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Wednesday, November 24, 2010

Molecular Biology CSIR NET Paper 2 Questions

Hi friends,
                 These are few questions from csir net paper 2 help me sort the answers

  1. Why dna replication occur in 5'-3' and not in 3'-5' ? Explain.
  2. Why ppl with Xeroderma pigmentosum develop neurological symptoms.
  3. Differentiate transcription from transactivation
  4. why the clamp loader in E.coli DNA pol III located assymetrically on the holoenzyme
  5. What's the effect of leader peptide sequence deletion on trp operon regulation
  6. whats the chemical difference between groups joined by dna pol and dna ligase.experimentally demonstrate it.
  7. what wil happen if TATA sequence is absent in the eukaryotic gene


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Mahantesh.I.B
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Cell Biology Multiple Choice Questions for GATE

1. Which of the following in not true of the nuclear envelope?A. The nuclear envelope is exactly like other cellular membranes.
B. The nuclear envelope separates the genetic material from the cytoplasm.
C. The nuclear envelope is a pair of concentric membranes.
D. The nuclear envelope is studded with pores.

2. Which cytoplasmic fibrils are most like the nuclear lamins?A. Microtubules
B. Microfilaments
C. intermediate filaments
D. actomyosin

3. What kind of molecules must pass between the nucleus and the cytoplasm?A. DNA
B. Protein
C. Lipids
D. Carbohydrates

4. Which statement best characterizes the nuclear localization signal?A. The NLS is typically a small molecular weight metabolic intermediate.
B. The NLS is a stretch of hydrophobic amino acids on a protein's N terminus.
C. The NLS is one or two stretches of basic amino acids on a protein's C-terminus.
D. The NLS is a steroid that binds to DNA.

5. Which sequence represents increasing levels of chromosomal organization, from most dispersed to most condensed?A. nucleosomes–30 nm filaments–supercoiled loops–mitotic chromosomes
B. nucleosomes–supercoiled loops–30 nm filaments–mitotic chromosomes
C. nucleosomes–30 nm filaments–mitotic chromosomes–supercoiled loops
D. mitotic chromosomes–30 nm filaments–supercoiled loops–nucleosomes

6. When chromatin is treated with nonspecific nucleases, what is the length of the resulting pieces of DNA?A. random numbers of base pairs
B. about 60 base pairs
C. about 8 base pairs
D. about 200 base pairs

7. Which of the following statements about histones is not true?A. Histones are very similar between species.
B. Histones have many basic amino acids.
C. Histones are rich in lysine and arginine.
D. Each histone has one single gene that codes for it.

8. In mammalian cells, the DNA of the centromere is characteristic of:A. facultative heterochromatin.
B. constitutive heterochromatin.
C. Euchromatin.
D. dispersed chromatin.

9. Why are adult women genetic mosaics?A. Inactivated X chromosomes are all derived from the male parent.
B. Inactivated X chromosomes are all derived from the female parent.
C. Inactivated X chromosomes can be from either the male or the female parent.
D. None of these are correct.

10. What do telomeres do?A. They protect the chromosomes from degradation by nucleases.
B. They prevent the ends of chromosomes from fusing with one another.
C. They are required for complete chromosomal replication.
D. All of these are correct.

11. When all or a piece of a chromosome becomes attached to another chromosome, the aberration is called a(n):A. inversion.
B. translocation.
C. deletion.
D. duplication.

12. If there were a mutation in the regulatory gene of an inducible promoter rendering the protein incapable of binding to the repressor, then:A. the structural genes would always be expressed.
B. the structural genes would never be expressed.
C. the structural genes would only be expressed in the presence of the inducer.
D. the structural genes would only be expressed in the absence of the inducer.

13. Which of the following is a difference between inducible versus repressible operons?A. In an inducible operon, the inducer binds to the regulator protein.
B. In a repressible operon, the corepressor-regulator complex binds to the operator.
C. In a repressible operon, all the structural gene products have related functions.
D. In an inducible operon, RNA polymerase binds to the promoter.

14. Which of the following is not a characteristic of transcription factors?A. Transcription factors always have two fold rotational symmetry.
B. Active transcription factors are commonly dimers.
C. Transcription factors are rich in basic amino acids.
D. Transcription factors have one of a few DNA-binding motifs.

15. Eukaryotes regulate gene expression at all of the following levels except:A. transcription.
B. translation.
C. RNA processing.
D. All of these are correct.

16. To stimulate transcription, enhancer sequences:A. must be within a few base pairs of the gene they enhance.
B. must be within a few hundred base pairs of the gene they enhance.
C. can be tens of thousands of base pairs away from the genes they enhance.
D. will not function if they are moved experimentally.

