Intro Bio: Chpt 4, 1.

Amino acids with hydrophobic R groups are most often found buried in the interior of folded proteins. True False

True

The individual polypeptide chains in a multi-subunit protein each have their own primary, secondary, and tertiary structure. True False

True

Consider the following two statements about protein structure: 1 - All polypeptides have tertiary structure. 2 - All proteins have quaternary structure. Which of the two statements above is CORRECT? 1. Statements 1 and 2 are both false. 2. Statements 1 and 2 are both true. 3. Statement 1 is true; statement 2 is false. 4. Statement 1 is false; statement 2 is true.

3. all polypeptides have proteins(2+) not all proteins contain quaternary all proteins have tertiary structure

α(alpha) helices are stabilized by hydrogen bonds between amino acids that are _____ residues apart. 4 2 20 10 100

4

Which of the following actions would affect the secondary, but not primary, structure of a protein? 1. disrupt the interactions between two different polypeptide chains 2. break the ionic bonds between amino acids 3. change the sequence of amino acids 4. break the hydrogen bonds between amino acids

4. break the hydrogen bonds between amino acids

Which one of the following can contribute to a protein's tertiary structure? covalent bonding van der Waal's forces hydrogen bonding All of the other answer options are correct. ionic bonding

All of the other answer options are correct https://www.khanacademy.org/science/biology/macromolecules/proteins-and-amino-acids/v/tertiary-structure-of-proteins

The unfolding of a protein by heat or chemical treatment is referred to as: 1. uncoupling. 2. denaturation. 3. hydrolysis. 4. disaggregation. 5. depolymerization.

2. denaturation

Most proteins retain metabolic activity when denatured. False True

False. Heating the protein to a denatured state removes bonds that are necessary in keeping the protein together and functional.

The interactions between amino acids are major factors in determining the shape of a protein. These interactions can be affected by the environment surrounding a protein. Which of the following would have an effect on the shape of a protein? the concentrations of ions present in the environment the pH of the environment All of the other answer options are correct. whether the other molecules in the environment are predominantly hydrophilic or hydrophobic the temperature of the environment

All of the other answer options are correct.

Which of the following statements is TRUE regarding a basic amino acid? The R group of a basic amino acid would only be able to form covalent bonds with other molecules. The hydrophilic R group of a basic amino acid will be located in the interior of a protein. A basic amino acid would be considered both polar and hydrophobic. The positively charged R group of a basic amino acid could bind DNA. All of these choices are correct.

The positively charged R group of a basic amino acid could bind DNA

Proteins that do not refold properly after being heated generally require the assistance of which one of the following types of molecules in cells? transferases chaperones enhancers ribosomes polymerases

chaperones

The bond that forms between amino acids: A peptide bond can form between any chemical groups of adjacent amino acids. connects hydrogen atoms of adjacent amino acids. connects amino groups and R groups of adjacent amino acids. connects water molecules and carboxyl groups of adjacent amino acids. connects amino groups and carboxyl groups of adjacent amino acids.

connects amino groups and carboxyl groups of adjacent amino acids.

Secondary structure is characterized by which one of the following types of interactions? 1. hydrogen bonding between R groups of amino acids 2. hydrogen bonding within the peptide backbone 3. the covalent bond between an amino nitrogen and a carboxyl carbon 4. ionic bonding between an acidic R group and a basic R group 5. a covalent bond between two cysteines

hydrogen bonding within the peptide backbone

Which one of the following amino acids has its R group covalently linked to the amino group? cysteine glutamic acid serine glycine proline

proline

Which one of the following is NOT a component of an amino acid? carboxyl group R group amino group triphosphate group α carbon

triphosphate group

In a ribbon model of a polypeptide, broad arrows indicate: β sheets. disulfide linkages. All of these choices are correct. β sheets and α helices. α helices.

β sheets