Chapter 4: Carbon and the Molecular Diversity of Life

Which of these is a thiol? ( Concept 4.3)

A thiol is a molecule containing a sulfhydryl functional group.

Which element is always associated with organic chemistry?

carbon

The two compounds are related to each other by being __________. ( Concept 4.2)

hydrocarbons, isomers, organic compounds, and double-bonded compounds. It is true that both compounds are organic compounds, but there is a better answer.

Which of the following are properties of hydrocarbons? ( Concept 4.2)

hydrophobic, nonpolar, good source of stored energy. Because they are nonpolar, hydrocarbons are hydrophobic. They also provide energy in the forms of things such as fossil fuels and fats.

Which of the following functional groups is associated with a release of energy when removed from the carbon skeleton with water? ( Concept 4.3)

phosphate group Consider which group is associated with the molecule ATP.

Carbon enters the biosphere when

photosynthetic organisms use the sun's energy to transform CO2 into organic molecules, which are taken in by plant-eating animals.

A straight-chain carbon compound constructed from __________ must contain at least one carbon-carbon double bond. (Concept 4.2)

6 hydrogen atoms and 3 carbon atoms If two carbons were double-bonded, there would not be enough bonds for the rest of the atoms, even if 3 hydrogen atoms bind to the 3 oxygen atoms to form hydroxyl groups.

What is ATP's importance in the cell? ( Concept 4.3)

ATP stores the potential to react with water, thereby removing a phosphate group and releasing energy for cellular processes. ATP releases energy during a hydrolysis reaction that removes a phosphate group.

Which of the following groups is capable of hydrogen bonding with an oxygen atom on another functional group? ( Concept 4.3)

All of the listed functional groups are polar, and thus capable of hydrogen bonding with the oxygen of another molecule.

Which of the following is an organic molecule?

CH4. Oxygen is not an organic molecule. Compounds containing carbon are said to be organic. O2 is a molecule of oxygen gas.

What is the reason carbon atoms are the most versatile building blocks of the molecules used by living organisms? ( Concept 4.2)

Each carbon atom acts as an intersection point from which a molecule can branch off in up to four directions. It is true that carbon is the central atom in carbon dioxide, but this does not make carbon versatile.

Pharmaceutical companies are selling billions of dollars' worth of single-enantiomer drugs. Why might it be important to use only one form of an enantiomer? ( Concept 4.2)

One enantiomer may provide an effective treatment whereas the other may be ineffective or even toxic. Not all enantiomers spontaneously change from one to the other, but it is important to understand their behavior in the body.

Which of the following molecules is a weak acid? ( Concept 4.3)

R—COOH No. The amino group (—NH2) of R—NH2 can function as a base. It can accept a proton (H+), but it cannot donate a proton (H+).

Which of the following molecules has a carboxyl functional group? ( Concept 4.3)

R—COOH The molecule R—COH contains the carbonyl functional group (—COH).

Which of the following molecules is a weak base? ( Concept 4.3)

R—NH2 The carboxyl group (—COOH) of R—COOH can donate a proton, but it cannot accept a proton (H+).

Carbon

The Backbone of Life

Which of the following examples best describes a unique functional property of the carboxyl group? ( Concept 4.3)

The covalent bond between oxygen and hydrogen is so polar that hydrogen ions tend to dissociate from oxygen reversibly. This is a property of the carboxyl group.

A pharmaceutical company was forced to recall a pain reliever medication that had been linked to the fatalities of several hundred people. Analysis of the recalled drug revealed the presence of two isomers due to an asymmetrical carbon atom in the drug molecule. What can be hypothesized from this observation?( Concept 4.2)

The isomers are enantiomers, with one having toxic effects on humans. Functional groups are covalently bonded to the carbon skeleton of organic molecules.

The carbon atom is tetravalent, which means that __________.

a carbon atom can complete its valence shell by forming four covalent bonds The first electron shell for carbon and all atoms, except hydrogen, holds two electrons (hydrogen has one electron).

What is the three-dimensional shape created by hybrid orbitals that are formed when a carbon atom is covalently bonded with four other atoms? ( Concept 4.2)

a tetrahedron with carbon in the center. A cube has six vertices; the carbon atom in the question is bonded to four other atoms.

Stanley Miller's experiments were significant because he demonstrated that __________. ( Concept 4.1)

a variety of simple organic compounds could be spontaneously synthesized from components in Earth's primitive atmosphere. The behavior of molecules containing carbon can be quite different and is influenced primarily by the construction of the carbon skeleton and the presence and variety of functional groups.

Choose the pair of terms that correctly completes this sentence about functional groups in organic chemistry: Carboxyl is to __________ as __________ is to base. ( Concept 4.3)

acid ... amino A ketone is a carbonyl type of functional group; hence, it cannot donate a proton (hydrogen ion) to a solution. The phosphate functional group can donate protons (hydrogen ions) to a solution.

Which of these is found in all amino acids? ( Concept 4.3)

both —COOH and —NH2 For a compound to be an amino acid, it must contain at least one carboxyl functional group and one amino functional group. In addition, it may contain one or more of the other functional groups.

Proteins, DNA, carbohydrates, and other molecules that distinguish living matter from inorganic material are all composed of carbon atoms bonded to each other and to atoms of other elements. o These other elements commonly include hydrogen (H), oxygen (O), nitrogen (N), sulfur (S), and phosphorus (P).

carbon atoms bonded to each other and to atoms of other elements. These other elements commonly include hydrogen (H), oxygen (O), nitrogen (N), sulfur (S), and phosphorus (P).

Organic chemistry is the study of

carbon compounds

What are the six most important chemical elements of life?

carbon, nitrogen, oxygen, hydrogen, phosphate, sulfur. All of these elements are capable of forming strong covalent bonds, important in building large, complex molecules.

Which of the following functional groups increases the solubility of organic compounds in water? ( Concept 4.3)

carbonyl group carboxyl group hydroxyl group amino group

Which functional group would you predict is part of abscisic acid? ( Concept 4.3)

carboxyl group Compounds containing the carboxyl functional group (—COOH) are known as carboxylic acids or organic acids. They can donate a hydrogen ion (proton) to a solution due to a highly polar oxygen atom of the functional group.

Carbon accounts for the

diversity of biological molecules, which has made possible the wide variety of living things.

Using modern equipment, a former graduate student of Stanley Miller recently reanalyzed the sample results of volcano simulation experiments that Miller conducted along with his classic experiment described in the text. This reanalysis did which of the following? ( Concept 4.1)

identified additional organic compounds that had not been found by Miller. The reanalysis gives further weight to the hypothesis that volcanic activity could have provided the energy needed for the abiotic synthesis of organic compounds.

Ethanol, propanol, and methanol are three simple alcohols. They can be grouped together because they __________. ( Concept 4.3)

share the same functional group: a hydroxyl The dissociation of a hydrogen ion is a characteristic of the carboxyl functional group.

Although cells are 70-95% water

the rest consists of mostly carbon-based compounds.

A molecule has one carbon-carbon double bond and four monovalent atoms or groups. How many different cis-trans isomers exist for this molecule?

two Try drawing possible configurations on a piece of scrap paper.

Which of the following functional groups is present in all amino acids? ( Concept 4.3)

—NH2. This is a hydroxyl group. This group is not present in all amino acids.