17. Coactivators assist in transcriptional activity by:A. interacting with general transcription factors.
B. modifying the activity of RNA polymerase II directly.
C. Changing chromatin structure to make transcription of certain genes more accessible.
D. All of these are correct.

18. Alternate splicing means that:A. the same gene can code for several different proteins.
B. several different genes can code for the same protein.
C. gene expression can be regulated at the level of transcription.
D. pieces of DNA can move around within the genome.

19. Which of the following statements is true?A. A cell can potentially make fewer different proteins than the number of different genes it contains.
B. A cell can potentially make only the same number of different proteins as the number of different genes it contains.
C. A cell can potentially make more different proteins than the number of different genes it contains.
D. None of these are correct.

20. The longevity of mRNA is related to:A. the length of the poly (A) tail.
B. the 5' cap on the mRNA.
C. All of these are correct.
D. None of these are correct



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Thank you&Regards
Mahantesh.I.B
support4bt@gmail.com
www.biotrack.yolasite.com
www.sitbiotech.blogspot.com
+91 9611558989
+91 9037652343



Immunology Multiple Choice Questions

1. Which of the following is not characteristic of an innate immune response?A. Inflammation
B. increase in blood levels of specific antibodies
C. increase in phagocytic cells at the site of infection
D. activation of complement

2. List the order in which the events involved in humoral immunity occur:
I B cell activation by TH cell
II B cell proliferation
III Antigen processing and display by APC
IV TH cell activation by professional APC
V Antibody production and secretion

A. III-IV-I-II-V
B. III-II-IV-V-I
C. V-III-II-I-IV
D. IV-III-II-I-V

3. According to the widely-accepted clonal selection theory:A. all the antibodies you will ever be able to make are already present in lymphoid tissue.
B. most of your lymphoid cells will never be recruited by antigen to produce antibodies.
C. cells in the lymph tissues look alike under the microscope, but differ in their affinity for foreign proteins.
D. All of these are correct.

4. Spleen cells from a mouse are separated and passed over column A containing beads coated with an antigen that the mouse has never encountered. The cells that are not retained by column A are poured over column B containing beads coated with an antigen the mouse has encountered in its life. What happens?A. A few cells stick to column A, but none stick to column B.
B. Many cells stick to column A, but only a few stick to column B.
C. No cells stick to column A, but many stick to column B.
D. A few cells stick to column A, but many stick to column B.

5. You are studying a particular type of immune cell, but you are not sure which type it is. It is a relatively large, ovoid cell and has an extensive array of rough endoplasmic reticulum. Biochemical studies indicate that your cells lack any surface cluster designation (CD) proteins. What kind of cell might you have?A. plasma cell
B. TH lymphocyte
C. natural killer cell
D. dendritic cell

6. Of the following cell types, which ones function in both innate and acquired immune responses and as "professional" antigen presenting cells?A. Dendritic cells
B. CTLs
C. TH lymphocytes
D. B cells

7. TH lymphocytes activate macrophages, CTLs, and B cells, but what activates TH cells?A. macrophages and/or dendritic cells
B. TH cells (i.e., self-activation)
C. IL-1 and IL-2
D. All of these are correct.

8. The _______ portion of an antibody molecule determines the antigen binding specificity, whereas the _______ portion determines the class to which it belongs.A. Heavy variable, light constant
B. IgM, IgG
C. light and heavy variable, heavy constant
D. light variable, heavy variable

9. Antibodies present in breast milk are taken up by the infant's stomach via receptor-mediated endocytosis. Which portion of the antibody molecule is most likely recognized by the infant's receptors?A. CH
B. VL
C. VH
D. CL

10. Which of the following is not a source of genetic diversity in immunoglobulin genes?A. multiple V exons and J exons in the DNA germ line
B. variability in V-J joining
C. genetic transposition
D. enzymatic insertion of nucleotides by deoxynucleotide transferase

11. The genetic rearrangements that occur when antibody-producing cells mature areA. temporary; the original genetic sequences are restored after antibody production ceases.
B. phenotypic; they do not involve the DNA.
C. permanent; a cell that has undergone genetic rearrangement is forever limited in the kinds of antibodies it can produce.
D. nonexistent; they are an artifact of the techniques used to study antibody production.

12. The significance of class switching is that the B cell lineage canA. recognize the same antigen but perform different effector functions.
B. perform the same effector function on different antigens.
C. convert to a T cell lineage.
D. All of these are correct.

13. The B cell receptor is to the intact antigen as the T cell receptor is to __________.A. humoral immunity.
B. cell-mediate immunity.
C. processed antigen fragments.
D. the intact antigen, also.

