Macromolecules

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GRE Subject Test: Biology › Macromolecules

Questions 1 - 10
1

Proteins have many functions. Which of the following can be functions of proteins?

I. Enzymes

II. Transcriptional regulators

III. Structural proteins

IV. Hormones

I, II, III, and IV

I, III, and IV

I and II

I, II, and III

I, III, IV

Explanation

Proteins serve all of these functions and many more. Most enzymes are proteins, which help to catalyze spontaneous reactions. Ribozymes can also serve this function but are instead made out of RNA. Proteins can act as transcriptional regulators which can turn on or off gene transcription. Structural proteins, such as actin, can help to maintain the shape of a cell. Other small proteins, such as insulin, can act as hormones which can diffuse throughout the body relaying important messages.

2

Proteins have many functions. Which of the following can be functions of proteins?

I. Enzymes

II. Transcriptional regulators

III. Structural proteins

IV. Hormones

I, II, III, and IV

I, III, and IV

I and II

I, II, and III

I, III, IV

Explanation

Proteins serve all of these functions and many more. Most enzymes are proteins, which help to catalyze spontaneous reactions. Ribozymes can also serve this function but are instead made out of RNA. Proteins can act as transcriptional regulators which can turn on or off gene transcription. Structural proteins, such as actin, can help to maintain the shape of a cell. Other small proteins, such as insulin, can act as hormones which can diffuse throughout the body relaying important messages.

3

Proteins have many functions. Which of the following can be functions of proteins?

I. Enzymes

II. Transcriptional regulators

III. Structural proteins

IV. Hormones

I, II, III, and IV

I, III, and IV

I and II

I, II, and III

I, III, IV

Explanation

Proteins serve all of these functions and many more. Most enzymes are proteins, which help to catalyze spontaneous reactions. Ribozymes can also serve this function but are instead made out of RNA. Proteins can act as transcriptional regulators which can turn on or off gene transcription. Structural proteins, such as actin, can help to maintain the shape of a cell. Other small proteins, such as insulin, can act as hormones which can diffuse throughout the body relaying important messages.

4

Fatty acids can vary in length. Which of the following fatty acids chains cannot not be synthesized in the human body?

A nineteen-carbon fatty acid chain

A twelve-carbon fatty acid chain

An eighteen-carbon fatty acid chain

A twenty-four-carbon fatty acid chain

A fourteen-carbon fatty acid chain

Explanation

Fatty acids synthesized in the human body always have an even number of carbon atoms usually between 12 and 28. Odd-numbered fatty acid chains will occasionally be found in plants and marine animals.

5

Fatty acids can vary in length. Which of the following fatty acids chains cannot not be synthesized in the human body?

A nineteen-carbon fatty acid chain

A twelve-carbon fatty acid chain

An eighteen-carbon fatty acid chain

A twenty-four-carbon fatty acid chain

A fourteen-carbon fatty acid chain

Explanation

Fatty acids synthesized in the human body always have an even number of carbon atoms usually between 12 and 28. Odd-numbered fatty acid chains will occasionally be found in plants and marine animals.

6

Fatty acids can vary in length. Which of the following fatty acids chains cannot not be synthesized in the human body?

A nineteen-carbon fatty acid chain

A twelve-carbon fatty acid chain

An eighteen-carbon fatty acid chain

A twenty-four-carbon fatty acid chain

A fourteen-carbon fatty acid chain

Explanation

Fatty acids synthesized in the human body always have an even number of carbon atoms usually between 12 and 28. Odd-numbered fatty acid chains will occasionally be found in plants and marine animals.

7

Ionic bonds, disulfide bridges, hydrogen bonds and hydrophobic interactions are all examples of protein __________ structure.

tertiary

primary

secondary

quaternary

None of these

Explanation

Ionic bonds, disulfide bridges, hydrogen bonds and hydrophobic interactions are all examples of protein tertiary structure when they occur within a single polypeptide chain. However, if these interactions were to occur between separate polypeptide chains then they would be defining the quaternary structure of the protein. The linear sequence of amino acids within a protein makes up the primary structure. Protein secondary structure is defined by the localized three-dimensional structure of amino acids. These localized structures are normally constructed through hydrogen bonding networks. Alpha helices and Beta pleated sheets are examples of secondary structures.

8

Ionic bonds, disulfide bridges, hydrogen bonds and hydrophobic interactions are all examples of protein __________ structure.

tertiary

primary

secondary

quaternary

None of these

Explanation

Ionic bonds, disulfide bridges, hydrogen bonds and hydrophobic interactions are all examples of protein tertiary structure when they occur within a single polypeptide chain. However, if these interactions were to occur between separate polypeptide chains then they would be defining the quaternary structure of the protein. The linear sequence of amino acids within a protein makes up the primary structure. Protein secondary structure is defined by the localized three-dimensional structure of amino acids. These localized structures are normally constructed through hydrogen bonding networks. Alpha helices and Beta pleated sheets are examples of secondary structures.

9

Ionic bonds, disulfide bridges, hydrogen bonds and hydrophobic interactions are all examples of protein __________ structure.

tertiary

primary

secondary

quaternary

None of these

Explanation

Ionic bonds, disulfide bridges, hydrogen bonds and hydrophobic interactions are all examples of protein tertiary structure when they occur within a single polypeptide chain. However, if these interactions were to occur between separate polypeptide chains then they would be defining the quaternary structure of the protein. The linear sequence of amino acids within a protein makes up the primary structure. Protein secondary structure is defined by the localized three-dimensional structure of amino acids. These localized structures are normally constructed through hydrogen bonding networks. Alpha helices and Beta pleated sheets are examples of secondary structures.

10

Which of the following is not typical of an enzyme?

It increases the amount of products made

It increases the rate of a reaction

It orients the substrates so they can react

It lowers the activation energy of a reaction

Explanation

Enzymes are used to increase the rate of a reaction. This is accomplished by lowering the activation energy required for substrates to react, often by altering the transition state. Enzymes do not, however, increase the amount of products formed; they simply help the equilibrium be reached more quickly. In other words, enzymes change the rate of a reaction, but not the equilibrium.

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