Answer:
please mark as brainliest answer as it will also give you 3 points
Explanation:
Cyclin-dependent kinases (CDKs) are the families of protein kinases first discovered for their role in regulating the cell cycle. They are also involved in regulating transcription, mRNA processing, and the differentiation of nerve cells.[1] They are present in all known eukaryotes, and their regulatory function in the cell cycle has been evolutionarily conserved. In fact, yeast cells can proliferate normally when their CDK gene has been replaced with the homologous human gene.[1][2] CDKs are relatively small proteins, with molecular weights ranging from 34 to 40 kDa, and contain little more than the kinase domain.[1] By definition, a CDK binds a regulatory protein called a cyclin. Without cyclin, CDK has little kinase activity; only the cyclin-CDK complex is an active kinase but its activity can be typically further modulated by phosphorylation and other binding proteins, like p27. CDKs phosphorylate their substrates on serines and threonines, so they are serine-threonine kinases.[1] The consensus sequence for the phosphorylation site in the amino acid sequence of a CDK substrate is [S/T*]PX[K/R], where S/T* is the phosphorylated serine or threonine, P is proline, X is any amino acid, K is lysine, and R is arginine.[1]
Answer:
a. inhibits cAMP phosphodiesterase, the enzyme that converts cAMP to AMP.
Explanation:
The phosphodiesterases are a group of enzymes that are capable of breaking phosphodiester bonds such as those between nucleotides in nucleic acids. The Cyclic adenosine monophosphate (cAMP) is a second messenger involved in intracellular signaling pathways. This molecule (cAMP) is hydrolyzed by the cAMP-dependent phosphodiesterase, which catalyzes the enzymatic breakdown of phosphodiester bonds (i.e., hydrolyzing cAMP to 5-AMP). The cAMP levels are modulated by the balance between its generation and the degradation via cyclic nucleotide phosphodiesterase.
Answer:
Natural selection
Explanation:
Natural populations have variations. Organisms of a population have various genetic traits. Some of these genetic variations make the organisms better suited to the prevailing environmental conditions. These organisms are more likely to produce more progeny. Over generations, the frequency of the beneficial genetic traits increases in the population due to the higher reproductive success of the organisms with these genetic traits.
This process of differential fitness of organisms of a population where the organisms with adaptive genetic traits have survival and reproductive benefits is called natural selection.
