First off, the jaw itself, is capable of projecting an impressive 30% of the total head length, which is over 10% more than the jaw protrusion of a lemon shark. Also note the teeth of <span>Squalus acanthias </span>actually interlock to form an almost uniform cutting surface. Finally on either side of the jaw you have what is referred to as labial cartilage. These structures fold out as the dogfish projects its jaw, essentially causing the jaw to take on a tubular shape, which increases suction pressure as the shark opens its mouth. As the jaws close these cartilages snap back into place in folds along the side of the jaw, which is why spiny dogfish, smooth dogs, nurse sharks, and other sharks that make use of this mechanism have such distinctive “cheeks.” The disadvantage it has is that it cannot open its mouth too much.
Correct answer is option D.
Transcription activators accelerate transcription, while transcription factors assist RNA polymerase binding.
<h2><u>
</u></h2><h2><u>
Explanation</u></h2>
Transcription factors are the proteins which help in proper binding of RNA polymerases in the promoter region of DNA so as to facilitate transcription.
Activators on the other hand, help in the enhancement of the transcription rate.
Transcriptional activators are basically proteins which bind to the regulatory elements known as enhancers so as to increase the rate of transcription. Enhancers are specific DNA sequences, which may be present in the upstream or downstream region of the gene which is going to be transcribed.
It may be noted here that transcription factors are only present in eukaryotes. In prokaryotes, sigma factors are present instead of transcription factors to facilitate proper binding of RNA polymerases on the DNA.
Strangulation. Cyanide poisoning. Low- voltage electrocution. Drowning.
