BIO203 Final Term Current Paper 2020 by Amaan Khan

BIO 203 Current Final Term Fall 2020

Qno1: Difference between Blotting Technique on basis of detection.

SOUTHERN BLOTTING

The Southern blot is used to detect the presence of a particular piece of DNA in a sample by a molecular probe.

NORTHERN BLOTTING

Northern blot is a method used for detection of a specific RNA sequence in RNA samples.

Qno2: Write down the limitations of Western blotting?

A minute imbalance at any level blotting of the procedure can skew the results of the entire process. Incorrect labeling of the protein can happen due to the reaction of secondary antibody. Cause erroneous in bands or no bands due to insufficient transfer. Well trained technicians are required for this technique. Primary antibody availability is crucial. It is just a semi-quantitative at best. Only an approx. estimation & not a precise measurement of molecular weight of the protein are possible.

Qno3: Nomenclature of enzyme.

A suitable system was proposed by Smith and Nathans (1973)

organisms is identified by the first letter of genus and first two letters of specific epithet

Strain identification is written as EcoK In case, host strain has several restriction and modification systems, these are identified by roman numerals, for example, in case of H. influenzae

•  HindI, HindII, HindIII etc.

All restriction enzymes have general name endonuclease Rand modification-methylase M followed by the system name, for example, in case of H. influenzae

•  R. HindIII or M. HindIII.

Qno4. Write properties of probes?

PROBES

฀ Labeled material to detect a target. ฀ For DNA: 20-30 nucleotides, complementary to a region in the gene or DNA.

Qno5: Write applications of PCR in clinical microbiology.

PCR-Medicine PCR has major impact on medicine especially in the field of clinical microbiology or diagnosis. Molecular tools have also allowed performing prenatal genetic diagnosis.

Qno6: Explain R-M system.

Types of restriction and modification (R-M) system

-M systems are known

Type I

first to be characterized from E. coli K12

consists of two restriction subunit, two modification subunit and one recognition subunit

ittle value for gene manipulation.

Type II

-M system is Type II.

recognize a defined sequence and cut within it.

Type III

symmetrical recognition sequences but otherwise resemble type I systems and are of little value.

Type IIs Type IIs systems have similar cofactors and structure to type II but restriction occurs at a distance from recognition site that limits their usefulness.

Qno7: Define SNP.

A SNP is defined as a single base change in a DNA sequence that occurs in a significant proportion (more than 1 percent) of a large population.

Qno8: Write down method of DNA Finger printing.

Types of DNA fingerprinting methods are…

• Electrophoresis.
• Polymerase chain reaction (PCR).
• Restriction fragment length polymorphism (RFLP).
• Random Amplified Polymorphic DNA (RAPD).
• Amplified fragment length polymorphism (AFLP).

Qno9: Explain Western Blotting.

WESTERN

BLOTTING

฀ To determine the molecular weight of a protein. ฀ To measure relative amounts (quantitation) of the protein present in complex mixtures of proteins that are not radiolabeled.

one of the most common analytical tools for the detection of viral proteins.

on of monoclonal and polyclonal antibody preparations and in determining the specificity of the immune response to viral antigens.

Qno10: When does RFLP occur?

An RFLP occurs when the length of a detected fragment varies between individuals. Each fragment length is considered an allele, and can be used in genetic analysis.

Qno11: Write down benefits is secondary antibodies in western blotting.