Deck 3: The Chemistry of Life: Organic Compounds

Question 1

What group of molecules is represented in this structure? ​

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A) structural proteins
B) polysaccharides
C) triacylglycerols
D) phospholipids
E) polypeptides

Answer 1

D

Question 2

Why are hydrocarbons considered hydrophobic?

A) Hydrocarbons exist as isomers.
B) Hydrocarbons contain oxygen atoms.
C) The covalent bonds between carbon atoms are polar.
D) The covalent bonds between hydrogen and carbon are nonpolar.
E) The hydrogen bonds between hydrogen and carbon are nonpolar.

Answer 2

D

Question 3

Which of the following is sometime referred to as animal starch?

A) cellulose
B) sugars
C) starch
D) fatty acid
E) glycogen

Answer 3

E

Question 4

What carbohydrate energy storage molecule is found in animal liver and muscle cells?

A) starch
B) cellulose
C) glycogen
D) a fatty acid
E) cholesterol

Question 5

A steroid consists of carbon atoms arranged in four attached rings. How many carbon atoms do three of the rings contain?

A) six carbon atoms
B) five carbon atoms
C) three carbon atoms
D) seven carbon atoms
E) two carbon atoms

Question 6

When we know what kinds of ____ are present in an organic compound, we can predict its chemical behavior.

A) proteins
B) enzymes
C) triacylglycerols
D) macromolecules
E) functional groups

Question 7

Figure 3-1 ​

Which is the main structural component of the walls that surround plant cells?

A) cellulose
B) sugars
C) starches
D) fatty acid
E) glucose

Question 8

Glucose and fructose are ____ because they have identical molecular formulas but their atoms are arranged differently.

A) polar
B) tertiary
C) enantiomers
D) structural isomers
E) geometric isomers

Question 9

Most animals convert carotenoids to which vitamin?

A) Vitamin K
B) Vitamin A
C) Vitamin D
D) Vitamin E
E) Vitamin B

Question 10

You isolate a compound that is insoluble in water, has alternating single and double bonds and has a bright orange color. You correctly conclude that this compound is a:

A) protein
B) nucleic acid
C) polysaccharide
D) steroid
E) carotenoid

Question 11

Which carbohydrate is the most structurally complex?

A) polymer
B) monomer
C) phospholipid
D) polysaccharide
E) monosaccharide

Question 12

Which of the following describes an amphipathic molecule?

A) A phospholipid with two polar ends
B) A phospholipid with two hydrophobic ends
C) A steroid with a hydrophilic functional group
D) A steroid with a hydrophobic functional group
E) A phospholipid with both a hydrophobic end and a hydrophilic end

Question 13

What substance is removed during a condensation reaction?

A) water
B) a dimer
C) a polymer
D) a hydrocarbon
E) a carboxyl group

Question 14

What are compounds that have the same molecular formulas but different structures and different molecules?

A) Thiols
B) Monomers
C) Hexoses
D) Amyloplasts
E) Isomers

Question 15

Which is a property of unsaturated fats?

A) They are more common in animals.
B) They are generally liquid at room temperature.
C) They have no double bonds in the carbon chains of their fatty acids.
D) They have fewer fatty acids per fat molecule than do saturated fats.
E) They contain more hydrogen than saturated fats that have the same number of carbon atoms.

Question 16

Which of the following fatty acids include one or more adjacent pairs of carbon atoms joined by a double bond?

A) saturated fatty acids
B) monounsaturated fatty acids
C) unsaturated fatty acids
D) polyunsaturated fatty acids
E) trans fatty acids

Question 17

Unlike lipids, hydrophilic functional groups typically contain ____ atoms, which make them more soluble in water.

A) carbon
B) oxygen
C) hydrogen
D) nitrogen
E) phosphate

Question 18

A molecule of a saturated triacylglycerol contains:

A) the maximum number of double bonds between carbons in the fatty acid chains
B) the maximum number of triple bonds between carbons in the fatty acid chains
C) the maximum number of hydrogen atoms in the fatty acid chains
D) fatty acid chains with both amino and carboxyl groups
E) alternating single and double bonds between carbons in the fatty acid chains

Question 19

How many covalent bonds are formed by carbon atoms, producing a wide variety of molecular shapes and sizes?

