Answer:
The correct answer would be a lipid-soluble signal.
Signal transduction refers to the set or cascade of bio-chemical reactions take place in a cell in order to transmit the chemical or physical signal from outside the cell to inside target molecule.
It is usually initiated by receptors present on the membrane of the cell which sense the extracellular stimulus (such as ligand, hormone, pressure, temperature, pressure etc). Once activated, these receptors activate the cascade of reaction which ultimately reaches the target molecule and produces a cell's response.
In contrast, the lipid-soluble signals (such as steroidal hormones, thyroid hormone etc) enter the cell membrane without any hindrance. They directly bind to intra-cellular receptor present in the cytoplasm or on the nuclear membrane.
The hormone-receptor complex then enters the nucleus and act as transcription factor and produces the response in the form of transcription.
Hippocampal neurogenesis<span> is impacted by environmental factors such as age, excercise, stress and anti-depressant use.</span>
The answer is 3
Synthesize enzymes from organic molecules
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1. The genetic material is a good evidence of evolution because it's been conserved through time but with some slight differences.
Another important aspect is the </span><span>mitochondria.</span><span> The mitochondria resulted from a symbiotic relationship
between bacteria and pre-eukaryotes. Explaining why the </span><span>mitochondria looks like a bacteria and has </span><span>bacterial DNA.
2. specialized cellular modifications:
There are cellular modifications happening in multicellular organisms. That means, they have different types of cells, with different functions and will express different characteristics. For example:
- </span><span>Nerve
cells have
dendrites which is important to receive the electrical signal from another neuron, other cells don't have that.
- Sperm cells have a tail ( </span><span><span><span>flagellum) in order to swim through the vagina and no other cell has that.
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