Animal cells each have a centrosome and lysosomes, whereas plant cells do not. Plant cells have a cell wall, chloroplasts and other specialized plastids, and a large central vacuole, whereas animal cells do not.
The process of RNA editing is the alteration of the sequence of nucleotides in the RNA after it has been transcribed from DNA, but before it is translated into a protein. RNA editing occurs by two distinct mechanisms:<em><u /><u>Substitution</u> <u>editing </u></em>and <u><em>Insertion/</em></u><em></em><u><em>deletion</em></u><em> <u>editing</u></em>.
<u><em>Substitution editing</em></u> is the chemical alteration of individual nucleotides. These alterations are catalyzed by enzymes that recognize a specific target sequence of nucleotides:
*Cytidine Deaminases that convert a C in the RNA to uracil.
*<em />adenosine deaminases that convert an A to inosine,which the ribosome translates as a G.<span>Thus a CAG codon</span><span> (for Gln) can be converted to a CGG codon (for Arg).
<em><u>*Insertion/deletion editing</u></em><em><u /></em><u /> is the insertion or deletion of nucleotides in an RNA.
These alterations are mediated by guide RNA molecules that base-pair as best they can with the RNA to be edited and serve as a template for the addition( or removal) in the target.</span>
Steps are required for a pathogen to infect a novel host species.
- A pathogen is defined as an organism causing disease to its host, with the severity of the disease symptoms referred to as virulence.
- The pathogens can be viruses or bacteria. If the host is humans then these pathogens can enter through nose, sputum, yes or any cut wounds.
- After entering the host species, the pathogens ejects its genome into the cell of the host for its multiplication. Such type of organisms require the machinery of the host to multiply.
- The pathogens after multiplying, increases in number and damages tissues and organs of the host thereby causing diseases.
Answer:
Basically exercise maintains the integrity of white matter which contains billions of neurons;
Therefore regular exercises reduces Alzheimer's diseases by 50 %. it stimulates the brain's ability to maintain old neuronal connections (synapses), and to make new ones.
Generally, exercise, increases cerebral blood flow, and therefore Oxygen supply to the brain.This stimulates neuronal metabolism.
Explanation:
