Nutrition
In order for the human body to be healthy
and resistant to disease, good nutrition is
required. All living things are made of
chemicals. In order to grow, develop and
maintain bodily structures and functions,
specific chemicals must be acquired from
the food we eat. In a sense, we are what
we eat. Nutrients can be divided into the
following categories:
Nutrients Overview
Carbohydrates – sugar based molecules that are
metabolized for energy in cellular respiration and
make up the structural components of plant cell walls.
Lipids – fat based molecules that store large quantities
of energy. These molecules also make up the
structure of cell membranes.
Proteins – polypeptide molecules that can store energy,
although their primary function is to provide the
structural building blocks for cells and to make
enzymes.
Vitamins – organic molecules that help mediate enzyme
action by promoting the binding of an enzyme to a
substrate. These are also called coenzymes.
Minerals – inorganic molecules that mediate enzyme
activities by promoting the binding of an enzyme to a
substrate. These are also called cofactors.
Chemistry of Living Things
Fats and Lipids
-energy storage
compounds,
insulation, warmth
-structural
Carbohydrates
components of cell Proteins
-primary energy
-make the
source
membranes
structural
-structural material
of cell walls
components of
cells
Chemicals
-make enzymes
of Life
Nucleic Acids
-form the genetic
material of cells
-make up ATP
energy
molecules
Vitamins and Minerals
-found in complex
chemicals
-help mediate
chemical reactions
General Types of Molecules
Polymers – are compounds made up of two or
more (many) subunits, which are often joined by
dehydration synthesis.
Monomers – are compounds made up of single
subunits, which can be produced by the
hydrolysis of polymers.
Dehydration Synthesis-Hydrolysis
Carbohydrates
Names usually have an ‘ose ending
Are either single unit sugar molecules called
monosaccharides, two unit sugar molecules
called disaccharides, or multiple unit sugar
molecules called polysaccharides. All sugar
molecules are made up of subunits with either a
6 ring (hexose) base structure or a 5 ring
(pentose) base structure.
Have the formula ratio of C1H2O1. For example,
glucose is C6H12O6
Monosaccharides
Are simple single sugars compounds composed
of 5 unit monomers (pentoses) or 6 unit polymers
(hexoses)
Main Types of Monosaccharides
1) Glucose: The main monosaccharide. Needed
for Cellular Respiration!
2) Fructose: a simple sugar often found in fruits
– Fructose and Glucose are isomers of each other,
which means that they have the same molecular
formula, but different structural arrangement
3) Galactose: a simple sugar found in dairy
products
4) Ribose: genetic sugar, helps make RNA
5) Deoxyribose: genetic sugar, helps make
DNA
Disaccharides
Disaccharides and polysaccharides are created from
monomers by a process called dehydration
synthesis or dehydrolysis. In this process, water
molecules are removed, as a saccharide bond is
formed.
Main types of Disaccharides
(2 monosaccharides joining up)
1) Sucrose: a glucose and a fructose
sugar molecule joining together
2) Maltose: 2 glucose molecules joining
together
3) Lactose: A glucose and a galactose
molecule joining together
Polysaccharides
When many subunits join together by
dehydration synthesis, a polysaccharide
(complex carbohydrate) such as glycogen,
amylose (starch) or cellulose is produced.
stored glucose in plants
found in cell walls of
plants. Can not be digested
in Humans
stored glucose in
animals
Tests for Carbohydrates
Benedicts test – detects reducing sugars (all
monosaccharides and some disaccharides).
The benedicts reagent turns from blue (little
amount) to orange/red (a lot) when reducing
sugars are present.
Starch test – detects the presence of complex
carbohydrates (polysaccharides) or starch.
Iodine is added and creates a blue-black iodine
starch complex.
Lipids
Are non-polar (and thus water insoluble), high energy
molecules composed of glycerol and fatty acids.
Like carbohydrates, these two molecules combine by
dehydration synthesis.
These actually contain 2X the amount of energy per
gram as Carbs, but are not the primary source of
energy due to being very hard to breakdown
Glycerol
Structure of a Lipid (Triglyceride)
All triglycerides have a glycerol
backbone (that is always the same) and 3
fatty acids attached. The fatty acids are
what differ among different types of
triglycerides.
1)Saturated Fats (fats, grease, lards)
fatty acid molecules that
have no double bonds in
the carbon chain. These
molecules have as many
hydrogen atoms as they
can hold. They are solid
at room temperature and
relatively unreactive
(difficult to digest).