A) Six
B) Two
C) Three
D) Four
E) Seven

Question 20

Figure 3-1 ​

The products of the process in the accompanying figure are:

A) enzymes
B) amino acids
C) monosaccharides
D) molecules of glycerol
E) representative of a glycoside linkage

Question 21

Which of the following describes the tertiary structure of a protein molecule?

A) bonding of two amino acids to form a dipeptide
B) folding of a peptide chain to form an alpha helix
C) association of several polypeptide chains by weak bonds
D) order in which amino acids are joined in a peptide chain
E) three-dimensional shape of an individual polypeptide chain

Question 22

Figure 3-2 ​

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In the accompanying figure, ionic bonds would form between the R groups of which amino acids?

A) 1 and 3
B) 2 and 4
C) 3 and 5
D) 4 and 6
E) 3 and 6

Question 23

When two amino acids combine in a condensation reaction, a ____________ is formed.

A) peptide bond
B) dipeptide bond
C) polypeptide chain
D) trans bond
E) cis bond

Question 24

What is the functionality of regulatory proteins?

A) strengthen and protect cells and tissues
B) store nutrients
C) control the activities of proteins, genes, cells, and tissues
D) generate movement in cells and tissues
E) move substances between cells and across cell membranes

Question 25

What is the purpose of regulatory proteins?

A) To store nutrients
B) To defend against foreign invaders
C) To catalyze a specific chemical reaction
D) To control the expression of specific genes
E) To strengthen and protect cells and tissues

Question 26

_____________ is a region where a polypeptide chain forms a uniform helical coil.

A) Beta globin
B) Alpha globin
C) Beta turns
D) α-helix
E) Beta-pleated sheet

Question 27

At which level of protein structure are peptide bonds most important?

A) primary
B) secondary
C) tertiary
D) quaternary
E) globular

Question 28

What type of protein accelerates the thousands of different chemical reactions that take place in an organism?

A) enzyme
B) amino acid
C) transport protein
D) regulatory protein
E) protective protein

Question 29

Assume that the shaded portions of the molecule in the accompanying figure each represent different polypeptide chains. What does this represent? ​

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A) Cellulose
B) A carotenoid
C) An amino acid
D) A steroid hormone
E) The quaternary structure of a protein

Question 30

When a nucleic acid undergoes hydrolysis, the resulting subunits are:

A) fatty acids
B) amino acids
C) nucleotides
D) carotenoids
E) monosaccharides

Question 31

Analysis of a certain polymer shows that it contains phosphate groups, ribose groups, and pyrimidines. Based on this information, what statement best describes this compound?

A) It is RNA.
B) It is DNA.
C) It is cylic AMP.
D) It is a polypeptide.
E) It is an inorganic compound.

Question 32

Figure 3-3 ​

The molecular fragment, represented in the accompanying figure is:

A) ATP
B) RNA
C) DNA
D) a nucleotide
E) a polysaccharide

Question 33

Which functional group in cysteine residues can form bridges that help stabilize a protein's tertiary structure?

A) amino
B) carbonyl
C) hydroxyl
D) phosphate
E) sulfhydryl

Question 34

The helical coil shape of an α-helix fibrous protein provides what type of property to that protein?

A) rigidity
B) strength
C) elasticity
D) heat tolerance
E) water retention

Question 35

Figure 3-2 ​

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In the accompanying figure, hydrophobic interactions would occur between the R groups of which two amino acids?

A) 1 and 4
B) 2 and 5
C) 3 and 6
D) 2 and 4
E) 3 and 5

Question 36

Which pair matches the correct macromolecule with the bond that joins its subunits?

A) protein−ester linkage
B) steroid−peptide bond
C) polysaccharide−peptide bond
D) triacylglycerol−glycosidic linkage
E) nucleic acid−phosphodiester linkage

Question 37

Which of the following is responsible for the alpha-helical structure of proteins?

