Excitation-contraction coupling refers to the series of events that begins with the excitation of the sarcolemma in response to stimulation by a neurotransmitter, and results in the release of calcium ions from the sarcoplasmic reticulum.
Hence, option D is the 1st process that starts the excitation-contraction coupling.
<span>In the duct system the atop testis where sperm mature from is known as the epididymis</span>
Answer:
Delivered small RNAs can inhibit protein A production through the RNA interference (RNAi) mechanism, and thus impairs angiogenesis
Explanation:
The pregnancy-associated plasma protein-A is a protease enzyme involved in the formation of new blood vessels by increasing insulin-like growth factor I (IGF-I) bioavailability. Moreover, small RNAs (<200 nucleotides in length, generally 18 to 30 nucleotides) are non-coding RNA molecules that function in RNA silencing through the RNA interference (RNAi) pathway. Small RNAs are widely used in molecular biology laboratories because they can be delivered into specific cells in order to silence target mRNAs such as, in this case, the mRNA encoding protein A, by complementary base pairing and thereby inducing translational repression. In consequence, mRNAs complementary to delivered small RNAs are silenced through RNAi pathways, i.e., by cleavage of the target mRNA and/or mRNA destabilization.
Video: DNA: Adenine, Guanine, Cytosine, Thymine & Complementary Base Pairing. Learn the language of nucleotides as we look at the nitrogenous bases adenine, guanine, cytosine and thymine.
Prokaryotic cells also have loose/free/a ring of DNA (not confined to a nucleus) and they can also sometimes have a capsule (slimy outer layer). Also they have slightly smaller ribosomes- 70s instead of 80s.
