Download Chemistry of Life

Chemistry of Life
Organism
Organ and organ systems
Tissue
Cells
Carbohydrates
Proteins
Lipids
Nucleic Acids
Hydrocarbons, Alcohols, Phenols, Ethers, Thiols, Aldehydes, Ketones,
Carboxylic Acids, Esters, Amines, Amides
Molecules (compounds)
Bonds - ionic, covalent, hydrogen
Atom (elements)
Chemistry of Life - Goals
At the end of this chapter you should:
• be able to identify the different classes of lipids.
• know the difference between saturated and unsaturated fatty acids.
• be able to describe the effect of chain length and unsaturation on the melting point of fatty acids.
• know the difference between fats and oils and be able to describe how the fatty acid composition
determines the physical properties of fats and oils.
• be familiar with the hydrolysis and saponification reactions of triglycerides.
• be able to describe the properties of glycerophospholipids and their role in the structure of cell
membranes.
• be able to describe the role of cholesterol in human health.
• be familiar with the role of lipoproteins in transporting lipids and know the difference between LDL
and HDL particles.
• be familiar with the importance of lipids in human health.
Lipids - it’s role in health
Coronary Artery Disease (CAD) - aka coronary heart disease (CHD),
ischemic heart disease (IHD), arteriosclerotic cardiovascular disease
(ASCVD).
Caused by the deposition and build up of fatty deposits (atherosclerosis:
from the greek ‘athera’ meaning porridge and sclerosis meaning hardening)
Risk factors:
- Hypertension
- Diabetes
- Elevated cholesterol
- smoking
- Sedentary lifestyle
- Stress
- Obesity
- Male sex
- Family history
- Older age
Lipids - it’s role in health
- What are triglycerides?
- What is HDL?
- What is LDL?
- How are there molecules made? what is their chemistry?
Lipids (from the greek ‘lipos’ meaning fat or lard) - types
Lipids are a class of molecules that are insoluble in water but are soluble in non-polar organic
solvents.
Lipids
Saponifiable lipids
(can be hydrolyzed)
non-Saponifiable lipids
(can NOT be hydrolyzed)
- Waxes
- Steroids
- Triglycerides
- Prostaglandins
- Glycerophospholipids
- Sphingolipids
- Glycosphingolipids
Remember the esters?
Lipids - types
Saponifiable lipids - (can be hydrolyzed)
Remember the esters?
Fatty acid
long chain alcohol
Waxes
G
l
y
c
e
r
o
l
G
l
y
c
e
r
o
l
Fatty acid
Fatty acid
Fatty acid
Triglycerides
S
p
h
i
n
g
o
s
i
n
e
Fatty acid
PO4
Amino alcohol
Sphingolipids
Fatty acid
Fatty acid
PO4
Amino alcohol
Glycerophospholipids
S
p
h
i
n
g
o
s
i
n
e
Fatty acid
Sugar
Glycosphingolipids
Lipids - types
nonSaponifiable lipids - (can NOT be hydrolyzed)
12
Steroids
Cholesterol
Bile salts
Hormones
11
2
3
1
10 9
A
4
B
5
C
13
17
D
16
14 15
8
7
6
Steroid Ring Structure
OH
Arachidonic acid
O
Prostaglandins
Cyclooxygenase
(COx-1 and COx-2)
O
COOH
O
OH
(prostaglandin H2)
Lipids - saponifiable, fatty acids in common
Saponifiable lipids - (can be hydrolyzed)
Remember the esters?
Fatty acid
long chain alcohol
Waxes
G
l
y
c
e
r
o
l
G
l
y
c
e
r
o
l
Fatty acid
Fatty acid
Fatty acid
Triglycerides
S
p
h
i
n
g
o
s
i
n
e
Fatty acid
PO4
Amino alcohol
Sphingolipids
Fatty acid
Fatty acid
PO4
Amino alcohol
Glycerophospholipids
S
p
h
i
n
g
o
s
i
n
e
Fatty acid
Sugar
Glycosphingolipids
Lipids - Fatty acids
O
OH
Palmitic acid (hexadecanoic acid) - a saturated fatty acid found in palm oil, butter, cheese, milk.
