BIO302 Final Term Mega File by Biotech Brainy Bunch

SHORT QUESTIONS

Q1. Two use of nitrogen mustard gas?

Mustard gas is a vesicant warfare agent synthesized by Fredrick Guthrie in 1860. It was widely used as a weapon during WWI by both sides of the conflict with particularly harmful and deadly effects. It was responsible for 1,205,655 non-fatal casualties and 91,198 deaths.

Q2. What are psi and phi values in a helix structure and mention value?

The phi angle is the angle between the alpha carbon atom and the nitrogen while the psi angle is the angle between the alpha carbon and the carbon of the carbonyl group. Typical value are Φ = - 140 degrees and Ψ = 130 degrees. In contrast, alpha helical residues have both negative 𝜑 and 𝜓 angles. A section of polypeptides residue with in the beta-conformation is referred to as a beta strand can associate by main chain hydrogen bonding interactions to forma sheet.

Q3. How many classes of splicing found in cell?

In cells, two type of splicing is found including alternative splicing and constitutive splicing. There are three kinds of self-splicing introns, Group I, Group II and Group III. Group I and II introns perform splicing similar to the spliceosome without requiring any protein. The similarity suggests that Group I and II introns may be evolutionarily related to the spliceosome.

Q4. What are the two RNA polymerase present in the eukaryotic other than RNA pol II and how the different from RNa pol II?

BIO302 FINALTERM SUBJECTIVE MEGA FILE · GROUP: BIOTECH BRAINY BUNCH · ALL DATA FROM PAST PAPERS (2018-2022) · ADMINS: MEHWISH MUGHAL & BELLA

Transcription in eukaryotes involves one of the three types of polymerases, depending on the gene being transcribed. RNA polymerase II transcribes all of the protein-coding genes, whereas RNA polymerase I transcribes rRNA genes, and RNA polymerase III transcribes rRNA, tRNA, and small nuclear RNA genes.

Q5. Define nuclear Scaffold, bacterial core and enzyme?

Nucleus Scaffold: The activity of type II topoisomerases is also critical to the segregation of large linear molecules. Although there is no inherent topological linkage after the replication of a linear molecule, the large sized chromosomes necessitates the intricate folding of the DNA into loops which are attached to a protein scaffold. These attachments lead to many of the same problems that circular chromosomes have after replication. This process occurs in nucleus, that’s why it is known as nucleus scaffold.

Bacterial Core: The bacterial core genes are defined as single-copy, homologous genes that are present in most of the known bacterial species.

Enzyme: An enzyme is a biological catalyst and is almost always a protein. It speeds up the rate of a specific chemical reaction in the cell. The enzyme is not destroyed during the reaction and is used over and over.

Q6. What will happen to cellular machinery and function if pyrimidine dimer is not removed?

These dimers distort the DNA structure and results in errors during DNA replication. They form an extra phosphodiester bond between them. They prevent the transcription of the DNA into RNA. If this damage does not repair, it will cause severe diseases such as Xeroderma pigmentosum and Cockayne Syndrome. Affected individuals have extreme sensitivity to the sunlight and develop skin cancers due to thymine dimer passing on generations to generations.

Q7. Mismatch repair system ?

Essential components of the MMR-system are MutS, MutL, MutH and Uvr.DNA mismatch repair functions to correct replication errors in newly synthesized DNA and to prevent recombination between related, but not identical (homologous), DNA sequences. The mechanism of mismatch repair is best understood in Escherichia coli.

Q8. Names of types of Mutations?

There are three types of DNA mutations:

•  base substitutions
•  deletions
•  insertions.

Q9. Write types of splicing?

Two different modes of splicing have been defined, that is: constitutive splicing and alternative splicing.

Q10. Template primer junction?

The primer is a short piece of RNA or DNA that is complementary to the 3' end of the template DNA and which provides a 3'-OH for DNA polymerase to add new nucleotides to. DNA polymerase cannot begin synthesis of a new strand of DNA without a primer.

Q11. Secondary structure of RNA?

Nucleus acid secondary structure is the base pairing interactions within a single nucleic acid polymer or between two polymers. I can be represented as a list of bases which are paired in a nucleic acid molecule. At a fundamental level, RNA secondary structure consists of nucleotides that are in one of two states, paired or unpaired, where pairing includes all base-base interactions. In general, most base pairings are adjacent and antiparallel with other base pairings to form secondary structure helices.

Q12. Explain termination sequence?

Two termination mechanisms are well known:

Intrinsic termination: (also called Rho-independent transcription termination) involves terminator sequences within the RNA that signal the RNA polymerase to stop. The terminator sequence is usually a palindromic sequence that forms a stem-loop hairpin structure that leads to the dissociation of the RNAP from the DNA template.

Rho-dependent termination: uses a termination factor called ρ factor (rho factor) which is a protein to stop RNA synthesis at specific sites. This protein binds at a rho utilisation site on the nascent RNA strand and runs along the mRNA towards the RNAP. A stem loop structure upstream of the terminator region pauses the RNAP, when ρ-factor reaches the RNAP, it causes RNAP to dissociate from the DNA, terminating transcription

OR

Once the polymerase has transcribed the length of the gene (or genes), it must stop and release the RNA product (as well as dissociating from the DNA itself). This step is called termination.

Q13. Write function of RNA ploymerase?

RNA polymerase is an enzyme that is responsible for copying a DNA sequence into an RNA sequence, duyring the process of transcription. In bacteria, RNA polymerase exists in two states. One form, known as the core enzyme, can catalyze RNA synthesis but is unable to bind to