In which domain is the bottom of the DNA-binding cleft? What type of secondary structure lines the bottom of the cleft? In which domain is the bottom of the DNA-binding cleft? What type of secondary structure lines the bottom of the cleft? The bottom of the cleft is in the fingers domain. It is lined with alpha helices. The bottom of the cleft is in the fingers domain. It is lined with a beta sheet. The bottom of the cleft is in the thumb domain. It is lined with both alpha helices and a beta sheet. The bottom of the cleft is in the palm domain. It is lined with alpha helices. The bottom of the cleft is in the palm domain. It is lined with a beta sheet.

Proteins are the workhorses of the cell, controlling virtually every reaction within as well as providing structure and serving as signals to other cells. proteins are long chains of  amino acids  , and the exact sequence of the amino acids determines the final structure and function of the protein. instructions for that sequence are encoded in  genes  . to make a particular protein, a messenger ribonucleic acid (mrna) copy is made from the gene (in the process called  transcription  ), and the mrna is transported to the  ribosome  . protein synthesis, also called  translation  , begins when the two ribosomal subunits link onto the mrna. this step, called initiation, is followed by elongation, in which successive amino acids are added to the growing chain, brought in by transfer rnas (trnas). in this step, the ribosome reads the  nucleotides  of mrna three by three, in units called  codons  , and matches each to three nucleotides on the trna, called the anticodon. finally, during termination, the ribosome unbinds from the mrna, and the  amino acid  chain goes on to be processed and folded to make the final, functional protein