O
OH
Stearic acid (octadecanoic acid) - a saturated fatty acid from plant and animal fats and oils.
O
OH
Linoleic acid - a poly unsaturated fatty acid from plant and animal fats and oils. An omega-6
fatty acid.
O
OH
Linolenic acid - a poly unsaturated fatty acid from fish oil, flax seed, hemp seed, and canola oil.
An omega-3 fatty acid.
Lipids - Fatty acids, solubility
Tail
Water soluble
polar
hydrophilic (water liking)
O
OH
Water insoluble
Non polar
hydrophobic (water fearing)
Head group
The hydrophobic tail is responsible for the fatty or oily characteristics of fatty acid
containing lipids
Lipids - Fatty acids, solubility and micells
The hydrophobic tails associate into the structure.
The hydrophilic head group points towards the water.
Micelles
Held together by weak dispersion forces.
Blast from the past - why are these fat soluble?
Hydrophobic
Lycopene
beta-carotene
CH3
HO
CH3
O
H3C
CH3
CH3
CH3
CH3
H3C
H3C
CH3
CH3
CH3
OH
Vitamin E
CH3
CH3
CH3
CH3
O
H
CH3
O
Retinoic acid
CH3
Retinal
H3C
O
CH3
CH3
CH3
*
3
OH
Retinol
CH3
O
Vitamin K(phylloquinone)
Lipids - Fatty acids, they are not flat
O
OH
Palmitic acid (hexadecanoic acid) - a saturated fatty acid found in palm oil, butter, cheese, milk.
O
OH
Stearic acid (octadecanoic acid) - a saturated fatty acid from plant and animal fats and oils.
O
OH
Linoleic acid - a poly unsaturated fatty acid from plant and animal fats and oils. An omega-6
fatty acid.
O
OH
Linolenic acid - a poly unsaturated fatty acid from fish oil, flax seed, hemp seed, and canola oil.
An omega-3 fatty acid.
Lipids - Fatty acids, three dimensional shape
Lipids - Fatty acids, three dimensional shape
Lipids - Fatty acids, some examples and their properties
Lipids - Fatty acids, unsaturation and packing
Lipids - Fatty acids, fish oils and the heart
O
OH
docosahexaenoic acid (DHA)
O
OH
eicosapentaenoic acid (EPA)
Polyunsaturated fatty acids (PUFAs), learn more at the AHA
Lipids - Fatty acids, trans fatty acids and health
The process that is used to convert polyunsaturated vegetable oils (liquids) to partially
hydrogenated solid fats to be used in margarine and shortening produces trans fats.
H
H
C
H3C
CH2
CH2
C
H
C
C
H3C
CH2
H
C
CH3
H
C
CH2
CH2
H
partial hydrogenation
cis-2,5-octadiene
Learn more qbout Trans Fatty acids at:
(1). The FDA
(2). About Trans Fatty acids in butter and margarine at the AHA
(2). About Trans Fatty acids and heart disease at the AHA
Fatty acids are thought to
(1). Increase the levels of LDL (Low Density Lipoproteins)
(2). Reduces the levels of HDL (high Density Lipoproteins)
trans-3-octene
CH2
CH3
Lipids - Fatty acids, those that are essential
O
OH
Linoleic acid - a poly unsaturated fatty acid from plant and animal fats and oils. An omega-6
fatty acid.
O
OH
Linolenic acid - a poly unsaturated fatty acid from fish oil, flax seed, hemp seed, and canola oil.
An omega-3 fatty acid.
OH
O
Arachidonic acid
These fatty acids cannot be synthesized in the body. Need to get them from our diet.
Lipids - Waxes
O
CH3(CH2)18
C
O
(CH2)19CH3
Jojoba wax
O
CH3(CH2)14
C
O
(CH2)29CH3
Bees wax
O
CH3(CH2)24
C
Carnauba wax
O
(CH2)29CH3
Lipids - Fats and Oils
Fats and Oils - are esters of glycerol. Also known as triglycerols
or triglycerides.
Fatty acids in the body are stored as triglycerides.
Triglycerides that are (usually) liquids at room temperature are
oils.
Triglycerides that are solids at room temperature are fats.
