How prokaryotes led to eukaryotes (GS Paper 3, Science)
Context:
- Organisms on planet earth are broadly divided into prokaryotes and eukaryotes. The former are unicellular, do not have any organelles such as mitochondria, and their DNA is not packaged into a nucleus.
- Eukaryotes have mitochondria, their DNA is packaged into a nucleus, and most of them are complex, multicellular beings.
Archaea:
- About 50 years ago, a subset of unicellular organisms, the Archaea, were shown to have a different line of descent as compared to bacteria. The two differ in the composition of their cell walls, and in the sequence of some of their genes.
- The term Archaea, was used because the first members of this domain were found living in extreme environments of very high temperatures or very high salt.
Asgard-mitochondrial union:
- One group of archaea were shown to have proteins that closely resembled eukaryotic proteins. These organisms are found in a geological formation where geothermally heated water is forced out of a ridge in the Atlantic Ocean floor at a depth of 2400 meters below sea level.
- Many other related members were later found in unusual ecosystems, and came to be collectively called the Asgard, which is the home of the Gods in Norse mythology.
- The mitochondria, which are the energy-generating organelles of eukaryotic cells, and the photosynthesizing chloroplasts found in plant cells, have evolved from free-living bacteria.
- The ancestor of mitochondria was a proteobacteria that was engulfed by an Asgard archaean organism. Descendants of this endosymbiotic union gave rise to animals, fungi and plants.
- In plants, the Asgard-mitochondrial union was followed by the intake of a photosynthesizing cyanobacterium, which became the chloroplast.
Reconfiguring of cellular processes
- Establishing a workable symbiotic relationship between two independent life forms poses many challenges. There was no need to retain two full sets of genes, so choices were made: for Information Technology (cell replication, etc.), archaean genes were retained; for operations and housekeeping (assembling proteins), bacterial genes were preferred.
- Over time, most genes of the organelle were transferred to the nucleus, perhaps a more efficient arrangement.
- The researchers has performed extensive studies on the reconfiguring of cellular processes in these endosymbiotic relationships. They compared animals and fungi with plants, where it is even more complicated as three gene sets were involved in the course of their evolution.
Outcome:
- The paper shows that animals and fungi work their way around this discrepancy by forcing the mitochondria to change.
- Plants segregate the two policing machineries in the cytoplasm and in mitochondria.
U.S. approval for lab meat
(GS Paper 3, Science and Technology)
Why in news?
- Recently, two California-based companies were cleared to make and sell cell-cultivated chicken, the ‘official’ name of chicken meat that is grown in a laboratory for human consumption.
- As a concept, it is being hailed by stakeholders as a major step towards reducing carbon emissions associated with the food industry worldwide.
What did the FDA approve?
- The two companies, Good Meat and Upside Foods, have received the U.S. government’s approval to make and sell their cell-cultivated chicken. In cases like these, a company in question is required to assess the safety of its own facilities and the veracity of its production process.
- Sometimes, in order to boost consumer and investor confidence, it may consult with the Food and Drug Administration (FDA). At the end of this process, if the FDA is satisfied by the company's submissions, it will send a “no questions” letter, signalling its tacit approval.
What is cell-cultivated chicken?
- To make cell-cultivated meat, the two companies isolate the cells that make up the meat (and put them in a setting where they have all the resources they need to grow and make more copies of themselves.
- These resources are typically nutrients, fats, carbohydrates, amino acids, the right temperature, etc.
- The ‘setting’ in which this process transpires is often a bioreactor (also known as a ‘cultivator’), a sensor-fit device that has been designed to support a particular biological environment.
- Once there are enough of these cells, which takes around two to three weeks in Upside’s process, they resemble a mass of minced meat. They are collected and processed with additives to improve texture.
Which forms of cell-cultivated meat exist?
- Chicken is the second most widely consumed meat in the world, according to the UN Food and Agriculture Organization (FAO). However, in the U.S. it has been the highest consumed meat since 2010.
- Good Meat and Upside have focused on chicken, and plan to expand their offerings to include other meats in the future.
- Researchers are also developing cell-cultivated versions of sea bass, tuna, and shrimp.
Why was cell-cultivated meat created?
- Its proponents have advanced the following arguments, among others — emissions, land use, prevention of animal cruelty, and food security. The first two are related to climate mitigation.
- The FAO has estimated that global livestock is responsible for 14.5% of all anthropogenic greenhouse-gas emissions. Of this, the production of beef as a commodity accounted for 41% whereas chicken meat and eggs accounted for 8%.
