Final Exam Review Answers
Home Up Final Exam Review Final Exam Review Answers Organic Summary Review

 

Answers to Review for Final Exam

Organic Review Answers

 1.      The names and classification are:

a.      2-hexyne (alkyne)

b.      4-ethyl-2,6,7-trimethyl-3-nonanone (ketone)

c.      sodium butanoate (carboxylic acid salt)

d.      2-methylbutanal (aldehyde)

e.      t-butyl propanoate (ester)

f.        N,N,2,3-tetramethylpentanamide (amide)

 

2.      The drawing and classification are:

 3.      The more soluble molecule is in bold.

a.      CH3CH2OCH2CH3 or CH3CH2CH2CH2CH3

b.      CH3CH2NHCH3 or CH3CH2CH2CH3

c.      CH3CH2OH or CH3CH2CH2CH2OH

d.      Acetone or cyclohexanone

 

4.      Since there is a double bond present, we are able to have cis and trans isomers.

 

 5.      The number of pi and sigma bonds and hybridization of all the carbons are listed below.

 


 

 6.      propane < ethyl methyl ether < 1-propanol < propanoic acid

 7.      Some examples are:

 

 

8.      There are two tests you can do identify the unknown bottles.

     a.      Place the unknown liquids into separate test tubes and to each add K2Cr2O7 and concentrated H2SO4.   These conditions will cause an oxidation for 1-butanol (a primary alcohol), but will have no affect on 2-methyl-2-butanol (tertiary alcohol.)   The test tube with 1-butanol would have a color change (from orange to blue-green) and the test tube with 2-methyl-2-butanol would have no color change.

    b.      Heat a clean copper wire and submerge into one of the alcohols, repeating several times.  Do the same for the second alcohol.  Heating the wire produces copper oxide, which acts a weak oxidizing agent.  This should cause the 1-butanol to oxidize to into butanal (an aldehyde) and no affect on 2-methyl-2-butanol (you can’t oxidize tertiary alcohols.)  To test for the presence of the aldehyde Schiff’s reagent can be added to each.  The aldehyde solution will turn pink.

 

9.      1-butene would first undergo and addition of water across the double bond, followed by an oxidation.

 

 

10. Ethene has only sp2 carbons present and therefore the C-H bonds absorption will only come to the left of 3000cm-1.  1-propene has both sp2 and sp3 carbons so you would see C-H absorptions to the left and right of 3000cm-1.

 

11. Since no reaction was seen with Br2, the unknown will not undergo an addition or substitution reactions.  Also since no color change was seen with K2Cr2O4 the unknown will not undergo oxidation reactions.  By looking an the IR data, a strong absorption is seen at ~1700cm-1, indicative of a carbonyl group.  Also the peak centered around 3000cm-1 is broad, showing the presence of an OH group on a carboxylic acid.  Therefore the unknown is a carboxylic acid.

 12. Complete the following reactions

 
 


Biochemistry Review Answers

  1.         Give some examples of compounds that are considered lipids. 

             Some examples would be fats, fatty acids, waxes, terpenes, or steroids.

 2.         How do fatty acids become neutral fats?  What is the role of fats in the structure of a cell membrane?

             When fatty acids and glycerol undergo intermolecular dehydration reactions, neutral fats are formed. 

            Fats provide the structure of a cell membrane by creating a bilayer with the hydrophobic ends of the fats pointing towards each other and the hydrophilic ends pointing to the inside and outside of the cell.  This structure provides protection for the cell and helps to regulate the molecules moving in/out of the cell.

 

3.  Label each of the following molecules as a fat, fatty acid, oil, or phosolipid.

 

 

 4.         Describe the “life cycle” of a carbohydrate, beginning with photosynthesis.

             During photosynthesis a plant uses water, CO2, and solar energy to create glucose (and other carbohydrates) and O2.  The carbons are reduced in the process of photosynthesis.  During respiration, if the carbohydrate is a polysaccharide it is broken down into monosaccharides which are in turn changed into pyruvic acid, then acetyl CoA.  The acetyl CoA enters the citric acid cycle which eventually produces CO2, H2O, and energy.  The carbons of the carbohydrate are oxidized in the process of respiration.

 

5.         What is the difference between D-glucose and L-glucose?  Draw those structures.

 The D or L refers to the position of the OH on the last asymmetric C of the glucose molecule.  D-glucose has the OH on the right of the C, L-glucose has the OH on the left of the C.

