Because we have smelled them so long we are used to them
Answer:
B
Explanation:
Birds and flowers have different arrangements of the bases.
Nucleotides are termed as organic molecules which serve as monomer units. Their work is to form nucleic acid polymers, for example, ribonucleic acid and deoxyribonucleic acid.
They serve as biomolecules in the life-forms on earth. Nucleotides work as building blocks of nucleic acid. They are composed of the phosphate group, five-carbon sugar, and nitrogenous base.
Answer: The calcium ion binds to troponin, and this slides the tropomyosin rods away from the binding sites.
Explanation:
Contraction and relaxation of muscle cells brings about movements of the body. The contractile myofilament called sarcomeres are bounded at each end by a dense stripe called the Z - line, to which the myosin fibres are attached, and lying in the middle of the sarcomere are the actin filaments, overlapping with the myosin.
When action potential spreads from the nerve along the sarcolemma (muscle cell membrane), it penetrates deep into the muscle cell through the sarcoplasm (cytoplasm of muscle cell), and releases CALCIUM from the intracellular stores.CALCIUM triggers the binding of myosin to the actin filament next to it forming CROSS BRIDGES.
For this to occur, ACTIN BINDING SITE has to be made available. TROPOMYOSIN is a protein that winds around the chains of the actin filament and covers the myosin-binding sites to prevent actin from binding to myosin. The first step in the process of contraction is for calcium ions to bind to troponin so that tropomyosin can slide away from the binding sites on the actin strands.
