AP Biology : Macromolecules

Study concepts, example questions & explanations for AP Biology

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Example Questions

Example Question #2511 : Ap Biology

Which of the following is true regarding enzymes?

Possible Answers:

All enzymes are made up of lipids

Enzymes cause chemical reactions to slow down using cofactors

Enzymes increase the activation energy of a reaction by lowering the energy of the transition state

Enzymes are not involved in DNA synthesis

Enzymes decrease the activation energy of a reaction by lowering the energy of the transition state

Correct answer:

Enzymes decrease the activation energy of a reaction by lowering the energy of the transition state

Explanation:

An enzyme lowers the energy of the transition state, which makes the chemical reaction proceed faster. Enzymes speed up many chemical reactions in processes like DNA synthesis and glycolysis. They are also proteins, so they're composed of amino acids.

Example Question #2517 : Ap Biology

Polymers of amino acids are __________.

Possible Answers:

proteins

polypeptides

cellulose

polysaccharides

Correct answer:

polypeptides

Explanation:

Polypeptides are are polymers of amino acids. Proteins consist of one or more polypeptide chains folded in a certain shape. Polysaccharides are polymers of monosaccharides and do not contain amino acids. Cellulose is a polysaccharide that is a major component of plant cell walls.

Example Question #2517 : Ap Biology

Which of the following levels of protein structure is defined as the sequence of amino acids?

Possible Answers:

Quaternary structure

Primary structure

Tertiary structure

Secondary structure

Correct answer:

Primary structure

Explanation:

The amino acid sequence is the primary structure of a protein, which is held together by peptide bonds. The secondary structure involves hydrogen bonding between the backbones of amino acids. Tertiary structure describes the unique folding pattern of a polypeptide as a result of intermolecular forces such as hydrogen bonds, hydrophobic interactions and covalent bonds such as disulfide bridges. Tertiary structure is the result of the amino acid side chains interacting with each other. Quaternary structure is the interaction of two or more polypeptide chains with each other.

Example Question #101 : Macromolecules

Which of the following are made of protein? 

Possible Answers:

Starch

Cholesterol 

Triacylglycerols

Enzymes

Steroids

Correct answer:

Enzymes

Explanation:

Steroids fall into the lipid category, characterized by a carbon skeleton composed of four fused rings  Cholesterol is a type of steroid; it is synthesized in the liver, and is necessary for the production of sex hormones. Triacylglycerol is also a type of lipid, composed of three fatty acid molecules and a glycerol (also known as a triglyceride). Starch is a polymer of glucose monomers. Its primary function is to store energy. A protein is a molecule that is composed of polypeptides, folded into a 3D structure. Each protein is composed of a combination of amino acids. Proteins make up over 50% of dry mass of a cell and have many different functions like speeding up chemical reactions, defense, storage, transport, cellular communication, movement, and structural support. Enzymes are types of proteins that speed up chemical reactions, and are never consumed during reactions.

Example Question #104 : Macromolecules

Proteins consist of a primary, secondary, tertiary, and sometimes a quaternary structure. The primary structure describes the protein’s amino acid sequences bonded together via peptide bonds. The secondary structure describes the protein’s folding pattern dictated by the hydrogen bonds. In the secondary structure, the two common formations are in the alpha or beta comfirmation. The tertiary structure describes the three dimensional structure of the protein that is formed by the following interactions: hydrogen bonding, hydrophobic interactions, van der Waal’s interactions, and electrostatic interactions between the R groups of the amino acids. These various interactions allow the protein to fold into a globular formation. Finally, the quaternary structure describes how multiple globular proteins can interact with each other to form a multi-subunit protein.

Drug X is able to disrupt the amino acids sequence. Which of the following protein structures will be altered by Drug X?