G
l
y
c
e
r
o
l
O
Fatty acid
CH2
O
C
O
(CH2)16CH3
CH
O
C
O
(CH2)16CH3
CH2
O
C
(CH2)16CH3
Fatty acid
Fatty acid
Triglycerides
Glyceryl tristearate
Lipids - Fats and Oils, triglycerides
O
CH2
OH
CH
OH
HO
(CH2)16CH3
O
+
HO
CH2
C
C
(CH2)16CH3
OH
O
HO
Glycerol
C
(CH2)16CH3
stearic acid
Three of them. One for each alcohol group.
Esterification
Ester group
O
CH2
O
C
O
(CH2)16CH3
CH
O
C
O
(CH2)16CH3
CH2
O
C
(CH2)16CH3
Glyceryltristearate
Lipids - Fats and Oils, triglycerides
O
Alcohol Part
In triglycerides
always Glycerol
CH2
O
C
O
(CH2)16CH3
CH
O
C
O
(CH2)16CH3
CH2
O
C
(CH2)16CH3
Carboxylic acid part
Three fatty acids
Glyceryltristearate
In Glyceryltristearate all three fatty acids are the same. But they do not have to be...
O
CH2
O
C
O
(CH2)16CH3
from stearic acid
CH
O
C
O
(CH2)14CH3
from Palmitic acid
Saturated fats
CH2
O
C
(CH2)12CH3
from Myristic acid
Unhealthy
In Glyceryltristearate all three fatty acids are saturated. But they do not have to be...
O
CH2
O
C
O
(CH2)16CH3
CH
O
C
O
(CH2)7CH
CH2
O
C
(CH2)12CH3
from stearic acid
CH(CH2)5CH3
from Palmitoleic acid
from Myristic acid
unSaturated fats
Lipids - Fats and Oils, triglycerides
Triglycerides from animal sources are usually solids at room temperature - they are called
Fats. There are exceptions the most notable being the triglycerides from fish.
Triglycerides from animal plant sources are usually liquids at room temperature - they are
called oils.
Think back to the melting points of different fatty acids. Can you predict what types of fatty
acids are prevalent in animal vs. plant triglycerides?
Lipids - Fats and Oils, triglycerides
Physical properties
O
CH2
O
C
O
(CH2)16CH3
CH
O
C
O
(CH2)7CH
CH2
O
C
(CH2)12CH3
hydrophobic tail
CH(CH2)5CH3
Ester group not as hydrophillic as the fatty acid carboxyl group. Overall more
hydrophobic than fatty acids. Do not form micells.
Compare To
hydrophilic Head group
O
OH
hydrophobic Tail
Lipids - Fats and Oils, triglycerides
Chemical properties
What groups do you think will determine the chemical properties of triglycerides?
Ester group
O
CH2
O
C
O
(CH2)16CH3
CH
O
C
O
(CH2)7CH
CH2
O
C
(CH2)12CH3
Alkene group
CH(CH2)5CH3
The ester and alkene functional groups will determine the chemical properties of triglycerides.
Lipids - Fats and Oils, triglycerides
Chemical properties, Hydrolysis
O
O
Heat/H+
CH3
C
O
CH3
+ H2O
CH3
Ester
C
OH
carboxylic acid
CH2
O
C
O
(CH2)16CH3
CH
O
C
O
(CH2)7CH
O
C
OH
Alcohol
O
O
CH2
+ CH3
(CH2)12CH3
Triglycerol - the ester
H2O/
acid
CH(CH2)5CH3
CH2
OH
CH
OH
CH2
HO
(CH2)16CH3
O
+
HO
C
(CH2)7CH
O
OH
Triglycerol
- the alcohol
C
HO
C
(CH2)12CH3
Fatty acids - the
carboxylic acids
CH(CH2)5CH3
Lipids - Fats and Oils, triglycerides
Chemical properties, saponification
O
O
CH3
C
O
CH3
+ NaOH
CH3
Ester
C
carboxylate ion
CH
CH2
O
O
O
C
O
(CH2)16CH3
C
O
(CH2)7CH
C
OH
Alcohol
O
O
CH2
+ CH3
O- Na+
CH2
OH
CH
OH
+Na-O
(CH2)12CH3
Triglycerol - the ester
CH2
OH
Triglycerol
- the alcohol
(CH2)16CH3
O
NaOH
CH(CH2)5CH3
C
+
+Na-O
C
(CH2)7CH
CH(CH2)5CH3
O
+Na-O
C
(CH2)12CH3
Salts of the Fatty acids
- the salts of the carboxylic acids
These are soaps
Coconut shampoo - which oil does this come from?
