Growth factors and cytokines both lead to tyrosine phosphorylation through receptors, but they do so through different mechanisms. what is the key difference between the receptors for these two classes of ligands in terms of their tyrosine kinase activity?

The growth factor receptors have a kinase domain while the Cytokines receptors do not contain a kinase domain as part of their structure.

Explanation:

The two are signaling molecules that control cell activities in some manners, such paracrine, endocrine and autocrine manners.

The receptor kinase domain can be specific for substrate sites in which phosphorylation occurs.

i don't know. the other person does though.

step 1: initiation

initiation is the beginning of transcription. it occurs when the enzyme rna polymerase binds to a region of a gene called the promoter. this signals the dna to unwind so the enzyme can ‘‘read’’ the bases in one of the dna strands. the enzyme is now ready to make a strand of mrna with a complementary sequence of bases.

step 2: elongation

elongation is the addition of nucleotides to the mrna strand. rna polymerase reads the unwound dna strand and builds the mrna molecule, using complementary base pairs. there is a brief time during this process when the newly formed rna is bound to the unwound dna. during this process, an adenine (a) in the dna binds to an uracil (u) in the rna.

step 3: termination

termination is the ending of transcription, and occurs when rna polymerase crosses a stop (termination) sequence in the gene. the mrna strand is complete, and it detaches from dna.