14. Professional antigen presenting cells have ________, whereas most other cells have ________.A. MHC I; MHC I and II
B. MHC II; MHC I
C. MHC I and II; MHC II
D. MHC I; MHC II

15. What is the purpose of antigen-presenting MHC proteins on cells that are not part of the immune system?A. They evolved to alert the immune system to the presence of intracellular pathogens.
B. They evolved to prevent tissue transplantation between individuals.
C. They evolved to rid the cell of endogenous protein.
D. They have no known function in non-immunological tissues.

16. The role of the Ii protein in class II MHC complexes isA. to display "self" proteins on the surface of APCs.
B. to target the MHC complex to the Golgi.
C. to provide targeting to lysosomes and a substrate for lysosomal enzymes.
D. to prevent the MHC from binding an endogenous peptide before it encounters an antigen fragment.

17. When you meet someone you find attractive, you might speak of having a certain "chemistry" with that person. What real chemistry might underlie your instinctive attraction?A. You share certain genes in common with that person.
B. Your different MHC genotypes would maximize the chances that any offspring you produce could recognize and fight pathogens.
C. Your similar MHC genotypes would ensure that you could donate tissue to that person in the event of an emergency.
D. You share the same abilities to make antibodies.

18. Which of the following is not a signal pathway between an activated B cell and a TH cell?A. CD40 and CD40 ligand
B. Cytokines
C. Neurotransmitters
D. neither CD40 and CD40 ligand nor Cytokines are signal pathways.

19. Of the following intracellular cascades invoked by signal transduction, which is novel to activation by cytokines?A. ras and the MAP kinase cascade
B. phosphatidylinositol 3-hydroxy kinase (PI(3)K) and membrane-bound lipid messengers
C. phospholipase C and the IP3 and DAG pathway
D. the JAK-STAT pathway for activating tyrosine kinases

20. Strep throat is a bacterial infection that can be followed several weeks later by rheumatic fever, an autoimmune disorder affecting the heart. How can the bacterial infection lead to the autoimmune disorder?A. Antibodies against Streptococcus cross react with a glycoprotein on heart valves.
B. The heart valves are weakened by the massive immune response to the bacterium.
C. Streptococcus bacteria escape the immune system and take up residence in the heart.
D. Streptococcus stimulates the heart valves to make antibodies.



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Thank you&Regards
Mahantesh.I.B
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www.biotrack.yolasite.com
www.sitbiotech.blogspot.com
+91 9611558989
+91 9037652343



COUNT DOWN STARTS FOR GATE 2011 (83 days left)

Hey Guys,
 Dak.. Dak.. Dak.. Your heart beats more, because the count down for GATE 2011 Started.
Let us discuss abt the preparations , we made till now.and also on the topics ,we havent concentrated much with other Gate 2011 Aspirants. we have 83 days left before us. Let us use this minimal time more efficiently.

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Thank you&Regards
Mahantesh.I.B
support4bt@gmail.com
www.biotrack.yolasite.com
www.sitbiotech.blogspot.com
+91 9611558989
+91 9037652343



National Symposium On Immunobiotechnology at Nainital

National Symposium
On
Immunobiotechnology
December 17-19, 2010
Venue: Institute of Biotechnology
(G.B. Pant University of Agri. & Tech.)
Patwadangar -263 128 (Nainital)
Uttarakhand, India

Introduction
Immunity is the resistance of body against extraneous etiological factors of disease, which is afforded by the interaction of chemical, humoral and cellular reactions in the body. This is an integral part of the body without which one cannot think of life. During the process of evolution, nature has provided this defence mechanism in the body of all living creatures particularly of higher animals and man that protects them from physical, chemical and biological insults. It can be classified as natural or
paraspecific and acquired or specific immunity. Due to increase resistance in bacteria, the efficacy of antibacterial drugs is reduced, in such circumstances immunomodulation with an aim to increase the immune power of body remains only alternative to control the infections.

Various types of immunomodulatory products are described including physiological products, chemicals, microbial products, herbal products etc. of which herbal immunomodulators based on ancient Indial Ayurveda System of medicine were more effective without causing any side effects or drug related problem.immunomodulation is one of the most important alternatives in order to control the diseases with additional advantages of amplifying specific responses to vaccines. The immunomodulatory compounds also offer the prospects of reversing immunosuppression caused by stress, viruses or environmental pollution. The convention aims to bring researchers, scientists and students together to exchange
and share their experiences, new ideas and the research outcome through the presentation and discussion of papers of all possible aspects of Immunobiotechnology.

Society for Immunology and Immunopathology

The Society for Immunology and Immunopathology (SIIP) was established with the aim to provide a forum for its members to participate in conventions/symposia/workshops/ training etc. and to provide a recent updated literature in the form of journal/newsletter.



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Thank you&Regards
Mahantesh.I.B
support4bt@gmail.com
www.biotrack.yolasite.com
www.sitbiotech.blogspot.com
+91 9611558989
+91 9037652343