Download 4-3 Proteins

Proteins
Proteins contain the following
elements:
C, H, O, N, P, S
Inorganic, or organic?
Organic!!!
It’s alive!
What’s so exciting about proteins?
Proteins do it all:
They’re structural (e.g. hair, fingernails,
bones, etc).
They act as messengers (hormones)
They act as catalysts (enzymes)
Protein blocks:
Proteins are made of building blocks
called amino acids (you built these
last week).
Amino Acids:
Each amino acid contains the following:
1 carboxyl group (COOH)
1 amino group (NH2)
1 hydrogen atom (H)
1 side chain, R, which is
different in each amino acid
Amino acids continued…
The side chain, or R, can be ANYTHING!!!
The simplest amino acid, glycine, has a side
chain that is simply a hydrogen atom.
There are a total of 20 amino acids used
by organisms, each with a different R.
Amino acid structure:
Carboxyl group
side chain
R
H
N
H
C
H
O
C
OH
Amino group
Making proteins…
How can we combine amino acids
together to form a more complicated
molecule (protein)?
Our old friend dehydration synthesis!!!
Dehydration Synthesis again?!?!?
H
R
N C C
H
H
Amino Acid
H
O
+
OH
O
N C C
H
+
R
H
Amino Acid
OH
Oh no…not again…
H
H
R O
H R
N C C
N C C
H
H
O
+ H2O
OH
peptide bond
Dipeptide
+ water
Di- = 2, many = ?
We’ve seen a dipeptide, which is the
combination of 2 amino acids.
What would we call a chain of amino
acids?
A polypeptide!!!
All proteins are made up of 1 or more
polypeptide.
But I thought polypeptides were
proteins…
The smallest protein is insulin, a molecule
composed of 51 amino acids linked
together.
Some proteins have over 100,000 amino
acids though…
Proteins in depth:
What makes the protein special is
how the amino acids are arranged…
• number of amino acids
• order of amino acids
If the protein gets overheated, the
structure can break down called
DENATURATION
Protein Structure