Question 1

How do amino acids like hydroxylysine and thyroxine, which are not among the 20 amino acids inserted into amino acid chains, get into proteins?

Accepted Answer

Hydroxylysine and thyroxine are not one of the 20 standard amino acids, but they can be formed from the modification of the side chains of some of the standard amino acids after their incorporation into the polypeptide chain. For example, hydroxylysine is formed from the post-translational modification of lysine, and thyroxine is derived from the amino acid tyrosine.

Question 2

An informative test for the diagnosis of diabetes is to monitor levels of Hemoglobin A1c, produced through the reaction of hemoglobin and __________________.

Accepted Answer

Hemoglobin A1c is produced through the reaction of hemoglobin and the linear aldose form of glucose. This test measures the average blood glucose level over the past 2 to 3 months and is used to diagnose and monitor diabetes.

Question 3

Which group of plants have nitrogen fixing symbionts?

Accepted Answer

Legumes are known to have symbiotic relationships with nitrogen fixing bacteria called rhizobia, which convert atmospheric nitrogen into a form that plants can use. Therefore, legumes are able to thrive in nutrient-poor soils and are often used in agriculture as a natural fertilizer.

Question 4

Which of the following is a nucleotide?

Accepted Answer

A nucleotide is made up of a nitrogenous base (in this case adenine), a five-carbon sugar (in this case ribose), and a phosphate group. Choice D contains all three components, making it the only option that fits the definition of a nucleotide.

Question 5

Why do sugars tend to be highly water soluble?

Accepted Answer

Sugars have large numbers of hydroxyl groups (-OH) which can participate in hydrogen bonding with water molecules, making them highly water soluble.

Question 6

Which organism would be a good candidate for researching genes related to nitrogen fixation?

Accepted Answer

The answer of Which organism would be a good candidate...

Question 7

Carbon's suitability as the molecular framework for biochemicals stems from its:

Accepted Answer

Carbon's ability to form elongated polymers is due to its tetravalency, allowing it to form stable covalent bonds with other carbon atoms and various elements, creating complex and diverse molecular structures essential for life.

Question 8

What level of structure in proteins is held together by R group interactions between different polypeptides?

Accepted Answer

Quaternary structure refers to the arrangement of multiple polypeptide chains to form a functional protein. R group interactions between different polypeptides are crucial for maintaining the 3D shape of the overall protein complex. Primary structure refers to the linear sequence of amino acids, secondary structure refers to local folding patterns like alpha helices and beta sheets, and tertiary structure refers to the overall 3D shape of an individual polypeptide chain.

Question 9

Proteins are often composed of two or more distinct modules that fold up independently of one another. They often represent parts of a protein that function in a semi-independent manner. These modules are called ______.

Accepted Answer

The correct term for distinct, independently folding parts of a protein is "domains". A protein motif refers to a short sequence of amino acids that has a particular function or structure, but it is not necessarily a distinct folding unit. "Functionals" and "dominoes" are not commonly used terms in protein structure and function.

Question 10

What type of protein secondary structure is characterized as being highly extensible because of its coiled structure?

Accepted Answer

The α-helix is characterized by its coiled structure, which can be highly extensible.

Question 11

Which element can only be obtained by plants through mineral uptake, rather than via atmospheric fixation by the plant or its symbiont?

Accepted Answer

Unlike carbon, nitrogen, and oxygen, which can be obtained by plants through atmospheric fixation or symbiotic relationships with nitrogen-fixing bacteria, phosphorus can only be obtained by plant roots through mineral uptake from the soil.

Question 12

Which polysaccharide bond cannot be broken by mammalian enzymes that normally digest polysaccharides?

Accepted Answer

Beta (β) 1->4 glycosidic linkages, as found in cellulose, cannot be broken down by mammalian digestive enzymes. This is why cellulose acts as dietary fiber in human diets.

Question 13

Select the order in which you might expect molecules involved in the synthesis of a polymer to be present as a cell grows.

Accepted Answer

The precursor molecules would be present first as they are the starting materials for synthesis. Then, metabolic intermediates would be formed as the precursor molecules are modified to form the final macromolecule. Finally, the macromolecules themselves would be present once synthesis is complete. Miscellaneous molecules may also be present throughout the process, but their order cannot be determined based on the information given.

Question 14

What bond is responsible for the branch points in glycogen and amylopectin?

Accepted Answer

The branch points in glycogen and amylopectin are due to the presence of alpha-1,6-glycosidic linkages, which connect branches of the polymer to the main chain of glucose molecules that are linked via alpha-1,4-glycosidic bonds. Therefore, the best choice is C, F1F1F1S1αF1F1F10(1->6)glycosidic linkages.

Question 15

The $\beta$-pleated sheet is characterized by the orientation of ______ to the molecular axis.

Accepted Answer

The F1F1F1S1F1F1F10-pleated sheet is characterized by the H bonds being perpendicular to the molecular axis. The alternating pattern of H bonds results in the beta-sheet structure.

