With reference to the recent developments in science, which one of the following statements is not correct?
Correct Answer:
(A)
Functional chromosomes can be created by joining segments of DNA taken from cells of different species.
Ques:
2
With reference to recent developments regarding ‘Recombinant Vector Vaccines’, consider the following statements:
Genetic engineering is applied in the development of these vaccines.
Bacteria and viruses are used as vectors.
Which of the statements given above is/are correct?
Correct Answer:
(C)
Both 1 and 2
Live recombinant vector vaccines are made of a live attenuated viral or bacterial strain used as a vector to carry the gene or genes encoding the desired vaccine antigens. In these vaccines live viral or bacterial vector is genetically engineered to express a variety of exogenous antigens in the cytoplasm of targeted T cells. Live recombinant vector vaccines have a number of attractive features, including the ability to stimulate both humoral and cell-mediated immunity. Recombinant vector vaccines (platform-based vaccines) act like a natural infection, so they're especially good at teaching the immune system how to fight germs.
Note: Recombinant DNA Technology is used to cut a known DNA sequence from one organism and introduce it into another organism thereby altering the genotype of the recipient. Foreign DNA sequences can be introduced into bacteria, yeast, viruses, plant and animal cells. Thus, genetic engineering (or recombinant DNA technology) allows selected individual gene sequences to be transferred from an organism into other and also between non-related species.
Steps in producing recombination DNA: → Identification and isolation of genetic material → Fragmenting the obtained DNA → Isolation of desired DNA fragments → Amplification of gene of interest → Ligation of DNA fragmentation into the vector → Transfer of recombinant DNA into the host cell/organism → Obtaining the foreign gene product → Downstream processing.
Ques:
3
What is Cas9 protein that is often mentioned in news?
Correct Answer:
(A)
A molecular scissors used in targeted gene editing
Cas9 protein (CRISPR associated protein 9) is actually a molecular scissors used in targeted gene editing. Its main function is to cut DNA and therefore it can alter a cell’s genome. In CRISPR-Cas9 gene editing technique, the ‘CRISPR’ stands for ‘clustered regularly interspaced short palindromic repeats’, which are specialized stretches of DNA. While the ‘Cas9’ is an enzyme that acts like a pair of molecular scissors capable of cutting strands of DNA. This technology was adapted from the natural defence mechanisms of bacteria and archaea. By delivering the Cas9 molecule complexed with a synthetic guide RNA (gRNA) into a cell, the cell’s genome can be cut at a desired location, allowing existing genes to be removed and/or new ones added.
Ques:
4
‘RNA interference (RNAi)’ technology has gained popularity in the last few years. Why?
It is used in developing gene silencing therapies.
It can be used in developing therapies for the treatment of cancer.
It can be used to develop hormone replacement therapies.
It can be used to produce crop plants that are resistant to viral pathogens.
Select the correct answer using the code given below:
Correct Answer:
(A)
1, 2 and 4
RNA interference (RNAi) is a biological process in which RNA molecules inhibit gene expression or translation, by neutralizing targeted mRNA (messenger RNA) molecules. Hence, it is used in developing gene silencing therapies. RNAi is being explored as a form of treatment for a variety of diseases, including HIV/AIDS, hepatitis, Huntington disease and cancer. Many studies have demonstrated that RNAi can provide a more specific approach to inhibit tumor growth by targeting oncogenes (cancer-related genes). Using RNAi technology, scientists have made major breakthroughs in introducing resistance to many viruses in various crops. Thus, RNAi technology can be used to produce crop plants that are resistant to viral pathogens. Thus statements 1, 2 and 4 are correct while, statement 3 is not correct because in development of hormone replacement therapies there is no role of RNA interference.
Ques:
5
In the context of hereditary diseases, consider the following statements:
Passing on mitochondrial diseases from parent to child can be prevented by mitochondrial replacement therapy either before or after in vitro fertilization of egg.
A child inherits mitochondrial diseases entirely from mother and not from father.
Which of the statements given above is/are correct?
