Answer: A natural killer cell (NK) is a type of lymphocyte that has an activating and inhibitory receptors extending from its plasma membrane
Explanation: A natural killer cell (Nk) is a type of lymphocyte (a white blood cell) that has an AC and inhibitory receptors. It plays a major role in host rejection of both tumours and virally infected cells. It contains specifical protein such as perforin and granules.
Answer:
Differences in mRNA splicing.
Explanation:
The exon is the region of a gene that is not separated during the cutting and splicing process and thus remains in the mature messenger RNA. In genes encoding a protein, it is the exons which contain the information to produce the protein encoded in the gene. In these cases, each exon encodes a specific portion of the complete protein, so that the set of exons forms the coding region of the gene. In eukaryotes, the exons of a gene are separated by long regions of DNA (called introns) which do not code.
RNA splicing is a post-transcriptional process of maturing RNA from which certain sequential fragments are removed. This process is very common in eukaryotes, and can occur in any type of RNA, although it is more common in mRNA. It consists of removing the introns from the primary transcript and then binding the exons. Particularly, <u>alternative RNA splicing takes place when one gene can produce different proteins as a result of what segments are considered as introns and exons</u>. When different segments are considered exons, the result is a great diversity of mature transcripts which produce different proteins.
<u>So, gene splicing is a post-transcriptional modification in which a gene can code for many proteins, which makes it an important source of protein diversity.</u>
The endosymbiotic hypothesis explains that how eukaryotic cells might have evolved chloroplasts and mitochondria within their cells.
The endosymbiotic hypothesis states that the eukaryotes have developed via a procedure whereby distinct kinds of free-living prokaryotes became assimilated within the bigger prokaryotic cells and ultimately evolved into chloroplasts, mitochondria, and various other organelles.
