Download Learning Target: I can analyze and teach my classmates about Radon.

Proteins are
multipurpose molecules.
2006-2007
Proteins
Examples
– muscle
insulin
– skin, hair, fingernails, claws
• collagen, keratin
pepsin
– pepsin
• digestive enzyme
in stomach
– insulin
• hormone that controls blood sugar
levels
collagen (skin)
Proteins
• Function:
– many, many functions
• hormones
– signals from one body system to another
– insulin
• movement
– muscle
• immune system
– protect against germs
• enzymes
– help chemical reactions
Proteins
• Building block =
amino amino amino amino amino
acid – acid – acid – acid – acid

20 different
H
O
H
||
|
C—OH
—N—
—C—
|
H
variable
group
There’s
20 of us…
like 20 different
letters in an
alphabet!
Can make lots of
different
words
20 DIFFERENT AMINO ACIDS
• How many words are there in the English
language?
• How many letters are there in the modern
English alphabet?
20 DIFFERENT AMINO ACIDS
APPLE
How many different three letter
words can you make using the
letters from the word above?
Proteins are similar. The order
of letters determines the
meaning of a word.
(Example: pal vs. lap)
The order of amino acids
determines the type of
protein and its function.
For proteins: SHAPE matters!
• Proteins fold & twist into 3-D shape
– that’s what happens in the cell!
• Different shapes =
growth
hormone
hemoglobin
pepsin
collagen
It’s SHAPE that matters!
• Proteins do their jobs, because
of their shape
• Unfolding a protein destroys its shape
– wrong shape = can’t do its job
– unfolding proteins = “denature”
• temperature
• pH (acidity)
unfolded
“denatured”
folded
Enzymes
Enzymes are proteins that ______________(speed up)
biochemical reactions, which otherwise would not take
place.
These enzymes are essential for chemical processes like
digestion and cellular metabolism. Without enzymes,
most physiological processes would proceed so slowly (or
not at all) that life could not exist.
Enzymes
Because form determines function, each enzyme is specific to its
substrates. The substrates are the reactants that undergo the
chemical reaction catalyzed by the enzyme.
The location where substrates bind to or interact with the enzyme
is known as the active site, because that is the site where the
chemistry occurs.
When the substrate binds to its active site at the enzyme, the
enzyme may help in its breakdown, rearrangement, or synthesis .
By placing the substrate into a specific shape and
microenvironment in the active site, the enzyme encourages the
chemical reaction to occur.
What the heck
does this
sentence mean?
Enzymes
Hormones
Some proteins function as chemical-signaling molecules
called hormones. These proteins are secreted by endocrine
cells that act to control or regulate specific physiological
processes, which include growth, development, metabolism,
and reproduction.
For example, insulin is a protein hormone that helps to
regulate blood glucose levels. Other proteins act as receptors
to detect the concentrations of chemicals and send signals to
respond.
Other hormones, such as estrogen and testosterone, are lipid
steroids, not proteins.
Other protein functions
Proteins perform essential functions throughout the systems
of the human body.
• In the respiratory system, hemoglobin (composed of four
protein subunits) transports oxygen for use in cellular
metabolism.
• The proteins actin and tubulin form cellular structures , while
keratin forms the structural support for the dead cells that
become fingernails and hair.
• Antibodies help recognize and destroy foreign pathogens in
the immune system.
• Actin and myosin allow muscles to contract, while albumin
nourishes the early development of an embryo or a seedling.