Answer:
DNA Helicase
Explanation:
The process of DNA replication is very complex and requires a variety of proteins in the form of Enzymes.
The DNA replication starts at the site which is about 245 base pairs long and is rich in AT sequences called Origin of replication. The origin of replication recognised by an enzyme called DNA helicase which breaks the hydrogen bonds present between the bases and unwinds the DNA. The RNA primase enzymes then synthesizes an RNA primer which gets attached and to which DNA polymerase binds and add nucleotides.
Thus, the first enzyme that binds to the DNA is DNA helicase.
Answer:
(C) Aminoacyl-tRNA synthetases have an additional active site that binds to non-cognate tRNAs. The tRNAs that bind to this second active are hydrolyzed and released from the enzyme.
Explanation:
In case of translation, proof reading is done by aminoacyl-tRNA synthetases only. Aminoacyl-tRNA synthetases have two mechanisms to avoid error during translation which are mentioned as under:
<u>(1) Chemical proof reading:</u> Incorrect amino acids rather than being hydrolyzed in catalytic pocket get hydrolyzed in editing pocket and thus they hardly get attached to tRNA.
For example: For distinguishing similar amino acids like isoleucine and valine, isoleucyl-tRNA synthetase uses a second active site which is meant for only valine not for isoleucine. In this particular site, valine which had entered the enzyme is cleaved away with the help of editing reaction after which the enzyme is well prepared to process isoleucine which is the correct amino acid for this enzyme.
<u>(2) Kinetic proof reading: </u>Even if an incorrect amino acid has entered a particular aminoacyl-tRNA synthetase, it does not cause appropriate conformational change in the enzyme because of which the incorrect amino acid loosens from the enzyme and does not get incorporated.
Note: In this example, only chemical proof reading is mentioned not kinetic proof reading.
The correct options are:
The organism would not grow.
If an organism were cut or burned, the damaged area would not heal.
The organism would not produce new cells.
The mitosis is essential for the division of the cells. The division of the cells allow the organism to grow and heal the damaged cells. The division of the cells replace the old cells and multiply the number of the cells in an organism. hence, in any condition, the organism would be affected and in the absence of the mitosis, the organism cannot heal and cannot grow, due to non-production of new cells.
Vestigial structures are considered evidence since scientists believe they are structures that were once used by a species ancestors but are no longer needed. They do not impair the organisms in any way, so there is no need for evolution to get rid of them. Vestigial structures are anatomical features that no longer seems to have a function or purpose in the current form of an organism of the given species. Examples are wisdom teeth, the muscles of the ear, the appendix, the tail bone among others in human.
The milky way is your answer
