Question 1

Denaturation disrupts the secondary and tertiary structure of proteins.However,denaturation is not strong enough to disrupt what interaction that is relevant to protein structure?

Accepted Answer

Peptide bonds are the covalent bonds that link amino acids in a protein chain and are not affected by denaturation. Denaturation primarily disrupts non-covalent interactions such as hydrogen bonds, ionic bonds, van der Waals attraction, and hydrophobic exclusion.

Question 2

Biological membranes contain bilayers containing mostly ________.

Accepted Answer

Biological membranes are composed of a phospholipid bilayer, which is made up of two layers of phospholipid molecules. The polar heads of the phospholipids face outwards towards the aqueous environment while the nonpolar tails face inwards, creating a hydrophobic core. While oils are lipids, they are not the predominant lipid in biological membranes. Prostaglandins and triglycerides are not major components of biological membranes. Cholesterol is another lipid that is present in small quantities in biological membranes, but it is not the primary component of the bilayer.

Question 3

This type of lipid is found in pigments such as chlorophyll,in the visual pigment retinal,and in rubber:

Accepted Answer

The type of lipid found in pigments such as chlorophyll, in the visual pigment retinal, and in rubber is terpene. Terpenes are a large class of lipids that are formed by the linear condensation of isoprene units, and are commonly found in plant oils and resins, as well as in some animal tissues.

Question 4

Which of the following reactions is a hydrolysis reaction?

Accepted Answer

A hydrolysis reaction involves the breaking of a bond in a molecule using water. In option A, water (H₂O) is a reactant, indicating that it is used to break down compound A into products B and C.

Question 5

Enzymes function to:

Accepted Answer

Enzymes are proteins that act as catalysts to accelerate chemical reactions in living organisms.

Question 6

The types of bonds found in nucleic acids are:

Accepted Answer

Phosphodiester bonds connect the sugar and phosphate groups in the backbone of nucleic acids, such as DNA and RNA. Peptide bonds connect amino acids in proteins, ionic bonds result from the attraction of positively and negatively charged ions, and nonpolar covalent bonds result from the sharing of electrons equally between atoms. While other types of bonds may play a role in the structure of nucleic acids, phosphodiester bonds are the primary type of bond found in this type of molecule.

Question 7

A nucleic acid contains uracil,allowing you to conclude that:

Accepted Answer

Uracil is only found in RNA, never in DNA. Therefore, the nucleic acid containing uracil must be RNA.

Question 8

Cellulose is composed of monomers of:

Accepted Answer

Cellulose is composed of β-glucose monomers, which are linked together through β-1,4-glycosidic bonds to form long, linear chains.

Question 9

The nitrogenous base that is only found in RNA and not DNA is:

Accepted Answer

Uracil is present in RNA but not in DNA. DNA contains thymine instead of uracil.

Question 10

What is the difference in the bonding between alpha-helix and beta sheets?

Accepted Answer

In alpha-helices, the hydrogen bonding occurs between the amides in different parts of the helices, while in beta sheets, the hydrogen bonding occurs between the amides of adjacent chains in the sheets.

Question 11

Fructose and galactose both have six carbon atoms,twelve hydrogen atoms and six oxygen atoms,just like glucose.A friend of yours says: "Since those sugars have the same number of atoms,they should have the same name." You answer: "While they do have the same number and type of atoms,

Accepted Answer

Fructose and galactose are both monosaccharides, which means that they are alternate forms of the monosaccharide glucose. They differ in the arrangement of functional groups around the carbon atoms, which results in slightly different chemical and physical properties. Therefore, they are named differently to reflect these differences, even though they have the same number and type of atoms as glucose.

Question 12

Proteins are created with:

Accepted Answer

Proteins are made up of long chains of amino acids joined together by peptide bonds.

Question 13

The nitrogenous base that is only found in DNA and not in RNA is:

Accepted Answer

Thymine is the nitrogenous base only found in DNA and not in RNA. RNA contains uracil instead of thymine.

Question 14

Phospholipids are made up of:

Accepted Answer

Phospholipids are composed of a phosphate head, two fatty acid tails, and a glycerol backbone.

Question 15

A nucleic acid contains thymine,allowing you to conclude that:

Accepted Answer

Thymine is only found in DNA and not in RNA. Therefore, the presence of thymine allows us to conclude that the nucleic acid is DNA.

Question 16

Amino acids are linked together by peptide bonds in a ________

Accepted Answer

Amino acids are linked together by peptide bonds to form a polypeptide, which is a chain of amino acids. Phospholipids, nucleic acids, polysaccharides, and starches are not composed of amino acids linked together by peptide bonds.

Question 17

A candy bar contains 108 calories per serving.There are 4 grams of carbohydrate,5 grams of protein,and 8 grams of fat in a serving.How many of the calories come from fat? Note: One food calorie equals one kilocalorie.

Accepted Answer

To find out how many calories come from fat, we need to multiply the amount of fat by 9 (because there are 9 calories per gram of fat).

8 grams of fat x 9 calories per gram = 72 calories from fat

Therefore, the answer is C) 72.

Question 18

The specific amino acid sequence of a protein is its ________.

Accepted Answer

The specific amino acid sequence of a protein is its primary structure.

Question 19

Which of the following reactions is a dehydration reaction?

Accepted Answer

A dehydration reaction involves the removal of water (H2O) from the reactants to form a product, as seen in choice B.

Question 20

The information storage molecules of cells are called:

Accepted Answer

Nucleic acids, such as DNA and RNA, are the information storage molecules in cells. Proteins, phospholipids, enzymes, and hormones all perform important roles in cells, but they do not store genetic information.

Quiz 3: The Chemical Building Blocks of Life