Possible Answers:

Only the primary structure will be disrupted

All four levels of protein structure will be disrupted

Only the quaternary structure will be disrupted

Only the secondary structure will be disrupted

Only the tertiary structure will be disrupted

Correct answer:

All four levels of protein structure will be disrupted

Explanation:

All of the protein structures will be altered and disrupted. Drug X disrupts the amino acid sequences in the primary structure of the protein. The primary structure acts as the protein’s blueprint. It can be concluded that if the primary sequence is altered, all of the subsequent structures will be disrupted as well. The sequence of amino acids encode for the protein’s particular shape and function; disrupting the code will change the shape and function of the primary, secondary, tertiary, and quaternary structures of the protein.

Example Question #71 : Identify Structure And Purpose Of Carbohydrates, Lipids, Proteins, And Nucleic Acids

Which of these does not give rise to the versatility of protein functions found in nature?

Possible Answers:

Primary structure

Secondary structure

None of these

Quaternary structure

Properties of side chains of each amino acid

Correct answer:

None of these

Explanation:

All of these affect protein function and give rise to the many functions of proteins. The order in which the individual residues (amino acids) are bonded contributes to the overall shape of a protein due to interactions between each amino acid side chain. This order matters so that the proper side chains can interact. The secondary structure of a protein consists of alpha helices and beta pleated sheets. Both of which play widely different roles structurally in cells. The quaternary structure categorizes interactions between different subunits of protein. Several subunits come together to perform a function they otherwise could not.

The different properties of the amino acid side chains are perhaps the most important aspect of protein function. Some are hydrophobic which are found in the centers of proteins (when the protein is globular). Others are hydrophilic and are found on the exterior of proteins. Yet are others are protonated or unprotonated in certain pH ranges. All of these give rise to incredibly diverse protein functions. As an example, there are pores in cell membranes called aquaporins that resemble hollow barrels or cylinders. These barrels are beta pleated sheets and the interior (the hole the membrane) is coated with hydrophilic amino acids while the exterior (which is hidden in the lipid bilayer of the cell membrane) consists of hydrophobic amino acids.

Example Question #102 : Macromolecules

Polymers of amino acids are called __________.

Possible Answers:

nucleic acids

polypeptides

carbohydrates

ribosomes

Correct answer:

polypeptides

Explanation:

Polymers of amino acids are called polypeptides. A protein is made up of one or more polypeptide chains that has folded and coiled in specific 3D configurations. Nucleic acids are polymers of nucleotides. Examples of nucleic acids are RNA and DNA. Ribosomes are the site of protein synthesis and are made of rRNA and protein.

Example Question #2523 : Ap Biology

How many naturally occurring amino acids are there?

Possible Answers:

It depends on the length of the polypeptide

Correct answer:

Explanation:

All proteins are made up of amino acids. Even though proteins are highly diverse they all can be built from the same set of 20 amino acids. Thus, the order in which these amino acids are linked together (primary structure, which is directly determined by the DNA sequence) determines its structure and function.

Example Question #2524 : Ap Biology

Amino acids possess both __________ and __________.

Possible Answers:

glycerol . . . carbonyl groups

carboxyl . . . amino groups

glycerol . . . amino groups

hydroxyl . . . amino groups

Correct answer:

carboxyl . . . amino groups

Explanation:

Amino acids are made up of carboxyl and amino groups. Hence their name, amino acids describes the functional groups found in all proteins, regardless of their R-groups. Carboxyl groups are also known as carboxylic acid groups. Glycerol is found in lipids, specifically fats where it is linked to fatty acid chains. Hydroxyl groups are also known as alcohol groups and are not present in all amino acids, although, some R-groups contain hydroxyl functional groups. 

Example Question #103 : Macromolecules

The covalent bond that links two amino acids together is called __________.

Possible Answers:

a peptide bond

an amino linkage

a phosphodiester bond

an ester bond

Correct answer:

a peptide bond

Explanation:

The covalent bond between two amino acids is called a peptide bond. This is formed by positioning two amino acids so the carboxyl group of one is adjacent to the amino group of another. An enzyme then joins the two via a dehydration synthesis reaction. Ester bonds link fatty acids to glycerol heads, and phosphodiester bonds are formed between the sugar and phosphate backbone of a nucleic acid.

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