Question

18. What attracts or directs the synthesis enzyme to the template in DNA Replication? a. Start Codon b. Promoter c. 5'-cap d. Primer e. Poly-A Tail

32. Which of the following statements is true regarding introns? a. human genes do not have introns b. introns encode for gene products c. introns are part of the mRNA that are translated d. introns have no function

28.Protein function? a. is determined b interaction of amino groups with other molecules b. is the same even with single amino acid modifications resulting from mutations c. will not change in different environments d. will not be affected by pH e. is dependent on its three-dimensional structure

36.There are FOUR major events in cell division. Which of the following is NOT one of them? a. Cytokinesis, the division of the cytoplasm and separation of the two new cells b. DNA segregation, which is the distribution of the DNA into the two new daugther cells c. Cell cycle arrest to allow the cells to recuperate d. Reproductive signals initiate cell division e. DNA Replication

Answer 1

18. d) option is correct. DNA dependent synthesis of new DNA is called replication which is catalysed by a metallo enzyme called DNA Polymerase. There are two basic requirements of DNA Polymerase: 1) Template- It is the single strand DNA which provide information of nucleotide selection. 2) Primer- It provides 3'OH group required for phosphodiester bond formation, primer is complementary to but always shorter than template.

32. d) option is correct. Splicing is the modification event of pre-mRNA which occurs in nucleus just after transcription but before the RNA moves to the cytoplasm. In RNA splicing, non-coding regions of pre-mRNA called introns are removed and coding regions called exons are religated. Removal of every intron requires two transesterification reaction: First transesterification reaction displaces exon from intron with 3'-OH group. Second transesterification reaction always catalysed by 3'-OH group of displaced exon at 3' splice site.

28. e) option is correct. Proteins are linear polymer of amino acids. Amino acids are organic molecules that are covalentally linked with each other to form protein. Due to bond rotation in polypeptide backbones and R chain peptide can adopt various different conformations which further determines the function of protein. Primary structure of protein represents the linear polypetide (sequence of amino acids), amino acids are linked together by peptide bond. Secondary structure is formed when primary structure fold in first step. Tertiary structure represents three dimensional structure of protein and is essential for proper function of protein.

36. c) option is correct. Cell division is an ordered series of events that leads cell division. The four major events in cell division are:

• Reproductive signals initiate cell division.
• Cell grows continuously and include DNA replication.
• DNA segregation, which is the distribution of the DNA into the two new daugther cells.
• Cytokinesis is the process by which cytoplasm is divided into two, thus generation of two daughter cells.