OH
CH2OH
CH2
O H H
O H H
O H
O H H
H
H
H
H
H
OH
H
OH
OH
OH
H
H
H
O
O
O
O
O
OH
H
H
OH
H
H
OH
OH
Glycogen and starch are polymers of glucose, with
branching
Fats or triglycerides
http://www.johnnyjet.com/images/PicForNewsletterItalyMarch2005FRIEDDOUGHnLARD.JPG
Fried dough with lard . . . .
FATS
(glycerol + 3 fatty acids)
Solid
Glycerol
O
C
OH
H
C
OH
C
OH
H
C
HO
H
O
C
H
C
H
O
Fat molecule
H
C
O
C
H
C
H
O
H
C
H
O
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
Liquid
C
H
H
C
H
H
Dehydration reaction
O
H
C
C
H
H
H
OILS
+ Fatty acid
H
H
WHY?
C
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
H
C
H
H
H
C
H
H
hydrophilic or hydrophobic?
Saturated
Unsaturated or
Polyunsaturated
5
Why soap works
What are trans fats?
Hydrophilic heads
Hydrophobic tails
Soap micele
Greasy mess on
plate
•  Phospholipids
Phospholipid Bilayer
CH2
CH2
O
Figure 5.13
O–
+
N(CH )
3 3
Choline
Phosphate
O
CH2
CH
O
O
C
O C
CH2
Glycerol
How will
phospholipids
behave in water?
O
Hydrophobic tails
Hydrophilic head
–  Glycerol + 2 fatty acids + phosphate
O
P
•  Grease is accommodated in the
interior of the micele
--> emulsified
Fatty acids
Hydrophilic head
Forms
Boundaries
Hydrophobic
tails
(a) Structural formula
6