IB Chemistry option B proteins and enzymes

Proteins are

• polymers of 2-amino acids joined by ester bonds

• polymers of 2-amino acids joined by ionic bonds

• polymers of 2-amino acids joined by amide bonds

• polymers of 2-amino acids joined by hydrogen bonds

Amino acids are

• acids

• neutral

• bases

• amphoteric

The -COOH group of an amino acid can

• lose a proton and become negatively charged

• lose a proton and become positively charged

• gain a proton and become negatively charged

• gain a proton and become positively charged

In an acidic environment amino acids

• act as a base and become a cation

• act as a base and become a anion

• act as an acid and become a cation

• act as an acid and become a anion

When an amino acid is in the zwitterion form,

• -COO is negative and -NH₃ is positive

• -COO is positive and -NH₃ is negative

• there is an overall positive charge

• there is an overall negative charge

The primary structure of proteins is

• a polypeptide folded into beta-pleats and alpha-helixes

• a polypeptide folded into a 3D shape

• a linear sequence of amino acids joined as a polypeptide chain

• when multiple polypeptide sub-units associate together to form a complex 3D shape

The region on an enzyme where a specific substrate is able to fit is the

• passive site

• collateral site

• active site

• allosteric site

The graph most likely represents

• the effect of pH on enzyme activity

• the effect of temperature on enzyme activity

• the effect of substrate concentration on enzyme activity

• the effect of light intensity on enzyme activity

High temperature changes the activity of an enzyme because

• it permanently changes the shape of the active site

• it competitively inhibits the enzyme

• it changes the primary structure of the enzyme

• it temporarily changes the shape of the active site

When two amino acids join together

• the -OH reacts with an -NH₂ group to form an amide bond

• the -OH reacts with a -COOH group to form an amide bond

• the -C=O reacts with an -NH₂ group to form an amide bond

• an ester bond results from carbon bonding to nitrogen