Question

Trivia Questions 1. This level of control in gene expression prevents a gene from being transcribed when it is not needed. 2. These genes produce proteins that govern the activity of structural genes. 3. These intervening sequences are cut out of an mRNA transcript before it can leave the nucleus. 4. A chromosome is made up of these two molecules. 5. This term refers to DNA that is composed of at least two species. 6. These two vectors are used to deliver a foreign gene into a host cell. 7. This molecule transports an amino acid to the ribosome where proteins are made. 8. This technique is used to create a DNA fingerprint by analyzing DNA sequences that are 3-5 bases long and are repeated multiple times. 9. These chromosomal ends help protect the integrity of the chromosome. 10. This technique is wholly automated and uses DNA polymerase from a heat-adapted bacterium harvested from Yellowstone.

Answer 1

1. Transcriptional control. It is the control of gene expression, by blocking the transcription of DNA to mRNA. Here regulatory proteins called repressors binds on the promoter region, therby blocking the binding of RNA polymerase. Thus the transcription of gene is blocked, thereby controlled the synthesis of the specific protein.

2. Regulatory genes. These genes are meant for regulating the expression of other genes. They codes for regulatory proteins, which binds to the regulatory regions of the DNA. After binding to the regulatory region they either promote ( called enhancers) the expression of the structural genes or repress( repressors) the expression of them.

3. Introns. These are the intervening nucleotide sequences between the exons. Exons are part of the mature mRNA, which will express during the protein synthesis. But the introns are not part of mature mRNA, are are cleaved from the pre-mRNA, by a process called RNA splicing. During the process the introns are being cleaved off and the exons are joined together to create the mature mRNA. RNA splicing occurs in the nucleus, after which the mature mRNA is released to the cytoplasm.

4. The chromosome is made up of deoxyribonucleic acid (DNA) and proteins.The chromosome have its tightly coiled DNA around the protein called histone. Histone helps the DNA to be packed properly. Histones are positively charged protiens.

5. Recombinant DNA ( rDNA ). These are DNA molecules formed by bringing together the DNA from two or more species. They are used in recombinat DNA technology to produced desirable gene products by gene cloning. Here the rDNA is transferred to a host using the vector. Inside the host cell, the rDNA will multiply and produces the gene product. Production of vaccine is an example.

6. Plasmid, bacteriophage vector. Vectors are used to transfer rDNA to the host cell. Plasmids are based on E.coli cells. These are extra chromosomal circular DNA molecules in the bacteria, which can replicate themselves. These plasmids are added with some genes, along with the foreign DNA. It is then inserted to the host cell. Bacteriophage vector is viral based. Bacteriophages are viruses which infects the bacterial cells, by injecting their genome to the bacteria.( E. coli). Thus these viruses are modified with the addition of gene of interest and is allowed to infect the bacteria, to make the bacterial cells transformed with the foreing gene.

7. tRNA molecule. The tRNA stands for transfer RNA. because they are RNA molecules meant to carry amino acids to the ribosome, during protein synthesis. The tRNA is having nucleotide sequence complementary to the three letter codon in the mRNA. The anticodon in tRNA carries specific aminoacid coded by the mRNA molecule, and brings it to the ribosome , to produce the protein molecule.

8. Gel electrophoresis. Here the DNA fragments are run throgh the gel across the electric field. The DNA being negatively charged, move towards the positive side on the gel. Also the rate of migration of DNA fragments vary with their size. Longer fragments move slowly,and shorter fragments move fast. After the process we get a band pattern, called DNA fingerprint, which is then analysed.

9. Telomeres. These are seen on both ends of the chromosome, and is made up of repetitive nucleotide seuences. It helps to protect the integrity of chromoome by preventing fusion with neighbouring chromosomes.

10. PCR. Polymerase Chain Reaction. It is the technique used for the rapid production of millions of copies of specific DNA molecule. Since the reaction occurs, at different stages like denaturation, primer annealing and extension , different temperature ranges are there for each step. During the annealing 48-72 degree celsius temperature is maintained. During the extension, 68-72 degre celsius is maintained. The normal polymerase enzyme will be denatured in the high temperature set up in the PCR. Therefore, Taq polymerase, from the bacteria Thermus aquaticus is used in PCR. These are seen in hotsprings, thus can withstand high temperature.