High School Biology : Understanding Protein Classifications

Study concepts, example questions & explanations for High School Biology

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Example Questions

Example Question #1 : Understanding Protein Classifications

Collagen is an example of which type of protein?

Possible Answers:

Structural protein

Enzyme

Integral protein

Globular protein

Correct answer:

Structural protein

Explanation:

Collagen is the most abundant protein in the human body. It adds great strength and flexibility to skin, tendons, and ligaments. These qualities are characteristic of structural proteins.

Globular proteins are generally rounded, protecting a nonpolar center from the aqueous environment around the protein. Most cytoplasmic proteins and enzymes are globular proteins. In contrast, fibrous proteins are generally elongated and designed for structural support; collagen is a fibrous protein, in addition to a structural protein. Integral proteins span the plasma membrane, often creating channels.

Example Question #2 : Understanding Protein Classifications

Which of the following types of protein can move around within the lipid bilayer?

Possible Answers:

Integral membrane proteins

Intermembrane proteins

Mitochondrial proteins

Peripheral membrane proteins

None of these can move around in the lipid bilayer

Correct answer:

Peripheral membrane proteins

Explanation:

Proteins are classified into several categories based on where they perform their function. Peripheral membrane proteins span only one side of the lipid bilayer and thus have mobility. Unlike integral membrane proteins, which span the entire lipid bilayer, peripheral membrane proteins have the liberty of traveling from layer to layer as well as flip flop between the two bilayers.

Example Question #3 : Understanding Protein Classifications

Which type of enzyme is responsible for rearranging a substrate, but not altering its chemical formula?

Possible Answers:

Isomerase

Hydrolase

Ligase

Oxidoreductase

Correct answer:

Isomerase

Explanation:

Isomers are molecules that have the same molecular formula, but have different chemical structures. Isomerases are enzymes that are able to rearrange the structure of a molecule while keeping its chemical formula the same.

Example Question #4 : Understanding Protein Classifications

Complete and incomplete are classifications of __________.

Possible Answers:

proteins

neurotransmitters

minerals

enzymes

electrolytes

Correct answer:

proteins

Explanation:

A protein consists of amino acids. Essential amino acids cannot be synthesized by the body, and must be included in the diet. A protein containing all of the essential amino acids is called a complete protein. An incomplete protein lacks one or more of the essential amino acids.

Neurotransmitters are chemicals that relay messages from one cell to the next. Enzymes are protein catalysts that speed up biological reactions. Minerals are inorganic compounds and are not present in the body in large amounts, with the exception of hydroxyapatite crystal found in bones. Electrolytes are ionic salts in the blood, tissue fluids, and cells, such as sodium, potassium, and chlorine. 

Example Question #1 : Understanding Protein Classifications

Bob, a biologist who was researching a new eukaryotic unicellular species, wanted to study a particular protein Y. After obtaining and purifying the sample, Bob discovered that this protein had 3 subunits: A, B, and C. Through substantive scientific analysis, Bob discovered that protein Y operated in a membrane; however, he could not deduce which particular membrane. Nonetheless, Bob found that only subunit B was traversed through the interior of the membrane. With Bob’s findings, please answer the following questions.

What is NOT a possible function of protein Y?

Possible Answers:

Used in nuclear trafficking

Used as a receptor in a signal transduction pathway

Used as an antiporter

Used in the electron transport chain

Used in DNA replication

Correct answer:

Used in DNA replication

Explanation:

Receptor proteins in a signal transduction pathways can be found both within the plasma membrane or cytosol; as a result, protein Y could potentially function as a receptor. The electron transport chain occurs in the mitochondria, and relies on the movement of electrons; the proteins that “move” these electrons, and subsequently pump protons (creating a gradient), are located in the inner membrane. An antiporter functions in a membrane as well due to its importance in creating and maintaining a concentration gradient. In a similar fashion, nuclear trafficking refers to the regulation or movement of molecules in and out of the nuclear membrane. Last, DNA replication occurs in the nucleus and does not involve a membrane of any sort; therefore, the membrane dwelling protein Y cannot function in this process.

 

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