Proteins

Which type of protein shields a newly forming protein from cytoplasmic influences while it is folding into its functional form?

Chaperonins

When a protein is denatured, why does it lose its functionality?

Denaturation breaks the intramolecular bonds, such as hydrogen bonds and van der Waals interactions, that hold the protein in its three-dimensional shape. Without the proper shape, the protein cannot function.

True or false? At the normal temperature, pressure, and pH in human cells, the amino group of an amino acid donates an H+ ion to solution, and thus carries a negative charge. Likewise, the carboxyl group of an amino acid accepts a proton from solution, and thus carries a positive charge

False

True or false? We can read the sequence of amino acids in a polypeptide like the words in a sentence. When we read the sequence of amino acids in a polypeptide, we read from the C terminus to the N terminus

False- you read it from N terminus to C terminus

Which kind (or kinds) of chemical interactions produces the quaternary structure of a protein?

Quaternary structure is based on the same kinds of chemical interactions among side chains that tertiary structure is. The only difference is that the interacting side chains are on different polypeptides instead of within the same polypeptide. *Hydrophobic interactions among the side chains (R-groups) of amino acids *Ionic bonds among the side chains (R-groups) of amino acids *Hydrogen bonds among the side chains (R-groups) of amino acids *Covalent bonds among the side chains (R-groups) of amino acids

Which statement, or statements, best describes the reason that a polypeptide loses its functionality when it is denatured?

The chemical interactions among the side chains of different amino acids that help create tertiary structure are altered

Which statement accurately describes the primary structure of a polypeptide?

The primary structure of a polypeptide is the number and sequence of amino acids read from the N-terminus to the C-terminus

Which statement accurately describes the primary structure of a polypeptide?

The primary structure of a polypeptide is the specific sequence of amino acids. It is genetically determined, and is not influenced by changes in temperature or pH

Which statement accurately describes the secondary structure of a polypeptide?

The secondary structure of a polypeptide is the result of hydrogen bonding among repeating constituents of the polypeptide backbone. It is influenced by changes in temperature and pH

Which statement accurately describes the tertiary structure of a polypeptide?

The tertiary structure of a polypeptide is the result of chemical interactions between the R-groups (side chains) of certain amino acids. It is influenced by changes in temperature and pH

How do amino acids differ from one another?

They have different side chains (r groups)

True or False? For a given set of chemical conditions (e.g., for a given temperature and pH), the primary structure of a polypeptide determines secondary and tertiary structure.

True

True or False? There are three basic types of amino acids: 1) those with electrically charged side chains; 2) those with polar side chains; and 3) those with nonpolar side chains. Correct!

True

True or false? A single protein can made from a single polypeptide. However, a single protein can also be made from two or more polypeptides.

True

True or false? Every polypeptide has a complete amino group at one end, which is called the N terminus, and a complete carboxyl group at one end , which is called the C terminus

True

True or false? Every polypeptide has a complete amino group at one end, which is called the N terminus, and a complete carboxyl group at one end, which is called the C terminus.

True

The peptide bond is __________.

a covalent bond joining amino acids together to form a polypeptide

Sickle-cell anemia is a disease that is caused by __________ in the __________ of the protein.

a single amino acid change; primary structure

Protein molecules are polymers (chains) of __________.

amino acid molecules

At a conference, the speaker's grand finale was sautéing mealworms (insect larvae) in butter and serving them to the audience. They were crunchy (like popcorn hulls) because their exoskeletons contain the polysaccharide __________.

chitin

The type of bond that forms to join monomers (such as sugars and amino acids) into polymers (such as starch and proteins) is a(n) __________ bond.

covalent

In living organisms, DNA exists as a __________ with the strand(s) __________.

double helix; running antiparallel

The secondary structure of a peptide backbone is stabilized by __________ forming either a(n) __________ or a(n) _________

hydrogen bonds; α helix; β pleated sheet

The proper three-dimensional shape and folding of a protein is assisted by _________.

molecules called chaperonins

The tertiary structure of a protein includes all of the following interactions except _________ bonds.

peptide

Suppose that we link 100 amino acids together. The resulting molecule can be referred to as...

polymer and a polypeptide

The structural level of a protein least affected by a disruption in hydrogen bonding is the

primary level

Which statement (or statements) accurately describes a peptide bond?

*A peptide bond is formed via (by way of) a dehydration (condensation) reaction that produces a molecule of water * In a peptide bond, a carbon atom that is double bonded to an oxygen atom is linked to nitrogen atom that is single bonded to a hydrogen atom

Which statement (or statements) accurately describes the structure of an amino acid?

*An amino acid has a central carbon atom that is linked to a hydrogen atom by a single covalent bond *An amino acid has a central carbon atom that is linked to an amino group by a single covalent bond *An amino acid has a central carbon atom that is linked to a carboxyl group by a single covalent bond

Which statement (or statements) accurately describes the R - group of an amino acid?

*The R-group (also termed the side chain) can be nonpolar *The R-group (also termed the side chain) can be polar *The R-group (also termed the side chain) can be acidic or basic and thus carry a positive or negative charge

All amino acids share a common "backbone". Which chemical component (or components) is part of the backbone of an amino acid?

-An amino group (NH2) -A carboxyl group (COOH) -A hydrogen atom -A central carbon atom that is commonly called an α-carbon atom

Which kind (or kinds) of chemical interactions produces the tertiary structure of a polypeptide?

-Hydrogen bonds among the side chains (R-groups) of amino acids -Hydrophobic interactions among the side chains (R-groups) of amino acids -Ionic bonds among the side chains (R-groups) of amino acids -Covalent bonds among the side chains (R-groups) of amino acids Correct!

Enzyme molecules require a specific shape to perform their catalytic function. Which of the following might alter the shape of an enzymatic protein?

-a change in salt concentrations or pH -treating the protein with a chemical that breaks hydrogen bonds -heating the protein -denaturing the protein

specific description of a polypeptide

A polypeptide is a chain of amino acids that have been linked together by dehydration reactions.

The structural level of a protein least affected by a disruption in hydrogen bonding is the

primary level.

he α helix and β pleated sheet represent which level of protein structure?

secondary structure

The "primary structure" of a protein refers to __________.

the sequence of amino acids along a polypeptide chain

True or false? All polypeptides are constructed from the same set of 20 Amino Acids.

true

lists rank these molecules in the correct order by size from smallest to largest?

water, glucose, sucrose, protein