A) hydrogen bonds
B) ionic interactions
C) polar covalent bonds
D) hydrophobic interactions
E) nonpolar covalent bonds

Question 38

What is the purpose of molecular chaperones?

A) To transfer an amino acid
B) To attach a carboxyl group
C) To straighten other molecular proteins
D) To strengthen the tertiary structure of a protein
E) To assist the folding of other molecular proteins

Question 39

The primary difference between the amino acids commonly found in proteins is in their:

A) R or variable groups
B) number of potassium groups
C) number of phosphate groups
D) number of carbonyl groups
E) number of asymmetric carbons

Question 40

The following amino acid would be characterized as ____ based on the chemical properties of its side chain. ​

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A) basic
B) acidic
C) nonpolar
D) hydrophilic
E) electrically charged

Question 41

Which lipid can be identified by its isoprene units?

A) Fats
B) Steroids
C) Carotenoids
D) Amino acids
E) Phospholipids

Question 42

Which of the following is a purine base found in nucleotides?

A) uracil
B) steroid
C) guanine
D) cytosine
E) thymine

Question 43

_______________________ are isomers that are mirror images of each other.

A) Geometric isomers
B) Structural isomers
C) Disaccharides
D) Enantiomers
E) Amino groups

Question 44

Since a carbon atom has 4 valence electrons, it can complete its valence shell by forming a total of 4 hydrogen bonds.

Question 45

The carboxyl group can exist in either an ionized or nonionized form.

Question 46

What does the term "functional group" mean in the context of organic molecules? Briefly describe two types of functional groups and their chemical properties.

Question 47

Cellulose is the main structural component of the walls that surround plant cells.

Question 48

Which organic compound is not only responsible for energy storage, but can also provide thermal insulation?

A) Lipids
B) Proteins
C) Nucleic acids
D) Carbohydrates
E) Monosaccharides

Question 49

By definition, geometric isomers are mirror images of each other.

Question 50

Hemoglobin consists of 574 amino acids arranged in four polypeptide chains.

Question 51

Why is ATP important in living organisms?

A) It is easily converted to starch for long-term storage.
B) It can transfer some of its energy to other chemicals.
C) It is an important structural component of cell membranes.
D) Like all other nucleic acids, it stores hereditary information.
E) Like RNA, it acts as a source code for the formation of proteins.

Question 52

When glucose and fructose undergo condensation, maltose is produced as a product.

Question 53

A phosphate group is weakly acidic.

Question 54

An essential amino acid is one that the body cannot synthesize in sufficient amounts.

Question 55

Fats and steroids have very different functions. However, both are structurally related and share some of the same characteristics. Briefly, describe the similarities and differences between the two molecules.

Question 56

You have discovered a protein that consists of three identical subunits (polypeptide chains). Each subunit has an alpha helix and two different domains that are connected by two cysteine residues. Describe the four levels of organization for this protein and list the type(s) of bond(s) involved in establishing each structural level.

Question 57

A disaccharide is composed of two monosaccharides joined by a glycosidic bond.

Question 58

The hydroxyl group is weakly acidic because of the presence of a strongly electronegative oxygen.

Question 59

Condensation and hydrolysis reactions are catalyzed by the same enzymes.

Question 60

Briefly describe three functions of proteins other than enzymes.

Question 61

A pyrimidine is a double-ring molecule.

Question 63

Cystic fibrosis is a genetic disease caused by the deletion of one amino acid in the cystic fibrosis transmembrane conductance regulator (CFTR) protein. This deletion changes the shape of the protein in dramatic ways, causing serious health issues. How can the deletion of one amino acid lead to such drastic results?

Question 65

Cyclic AMP is a type of nucleotide.

Question 68

Methane, which is composed of one carbon and four hydrogens is a gas at room temperature. Upon replacing one of the hydrogen atoms with a hydroxyl group, methane is converted to methanol, which is a liquid at room temperature. Explain the reason behind this difference in physical properties.

Question 70

What factors allow carbon to be ideally suitable to serve as the "backbone" for large molecules?

Question 73

A beta-pleated sheet is an example of a protein's tertiary structure.

Question 75

Molecular chaperones mediate the folding of other protein molecules.