Cretaceous extinction also known as Paleogene extinction was a period of time when suddenly around three quarter of the animal and plant species began to get extinct from the land. The event happened around 66 million years ago and is considered as the end of cretaceous era that lead to the beginning of Mesozoic era.
Reasons for the mass extinction:
- Scientists think that a major asteroid or comet hit the surface of earth which deteriorated the earth’s environment, especially by making it difficult for plants to perform the process of photosysnthesis. This is called as Impact hypothesis and scientists think that it was the reason of extinction of so many species because they found debris of asteroid in the land.
- There could also be some other reasons like climate changes,volcanic eruptions and changes in the sea level which made the environment unfavorable for the survival of living organisms.
- One of the best known organism that is thought to extinct in cretaceous period was dinosaur.
Extinction of Dinosaurs:
As stated above the exact cause of dinosaur extinction can not be stated with confidence. This is because cretaceous period was the time when so many unfavorable circumstances took place like diseases, geologic events ,climate change etc.
However, the most believed theory is that some Asteroid hit the surface of earth and turned the climate very very old. Therefore, those amazing creatures were not able to survive that climate.
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2. Thymine with Adenine & Cytosine with Guanine
3. The Dna double helix must unwind near the gene which is supposed to get transcribed.
4. RNA polymerase
5. Uracil with Adenine & Cytosine with Guanine
8. Nucleotides
9. RNA polymerase
10. Dna - 2 strands MRNA - 4 strands
11. MRNA is an intermediary between the genetic info in Dna and the sequence of amino acids in proteins
The best description of expression gene process is constitutive. this is because it is the partial diploid strain whereby the strain containing a beta-galactosidase gene which is constitutive.
Gene expression process is the process by which information from a gene is being used in the synthesis of the functional gene product. The process gene expression is used by different known life. For example, we eukaryotes, prokaryotes and utilized by viruses which are used to generate the macromolecular machinery which is for life.
