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:
The possible fate of the cell that it may turn cancerous.
Explanation:
The cells present in the body generally work in harmony. However, if a cell attains a mutation, it can make it proliferate in the case when it should not do, and make it thrive in the case when other cells are dying. Due to proliferation, the unusual cell produces more abnormal cells also known as cancerous cells. These cancerous cells become more favorable in comparison to the normal cells due to the phenomenon of natural selection. These cells eventually result in a lethal form of tumors.
In the normal cells, the destructed gene or the damaged cells get repaired easily, in case if the damage is worse the cell dies. A protein known as p53 helps in repairing damaged cells or kills them if the damage is too severe. But in the case of cancer cells, the p53 protein does not work appropriately as they possess a mutated or changed form of p53 protein. Thus, in the case of cancerous cells, the rate of repair lags behind the rate of mutation, which makes the cancer cells thrive and increase in numbers resulting in further destruction.
Answer:
B) Krebs cycle (citric acid cycle)
Explanation:
Glycolysis breaks glucose into two pyruvate molecules. Pyruvate is decarboxylated into acetyl CoA and the reaction occurs in the matrix of mitochondria. In the mitochondrial matrix, acetyl CoA enters Kreb's cycle and is broken down into CO2 and H2O. For one molecule of acetyl CoA, two molecules of CO2 are released as a by-product. Therefore, out of three carbon atoms of pyruvate, two are released as CO2 during Kreb's cycle.