 

 6.         What is the difference between a-D-glucose and b-D-glucose?  Which one is the monosaccharide that creates cellulose?  the one that creates glycogen?

             The a or b refers to the position of the newly created OH (during ring closure) in relation to C#6.  If both the OH and C#6 are pointed in the same direction (usually draw “up”) then that is the b form.  If the OH and C#6 are opposite to each other then that is the a form.  

            The monosaccharide that creates cellulose is the b form; the a form creates glycogen (and starch).

 

7.         Draw the structure of sucrose.   What are the monomers that make up this disaccharide?  Is sucrose a reducing or non-reducing sugar – why?

            a-D-glucose and b-D-fructose are combined (through intermolecular dehydration) to make sucrose.  Sucrose is a non-reducing sugar because the monomers are linked by the OH’s that are created by ring closure; neither ring can open, so this sugar is unable to be oxidized and so cannot act as a reducing agent.

 

 

 8.         Compare fats and carbohydrates as energy sources.  Which gives more energy (per gram)? Why? Which gives energy more quickly? Why?

 Fats give more energy per gram because the carbons in fats need more oxidation (to end up as CO2) than the carbons in carbohydrates.  In other words, there is more carbon and less oxygen per gram in fats than in carbohydrates.  On the other hand, carbohydrates give energy more quickly because less oxidation is required to complete the path through the citric acid cycle.

 

 9.         Why is ATP called a “high energy compound”? 

             ATP is used to store energy in the body; when ATP is hydrolyzed to ADP, the reaction is exothermic – energy is released.

 

10.       What type of reaction occurs when:

a.      Intermolecular dehydration

b.      hydrolysis

c.      intermolecular dehydration

d.      intermolecular dehydration

 

11.       Draw the a-L-amino acid where R = methyl.

 

 

 12.       Describe the four primary functions of proteins and give an example of each.

            Structural:       Used for structures in the body ; examples are the keratins that make up hair/fur/horns/etc., the actin and myosin proteins in muscle, and the collagen proteins in tendons and hides.

             Messenger:    Used for communication between cells; examples are oxytocin, vasopressin, or insulin.  Many (but not all) hormones are messenger proteins.

             Enzyme:         Catalyze reactions in the body.  Enzymes are usually named after the process and/or the chemical that is reacting and are given an “-ase” ending.  Lactase and alcohol dehydrogenase are two examples of enzymes.         

             Transport:       Carry molecules throughout the body; hemoglobin (transports O2) and the cytochromes (transport electrons in the electron transport chain).

 

13. Leu-Leu-Ala-Arg-Gln-Thr-His-Ser is an example of the __primary_ structure of a protein.

     The a-helix is an example of the _secondary__ structure of a protein.

 “Three peptide chains are held together by hydrogen, van der Waals, and ionic bonding” describes an example of the __quaternary__ structure of a protein.

 

14.  What two things determine which bases will pair up in DNA or RNA?  What are the complementary base pairs for DNA? For RNA?

 A purine must pair with a pyrimidine and the number of hydrogen bonding sites on each must match (either two sites or three sites).  The base pairs in DNA are A –T and C – G.  The base pairs for RNA are A – U and C – G.

 

 15. List the differences between DNA and RNA.

 DNA has a double helix, uses the pentose 2-deoxyribose, and the complementary base to A is T.

 RNA has a single strand, uses the pentose ribose, and the complementary base to A is U.

 

16. What is the primary function of DNA?

 To store genetic information.

 

17. Describe the following processes.  What molecules are involved?

     Replication:          Exact copy of DNA is produced.  DNA and the correct enzyme are     involved. 

Transcription:       mRNA that is complementary to DNA is produced.  DNA, mRNA, and the correct enzyme are involved.

 Translation:          mRNA enters the ribosome.  Complementary tRNA molecules (with correct anti-codons to match codons of the mRNA) line up and hydrogen bond to the mRNA.  The tRNA molecules each bring an amino acid, which are bonded together to create a protein.  mRNA, tRNA, amino acids, and the ribosome are involved.

 

 

Top of Page

Clackamas Community College E-mail instructor: Kerry Cotter
Science Department
19600 South Molalla Avenue
Oregon City, OR 97045
(503) 594-3352
TDD (503) 650-6649

Distance Learning questions

Clackamas Community College
©2001, 2003 Clackamas Community College, Hal Bender