Download Macromolecules Part 2

Macromolecules Part 2
Polysaccharides and Lipids
Carb Review
 Monosaccharides - single molecules, usually with 5 or 6
carbons
 pentoses - sugars with 5 carbons, including arabinose, xylose, ribose
 hexoses - sugars with 6 carbons, including glucose, fructose,
galactose, mannose
 Disaccharides - sugars containing 2 monosaccharides
 sucrose = glucose + fructose
 maltose = glucose + glucose
 lactose = glucose + galactose
 Polysaccharides - combinations of a large number of
monosaccharides into complex three dimensional forms
Carbs continued
 Monosaccharides: Glucose & fructose
 Disaccharides: sucrose, maltose, lactose
 Polysaccharides
 Starch (amylose + amylopectin)
 In plant cells; chain of glucose molecules coiled up like a phone cord
 Glycogen (similar structure to amylopectin)
 Excess sugar in animal cells is stored in this form; highly branched
and more complex chain of glucose monomers
 Stored in muscle and liver cells
 When body needs energy, glycogen is broken down into glucose
 Cellulose
 Found in plant cell walls; made of glucose monomer;
 building material;
 aka FIBER; humans do NOT have the enzyme to break this
polysaccharide down
 Passes through digestive tract and keeps it healthy but
NOT a nutrient
 Some animals (cows) have microorganisms that live in
their digestive tract that help break down cellulose
Review our monosacc.
Polysaccharides
 Its subunits are monosaccahrides
 Made by condensation rxn
 Glycosidic linkage between glucose
molecules
 Final molecule will be several
monosaccharides long
 They are NOT sugars
 Function: energy storage and structure
 Excess glucose in living organisms can be
dangerous because it changes
concentration in/out of cellschgs in
osmotic propertiesloss/gaining of
wtaercell shriveling up/bursting
Amylose
 glucose polymer
 Made by condensation RXN b/t alpha glucose molecules
 1-4 glycosidic linkages b/t alpha glucoses
 Make long, curve chains that eventually coil up to form
springs
 Very compact
 end of the polysaccharide carbon (C1) that is not involved in a
glycosidic bond is called the reducing end
 This is because it has an extra electron compared to all
the other glucose molecules and it can donate an
electron (and can REDUCE, make more negative, the
charge of another molecule)
Amylopectin
 Polysaccharide made with 1-4 glycosidic linkages between alpha
molecules
 Different from amylose b/c…
 the chains are shorter
 There are branches
 Branches are formed by a 1-6 linkage
 Mixtures of amylose and amylopectin make up STARTCH grains
we find in chloroplast as and storage organs of plants (vacuoles)
 Amylopectin and amylose
Starch  Not in animal cells
 Only plant cells
Glycogen
 glucose storage polymer in animals
 similar in structure to amylopectin
 Made of chains of 1-4 linked alpha glucose
molecules and 16 linked branches
 But glycogen has more 1-6 branches
 MORE BRANCHED than
amylopectin molecules
 highly branched structure permits rapid
release of glucose from glycogen stores
 Such as in muscle cells during exercise
 The ability to rapidly mobilize glucose is
more essential to animals than to plants
 Important in ruminants
 Critical glucose storage
 Glycogen molecules clump together to
form granules
 Visible in liver and muscle cells
 Store energy
Cellulose
 a major constituent of plant cell walls
 consists of long linear chains of
beta glucose molecules with 1-4
linkages.
 Every other glucose in cellulose is
flipped over, due to the 1-4 beta
linkages (repulsion forces of electrons)
 promotes intrachain and interchain
hydrogen bonds, as well as van der
Waals interactions
 causes linear cellulose chains…
 to be straight and rigid
 To pack with a crystalline arrangement in
thick bundles called microfibrils
Cellulose
 Function: structure
 Rigid to form cell wall of
plants
 Protection
 CANNOT be digest by
animals
 some bacteria, fungi, and
protozoans do produce
cellulase, the enzyme that
breaks down cellulose
One more polysacch….