Lipids - Fats and Oils, triglycerides
Chemical properties, Hydrogenation
O
O
CH2
O
C
O
(CH2)7CH
CH(CH2)5CH3
CH
O
C
O
(CH2)7CH
CH(CH2)5CH3
CH2
O
C
(CH2)12CH3
H2/Ni
CH2
O
C
O
(CH2)14CH3
CH
O
C
O
(CH2)7CH
CH2
O
C
(CH2)12CH3
Partial hydrogenation
Used to convert vegetable oils to produce spreadable fats (like
margarine). Causes the production of trans fats.
Learn more qbout Trans Fats at:
(1). The FDA
(2). About Trans Fatty acids in butter and margarine at the AHA
(2). About Trans Fatty acids and heart disease at the AHA
Trans Fats are thought to
(1). Increase the levels of LDL (Low Density Lipoproteins)
(2). Reduces the levels of HDL (high Density Lipoproteins)
CH(CH2)5CH3
Trans Fats: Coming in 2006, to a label near you...
Trans Fats: Coming in 2006, to a label near you...
Lipids - Fats and Oils, the hunt for new fats
The glycerol molecule in triglycerides had three alcohol groups to form esters.
What other molecules have we seen with multiple alcohol groups?
O
CH2
O
C
= fatty acid
O
O
Acid Fatty
Fatty Acid
O
O
Fatty Acid
O
Acid Fatty
O
CH2 O
O
O
Acid Fatty
Fatty Acid
Fatty Acid
O
Olestra - a fat substitute made by combining sucrose with fatty acids
no enzymes to break it down, large size prevents absorption. Contributes no
calories.
May lead to lipid soluble vitamin (A, D, E and K) deficiency.
Lipids - Fats and Oils, triglycerides
- What are triglycerides?
Are triesters of glycerol and fatty acids.
- those that are liquid at room temperature are oils.
- those that are solids at room temperature are Fats.
- triglycerides have chemical properties of esters and alkenes.
- triglycerides are the major source of energy storage of animals.
- triglycerides with a high content of saturated fatty acids or with
trans fatty acids are unhealthy.
Lipids - types
Saponifiable lipids - (can be hydrolyzed)
Remember the esters?
Fatty acid
long chain alcohol
Waxes
G
l
y
c
e
r
o
l
G
l
y
c
e
r
o
l
Fatty acid
Fatty acid
Fatty acid
Triglycerides
S
p
h
i
n
g
o
s
i
n
e
Fatty acid
PO4
Amino alcohol
Sphingolipids
Fatty acid
Fatty acid
PO4
Amino alcohol
Glycerophospholipids
S
p
h
i
n
g
o
s
i
n
e
Fatty acid
Sugar
Glycosphingolipids
Lipids - Glycerophospholipids
G
l
y
c
e
r
o
l
Fatty acid
Fatty acid
PO4
Compare To
Amino alcohol
Glycerophospholipids
G
l
y
c
e
r
o
l
Fatty acid
Fatty acid
Fatty acid
Triglycerides
In glycerophospholipids one of the hydroxyl groups in glycerol is bonded to a phosphate (PO4)
via an ester link. The phosphate is in turn linked to another alcohol (usually an amino
alcohol), via another ester link.
These lipids are also known as phospholipids.
