L4: Protein Synthesis I Flashcards
3 functions of proteins in living systems
1) Structural
2) Movement
3) Transport
Examples of structural function
1) Collagen
2) Keratin
Examples of movement functions in living systems
1) Actin
2) Myosin
Examples of membrane transport function in living systems
Na+/K+ Pump
What does a polypeptide begin with?
Amino acid
What is the N-terminus?
Start of a protein, started by the free amine group (NH2)
What is the C-terminus?
End of the amino acid chain, terminated by a free carboxyl group (-COOH)
What are series of repeating atoms of polypeptide chain called?
Backbone
What are functional groups bounded to alpha-carbon called?
R-groups
How are structure of amino acids formed?
Determined by interactions between backbone atoms, amino acid R groups
How does the structure of a protein related to its performance?
Directly related
Define enatiomers
Pair of molecules that exist in 2 forms that are mirror images of 1 another, cannot be laid over each other
How do each amino acid differ?
Properties of side chain (R-group)
What 3 features can side chains be?
1) Polar charged
2) Polar uncharged
3) Non-polar
When is a molecule polar?
Unequal distribution of charge
What does unequal distribution create?
Full/partial negative & positive charge
What does partial positive charge on H of water molecule attract?
Negative Charge
What does negative charge on O of water molecule attract?
Positive Charge
Are charged side chains hydrophilic or hydrophobic?
Hydrophilic
What can the side chains form with water with partial charges?
Hydrogen Bonds
Are polar uncharged side chains hydrophilic or hydrophobic?
Hydrophilic
What can’t non-polar side chains bind to?
Water
Are non-polar side chains hydrophobic/hydrophilic?
Hydrophobic
How are amino acids grouped?
Characteristics of their side chains
What do side chain characteristics determine?
How proteins fold
4 categories of R-groups
1) Charged
2) Uncharged
3) Positively Charged
4) Negatively charged
What do disulfide bridges form between?
2 Cysteine residues
What bonds are amino acids linked by?
Peptide Bonds
Are side chains (R groups) involved in peptide bonding?
No
Which terminuses are proteins synthesised from?
N-terminus to C-terminus