 Lignin - the polysaccharide
that comprises the woody
parts of plants
 Cobs, hulls, and the woody
portions of trees and shrubs
all contain this complex
carbohydrate
 largely
indigestible=unavailable to
animals
 Some classify lignin in a
separate category of
compounds due to the
complexity of the chemical
structure
Practice Set 3 (1 SAQ and 3 MC)
Lipids
 Diverse group of chemicals
 Made of mostly carbon and
hydrogen…some oxygen
 Usually not soluble in water
 Not a polymer but is made of molecular
units
 Most common is TRIGLYCERIDE
 AKA Fats and Oils
 At room temp, FATS are solids
 At room temp., OILS are liquid
Triglycerides
 Combo of 3 fatty acid molecules with one
glycerol molecule
 Fatty acidsorganic molecules
 Carboxyl group (COOH) attached to hydrocarbon
tail
 Glycerol ALCOHOL
 3 carbons with a hydroxyl group (OH) attached to
each carbon
 Each fatty acid tail joins onto the glycerol
molecule through CONDENSATION reaction
between the hydroxyl group of the glycerol
molecule and the carboxyl group of the fatty acid
chain
Fats/Lipids
 Glycerol + 3 Fatty Acids=
TRIGKYCERIDE
 Linkage is called ESTER linkage
 Condensation/Dehydration reaction
 INSOLUBLE in water
 Long hydrocarboin tails have NO
uneven distribution of electrical charge
 Non-polar and HYDROPHOBIC
 SOLUBLE in certain organic solvents
 Ether
 Chloroform
 ethanol
 Function
 Energy storage
 Insulation
 Water formation
 Water Proofing
Saturated Fats
 Saturated
 Solid at room temperature
 Animal fats
 meat, dairy and eggs
 also found in some plant-based sources such as coconut, palm and palm kernel oils
 All the carbons in the fatty acid chains contain the MAXIMUM # of
hydrogen atoms around each atom
 SATURATED with hydrogen
 Only single bonds in fatty acid chain
 Saturated fats directly raise total and LDL (bad) cholesterol levels
Unsaturated Fats
 Unsaturated/polyunsaturated fats
 -C-C=C-C One or more double bonded carbon
atoms in fatty acid chain, then it is
unsaturated
 Do NOT contain maximum # of
hydrogens
 Double bonds make fatty acids melt more
easily
 Liquid at room temperature
 Plant oils, fish oils
 POLYUNSATURATED
 More than one double bond
 MONOUNSATURATED
 Only one double bond
Mono vs.Poly
 Monounsaturated fats
 liquid at room temperature
but begin to solidify at cold
temperatures
 preferable to other types of
fat
 found in olives, olive oil,
nuts, peanut oil, canola oil
and avocados
 Some studies have shown that
these kinds of fats can actually
lower LDL (bad) cholesterol
and maintain HDL (good)
cholesterol
 Polyunsaturated fats
 liquid at room temperature
 found in safflower, sesame,
corn, cottonseed and soybean
oils
 shown to reduce levels of
LDL cholesterol, but too
much can also lower your
HDL cholesterol
Trans fats or hydrogenated fats
 unsaturated fats
 raise total LDL (bad) cholesterol levels while also lowering
HDL (good) cholesterol levels
 Trans fats are used to extend the shelf life of processed foods,
typically cookies, cakes, fries and donuts
 Any item that contains “hydrogenated oil” or “partially
hydrogenated oil” likely contains trans fats
 Hydrogenation is the chemical process that changes liquid
oils into solid fats
Omega 3 Fatty acids
 an “essential” fatty acid
 Critical for our health but cannot be manufactured by our
bodies
 Good sources include
 cold-water fish, flax seed, soy, and walnuts
 Reduce the risk of coronary heart disease and also boost our
immune systems
Alcohols and Esters
Esters
 The chemical produced with the
Alcohols
 Series of organic molecules
which combine a hydroxyl
(-OH) group, attached to a
carbon atom
 Example: Glycerol
 Three linked carbon atoms
with an –OH attached to
each carbon
reaction of an acid and an
alcohol
 Ester Bond (linkage)
 Chemical link between alcohol
and the acid
 Carboxyl group (carboxylic
acid) –COOH reacts with the
hydroxyl group (-OH) to form
ester bond (-COO)
 Condensation reaction
 Reverse this reaction by adding
water (hydrolysis)
Role of Triglycerides
 Energy Reserves
 Rich in C-H bonds (even more so than carbs)
 A mass of a given lipid yields more ENERGY on oxidation
than the same given mass of a carbohydrate
 Fat has a higher calorific value
 Insulator
 Fat is stored below the dermis of the skin and around the
kidneys
 Prevents the loss of heat
 Blubber
 Provides insulation and buoyancy for sea mammals (whales and
manatees)
 Metabolic Source of Water
 When OXIDIZED in respiration CO2 and H2O
 Important for organisms in dry habitats (kangaroo rat)
Phospholipids
 One end is soluble in water (unique)
 Similar to triglyceride except that one of
the fatty acid chains is replace by a
POLAR phosphate group
 HYDOPHILIC
 The two remaining fatty acid chains are
HYDROPHOBIC (fear water)
 Important in cell membranes
Steroids
 Chemical messengers
 Structure
 4 fused carbon rings
 Ex. Cholesterol, testosterone, estradiol
 Function
 structural component of mammalian cell
membranes
 resilience and fluidity of human
membranes
 mobilized for the synthesis of steroid
hormones
 protecting the human skin against
external irritants and for holding water
content




Improvement of water balance in human skin
Enhanced barrier function for stratum
Inhibition of aging of skin
Water retention for hair
Cholesterol
 Cant move around blood stream on its
own (insoluble in water, blood is water
based..)
 Hitches a ride on a protein to travel
around body
 LIPOPROTEIN (lipid+protein)
 Protein coats cholesterol
 Different types of lipoproteins
 HDLs (high density lipoproteins) GOOD
 More protein than cholesterol
 LDLs (low density lipoproteins) BAD
 More cholesterol than protein
Practice set 5