Question 16

The endosymbiotic theory proposes that bacteria were engulfed by ancestral eukaryotic cells and sheltered within their cytoplasm whilst providing a survival advantage to the eukaryotic cell as well. Mitochondria and chloroplasts, now organelles, possess DNA with sequence homology to rickettsia and cyanobacteria, respectively. Which of the choices below best describes an organelle-like structure with a similar beneficial relationship when considering plant growth in nitrogen-limited soils?

Accepted Answer

Bacteroids are a form of rhizobia bacteria that have been engulfed by legume root cells, forming a symbiotic relationship where the bacteroids fix atmospheric nitrogen into a form that the plant can use, aiding in its growth in nitrogen-limited soils.

Question 17

If a polypeptide is 100 amino acids long, and could be made of any of the 20 amino acids in any order, what is the total number of possible variations for this polypetide?

Accepted Answer

The total number of possible variations for a polypeptide 100 amino acids long, with 20 different amino acids available for each position, is calculated as $20^{100}$. This is because for each position in the polypeptide chain, there are 20 choices, and this choice is independent for each of the 100 positions.

Question 18

Which of these amino acids is most likely to be found in the core of a protein?

Accepted Answer

Methionine is a hydrophobic amino acid due to its large, nonpolar side chain. Therefore, it is most likely to be found in the core of a protein, away from the aqueous environment.

Question 19

Which of these statements regarding glyceraldehyde is NOT correct?

Accepted Answer

The answer of Which of these statements regarding glyceraldehyde is...

Question 20

Which of these functional groups is the LEAST polar? Refer to Table 2.2 for more information if you are uncertain of the molecular structure of each one.

Accepted Answer

CH₃ is the least polar functional group because it is a nonpolar hydrocarbon.

Quiz 2: The Chemical Basis of Life

How do amino acids like hydroxylysine and thyroxine, which are not among the 20 amino acids inserted into amino acid chains, get into proteins?

An informative test for the diagnosis of diabetes is to monitor levels of Hemoglobin A1c, produced through the reaction of hemoglobin and __________________.

Which group of plants have nitrogen fixing symbionts?

Which of the following is a nucleotide?

Why do sugars tend to be highly water soluble?

Which organism would be a good candidate for researching genes related to nitrogen fixation?

Carbon's suitability as the molecular framework for biochemicals stems from its:

What level of structure in proteins is held together by R group interactions between different polypeptides?

Proteins are often composed of two or more distinct modules that fold up independently of one another. They often represent parts of a protein that function in a semi-independent manner. These modules are called ______.

What type of protein secondary structure is characterized as being highly extensible because of its coiled structure?

Which element can only be obtained by plants through mineral uptake, rather than via atmospheric fixation by the plant or its symbiont?

Which polysaccharide bond cannot be broken by mammalian enzymes that normally digest polysaccharides?

Select the order in which you might expect molecules involved in the synthesis of a polymer to be present as a cell grows.

What bond is responsible for the branch points in glycogen and amylopectin?

The $\beta$ -pleated sheet is characterized by the orientation of ______ to the molecular axis.

If a polypeptide is 100 amino acids long, and could be made of any of the 20 amino acids in any order, what is the total number of possible variations for this polypetide?

Which of these amino acids is most likely to be found in the core of a protein?

Which of these statements regarding glyceraldehyde is NOT correct?

Which of these functional groups is the LEAST polar? Refer to Table 2.2 for more information if you are uncertain of the molecular structure of each one.

Quiz 2: The Chemical Basis of Life

How do amino acids like hydroxylysine and thyroxine, which are not among the 20 amino acids inserted into amino acid chains, get into proteins?

An informative test for the diagnosis of diabetes is to monitor levels of Hemoglobin A1c, produced through the reaction of hemoglobin and __________________.

Which group of plants have nitrogen fixing symbionts?

Which of the following is a nucleotide?

Why do sugars tend to be highly water soluble?

Which organism would be a good candidate for researching genes related to nitrogen fixation?

Carbon's suitability as the molecular framework for biochemicals stems from its:

What level of structure in proteins is held together by R group interactions between different polypeptides?

Proteins are often composed of two or more distinct modules that fold up independently of one another. They often represent parts of a protein that function in a semi-independent manner. These modules are called ______.

What type of protein secondary structure is characterized as being highly extensible because of its coiled structure?

Which element can only be obtained by plants through mineral uptake, rather than via atmospheric fixation by the plant or its symbiont?

Which polysaccharide bond cannot be broken by mammalian enzymes that normally digest polysaccharides?

Select the order in which you might expect molecules involved in the synthesis of a polymer to be present as a cell grows.

What bond is responsible for the branch points in glycogen and amylopectin?

The β\betaβ -pleated sheet is characterized by the orientation of ______ to the molecular axis.

If a polypeptide is 100 amino acids long, and could be made of any of the 20 amino acids in any order, what is the total number of possible variations for this polypetide?

Which of these amino acids is most likely to be found in the core of a protein?

Which of these statements regarding glyceraldehyde is NOT correct?

Which of these functional groups is the LEAST polar? Refer to Table 2.2 for more information if you are uncertain of the molecular structure of each one.

The $\beta$ -pleated sheet is characterized by the orientation of ______ to the molecular axis.