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Welcome Back!
February 27, 2012
• Sit in any seat for today.
You will have assigned seats tomorrow
• Were you absent before the break?
Plan on coming to tutorial today or tomorrow
to makeup the test (from Thursday), it must be
completed by Tuesday in tutorial.
Open Logbook…do you have an entry
from Friday before break?
• Entry10: Proteins Beginning Ideas
Make an entryEntry 11. Proteins: Amino Acids in 3 D2/27/12
2 Types of Proteins
1) Structural – proteins that form physical parts.
Examples –
-keratin (hair and nails)
-actin (muscle)
-microtubules (cell membrane skeletons)
- gelatin
- collagen
2) Functional – Proteins that have activity
Examples-Hormones – used for signaling
-Defensive – antibodies that recognize foreign
invaders
-Transport – Carrier proteins!!!
-Enzymes – used for chemical reaction
- Hemoglobin – found on RBC and carry oxygen
Protein Shape Determines Function
Example – Fibrous proteins are long and thin, and are
used for structure
What will we learn today?
HOW is the shape of a protein determined?
Proteins are made of
chains of amino acids
What are amino acids?
Link to amino acid 3-D models
There are 20 different amino acids.
All have the same general form.
H
Amino
group
H2N
C
R
O
Carboxyl
group
C
OH
Side chain
Non-ionized form
Each amino acid has a different side chain.
H
H3N+
C C
H
H
O
–
O
Glycine (G)
Gly
H3N+
H
O
C C
–
CH3 O
Alanine (A)
Ala
C C –
CH O
H3C CH3
H3N+
Valine (V)
Val
H
O
H
O
H
O
O
C C –
CH2 O
CH
H3C CH3
H3N+
N+
Leucine (L)
Leu
Isoleucine (I)
Ile
Proline (P)
Pro
H3N+
C C – H2
C C –
O
O
H3C CH
H2C CH2
CH2
CH2
CH3
Side chains contain carbon and/or hydrogen
Each amino acid has a different side chain.
H
H
O
H3N+
C
H3N+
C
C
CH2
H3N+
C
–
O
H
O
C
O
C
–
CH2
O
–
O
CH2
NH
OH
Phenylalanine (F)
Phe
Tyrosine (Y)
Tyr
Side chains contain ring structures
Tryptophan (W)
Trp
Each amino acid has a different side chain.
H
H3N+
C
H
O
H3N+
C
C
O
C
–
–
CH2
O
CH2
O
CH2
SH
S
CH3
Methionine (M)
Met
Side chains contain sulfur
Cysteine (C)
Cys
Each amino acid has a different side chain.
H
H
O
H3N+
C
O
H3N+
C
C
C
–
–
O
O
CH2
OH
Serine (S)
Ser
CH
HO
CH3
Threonine (T)
Thr
Side chains contain hydroxyl functional groups
Each amino acid has a different side chain.
H
H
H3N+
O
O
C
H3N+
C
C
C
–
–
CH2
O
CH2
C
H2N
CH2
O
C
H2N
Asparagine (N)
Asn
O
Glutamine (Q)
Gln
Side chains contain amino functional groups
O
Each amino acid has a different side chain.
H
H3N+
O
C
H3N+
C
H
H
C
CH2
NH
+NH
H3N+
C
C
–
–
O
O
O
CH2
O
–
CH2
CH2
CH2
CH2
CH2
CH2
NH
+NH
3
C
C
O
+NH
2
NH2
Histidine (H)
His
Lysine (K)
Lys
Basic side chains
Arginine (R)
Arg
Each amino acid has a different side chain.
H
H3N+
H
O
C
H3N+
C
O
C
C
–
–
CH2
O
CH2
C
–
O
CH2
O
C
–
O
Aspartate (D)
Asp
O
Glutamate (E)
Glu
Acidic side chains
O
Proteins are chains of amino acids
H
H2N
H
O
+
C
C
H
OH
Carboxyl
group
H2N
Amino
group
C
O
H2N
C
CH3
OH
H
O
H
H
C
C
N
C
H
Peptide
bond
O
C
+
OH
CH3
C-terminus
N-terminus
H
H2O
H
H
O
H
H
O
H
H
O
H
H
O
H
H
O
H
H
O
H
H
O
H
H
O
N
C
C
N
C
C
N
C
C
N
C
C
N
C
C
N
C
C
N
C
C
N
C
C
CH3
H
CH2
CH2
OH
C
CH2
CH
H3C
OH
CH2
CH3
OH
CH2
SH
O
OH
N-terminus
H2N
C-terminus
Gly
Ala
Ser
Asp
Phe
Val
Tyr
Cys
1
2
3
4
5
6
7
8
COOH
Amino Acids Model activity
Peptides are chains of amino acids and sometimes
used as another word for protein.
Follow the instructions of your teacher to build
peptides using the paper amino acid models for
questions #1-4.
Then join your chain with another groups chain to
form an 8 amino acid chain for #5