Organization: The 6
Essential Elements
Section 4
I. Why do living things need the six essential
elements (CHNOPS)?
A. Organization of an Organism – Living
things are composed of two main types
of chemical compounds:
1. Inorganic: compounds that do not contain
carbon, oxygen, and hydrogen
C
I. Why do living things need the six essential
elements (CHNOPS)?
a. Water – (hydrogen and oxygen) the most
important inorganic compound to living
organisms
i.
ii.
60-90% of all living organisms are made of water.
Ex. the most abundant compound that makes up a
cell is water
Most chemical reactions occur in water because it
provides an optimum environment
Ex. transport of molecules in the cell
I. Why do living things need the six essential
elements (CHNOPS)?
b.
Salts – often donate trace elements and
influence the environment of the cell
Ex. NaCl dissolves in solution to form
Na+ and Cl-
I. Why do living things need the six essential
elements (CHNOPS)?
2.
Organic: compounds that DO contain carbon, oxygen,
and hydrogen
a.
Carbohydrates (carbon, hydrogen, oxygen)
Ex. Provide energy source for respiration (glucose)
b.
Lipids (carbon, hydrogen, oxygen)
Ex. Insulate and protect organs in the body (fats)
c.
Nucleic Acids (carbon, hydrogen, oxygen, nitrogen
and phosphorus)
Ex. Allow traits to be passed from parent to child
(DNA)
d.
Proteins (carbon, hydrogen, oxygen, nitrogen, sulfur,
phosphorus)
Ex. Provide specifically shaped molecules that can
carry other molecules (hemoglobin carries oxygen)
I. Why do living things need the six
essential elements (CHNOPS)?
B.
To Maintain Homeostasis
The elements make up essential organic
and inorganic compounds. Each type of
molecule performs specific jobs in
organisms (see examples above).
2. Hydrogen is donated or accepted by weak
acid-base pairs to regulate the pH of a
system (i.e. cell, blood). These weak acidbase pairs are called buffers.
1.
Buffers Regulate pH
Not enough
hydrogen?
Here’s
another H
atom!
Buffers can
donate hydrogen
Too much
hydrogen?
I’ll hold a
hydrogen
atom!
Ahhhhh – just the right
Buffers can
pH!
accept hydrogen.
Review Questions

What are the six essential elements?


What is the most important inorganic compound to life?


Water
What are the four major organic compounds important to life?


CHNOPS
Proteins, Carbohydrates, Lipids, Nucleic Acids
How do the six essential elements help organisms maintain homeostasis
(two ways)?





