Answer:
The correct answer is D. The seventh cranial nerve is the facial nerve.
Explanation:
The facial nerve is a mixed cranial nerve, that is, it contains both sensory and motor fibers, present in mammals including humans in which it forms the seventh cranial nerve. Being a cranial nerve, it emits two fibers, one that runs on the right side of the face and the contralateral on the left. It starts of the brain stem, just between the brainstem and the medulla and controls the facial expression muscles, as well as the taste in the previous two thirds of the tongue. It also supplies parasympathetic preganglionic innervation to various nerve nodes in the head and neck.
Answer:
a. repressor
b. regulator
c. operator
Explanation:
All constituent genes of an operon are transcribed in a coordinated manner, such as polycistronic mRNA, that is, multigenic, which is sequentially translated into proteins by ribosomes. The initiation of transcription can be regulated positively or negatively. The genes under negative control are constantly expressed unless they are "disconnected" by a repressor protein that will prevent gene expression by binding to a specific DNA sequence called operator, preventing RNA polymerase from initiating transcription in the promoter.
Those genes whose expression is under positive control will not be transcribed unless an activating protein is present which binds to a specific DNA sequence and helps RNA polymerase in the initial steps of transcription.
Answer:
B
Explanation:
I'm pretty certain the answer is B. I really hope this help's you! Have a lovely day.
Answer:
The intracellular molecule produced by the receptor ligand complex is called Second messenger.
Explanation:
Receptors are membrane bound proteins which bind to the ligands which are also called first messengers and cause cellular changes. These intracellular changes are mediated by second messengers such as proliferation, differentiation, migration, apoptosis, transcription, contractions etc. They are specific for specific first messengers such as homones and growth factors. They relay the signals between the ligands to their target molecules in the cytosol or nucleus. Most common second messengers are cAMP, cGMP, DAG, IP3.
Signal amplification by second messenger can be explained by the example of IP3 which cayses the release of Calcium ions from the intracellular stores and cause contractions.