Current Affairs Dec 12, 2021

Chicxulub meteorite

  • A study published in Scientific Reports conclusively pins down impact of the chicxulub meteorite in springtime.
  • This, 66 million years ago, ended the 165-million-year dominion of dinosaurs, wiping out 75% of life on Earth, allowing a new order to emerge.
  • This has been a major question until now; the answer enhances the ability to trace the first stages of damage to life on Earth.


Dark Matter

  • Astronomers led by researchers from the Netherlands have found no trace of dark matter in the galaxy AGC 114905.
  • An ultra-diffuse dwarf galaxy, AGC 114905, is about 250 million light-years away.
  • The word dwarf here refers to its luminosity (MNRAS).
  • Dark matter
  • Dark matter is a hypothetical form of matter thought to account for approximately 85% of the matter in the universe.
  • Its presence is implied in a variety of astrophysical observations, including gravitational effects that cannot be explained by accepted theories of gravity unless more matter is present than can be seen.
  • For this reason, most experts think that dark matter is abundant in the universe and that it has had a strong influence on its structure and evolution.
  • Dark matter is called dark because it does not appear to interact with the electromagnetic field, which means it does not absorb, reflect or emit electromagnetic radiation, and is therefore difficult to detect.


Heat shock protein

  • DNA is a linear chain of nucleotides, portions of which are faithfully transcribed into linear messenger RNA.
  • The message in this RNA is translated into strings of amino acids – proteins.
  • Proteins need to take a precise three dimensional shape to become functional entities.
  • This protein folding does not happen all by itself, at least most of the time.
  • A special bunch of proteins called molecular chaperones assist in correctly folding the protein.

Protein and chaperone

  • After the new protein chain has been shaped correctly, chaperones move on. Or else the new chain is eliminated.
  • Without chaperones, newly synthesized proteins would soon become a tangled mess of insoluble aggregates, hindering cellular processes.
  • Many molecular chaperones belong to the class of “heat shock” proteins (or stress-response proteins).
  • This is because whenever an organism is subjected to elevated temperatures a heat shock proteins in the system begin to lose their native shapes, and chaperones are produced in large quantities to restore order.
  • Chaperones are needed under physiological conditions too, for normal cellular function.
  • Misfolding of proteins can cause a number of diseases. Alpha-synuclein protein, present in neurons, is wrongly folded in Parkinson’s disease. Brains of Alzheimer’s patients have plaques formed from aggregates of amyloid beta-peptide.
  • This accumulation of amyloid fibrils is toxic, leading to widespread destruction of neurons a ‘neurodegenerative’ disorder.
  • Aberrant folding of crystallins of the eye lens leads to cataract.
  • In the eye lens, an abundant subset of proteins called alpha-crystallins themselves serve as chaperones a single R116G mutation in human alpha crystallin is responsible for autosomal dominant congenital cataract
  • Major chaperones in humans include HSP70, HSC70 and HSP90: the numbers express the size of the proteins in kilo Daltons.
  • In normal cells 1%–2% of all proteins present are heat shock proteins.
  • This number rises threefold during stressful conditions.
  • HSP70 is induced by heat, whereas HSC70 is always present at high levels in normal cells. HSC70 appears to be more like a molecular thermometer, with an ability to sense cold temperatures.


  • Indian Institute of Technology Madras researchers use a combination of deep learning techniques and traditional machine learning to develop a tool that can diagnose cancer by looking at whole slide images of the tumor.
  • The tool has been tested on datasets of breast, liver and colon cancer tissue images.
  • Digital pathology is a sub-field of pathology that focuses on data management based on information generated from digitized specimen slides. Through the use of computer-based technology, digital pathology utilizes virtual microscopy.
  • Deep learning is a machine learning technique that teaches computers to do what comes naturally to humans: learn by example.
  • Deep learning is a key technology behind driverless cars, enabling them to recognize a stop sign, or to distinguish a pedestrian from a lamppost.
  • It is the key to voice control in consumer devices like phones, tablets, TVs, and hands-free speakers.
  • Histopathology is the diagnosis and study of diseases of the tissues, and involves examining tissues and/or cells under a microscope.
  • Histopathologists are responsible for making tissue diagnoses and helping clinicians manage a patient’s care.



  • Using CRISPR-Cas9 tool, scientists have created female-only and male-only mice litters with 100% efficiency.
  • CRISPR gene editing is a genetic engineering technique in molecular biology by which the genomes of living organisms may be modified. It is based on a simplified version of the bacterial CRISPR-Cas9 antiviral Defence system
  • The proof-of-principle study, published in Nature Communications, uses a two-part genetic system to inactivate embryos shortly after fertilization so that only the desired sex would grow further.
  • A female mouse gets pregnant about 5 to 10 times each year and can give birth to a litter of 3 to 14 pups. On average, the litter size ranges from 6 to 8 pups. On average, you are looking at least 32 to 56 pups each year from one female mouse.



  • Most meteorites contain tiny beads of glass that date back to the earliest days of the solar system, before planets formed.
  • The beads of glass inside these meteorites are called chondrules. But what exactly caused the formation of these chondrules remains unclear.
  • Scientists can find clues about the early days of the solar system by looking at the types of a given element in a rock.
  • Elements can come in several different forms, called isotopes, and the proportion in each rock varies according to what happened when that rock was born, how hot it was, whether it cooled slowly or was flash-frozen.
  • The team pieced together what must have been happening as the chondrules formed.
  • The elements would have been part of a clump of dust that got hot enough to melt, and then to vaporize.
  • Then, as the material cooled at a rate of around 500 degrees C per hour, some of that vapors coalesced back into chondrules.



  • Luminosity is an absolute measure of radiated electromagnetic power, the radiant power emitted by a light-emitting object over time.
  • In astronomy, luminosity is the total amount of electromagnetic energy emitted per unit of time by a star, galaxy, or other astronomical object.