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.
Answer:
B. polio—polyhedral shape
Explanation:
A virus is a small parasite which cannot self reproduce. For a virus to produce more viruses, it uses the cell to duplicate itself. Viruses contain RNA or DNA as their genetic material.
Poliovirus is composed of an RNA genetic material and it is responsible for Polio. Polio leads to paralysis and is transmitted through contaminated water or food, or contact with an infected person.
The shape of Poliovirus is formed by polyhedral (many-sided) shell or capsid.
The expression of the alleles is independent of the organism's sex; both males and females express the allele.
Answer: When the DNA collected on the crime scene is being analysed in the forensic lab, the results will be inconclusive, because error in DNA transcription, particularly in mRNA encoding leads to inheritable phenotype change by reprogramming the transcriptional network, without changing the DNA. Transcription errors are brief with no long-term consequences. Due to mRNA being short-lived and the erroneous proteins are degraded. A decrease in transcription accuracy triggers cellular identity change.
Explanation: This is called epimutation, a heritable modification that results in the change of gene expression, but not the DNA sequence. Epimutation is not associated with DNA mutation, but is associated with the loss or gain of DNA methylation or other heritable changes of the chromatin.
Hey there!
El Nino typically involves waters with a warmer than usual surface temperature, a flatter thermocline (cooler water moves to the surface), and weaker trade winds. As for La Nina, think of it as the opposite of El Nino. There will be stronger trade winds, and cooler surface water temperatures.
Hope this helps!
