Answer:
During translation, tRNA (transfer RNA) molecules match a sequence of three nucleotides in the mRNA to a specific amino acid, which is added to the growing polypeptide chain. RNA primers are not used in protein synthesis. RNA primers are only needed to initiate a new strand of DNA during DNA replication.
Answer:
The article mainly represents the interests of future generations.
1)Flippases are proteins able translocate lipids from the outer leaflet( extracellular) to inner leaflet (cytosolic); They are enzymes that depend on ATP to function.
Phospholipid flippases,translocate phospholipids against a concentration gradient.
2)Floppases- move lipids from the inner leaflet (cytosolic) to inner leaflet ( extracellular). Floppases are ABC-transporters that do the opossite of the flippases.
3)scramblases- The activity of scramblases does not require energy (not ATP dependent). Their activation can result in increased symmetry between phospholipids of both leaflets of the lipid bilayer.
Scramblases translocate phosphatidylserine, preventing apoptosis and engulfment by macrophages.
Answer:
The correct answer is "There are several mechanisms that explain why a hormone have different effects in different cells. These mechanisms include: multiple receptors for the same hormone, a single receptor coupled to different pathways and hormones interacting with receptors for other molecules".
Explanation:
Hormones are among the most versatile molecules of the body, responsible for different biological processes such as human growth, sex development and metabolisms. Hormones are responsible of these complex biological processes because they have drastically different effects in different cells. There are several mechanisms that explain why a hormone have different effects in different cells. These mechanisms include:
- Multiple receptors for the same hormone. For instance, there are multiple receptor for dopamine, a hormone and neurotransmitter responsible for different functions such as movement, memory, sleep and motivation.
- A single receptor coupled to different pathways. Most hormone receptors act with a cascade of signaling. This in consequence results in a single receptor interacting with different molecules having multiple effects.
- Hormones interacting with receptors for other molecules. One example is the action of one metabolite of progesterone named allopregnanolone. This metabolite interacts with GABA-A receptor, which gives it anxiolitic properties.