Lipids - Glycerophospholipids
Fatty Acids
glycerol
G
l
y
c
e
r
o
l
Fatty acid
H2C
O
O
C
(CH2)7CH
CH(CH2)5CH3
(CH2)7CH
CH(CH2)5CH3
O
CH
Fatty acid
O
C
O
PO4
H2C
Amino alcohol
O
P
CH3
O
O-
phosphate
O
H2C
O
C
(CH2)7CH
CH(CH2)5CH3
(CH2)7CH
CH(CH2)5CH3
O
CH
O
C
O
H2C
O
P
O-
CH3
O
CH2CH2
N+
CH3
CH3
Ester links (phosphodiester)
CH2CH2
N+
CH3
CH3
amino alcohol
(choline)
Lipids - Glycerophospholipids
O
H2C
O
C
(CH2)7CH
CH(CH2)5CH3
(CH2)7CH
CH(CH2)5CH3
O
CH
O
C
O
H2C
O
P
CH3
O
CH2CH2 alcohol
N+
CH3
amino
O-
CH3
CH3
HO
CH2CH2
N+
CH3
HO
CH2CH2
NH3+
HO
CH2CH
COO-
CH3
Choline
(quatenary ammonium ion)
Ethanolamine
Serine
NH3+
Lipids - Glycerophospholipids
O
H2C
O
C
(CH2)7CH
CH(CH2)5CH3
(CH2)7CH
CH(CH2)5CH3
O
CH
O
C
O
H2C
O
P
CH3
O
CH2CH2
O-
N+
CH3
CH3
phosphatidyl choline
A typical phosphoglyceride (glycerophospholipid).
Also called lecithin. All phosphoglycerides that contain a choline are called lecithins.
The fatty acids can be the same or differet. Can be saturated or unsaturated or can be a
mixture.
Lipids - Glycerophospholipids
O
Physical properties
H2C
O
C
(CH2)7CH
CH(CH2)5CH3
(CH2)7CH
CH(CH2)5CH3
hydrophobic tails
O
CH
O
C
O
H2C
O
P
CH3
O
CH2CH2
O-
N+
CH3
hydrophillic head group
CH3
The negatively charged phosphate and the positively charges ammonium group make the head
group hydrophillic. Glycerophospholipids form micells.
O
CH2
O
C
O
(CH2)16CH3
CH
O
C
O
(CH2)7CH
CH2
O
C
(CH2)12CH3
hydrophobic tail
CH(CH2)5CH3
hydrophilic Head group
O
OH
hydrophobic Tail
Lipids - Glycerophospholipids
The 3D structure
Palmitoyl Oleoyl phosphatidyl choline
Lipids - and cell membranes
Lipids - and cell membranes
Lipid membranes are ‘fluid’ - they
permit movement of proteins and lipids.
Lipid membranes (Bilayers) typically
contain:
Phosphatidylcholine
Phosphatidylethanolamine
Phosphatidylserine
Sphingomyelins
Glycerophospholipids
Lipids (from the greek ‘lipos’ meaning fat or lard) - types
Lipids are a class of molecules that are insoluble in water but are soluble in non-polar organic
solvents.
Lipids
Saponifiable lipids
(can be hydrolyzed)
non-Saponifiable lipids
(can NOT be hydrolyzed)
- Waxes
- Steroids
- Triglycerides
- Prostaglandins
- Glycerophospholipids
- Sphingolipids
- Glycosphingolipids
Remember the esters?
Lipids - nonsaponifiable
- Steroids - they have the same distinguishing feature of the saponifiable lipids, i.e. they do
not dissolve in water. BUT their structures are completely different.
12
11
2
3
1
10 9
A
4
B
5
C
13
17
D
16
14 15
8
7
6
Steroid Ring Structure
The most important and most abundant steroid is cholesterol.
Lipids - nonsaponifiable, cholesterol
Cholesterol is a sterol
CH3
CH3
CH3
CH(CH2)3CHCH3
CH3
HO
component of cell membranes
component of
myelin sheath, nerve
and brain tissue
used in the synthesis of other
steroids including steroid
hormones, bile salts, and
vitamin D etc.
Lipids - nonsaponifiable, cholesterol in a membrane
HO
Hydrophilic
Hydrophobic
3
CH
3
CH
C
3
CH
2 )3
C
H(
CH
3
CH
3
HC
H
Cholesterol helps maintain the ‘fluidity’ of the
membrane. Acts as a ‘buffer’ that does not allow big
changes in membrane fluidity.
