Biochemistry II
Functional Groups, Lipids,
Nucleic Acids &
Metabolism
Functional Groups
A
functional group is a portion of a
molecule that is a recognizable /
classified group of bound atoms.
 In organic chemistry it is very common
to see molecules comprised mainly of a
carbon backbone with functional
groups attached to the chain.
Functional Groups
 The
functional group gives the
molecule its properties, regardless
of what molecule contains it
 They are centers of chemical
reactivity.
 The functional groups within a
molecule need to be identified
when naming as well.
Functional Groups
 These
are things like
 Hydroxyl
groups which form alcohols,
 Carbonyl groups which form aldehydes
or ketones,
 Carboxyl groups which form carboxylic
acids
 Amino groups which form amines.
 There
are about 20 key functional groups in
organic chemistry Crash Course
A Simple Analogy
 One
way you can think of functional
groups are like wood and hardware.
 Most biological molecules are composed
of carbon which can be analogous to a
piece of wood.
 Once you start to add hardware to the
wood, it begins to take on a certain
appearance and function.
Stay with me…..
 If
you take your piece of wood and add
hinges and a doorknob it will begin to
look like a door.
 If you add legs to your piece of wood, it
begins to look like a table.
 Functional groups are like the hinges or
legs added to your original piece of wood
or carbon molecule
Lipids (aka Triglycerides)
 Fats,
oils, and other water-insoluble
compounds are called lipids.
 Waxes and steriods also fall into this
category
 Natural fats and oils exist as triesters
of glycerol with fatty acids, which
are long-chain carboxylic acids (C12
through C24). This form of lipid is
known as a triglyceride.
Solubility of Lipids
 Lipids
tend to dissolve readily in
organic solvents, such as ether and
chloroform, rather than in highly
polar solvents such as water.
 This property sets them apart from
most biological substances such as
carbohydrates and proteins.
Saturated vs. Unsaturated Fats
Where are Lipids found?
 The
hydrolysis of oils or fats by boiling with
an aqueous solution of an alkali-metal
hydroxide is called saponification
 Saponification is used to make soap.
 Phospholipids, or lipids that contain
phosphate groups, are abundant in cells.
Phospholipid Bilayer
 In
water, phospholipids spontaneously
form a spherical double layer, called a
lipid bilayer, in which the hydrophobic
tails of phospholipid molecules are
sandwiched between two layers of
hydrophilic heads
Nucleic Acids
 The
fourth type of organic compound in
all living things is DNA and RNA.
Substantially covered in your biology
class.
 Composed of a sugar phosphate
backbone and base pairs (Uracil,
Thymine, Guanine, Adenine, Cytosine)
 They are the blueprint for making proteins
that control EVERYthing in an organism.
 Adenosine
triphosphate (ATP) is a
molecule that transmits energy in
the cells of living organisms.
 In living cells, ATP is the energy
carrier between the spontaneous
reactions that release energy and
nonspontaneous reactions that use
energy.
 The
entire set of chemical reactions
carried out by an organism is
known as the organism’s metabolism.
 In metabolism, unneeded cellular
components and the nutrients in food are
broken down into simpler compounds by
chemical reactions collectively called
catabolism.
Catabolism
 The
degradation of complex
biological molecules such as
carbohydrates, lipids, proteins, and
nucleic acids during catabolism
provides the energy and the
building blocks for the construction
of new biological compounds
needed by the cell.
Anabolism
 The
synthesis reactions of metabolism are
called anabolism.
 In anabolism, the products and the
energy of catabolism are used to make
new cell parts and compounds needed
for cellular life and growth.
 Simple compounds produced by
catabolism are used in the synthesis
reactions of anabolism.
Free Radicals
 The
body generates free radicals as the
inevitable byproducts of turning food into
energy.
 Others are in the food you eat and the air
you breathe.
 Some are generated by sunlight’s action
on the skin and eyes.
Free
radicals have a voracious
appetite for electrons.
This electron theft can radically
alter the “loser’s” structure or
function.
 Free
radical damage can change the
instructions coded in a strand of DNA.
 It can make a circulating low-density
lipoprotein (LDL, sometimes called bad
cholesterol) molecule more likely to get
trapped in an artery wall.
 It
can alter a cell’s membrane, changing
the flow of what enters the cell and what
leaves it.
 Free radical damage is involved in the
early stages of artery-clogging
atherosclerosis and may contribute to
cancer, vision loss, and a host of other
chronic conditions.
Antioxidants
 Antioxidants
work by generously
giving electrons to free radicals
without turning into electronscavenging substances themselves.
 The
most familiar ones are vitamin C,
vitamin E, beta-carotene, and the
minerals selenium and manganese.
 They’re joined by glutathione, coenzyme
Q10, lipoic acid, flavonoids, phenols,
polyphenols, phytoestrogens, and many
more.
 How do vitamins work?
 But
using the term “antioxidant” to refer to
substances is misleading.
 It is really a chemical property, namely,
the ability to act as an electron donor.
 Some
substances that act as antioxidants
in one situation may be pro-oxidants—
electron grabbers—in a different
chemical situation.
 Another big misconception is that
antioxidants are interchangeable.
 They aren’t. Each one has unique
chemical behaviors and biological
properties.
The Bottom Line
 Free
radicals contribute to chronic
diseases.
 This doesn’t automatically mean that
substances with antioxidant properties will
fix the problem.
 At the same time, abundant evidence
suggests that eating whole fruits,
vegetables, and whole grains—all rich in
networks of antioxidants and their helper
molecules—provides protection against
many contributing factors to disease and
aging.
 Simply Put.......