Asignal sequence (gray) at the n-terminal end of the insulin precursor protein targets the protein to the lumen of the er. in the er, the signal sequence is cleaved off, and three disulfide bonds are formed between pairs of cys residues. proteases then cleave the precursor protein at two sites, each adjacent to a pair of basic amino acids (called dibasic sites, green), releasing the c peptide (blue). finally, the dibasic sites are removed. this generates the mature insulin protein, consisting of the a (yellow) and b (purple) chains joined by a pair of disulfide bonds. it is this mature form of the insulin protein that is secreted into the blood.

With the description of the different cell walls, membranes, and associated proteins set in the students' minds, you now need to introduce them to the idea that the cell wall can also act as a foundation to build things upon. bacterial appendages require a strong foundation that will offer the support needed to move and function in a dynamic world. for example, flagella are long, whiplike protein structures that are used by many gram-positive and gram-negative bacteria for locomotion. in order to function effectively, a flagellum must be firmly anchored to the cell wall. how will you be able to get across the idea that the peptidoglycan cell wall is strong enough to support such a mechanism? with a protein rod that passes through the cell wall and protein rings used to anchor it in the membranes, these basal bodies are the rudimentary biological motors that use atp power to spin the hook and the flagella attached to it. bacterial flagella have a biological motor that spins within the cell wall and is powered by atp. this allows the flagella to spin in a whiplike motion to propel the bacterium.

Sweating and breathing is an example of differentiation specialization maintaining homeostasis metabolism

The rapid decomposition of organic matter produces evidence which supports: the slow accumulation of coal deposits long ages of the earth rapid burial of vast amounts of vegetation biblical account of noah's flood