University of Gaza
Faculty of Nursing
Fall semester 2009-2010
Biochemistry
25/01/2010
Time: 2 Hours
A. Choose the correct answer for each of the following:
(10 points)
1. If a compound contains three chiral carbon atoms, how many optical isomers are possible?
a. 2
b. 4
c. 8
d. 16
2. An example of a disaccharide is
a. glucose b. maltose
c. cellulose
d. starch
3. an example of a hexose is
a. sucrose
b. lactose
c. galactose
4. Animals store carbohydrates in form of
a. cellulose b. glucose
c. starch
d. glycogen
5. An example of a polysaccharide is
a. Starch
b. glycogen c. cellulose
d. all of these
6. When sucrose is hydrolyzed, it yields
a. glucose only
b. glucose and fructose c.
d. ribose
c. glucose and galactose
d. ribose and galactose
7. Which substance can be used to convert a fatty acid into a soap?
a. CaCl2
b. O2
c. H2
d. NaOH
8. Which of the following is contained in fats and oils
a.
a phosphate group
b. lecithin
c. glycerol
d. cholesterol
9. The higher the iodine number of a fat or oil, the greater the degree of
a. rancidity
b. acidity
c. unsaturation
d. hydrolysis
10. Lipids
a. yield fatty acids upon hydrolysis
b. are insoluble in water
c. are soluble in organic solvents
d. all of the above
11. An example of an amino acid is
a. benzene
b. toluene
c. glycine
d. histamine
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12. Which of the following will not denature protein?
a. acid
b. water
c. heat
d. alcohol
13. Which structure refers to the number and sequence of amino acids in a protein?
a. primary
b. secondary c. tertiary
d. quaternary
14. The insertion of the wrong nucleotide into a DNA code group could result in
a. mutation
b. splicing
c. recombination
d. cloning
15. The RNA concerned with the transcription of genetic information is
a. homogeneous
b. messenger c. transfer
d. ribosomal
16. The number of nucleotides necessary to code for an amino acid is
a. 1
b. 2
c. 3
d. 4
17. How many different amino acids are involved in the genetic code?
a. 5
b. 10
c. 20
d. an infinite number
c. thymine
d. adenine
18. Guanine pairs with
a. uracil
b. cytosine
19. Most enzymes are
a. carbohydrates
b. lipids
c. nucleic acids
d. proteins
20. The protein part of an enzyme is called the
a. inhibitor
b. coenzyme
c. apoenzyme
d. activator
------------------------------------------------------------------------------------------B. Which of the following is correct/ incorrect?
(10 points)
1. Monosaccharides are simple sugars that can be categorized according to the number
of carbon atoms they contain (
)
2. Galactosemia is a severe inherited disease results in the inability of infants to metabolize
galactose (
)
3. The reducing property of hexoses is the basis of the test for sugar in blood but not
in urine (
)
4. Amino sugars are compounds that contain an amino group in place of an OH group (
)
2
5. Simple lipids are esters of organic acids (
)
6. Phospholipids are divided into 2 groups (
)
7. Precursor lipids are compounds produced from hydrolysis of simple and complex lipids (
8. Water & proteins are not the chief constituents of all cells of the body (
)
)
9. All proteins contain C, H, O, N but only some of them contain P (
)
10. Some amino acids must be taken from food, because the body can not synthesize them (
)
11. Nucleic acids are named nucleic because they were first isolated from the
mitochondria (
)
12. RNA carries the genetic information, while DNA is responsible for the synthesis
of proteins (
)
13. Adenine and Guanine are derivatives of pyrimidine (
)
14. The role of tRNA is to hold a specific amino acid for incorporation into a protein molecule
during protein synthesis (
)
15. Albinism is a genetic disease caused by the lack of the enzyme dystrophin (
16. Oncogenes are genes that trigger the uncontrolled or cancerous growth (
17. RFLP is the primary method used in DNA fingerprinting (
)
)
18. Since enzymes are proteins, they have same properties (
19. Mg2+ and Zn2+ both activate the enzyme phosphatase (
)
)
)
20. Cyclic AMP (cAMP) acts as a chemical messenger to regulate enzyme activity within
the cells that store carbohydrate and fat (
)
------------------------------------------------------------------------------------------C.
1. What is Iodine number? Explain how it helps in distinguishing between animal fats and
vegetable oils?
(3 points)
3
2. What is the role of fats in the body?
(3 points)
----------------------------------------------------------------------------------3. Describe the nitrogen cycle in nature.
(3 points)
4
4. What products are formed when a fat is hydrolyzed?
(2 points)
-----------------------------------------------------------------------------------5. When proteins are slowly hydrolyzed what products are formed?
(2 points)
-------------------------------------------------------------------------------------6. Give the general structural formula of an amino acid? Why do amino acids have an
amphoteric nature?
(3 points)
5
7. What is meant by the term isoelectric point of a protein?
(1 point)
----------------------------------------------------------------------------------8. What is a peptide linkage? What is a polypeptide? Make the possible tripeptides of the
following amino acids: Gly, Ala, Val.
(4 points)
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9. Proteins are classified according to several properties such as solubility, composition,
function, and shape. Are they further classified according to composition and function? If yes
give more details?
(4 points)
-------------------------------------------------------------------------------------10. What do you know about the colloidal nature of proteins?
(2 points)
7
11. How mRNA and tRNA function in the ribosomes during the synthesis of
a protein?
(3 points)
------The End-----Dr. Tarek M. Zaida
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