Correct Answer:
(A)
1 only
Mitochondrial Replacement Therapy (MRT), sometimes called mitochondrial donation, is the replacement of mitochondria in one or more cells to prevent or ameliorate disease. MRT originated as a special form of in vitro fertilization in which some or all of the future baby's mitochondrial DNA (mt DNA) comes from a third party. This technique is used in cases when mothers carry genes for mitochondrial diseases. The therapy is approved for use in the United Kingdom. At present, there are three MRT techniques in use: maternal spindle transfer (MST); pronuclear transfer (PNT); and the newest technique, polar body transfer (PBT). Mitochondrial donation can be performed either prior to or shortly after fertilization. In both cases, this is before the fertilized egg becomes an embryo. Hence, statement 1 is correct. Mitochondrial diseases may be caused by mutations (acquired or inherited) in mitochondrial DNA (mt DNA), or in nuclear genes that code for mitochondrial components. Nuclear DNA has two copies per cell (except for sperm and egg cells), one copy being inherited from the father and the other from the mother. Mitochondrial DNA, however, is inherited from the mother only (with some exceptions). Typically, humans inherit mitochondria and mitochondrial DNA from their mothers only. But researchers have identified some individuals who inherited mt DNA from both parents (as per a research paper published in November 2018). Hence, statement 2 is incorrect.
Ques:
6
Which of the following statements about a clone of an organism is correct?
Correct Answer:
(B)
A clone is produced asexually
Any organism whose genetic information is identical to that of a parent organism is known as a clone. They have produced asexually and are identical to parent in all Any organism characters. The process to obtain clone is called as cloning. Identical twins are not clones and two clones of an organism are identical.
Ques:
7
In the case of a test-tube baby –
Correct Answer:
(C)
Fertilization takes place outside the mother’s body
Females, who are not able to conceive a natural pregnancy, their eggs are artificially fertilized. The child born by IVF technique is known as ‘Test-tube baby’. Sperm-egg fertilization which is naturally in female fallopian tubes, takes place in petridishes artificially outside of mother’s body. After these fertilized embryos are implanted in the uterus of a female in between 16 to 48 hours for getting new offspring.
Ques:
8
Consider the following effects of genetic engineering:
Disease resistance
Growth promotion
Animal cloning
Human cloning
Of the above, that have been tried with a certain amount of success include:
Correct Answer:
(D)
1, 2 and 3
Through genetic engineering, disease resistance, growth enhancement and animal cloning have been achieved successfully but human cloning has not got proper fruitful results because it is controversial and banned.
Ques:
9
Match List-I with List-II and select the correct answer using the codes given below:
List-I (Achievement in Genetics)
Discovery of transduction and conjugation in bacteria
Establishing the sex-linked inheritance
Isolation of DNA polymerase from E. coli
Establishing the complete genetic code
List-II (Scientists)
Khorana
Correct Answer:
(D)
Ochoa
Bacterial conjugation is the transfer of genetic material between bacterial cells by direct cell-to-cell contact or by a bridge-like connection between two cells, discovered in 1946 by Joshua Lederberg and Edward Tatum. Morgan was the first to establish the chromosome theory of inheritance. He used fruit flies with eye colour mutations to demonstrate sex- linked inheritance patterns. Discovered by Arthur Kornberg in 1956, it was the first known DNA polymerase (and, indeed, the first known of any kind of polymerase). It was initially characterized in E. coli and is ubiquitous in prokaryotes. Hargobind Khorana was an Indian-American biochemist who shared the 1968 Nobel Prize in Physiology or Medicine with Marshall W. Nirenberg and Robert W. Holley for research that helped to show how the order of nucleotides in nucleic acids, which carry the genetic code of the cell, control the cell’s synthesis of proteins.
Ques:
10
What is the application of Somatic Cell Nuclear Transfer Technology?
Correct Answer:
(C)
Reproductive cloning of animals
Somatic cell nuclear transfer (SCNT) can be used in embryonic stem cell research, or in regenerative medicine where it is sometimes referred to as ‘therapeutic cloning’. It can also be used as the first step in the process of reproductive cloning. The nucleus of the somatic cell is inserted into the enucleated (after removal of nucleus) egg cell.