What role do condensation and hydrolysis reactions play in biological processes?

Condensation reaction -> produce H2O molecule

1. make a long chain of amino acids
2. gives primary structure
3. gives function to protein
4. essentially makes large macromolecules used in biological processes

Structure of amino acids and R groups

1. Carboxyl and amino group
2. Structure is correlated to function
3. Biggest factor is size and shape

Hydrolysis -> gain H2O molecule, breaks up polymers

1. water comes in and protein gets cut into pieces

Monomers form polymers which form proteins which help cells

What determines the properties of a particular amino acid?

• Non-polar = Carbon and Hydrogen on R group
• Polar = Oxygen molecule on R group
• Acidic = Side chain has negative charge
• Basic = Side chain has positive charge

Draw the chemical structure of the polypeptide Ile-Gln-Tyr-Lys. Label the side chains and peptide bonds. Explain the terms N- and C-termini, and indicate each on your drawing.

Distinguish what makes a side chain polar, non-polar, charged or non-charged.

1. Does the side chain have a negative charge? If so, it has lost a proton, so it must be acidic.
2. Does the side chain have a positive charge? If so, it has taken on a proton, so it must be basic.
3. If the side chain is uncharged, does it have an oxygen atom? If so, the highly electronegative oxygen will result in a polar covalent bond and thus is uncharged polar.

N-terminus: The beginning of a polypeptide has the amino group which is NH3

C-terminus: The ending of a polypeptide chain, has the carboxyl group which is OH.

Peptide bond: The C-N covalent bond that results from a condensation reaction, is planar and limits movement of the atoms participating in the peptide bond, amino acids linked by a peptide bond are referred to as residues to distinguish them from free monomers

Explain how secondary, tertiary, and quaternary levels of structure depend on primary structure. Give an example of a how a change in amino acid sequence can alter protein structure and function.

• Primary structure: the unique sequence of amino acids in a protein
• Secondary structure: created by hydrogen bonding between the oxygen on the C=O group of one amino acid residue and the hydrogen on the N-H groups of another, although these hydrogen bonds are relatively weak, their large number makes them highly stable
• Alpha helix: the polypeptide backbone is coiled, hydrogen bonds form between residues that are just four linear positions apart in the polypeptide’s primary sequence
• Beta-pleated sheet: segments of a peptide chain bend 180 degrees and then fold in the same plane
• Tertiary: overall shape of a polypeptide, results from the interaction between R-groups or between R-groups and the backbone, each contact between the R-groups causes the peptide-bonded backbone to bend and fold which results in the distinctive three dimensional shape of a polypeptide, these side chains can be involved in a wide variety of bonds
• Macromolecular machines: groups of macromolecules that assemble to carry out a particular function
• Hydrogen bonding: in the peptide backbone or the R-groups
• Hydrophobic interactions: water molecules interact with the hydrophilic polar side chains and force the hydrophobic nonpolar side chains into globular masses
• van der Waals interactions: further stabilizes their association once hydrophobic side chains are close together
• Covalent bonding: occurs between two cysteines through a reaction between the sulfhydryl groups
• Ionic bonding: between groups that have full and opposing charges such as ionized acidic and basic side chains
• Quaternary: when polypeptides (subunits) come together to form new proteins, held together by the same type of bonds that tertiary structures contain
• In some individuals, hemoglobin has a valine instead of glutamate and this produces hemoglobin molecules that stick to one another and form fibers when oxygen concentrations in the blood are low