Topic 3
Molecules with which functional groups may form polymers via dehydration reactions?
Either hydroxyl or carboxyl groups
The amino acids of the protein keratin are arranged predominantly in an alpha helix. This secondary structure is stabilized by
Hydrogen bonds
Herman Kolbe's synthesis of an organic compound, acetic acid, from inorganic substances that had been prepared directly from pure elements was a significant milestone for what reason?
It proved that organic compounds could be synthesized from inorganic compounds and disproved the concept of vitalism.
Which of the following statements is/are true regarding the chemical reaction illustrated in figure 5.5?
It results in a peptide bond.
A compound contains hydroxyl groups as its predominant functional group. Which of the following statements is true concerning this compound?
It should dissolve in water.
Which of the pairs of molecular structures shown below depict enantiomers (enantiomeric forms) of the same molecule?
Left (CO2H, CH3, H, H2N) Right (CO2H, NH2, H, H3C)
Which of the following statements is true regarding the molecule illustrated in Figure 5.3?
Molecules of this type are usually liquid at room temperature.
Which bonds are created during the formation of the primary structure of a protein?
Peptide bonds
Professor Jamey Marth at the University of California, Santa Barbara, identified 70 molecules that are used to build cellular macromolecules and structures. These include at least 34 saccharides, 8 nucleosides, and 20 amino acids. in theory, then, which class of biological polymer has the greatest information-coding capacity
Polysaccharides
What is the structure shown in Figure 5.4?
Steroid molecule
Choose the term that correctly describes the relationship between these two sugar molecules:
Structural isomers
The two molecules show in the figure above are best described as?
Structural isomers
At which level of protein structure are interactions between the side chains (R groups) most important?
Tertiary
the label on a container of margarine lists "hydrogenated vegetable oil" as the major ingredient. What is the result of adding hydrogens to vegetable oil?
The hydrogenated vegetable oil stays solid at room temperature.
Why are hydrocarbons insoluble in water?
The majority of their bonds are non polar covalent carbon-to-hydrogen linkages.
What determines whether a carbon atom's covalent bonds to other atoms are in a tetrahedral configuration or a planar configuration?
The presence or absence of double bonds between the carbon atom and other atoms.
The bonding of two amino acid molecules to form a larger molecule requires
The release of a water molecule
Which of the following statements is true for the class of biological molecules known as lipids?
They are insoluble in water.
Which of the following is a false statement concerning amino groups?
They are nonpolar.
Which of the following is true regarding saturated fatty acids?
They are the principal molecules in lard and butter.
Which of the following statements concerning unsaturated fats is true?
They have double bonds in the carbon chains of their fatty acids.
Which of the following statements correctly describes cis-trans isomers?
They have variations in arrangement around a double bond.
Dehydration reactions are used in forming which of the following compounds?
Triacylglycerides, polysaccharides, and proteins.
Large organic molecules are usually assembled by polymerization of a few kinds of simple subunits. Which of the following is an exception to this statement?
a steroid
Normal hemoglobin is a tetramer, consisting of two molecule of beta hemoglobin and two molecules of alpha hemoglobin. in sickle-cell disease, as a result of a single amino acid change, the mutant hemoglobin tetramers associate with each other and assemble into large fibers. Based on this information alone, we can conclude that sickle-cell hemoglobin exhibits
altered primary structure and altered quaternary structure; the secondary and tertiary structures may or may not be altered.
What methods may be used to elucidate the structures of purified proteins?
both x-ray crystallography and NMR spectroscopy.
The element present in all organic molecules is
carbon
Differences among organisms are caused by
differences in the types and relative amounts of organic molecules synthesized by each organism.
Which of the following is not a polymer?
glucose
In a normal cellular protein, where would you expect to find a hydrophobic amino acid like valine?
in the interior of the folded protein, away from water, or in a transmembrane portion interacting with lipid fatty acid chains
Which functional group is not present in this molecule
sulfhydryl
The complexity and variety of organic molecules is due to
the chemical versatility of carbon atoms.
A carbon skeleton is covalently bonded to both an amino group and a carboxyl group. When placed in water it
would function as both an acid and a base.
Which of the following molecules contain(s) an aldehyde type of carbonyl functional group?
1 and 4
How many molecules of water are needed to completely hydrolyze a polymer that is 11 monomers long?
10
Which of the following molecules is the pentose sugar found in RNA?
12
A double-stranded DNA molecule contains a total of 120 purines and pyrimidines. This DNA molecule could be composed of
120 Thymine and 120 Adenine molecules
Which of the following molecules is a purine type of nitrogenous base?
13
Which of the following molecules act as building blocks (monomers) of polypeptides?
2, 7, and 8
Which of the following molecules consists of a hydrophilic "head" region and a hydrophobic "tail" region?
5
Which molecule is a saturated fatty acid?
9
Which molecules shown above is (are) ionized in aqueous solution at pH 7?
A
Which functional group shown above is characteristic of alcohols?
A -OH
Research indicates that ibuprofen, a drug used to relieve inflammation and pain, is a mixture of two enantiomers; that is, molecules that
Are mirror images of one another.
Thalidomide and L-dopa, shown below, are examples of pharmaceutical drugs that occur as enantiomers, or molecules that
Are mirror images of one another.
Polysaccharides, triacylglycerides, and proteins are similar in that they
Are synthesized from subunits by dehydration of hydrolysis.
Identify the asymmetric carbon in this molecule.
B
Which of the groups shown above is a carbonyl functional group?
B
Which of the structures illustrated above cannot form hydrogen bonds with water molecules?
B
Which bond is a peptide bond?
C
Which molecule shown above has a carbonyl functional group in the form of a ketone?
C
Which of the structures illustrated above is an impossible covalently bonded molecule?
C
Which functional group(s) shown above is (are) present in all amino acids?
C and D
The molecular formula for glucose is C6H12O6. What would be the molecular formula for a polymer made by linking ten glucose molecules together by dehydration reactions?
C60H102O51
A molecule with the chemical formula C6H12O6 is probably a
Carbohydrate and monosaccharide only.
Amino acids are acids because they always possess which functional group?
Carboxyl
What is the name of the functional group shown in the figure above?
Carboxyl
Which of the following are nitrogenous bases of the pyrimidine type?
Cytosine and Uracil
Approximately 32 different monomeric carbohydrate subunits are found in various natural polysaccharides. Proteins are composed of 20 different amino acids. DNA and RNA are each synthesized from four nucleotides. Among these biological polymers, which as the least structural variety?
DNA
What is the chemical reaction mechanism by which cells make polymers from monomers?
Dehydration reactions
Which of the following best summarizes the relationship between dehydration reactions and hydrolysis?
Dehydration reactions assemble polymers, and hydrolysis reactions break down polymers.
