Answer:
1. Signaling molecule
2. Signaling receptors
Explanation:
Hormones, growth factors, neurotransmitters, etc. serve the function of signaling molecules for cells. These molecules are released by one cell and bind to the receptors present on/in the target cells to elicit the desired response. Thereby, the signaling molecules serve in cell-cell communication.
For example, insulin hormone synthesized and released from beta cells of pancreas binds to its cell surface receptors present on the surfaces of liver cells and muscle cells to stimulate the uptake of the glucose from the blood.
Likewise, neurotransmitters released from the presynaptic neuron bind to receptors present on the membrane of postsynaptic neuron and serve to carry the nerve impulse to the postsynaptic neuron.
The right answer is C) vector
In molecular biology and genetic engineering, vectors are DNA molecules that allow the propagation of sequences of interest. These are chimeric DNA molecules such as plasmids or artificial bacterial chromosomes, containing an origin of replication and one or more genetic markers. The origin of replication allows the maintenance of the vector in the target cell during generations.
Answer:
Atoms combine when their electrons are shared or transferred