Can lead to heart failure
and atherosclerosis
Usually come from animal
(clogging of arteries)
products
2) Unsaturated Fats (Oils)
fatty acid molecules
that have one or more
double bonds in the
carbon chain.
Additional hydrogen
atoms can be added
to these molecules.
They are liquid at
room temperature and
are more reactive, so
they can be broken
down more easily.
Can reduce heart
Usually come from plant products
problems!!
Other types of Lipids
3) Phospholipids: needed in cell
membranes
4) Waxes
5) Cholesterols: HDLs and LDLs. see
reading
6) Steroids: hormones, similar to
cholesterol, help muscle growth and
repair.
Tests for Lipids
Translucence test –
lipids cause unglazed
brown paper to
become translucent.
Non-lipids do not.
Sudan IV test – lipids
dissolve in the sudan
IV indicator turning it
from a black granular
form to a pink or red
paste.
Proteins
Are polymers made up
of combinations of 20
different amino acid
subunits joined together
by dehydration
synthesis. Amino
acids are held together
by peptide bonds.
Proteins form structural
components of cells
and enzymes, and they
store useful energy.
Protein Primary Structure
All amino acids have a
basic amino group and a
carboxylic acid. Different
amino acids have different
R groups or side chains.
There are 20 different
amino acids in total.
Proteins are formed from
long chains of amino acids
that are joined together by
peptide bonds. These
bonds form from a
dehydration synthesis
reaction.
Protein Secondary Structure
hydrogen bonds cause proteins to fold into
pleated sheets, or coil into helixes.
Protein Tertiary Structure
further folding of a polypeptide creates a
larger globular structure, such as that found in
the hemoglobin groups in red blood cells.
Quaternary Structure
are large
globular proteins
formed form two
or more
interacting
polypeptides.
Tests for Proteins
Biuret Test – when the blue biuret
reagent is added to proteins, the
peptide bonds turn the biuret reagent
a purple color.
When exposed to excessive heat,
radiation or changes in pH, the
hydrogen bonds that hold proteins
together break down, disrupting the
configuration/shape of the protein.
This process is called protein
denaturation. When the change is
irreversible, the process is called
coagulation. Boiling an egg, or
cooking meat is an example of this.
Enzymes
Catalysts – are chemicals
that increase the rate of
chemical reactions and
allow reactions to occur at
lower temperature, without
being used themselves.
Catalysts provide an
alternate reaction
pathway, thus
decreasing the energy
(temperature) required
for the reaction to take
place.
Enzymes
are protein catalysts found within living
organisms. All enzymes have an active site, or
area where the substrate (what is being reacted)
binds to the enzyme.
Enzyme activity
Factors Affecting Enzyme Reactions
pH – specific enzymes
function best within a
specific range of pH.
For example, enzymes
in your blood function
best at a pH of about
7.2-7.4. Enzymes in
your stomach function
best at a pH of about
1.0. If the pH is too low
or too high, the enzyme
may denature.
Substrate concentration –
higher the substrate
concentrations usually
produce greater enzyme
activity until all of the active
sites are occupied.
Temperature – increased
temperatures increase
enzyme activity until the
enzyme starts to denature.
Very high temperature break
down proteins, and render
the enzymes ineffective.
Competitive Inhibitors
molecules that have a shape similar to the
substrate and binds to the active site of an
enzyme, preventing the desired reaction. CO is
a competitive inhibitor to the binding of oxygen.
Regulation of Enzyme Activity
Feedback Inhibition – is the inhibition of an
enzyme by the final product in the metabolic
pathway.
Precursor Activity - is the activation of the last
enzyme in a metabolic pathway, by the initial
substrate.
Allosteric Activity – is the change in an enzyme
caused by the binding of a molecule. This may
promote or prevent enzyme activity.
BIOL 230 Lecture Guide - Animation of
Noncompetitive Inhibition with Allosteric
Enzymes
Co-factors – are inorganic ions that help
enzymes combine with substrate molecules.
These come from mineral supplements. Ex.
iron helps oxygen bind to hemoglobin.
http://www.facsup.armstrong.edu/videopr
oduction/exmedia/Instruct1.swf
Co-enzymes – are organic molecules that
help enzymes combine with substrate
molecules. These come from vitamins.