Friday, November 9, 2012

biochemistry MCQ



*1.  The most abundant biomolecule on earth *
a) proteins
b) lipids
c) nucleic acids
d) Carbohydrates

*2.  Carbohydratesnare *
a) polyhydroxy alkynes or aldehydes
b) polyhydroxy phenols or aldehydes
c) polyhydroxy ketones or aldehydes
d) polyhydroxy alkenes and aldehydes

*3.  Carbohydrates occur naturally in *
a) L- form and D-form
b) L- form only
c) D- form only
d) Dependent on the pH

*4. Which of the following polysaccharide has **α-1-3 linkage  *
a) cellulose
b) dextran
c) starch
d) glycogen

*5. The most important interaction that contribute to polysaccharide
folding  *
a) Ionic bond
b) hydrophobic interaction
c) Vanderwalls interaction
d) hydrogen bond

*6.   All of the following are extracellular heteropolyscacharides except*
a) dextran
b) chondroitin
c) hyaluronate
d) dermatan sulpahte

*7.   Functions of carbohydrates include*
a) cell recognition
b) cell to cell interaction
c) imparting structure and store energy.
d) All of the above

*8.   Lipopolysaccharide in the outer membrane is responsible for the
antigenic property in*
a) Gram positive bacteria
b) Gram positive and gram negative bacteria
c) Gram negative bacteria
d) Actinomycetes

*9.   Many plasma glycoproteins has a terminal sialic acid residue that
helps in*
a) cell to cell recognition
b) cells interaction with extracellular matrix
c) protection form degradation by liver
d) generating signals that favours degradation by liver

*10.   Lectins are*
a) Carbohydrate degrading proteins
b) proteins that binds to carbohydrates with high affinity and specificity
c) are glycoproteins that binds to carbohydrates
d) are glycoproteins present in bacteria

*11. Selectins are   *
a) Plasma membrane lectins involved in cell-cell recognition
b) cytosolic lectins involved in intracellular signalling
c) Plasma membrane glycoproteins involved in cell to cell interaction
d) Plasma membrane glycoproteins that functions as second messengers

*12.   Lectins binds preferentially to *
a) more polar region of the carbohydrate residue
b) less polar region of the carbohydrate residue
c) both polar and non-polar region of the carbohydrate residue
d) All of the above

*13. Glycosylation takes place in   *
a) SER and golgi
b) RER and golgi
c) SER, RER and golgi
d) RER, golgi and mitochondria

*14. O- linked oligosaccharides are attached to the protein via   *
a) OH group of serine or tyrosine
b) OH group of serine or threonine
c) OH group of tyrosine or threonine
d) OH group of threonine only

*15. N-linked oligosaccharides are linked to protein via NH2 groups of
Asparagine. The sequence containing asparagine is usually asp-X-ser/thr.
X can be any amino acid except   *
a) glycine
b) histidine
c) proline
d) serine



*Answers*
==========
1-d) carbohydrates
2-c) polyhydroxy ketones or aldehydes
3- c) D- form only
4- b) dextran
5-d) hydrogen bond
6- a) dextran
7- d) All of the above
8- c) Gram negative bacteria
9- c) protection form degradation by liver
10- b) proteins that binds to carbohydrates with high affinity and specificity
11- a) Plasma membrane lectins involved in cell-cell recognition
12- a) more polar region of the carbohydrate residue
13- b) RER and golgi
14- b) OH group of serine or threonine
15- c) proline



------------------------------------------ Best Wishes: Dr.Ehab Aboueladab, Tel:01007834123 Email:ehab10f@gmail.com,ehababoueladab@yahoo.com ------------------------------------------
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