3 Carbon and the Molecular Diversity of Life

Question 1

The element present in all organic molecules is

Answer 1

carbon.

Question 2

The complexity and variety of organic molecules is due to

Answer 2

the chemical versatility of carbon atoms.

Question 3

How many electron pairs does carbon share in order to complete its valence shell?

Answer 3

4

Question 4

A carbon atom is most likely to form what kind of bond(s) with other atoms?

Answer 4

covalent

Question 5

How many structural isomers are possible for a substance having the molecular formula C4H10?

Answer 5

2

Question 6

What determines whether a carbon atom’s covalent bonds to other atoms are in a tetrahedral configuration or a planar configuration?

Answer 6

the presence or absence of double bonds between the carbon atom and other atoms

Question 7

Compared to a hydrocarbon chain where all the carbon atoms are linked by single bonds, a hydrocarbon chain with the same number of carbon atoms, but with one or more double bonds, will

Answer 7

be more constrained in structure.

Question 8

A compound contains hydroxyl groups as its predominant functional group. Which of the following statements is true concerning this compound?

Answer 8

-OH

It should dissolve in water.

Question 9

The large diversity of shapes of biological molecules is possible because of the extensive presence of _____ in the molecules.

Answer 9

carbon

Question 10

What functional group is commonly used in cells to transfer energy from one organic molecule to another?

Answer 10

phosphate

Question 11

Which two functional groups are always found in amino acids?

Answer 11

carboxyl and amino

Question 12

The bonding of two amino acid molecules to form a larger molecule requires

Answer 12

the release of a water molecule.

Question 13

Sucrose is formed when glucose is joined to fructose by a(n) _____.

Answer 13

glycosidic linkage join simple sugars to form polysaccharides.

Question 14

Plant cell walls consist mainly of _____.

Answer 14

Cellulose is a polysaccharide that is a major component of the tough walls that enclose plant cells.

Question 15

A hydrophobic amino acid R group (side group) would be found where in a protein?

Answer 15

on the inside of the folded chain, away from water
Hydrophobic R groups are nonpolar. By orienting within the folded chain they associate with other nonpolar R groups or side chains and avoid coming into contact with water.

Question 16

Which bonds are created during the formation of the primary structure of a protein?

Answer 16

peptide bonds

Question 17

Which level of protein structure do the α helix and the β pleated sheet represent?

Answer 17

secondary

Question 18

In a normal cellular protein, where would you expect to find a hydrophobic amino acid such as valine?

Answer 18

in the interior of the folded protein, away from water, or in a transmembrane portion interacting with lipid fatty acid chains

Question 19

The flow of genetic information in a cell goes from _____.

Answer 19

DNA to RNA to protein

The information in DNA is transcribed into RNA and then translated into protein.

Question 20

The building blocks or monomers of nucleic acid molecules are called _____.

Answer 20

A nucleotide is a nucleic acid monomer consisting of a nitrogen base, a pentose sugar, and a phosphate group. Nucleotides joined together by covalent bonds called phosphodiester linkages form nucleic acid molecules.

Question 21

Which of the following descriptions best fits the class of molecules known as nucleotides?

Answer 21

a nitrogenous base, a phosphate group, and a pentose sugar

Question 22

The difference between the sugar in DNA and the sugar in RNA is that the sugar in DNA

Answer 22

contains one less oxygen atom.