CELL BIOLOGY
Which of the following characteristics was discovered by electron microscopy and distinguishes prokaryotic and eukaryotic cell types?
a. number of chromosomes
b. color
c. presence or absence of organelles
d. presence or absence of a cell wall
e. cell shape
The most common mutation found in sickle cell anemia is an amino acid substitution in which a glutamic acid residue is replaced by a valine in the gene for Hemoglobin, dramatically disrupting the protein structure and function. Which amino acid subsitution for glutamic acid would you expect to have less of an impact on protein structure?
a. lysine
b. alanine
c. aspartic acid
d. tryptophan
e. phenylalanine
An important aspect of transport by facilitated transporters and pumps is ____.
a. their rigidity
b. their alpha-helices
c. these proteins have beta-pleated sheets
d. these proteins can move in and out of the membrane
e. these proteins undergo conformational changes