H and O can form water, which provides the optimum environment for chemical
reactions
C, H, and O can form carbohydrates which help maintain energy
C, H, and O can form lipids which help keep some animals warm
C, H, O, N, P, and S can form proteins which help regulate reactions
H can be donated or accepted by buffers to help regulate pH
How does synthesis provide important
organic macromolecules using six essential
elements?
A.
Carbohydrates
1.
Carbon, hydrogen, and oxygen make up subunits
called monosaccharide. Many monosaccharides
bond together forming larger carbohydrates.
a. In plants many monosaccharides called glucose
(C6H12O6) bond together to form starch.
b. In animals excess glucose bond together to form
a compound (similar to starch) called glycogen.
2.
Functions of carbohydrates
Energy is released when carbohydrates are
digested. This is because glucose is used
for cellular respiration.
a.
i.
ii.
Monosaccharides (simple sugars) provide short
term energy.
Starch and glycogen are considered longer term
energy sources because they can be broken
down over a period of minutes, hours or days to
provide glucose for energy.
b.
c.
Some carbohydrates are very stable and can
be used for structure and support in the cell
and body (cellulose in the cell wall of plant
cells).
Carbohydrate chains on the surface of cell
membranes are used as identifiers (like name
tags).
How does synthesis provide important
organic macromolecules using six essential
elements?
B.
Lipids
1. There are several types of lipids, but all contain
subunits of glycerol and fatty acids made of carbon,
hydrogen, and oxygen. These combine to make a
very large molecule (macromolecule), but not a
chain.
a. Fats can be saturated (usually solid at room
temperature) or unsaturated (usually liquid).
b. Phospholipids also contain a phosphate group
and make up most of the cell membrane.
2.
Functions of lipids
a. Because of the numerous bonds and the way the
body stores lipids, they can be used as very longterm (weeks, months) energy sources.
Ex. Bears accumulate a layer of fat before winter
(when food will be less available)
b. Fats stored in the body act as insulation and
protection for internal organs.
c. Some hormones are composed of lipids (steroids).
Review Questions
1.
What three elements make up both carbohydrates and
lipids?
A.
2.
What function do both carbohydrates and lipids
provide?
A.
3.
Energy use in the body
What is the subunit of both starch and glycogen?
A.
4.
Carbon, hydrogen, and oxygen
Glucose
What are the two subunits found in all lipids?
A.
Glycerol and fatty acids
II. How does synthesis provide important
organic macromolecules using six
essential elements?
A.
Nucleic Acids
1.
Carbon, hydrogen, oxygen, nitrogen, and
phosphorus make up subunits called
nucleotides. Many nucleotides bond together to
make up a long chain – a nucleic acid.
a. DNA is a double chain of nucleotides found in
all living cells.
b. RNA is a single chain of nucleotides that
provides the structures needed for the cell to
make proteins.
2. Functions of nucleic acids
a. DNA makes up the genes. Genes
are used to pass traits from parent
to offspring. Genes determine
traits.
b. DNA controls cellular activities by
controlling the production of
proteins in response to hormones
and other cellular signals.
c. RNA is used in the production of
proteins.
How does synthesis provide important
organic macromolecules using six essential
elements?
D.
Proteins
1.
All six essential elements may be used in the production of
small subunits called amino acids. Amino acids bond to
form a long chain called a protein. These chains of amino
acids fold into a particular shape when forming. The shape
of a protein will determine its function. If a protein
denatures (loses its shape) it can no longer function.
a. Hemoglobin is a protein shaped to hold oxygen for
transport through the bloodstream.
b. A group of proteins called enzymes are shaped to fit and
react with specific molecules.
2.
Functions of proteins
a. Some proteins absorb light to maintain
homeostasis. These are called pigments.
They create color by reflecting certain
wavelengths of light.
 Ex. Chlorophyll absorbs light to gather energy
for photosynthesis.
b. Some proteins are constructed by cells to bind
with and inactivate foreign particles in the
body. These are called antibodies.
c. Proteins may form structural parts in an
organism – such as keratin in hair and nails.
d.
e.
f.
Some proteins are used for transport
through the cell membrane or in the
bloodstream (ex. hemoglobin)
Some proteins are used for
communication between cells. These
may be hormones (insulin) or
neurotransmitters.
Enzymes (a special class of protein)
act to speed up chemical reactions.
Review Questions
What is the subunit of a nucleic acid?
1.
A.
Nucleotide
What is the function of DNA?
2.
A.
Hereditary material and Protein synthesis
What is the subunit of proteins?
3.
A.
Amino acids
How do amino acids form specific shapes when they bond to make a chain?
4.
A.
They fold to make a three-dimensional shape
What protein carries oxygen?
5.
A.
Hemoglobin
Name three functions of proteins.
6.
A.
B.
C.
D.
E.
F.
Pigments
Antibodies
Structures
Transport
Communication
Enzymes
III. Why are enzymes necessary
for life?
A.
Enzymes help maintain homeostasis
1.
2.
All organisms have metabolism. Metabolism includes all of
the chemical reactions that occur in that organism.
Metabolism includes digestion and production. Metabolism
(chemical reactions) requires certain conditions to occur.
Enzymes regulate metabolism, allowing life to continue.
Metabolism (each reaction) has a small range of
temperature and pH at which it can proceed. Each
reaction also needs some energy to begin. This is called
activation energy. Enzymes allow reactions to occur at
lower activation energy (body temperature). This means
enzymes act as biological catalysts (speeds reactions).
Graph of a reaction with and
without an enzyme
B. The structure of an enzyme
determines its function
1.
Enzymes are usually proteins. Proteins have a definite
3-D structure because the amino acid chains fold.
a.
b.
On the enzyme, there is a place where the target
molecule can attach. This place is called the active site.
The target molecule/chemical is the substrate.
If the enzyme’s active site changes shape too much, the
substrate will not fit. An enzyme may change shape if it
is denatured by a change in temperature, pH, or salinity.
This means the enzyme will not be able to speed up the
reaction.
2.
Enzymes mediate (help) chemical reactions using
a specific chemical pathway (series of steps).
a.
b.
c.
d.
The enzyme collides with the substrate.
The enzyme and substrate fit together at the active site
like a lock and key.
The enzyme changes the substrate in some way
i. It may help break the substrate apart.
ii. It may hold two (or more) substrates together
closely so the two parts interact.
The enzyme and the substrate separate. The substrate
(now changed) is called the product.
Enzyme-Mediated Pathway
C. Enzymes have distinguishing
characteristics
1.
2.
3.
Enzymes are biological catalysts. This means they speed
up chemical reactions in living things.
Enzymes are specific. This means enzymes will catalyze
only one specific reaction because only certain substrates
fit due to the shape of the active site.
Enzymes are reusable. Notice in the diagram above that
the enzyme did not change shape or split. This means it
can now fit with another substrate or set of substrates and
repeat its role in speeding up the reaction.
Reversible Enzyme Reactions Animation
Review Questions
1.
What do enzymes lower, allowing reactions to occur at body
temperature?
A.
2.
What organic compound are most enzymes?
A.
A.
Substrate
Is the active site located on the enzyme or the substrate?
A.
5.
Proteins
What is the name of the target chemical on which the enzyme works?
3.
4.
Activation Energy
Enzyme
Name two characteristics of enzymes.
A.
B.
C.
Enzymes are catalysts; they speed up reactions
Enzymes are specific
Enzymes are reusable; they are not used up in the reaction
IV. How do we use technology to
identify chemical compounds?
A.
Indicators – a chemical or tool that indicates a substance
is present by changing color. These may be necessary for
analyzing blood, hair, or urine in a drug test. Below are a
few examples:
1.
2.
3.
pH can be determined using pH paper (different colors
indicate different pH levels) or bromothymol blue/BTB (turns
yellow in the presence of an acid).
The presence of starch (a carbohydrate) is indicated when
iodine changes from a rusty brown to a blue or black.
The presence of blood is indicated when luminal is added
and glows under a black light.
IV. How do we use technology to
identify chemical compounds?
A.
Chromatography – the
separation of chemicals
in solutions based on
differing chemical
properties so that each
part can be identified.
Ex. Gas chromatography
may be used to identify
unknown chemicals
found at a crime scene
or samples from other
planets
Review Questions
1.
What is an indicator?
A.
2.
How does iodine indicate the presence of
starch?
A.
3.
A chemical or tool that changes color in the
presence of a particular substance.
It turns a blue-black color
What allows the separation of chemicals in
chromatography?
A.
The different chemical properties (such as solubility)