Chapter 11 Biotechnology Principles and Processes Solutions
Question - 1 : - Can you list 10 recombinant proteins which are used in medical practice? Find out where they are used as therapeutics (use the internet).
Answer - 1 : -
Recombinant proteins are obtained from the recombinant DNA technology. This technology involves the transfer of specific genes from an organism into another organism using vectors and restriction enzymes as molecular tools.
Ten recombinant proteins used in medical practice are −
| Recombinant protein | Therapeutic use |
| 1. | Insulin | Treatment for type I diabetes mellitus |
| 2. | Interferon-α | Used for chronic hepatitis C |
| 3. | Interferon -β | Used against herpes and viral enteritis |
| 4. | Coagulation factor VIII | Treatment of haemophilia A |
| 5. | Coagulation factor IX | Treatment of haemophilia B |
| 6. | DNAase I | Treatment of cystic fibrosis |
| 7. | Anti-thrombin III | Prevention of blood clot |
| 8. | Interferon B | For treatment of multiple sclerosis |
| 9. | Human recombinant growth hormone | For promoting growth in an individual |
| 10. | Tissue plasminogen activator | Treatment of acute myocardial infarction |
Answer - 2 : - The name of the restriction enzyme is Bam H 1.
Question - 3 : - From what you have learnt, can you tell whether enzymes are bigger or DNA is bigger in molecular size? How did you know?
Answer - 3 : - Enzymes are smaller in size than DNA molecules. This is because DNA contains genetic information for the development and functioning of all living organisms. It contains instructions for the synthesis of proteins and DNA molecules. On the other hand, enzymes are proteins which are synthesised from a small stretch of DNA known as ‘genes’, which are involved in the production of the polypeptide chain.
Question - 4 : - What would be the molar concentration of human DNA in a human cell? Consult your teacher.
Answer - 4 : -
The molar concentration of humanDNA in a human diploid cell is as follows:
⇒ Total number of chromosomes × 6.023 × 1023
⇒ 46 × 6.023 × 1023
⇒ 2.77 ×1018 Moles
Hence,the molar concentration of DNA in each diploid cell in humans is 2.77 × 10 23 moles.
Question - 5 : - Do eukaryotic cells have restriction endonucleases? Justify your answer.
Answer - 5 : - No, eukaryotic cells do not have restriction endonucleases. This is because the DNA of eukaryotes is highly methylated by a modification enzyme, called methylase. Methylation protects the DNA from the activity of restriction enzymes .These enzymes are present in prokaryotic cells where they help prevent the invasion of DNA by virus.
Question - 6 : - Besides better aeration and mixing properties, what other advantages do stirred tank bioreactors have over shake flasks?
Answer - 6 : -
The shake flask method is used for a small-scale production of biotechnological products in a laboratory. On the other hand, stirred tank bioreactors are used for a large-scale production of biotechnology products.
Stirred tank bioreactors have several advantages over shake flasks:
(1) Small volumes of culture can be taken out from the reactor for sampling or testing.
(2) It has a foam breaker for regulating the foam.
(3) It has a control system that regulates the temperature and pH.
Question - 7 : - Collect 5 examples of palindromic DNA sequences by consulting your teacher. Better try to create a palindromic sequence by following base-pair rules.
Answer - 7 : -
The palindromic sequence is a certain sequence of the DNA that reads the same whether read from 5’ → 3’ direction or from 3’→ 5’ direction. They are the site for the action of restriction enzymes. Most restriction enzymes are palindromic sequences.
Five examples of palindromic sequences are:
Question - 8 : - Can you recall meiosis and indicate at what stage a recombinant DNA is made?
Answer - 8 : - Meiosis is a process that involves the reduction in the amount of genetic material. It is two types, namely meiosis I and meiosis II. During the pachytene stage of prophase I, crossing over of chromosomes takes place where the exchange of segments between non-sister chromatids of homlogous chromosomes takes place. This results in the formation of recombinant DNA.
Question - 9 : - Can you think and answer how a reporter enzyme can be used to monitor transformation of host cells by foreign DNA in addition to a selectable marker?
Answer - 9 : - A reporter gene can be used to monitor the transformation of host cells by foreign DNA. They act as a selectable marker to determine whether the host cell has taken up the foreign DNA or the foreign gene gets expressed in the cell. The researchers place the reporter gene and the foreign gene in the same DNA construct. Then, this combined DNA construct is inserted in the cell. Here, the reporter gene is used as a selectable marker to find out the successful uptake of genes of interest (foreign genes). An example of reporter genes includes lac Z gene, which encodes a green fluorescent protein in a jelly fish.
Question - 10 : - Describe briefly the followings:
Answer - 10 : -
(a) Origin of replication
(b) Bioreactors
(c) Downstream processing
Answer
(a) Origin of replication −Origin of replication is defined as the DNA sequence in a genome from where replication initiates. The initiation of replication can be either uni-directional or bi-directional. A protein complex recognizes the ‘on’ site, unwinds the two strands, and initiates the copying of the DNA.
(b) Bioreactors − Bioreactors are large vessels used for the large-scale production of biotechnology products from raw materials. They provide optimal conditions to obtain the desired product by providing the optimum temperature, pH, vitamin, oxygen, etc. Bioreactors have an oxygen delivery system, a foam control system, a PH, a temperature control system, and a sampling port to obtain a small volume of culture for sampling.
(c) Downstream processing − Downstream processing is a method of separation and purification of foreign gene products after the completion of the biosynthetic stage. The product is subjected to various processes in order to separate and purify the product. After downstream processing, the product is formulated and is passed through various clinical trials for quality control and other tests.