- Similarly, the 2021 report estimated that lab-cultivated meat would use 63% less land in the case of chicken. Alternative meat’s proponents have advanced it as a way to meet the world’s nutritional security needs.
What are the challenges?
- Consumer Acceptance: Perfectly substituting animal meat with alternative meat requires it to match the original in taste, texture and appearance. Researchers have achieved some success on these counts but it remains a work in progress.
- Cost factor: The cost of cell-cultivated meat is expected to remain high in the near future. One 2020 analysis concluded that it may never be cost-competitive, while reports have also expressed concerns about the costs imposed by quality control, especially at scale.
- High quality cells: For cultivation, researchers require high quality cells, a suitable growth-medium in which the cells can be cultured, plus other resources required to maintain the quality of the final product.
- Risks: The uncertainties associated with it.
Does China-Pak N-deal flout global rules?
(GS Paper 2, International Relation)
Why in news?
- Recently, China and Pakistan signed an agreement for a 1,200 MW nuclear power plant in the Chashma nuclear complex in Pakistan.
- The deal, reported to be worth $4.8 billion, comes amid Pakistan facing a dual energy and economic crisis.
- The latest nuclear deal between China and Pakistan has implications not only for the crisis-hit country but also for the global governance of nuclear commerce, with China proceeding with the recent deal without seeking necessary waivers from the Nuclear Suppliers Group (NSG).
What is the latest deal?
- This is the fifth reactor at the Chashma nuclear complex (C-5).
- C-5 will be the biggest reactor at Chashma, where China has already constructed four phases of the complex, with four reactors of around 325 MW each.
- It will use China’s Hualong One reactor, which has also been installed in two plants in Karachi.
How many other nuclear plants has China built for Pakistan?
- Pakistan is currently operating six China-built nuclear plants, four smaller reactors at the Chashma complex and two at the Karachi Nuclear Power Plant (KANUPP).
- Pakistan’s oldest reactor, the Canada-built KANUPP-1, is now decommissioned, while KANUPP-2 and KANUPP-3 both use 1,100 MW Chinese Hualong
- One reactors. KANUPP-3, with a $2.7 billion investment, went fully online in 2022.
- An agreement for KANUPP-3 was signed in 2013, the year Chinese President Xi Jinping launched his Belt and Road Initiative (BRI), and became a flagship energy project as part of the China Pakistan Economic Corridor (CPEC) of the BRI.
- The Alternative and Renewable Energy Policy rolled out in 2019 envisages increasing the share of renewables to 30% by 2030.
- Currently, thermal sources account for 61% of the energy mix, while hydropower accounts for 24%, nuclear 12%, and wind and solar only 3%, according to the 2021-22 Economic Survey. On the nuclear side, gross capacity of nuclear plants had increased by 39% annually to 3,530 MW.
What are the broader implications?
- China’s civilian nuclear projects with Pakistan have come under scrutiny because the Nuclear Suppliers Group (NSG), which describes itself as a group of nuclear supplier countries “that seeks to contribute to the non-proliferation of nuclear weapons through the implementation of two sets of Guidelines for nuclear exports and nuclear-related exports”, explicitly prohibits the transfer of nuclear technology by its members to countries that have not signed the nuclear Non-Proliferation Treaty (NPT).
- China joined the 48-member grouping in 2004, and argued subsequently that the Chashma 3 and Chashma 4 reactors were “grandfathered” under its earlier Chashma deals with Pakistan that pre-dated its joining of the NSG.
- Chinese analysts have now justified the continuing nuclear commerce, despite it’s NSG commitments, by pointing to the India-U.S. nuclear deal. There are, however, significant differences.
NSG Waiver:
- For one, India and the U.S. had to seek a waiver from the NSG for their civilian nuclear deal, which was granted in 2008, paving the way for India to enter the tent of global nuclear commerce.
- That was, however, only granted after India undertook a number of commitments such as placing facilities under International Atomic Energy Agency (IAEA) safeguards, separating civilian and military nuclear programmes and a continued moratorium on testing.
- Neither has China sought any such waiver from the NSG nor has Pakistan undertaken similar commitments. China has suggested that the reactors being under IAEA safeguards would suffice.
- While China had explained its C-4 and C-5 deals as being part of an earlier agreement, the KANUPP-2 and KANUPP-3 plants were agreed to in 2013, a decade into its NSG membership.
Concerns:
- Experts fear the latest deals have only further eroded the global rules governing nuclear commerce, and also raised questions about both the continuing relevance and future of the NSG and governance of global nuclear commerce.