Lipids - cholesterol in steroid hormone synthesis
CH3
CH3
CH3
CH3
CH(CH2)3CHCH3
CH3
O
O
CH3
CH3
CH3
CH3
CH3
O
HO
HO
Cholesterol
O
Pregnenolone
O
CH2OH
CH3
O
OH
HO
CH3
CH
CH3
O
Cortisol
CH2OH
HO
CH3
O
Progesterone
CH3
O
aldosterone
testosterone
OH
The steroid hormones
Progesterone
Prepares uterus for fertilized egg
testosterone
Development of male organs; male sexual
characteristics; sperm formation
Cortisol
(a glucocorticoid)
Stimulated glycogen synthesis from amino acids and
increased blood glucose levels.
Inhibits allergic and inflammatory responses.
aldosterone
(a mineralocorticoid)
Helps maintain Na and K balance in tissues; water
retention.
Lipids - cholesterol and bile salts
CH3
CH3
CH3
CH3
CH(CH2)3CHCH3
CH3
Cholesterol
OH
CH3
CH3
O
CHCH2CH2
C
NH
CH2
CH2
Taurocholic acid
Hydrophobic
O
CHCH2CH2
C
O-
OH
Cholic acid
OH
SO3-
CH3
Hydrophilic
OH
CH3
CH3
HO
OH
7alpha-hydroxycholesterol
CH3
HO
CH3
Many steps
HO
HO
OH
CH(CH2)3CHCH3
CH3
CH3
CH3
CH3
O
CHCH2CH2
C
NH
CH2
C
O-
Hydrophilic
CH3
HO
O
OH
Hydrophobic
Glycocholic acid
Bile satls (the salts of the acid) - derived from cholesterol; are made in the liver and stored in
the gallbladder; secreated in to the intestine after meals to solubilize fats.
The contain both hydrophobic and hydrophilic parts and therefore act as very good
detergents. The micelles help break up fat in the diet so that they can be broken down.
Lipids - cholesterol, the dark side
Cholesterol is a major constituent of atherosclerotic plaques.
Lipids - cholesterol, a summary
- What is cholesterol?
- cholesterol is a lipid that is a steroid, a compound that
contains a steroid nucleus.
- cholesterol is a sterol because it contains a OH group.
- cholesterol is a sterol because it contains a OH group.
- cholesterol is a major constituent of cellular membranes and helps
membrane maintain its rigidity.
- cholesterol is needed for the synthesis of other important steroid
hormones like progesterone and testosterone, and also for the
synthesis of bile salts.
- cholesterol is a major component of atherosclerotic plaques and
therefore plays an important role in heart disease.
Lipids - transporting
If triglycerides (the major storage molecule of fatty acids) and cholesterol are
mainly hydrophobic (non-soluble in water) then how are they transported in the
blood which is mainly water?
Use lipoprotein particles.
transports lipids from intestine to
cells for use as energy and for
storage.
transports lipids from liver to cells
for use as energy and for storage.
transports lipids to cells to be used
in cell membranes, synthesis of
steroids. Excess LDL causes
cholesterol to deposit in plaques.
transports excess lipids from cells
to liver to be converted to bile salts
and eliminated.
Lipids - transporting
- What are LDLs and HDLs?
- Low density lipoproteins (LDLs) and High density
lipoproteins (HDLs) are lipid/protein particles that are
responsible for the transport of lipids in the blood.
- LDLs are bad cholesterol, because the cholesterol within the LDL
can be deposited in plaques.
- HDLs are good cholesterol, because they help remove excess
cholesterol to the liver to be eliminated.
Lipids - nonsaponifiable, prostaglandins
Why are they nonsaponifiable?
OH
Arachidonic acid
O
Cyclooxygenase
(COx-1 and COx-2)
~ 20 others
O
COOH
O
OH
(prostaglandin H2)
- involved in almost every phase of the reproduction.
- involved in blood clotting.
- involved in inflammation and pain.
Lipids (from the greek ‘lipos’ meaning fat or lard) - types
Lipids are a class of molecules that are insoluble in water but are soluble in non-polar organic
solvents.
Lipids
Saponifiable lipids
(can be hydrolyzed)
non-Saponifiable lipids
(can NOT be hydrolyzed)
- Waxes
- Steroids
- Triglycerides
- Prostaglandins
- Glycerophospholipids
- Sphingolipids
- Glycosphingolipids
Remember the esters?