BT301 Midterm Short Questions

MUMAMMAD IMRAN

1. “Chargaff Rules”: 5

1. Base composition of DNA varies from one species to another.
2. The DNA isolated from different tissues of the same species has the same base composition.
3. The base composition of DNA in a given species does not change with an organism’s age, nutritional state, or changing environment.
4. In DNA, the number of adenosine residues is equal to the number of thymidine (A=T) and the number of guanosine residues is equal to the number of cytidine (G=C).
5. It means that the sum of the purine residues equals the sum of the pyrimidine residues (AG=TC).

Q2. Define gene?

a gene is a sequence of DNA or RNA that codes for a molecule that has a function. During gene expression, the DNA is first copied into RNA. The RNA can be directly functional or be the intermediate template for a protein that performs a function.

a unit of heredity which is transferred from a parent to offspring and is held to determine some characteristic of the offspring.

Q3. Natural plasmid

1. Plasmids which were not constructed in vitro for the sole purpose of cloning are called natural plasmids
2. Col E1 is a natural occurring plasmid
3. RSF2124 is a derivative of Col E1
4. pSC101 is natural plasmid from Salmonella panama

Q4. Griffith Experiment?

Griffith's experiment was an experiment done in 1928 by Frederick Griffith. It was one of the first experiments showing that bacteria can get DNA through a process called transformation. Griffith used two strains of Streptococcus pneumoniae. These bacteria infect mice, Griffith's favorite animals. Experiment: Griffith injected both S and R strains to mice. ... The R strain inherited some 'transforming principle' from the heat-killed S strain bacteria which made them virulent. And he assumed this transforming principle as genetic material. Frede performed this law in 1928. He had isolated different strains of S-Pneumoma. IS ulent and Rform is non-virulent.

rm bacteria mouse will be survive because It is a non-virulent form. - Form bacteria mouse will be died because it is a virulent form.

e heated S-Form bacteria mouse will be survive because S-type bacteria will be letely heated.

) In the heated S-type and R-type bacteria mouse will be died because some S-type bacteria will remam in the culture.

Q5. How do deoxyribonucleic acid join?

The successive nucleotides of DNA are joined together through phosphodiester linkages.

6. major and minor groove , number of nucleotide in them (3)

The major groove occurs where the backbones are far apart, the minor groove occurs where they are close together. The grooves twist around the molecule on opposite sides. Certain proteins bind o DNA to alter its structure or to regulate transcription (copying DNA to RNA) or replication (copying DNA to DNA). It is 23.7 Å wide and extends 34 Å per 10 bp of sequence. The double helix makes one complete turn about its axis every 10.4-10.5 base pairs in solution.

7. Secondary structure of proteins

 Secondary structure of proteins refers to the local conformation of some part of a polypeptide.  A few types of secondary structures are particularly stable and occur widely in proteins.  The most prominent are:- 1.  -helix A polypeptide chain is helically coiled around an imaginary axis and it makes  -helix. It is a prominent structure in the proteins. 2. βconformations Polypeptide chains stretch side by side longitudinally and form sheets. These sheets are called β – sheets.

8. Secondary, Tertiary, primary structure of protein? 5

Primary structure is the order in which what amino acid is bound the other with a peptide bond. This is coded for by the order of codons in a gene.

Secondary structure is how the chains on amino acids interact with each other to form beta barrels and alpha helixes. This structure is determined by hydrogen bonds between the different amino acids.

Tertiary structure is when the secondary structures interact with each other through disulphide bonds, hydrogen bonds, hydrophobic/hydrophilic interactions etc. This is all determined by the placement of certain amino acids within the proteins secondary structure.

9. Principle of western blotting? 3

Western blotting

a. It involves the transfer of electrophoreses protein bands from a gel on to a membrane b. The bounded proteins are then available for analysis c. Most commonly, antibodies are used to detect specific antigens

10.

hairpin like structure of RNA

 RNA has no any regular secondary structure that serves as a reference point. The threedimensional structures of many RNAs are complex and unique.  Breaks in the helix caused by mismatched or unmatched bases in one or both strands are common and result in bulges or internal loops.  Hairpin loops form between nearby self-complementary sequences.

Q11. What type of cell can be transformed using liposomes?

Animal cells, protoplasts (without cell wall) of yeast and plant are susceptible to transformation by liposomes.

Q12. Relaxed plasmid?

A plasmid that replicatesindependently of the main bacterial chromosome and is present in 10500 copies per cell.

Q13. What is the role of electroporation?

Electroporation. Electroporation, or electropermeabilization, is a microbiology technique in which an electrical field is applied to cells in order to increase the permeability of the cell membrane, allowing chemicals, drugs, or DNA to be introduced into the cell (also called electrotransfer).

Q14. Define green biotechnology with example. (3 marks)

Green Biotechnology

It is concerned with the modification of the genetic composition of plants to enhance existing traits or add new ones.

An additional gene was inserted into the normal genome of this corn that triggers the production of proteins that then protect the plant from harmful insects. This reduces the need for pesticides & increases crop yields

Green Biotechnology

Example

Bt corn from Syngenta

Bt cotton from Monsanto

15. · Write about electroporation role? technique · Electroporation

a. A rapid and simple technique for introducing cloned genes into a wide variety of microbial, plant and animal cell, including E. coli,is electroporation b. In electroporation, electric field is applied to cells in order to increase permeability of the cell membrane to take DNA

Q16. Electroporation techniques?

Electroporation. Electroporation, or electropermeabilization, is a microbiology techniquein which an electrical field is applied to cells in order to increase the permeability of the cell membrane, allowing chemicals, drugs, or DNA to be introduced into the cell (also called electrotransfer).

17. Major Techniques used for Genomes Characterization:

1. Cloning 2. Hybridization 3. PCR amplification 4. Sequencing 5. Computational tool

1 Genomes Characterization Techniques - Cloning

Genomes digested with restriction enzymes and inserted in vectors to produce genomic libraries. Examples of such libraries are: BACSs YACSs Bacterial Artificial Chromosomes (BACs) were used to prepare genomic libraries. Yeast Artificial Chromosomes (YACs) were used to prepare genomic libraries for the sequencing of the genomes.

2 Genomes Characterization Techniques - Hybridization

To arrange large contigs of genomes to produce genetic maps and physical maps of genomes.

3 Genomes Characterization Techniques – PCR

• Technique to amplify the DNA. Different variants of the technique used

4 Genomes Characterization Techniques – DNA Sequencing

One of the important technique used to characterize the genomes . To study structure and function of genomes. DNAs are amplified and sequenced (Figure):

5 Genomes Characterization Techniques – Computational Tools

• Used to align the sequenced DNA to produce physical maps of the genomes.

18. Name any five amino acids (3)

These six are arginine, cysteine, glycine, glutamine, proline, and tyrosine. Five amino acids are dispensable in humans, meaning they can be synthesized

in sufficient quantities in the body. These five are alanine, aspartic acid, asparagine, glutamic acid and serine.

Q19. What factor affect the DNA mobility in electrophoresis gel?

Concentration of gel either high concentration or lower concentration. Ionic strength of buffer. Voltage Ethidium bromide (A chemical used as a stain to dye gel)

20.

Restriction modification

•  Host-controlled restriction/ modification
•  Restriction system allow bacteria to monitor the origin of incoming DNA
•  When the incoming DNA is a bacteriophage genome, the effect is to reduce the efficiency of plating i.e. o to reduce the number of plaques in plating test