Biology Chapter 3.2 Proteins and their Function

Enzymes

Catalyze (speed up) biochemical reactions

Structural proteins

Provide physical stability and movement

Defensive proteins

Recognize and respond to nonself substances (like antibodies)

Signaling proteins

Control physiological processes (like hormones)

Receptor proteins

Receive and respond to chemical signals

Membrane transporters

Regulate passage of substances across cellular membranes

Storage proteins

Store amino acids for later use

Transport proteins

Bind and carry substances within the organism

Gene regulatory proteins

Determine the rate of expression of a gene

Motor proteins

Cause movement of structures in the cel

Enzymes

Catalyze (speed up) biochemical reactions

Structural proteins

Provide physical stability and movement

Defensive proteins

Recognize and respond to nonself substances (like antibodies)

Signaling proteins

Control physiological processes (like hormones)

Receptor proteins

Receive and respond to chemical signals

Membrane transporters

Regulate passage of substances across cellular membranes

Storage proteins

Store amino acids for later use

Transport proteins

Bind and carry substances within the organism

Gene regulatory proteins

Determine the rate of expression of a gene

Motor proteins

Cause movement of structures in the cell

Amino acid component responsible for tertiary structure interactions

The R-groups (side chains)

Formation and function of covalent disulfide bridges

Formed between two cysteine side chains; acts like an industrial staple to hold a folded polypeptide firmly in place

The only covalent bond that stabilizes tertiary structure

Disulfide bridges

Location and role of hydrogen bonds in tertiary structure

Form between polar side chains (such as those with $\text{-OH}$ groups) to fine-tune and stabilize folds

Behavior of nonpolar side chains in hydrophobic interactions

Aggregate together in the interior core of the protein to hide away from water

Function of Van der Waals forces in tertiary structure

Act like microscopic Velcro to stabilize close-packed interactions between huddled hydrophobic side chains

Components that form ionic bonds (salt bridges)

A positively charged side chain and a negatively charged side chain snapping together like magnets

Example of an acidic/basic amino acid pair that forms a salt bridge

Glutamic acid (negative R group) and Arginine (positive R group)

Permissible locations for salt bridges in a protein structure

Can exist on the watery surface or buried deep within the dry interior of a protein

Enzymes

Catalyze (speed up) biochemical reactions

Structural proteins

Provide physical stability and movement

Defensive proteins

Recognize and respond to nonself substances (like antibodies)

Signaling proteins

Control physiological processes (like hormones)

Receptor proteins

Receive and respond to chemical signals

Membrane transporters

Regulate passage of substances across cellular membranes

Storage proteins

Store amino acids for later use

Transport proteins

Bind and carry substances within the organism

Gene regulatory proteins

Determine the rate of expression of a gene

Motor proteins

Cause movement of structures in the cell

Amino acid component responsible for tertiary structure interactions

The R-groups (side chains)

Formation and function of covalent disulfide bridges

Formed between two cysteine side chains; acts like an industrial staple to hold a folded polypeptide firmly in place

The only covalent bond that stabilizes tertiary structure

Disulfide bridges

Location and role of hydrogen bonds in tertiary structure

Form between polar side chains (such as those with $\text{-OH}$ groups) to fine-tune and stabilize folds

Behavior of nonpolar side chains in hydrophobic interactions

Aggregate together in the interior core of the protein to hide away from water

Function of Van der Waals forces in tertiary structure

Act like microscopic Velcro to stabilize close-packed interactions between huddled hydrophobic side chains

Components that form ionic bonds (salt bridges)

A positively charged side chain and a negatively charged side chain snapping together like magnets

Example of an acidic/basic amino acid pair that forms a salt bridge

Glutamic acid (negative R group) and Arginine (positive R group)

Permissible locations for salt bridges in a protein structure

Can exist on the watery surface or buried deep within the dry interior of a protein

Bonds broken when protein temperature increases

Hydrogen bonds and hydrophobic interactions due to rapid molecular movements

Effect of rising pH on lysine and arginine

$\text{H}^+$ ions are removed from their $\text{H}_3\text{N}^+$ groups, making them less charged and less polar

Effect of rising pH on aspartic and glutamic acids

Their $\text{COOH}$ groups ionize, making them negatively charged and more polar

Impact of polarity shifts on protein tertiary structure

More polar groups move to the outside to interact with water, while less polar groups move to the inside

Effect of high concentrations of polar substances (e.g., urea) on proteins

Disrupts the hydrogen bonding crucial to protein structure

Chemical used in classic reversible protein denaturation experiments

Urea

Substances capable of disrupting hydrophobic interactions in proteins

Nonpolar substances