Question

15.Mycoplasma cells don't have cell wall. What is the shape of these cells and how do these reinforce their cell membrane? 16.What are some of the functions of the bacterial plasma membrane? 17.What is meant by active transport of a solute?

Answer 1

15- mycoplasma are vary in shape these may be entire spherical,polymorphic or irregular filamentous in form.The filament may be branched or unbranched.

the cell are small having diameter range between 0.3 and 0.9 $\mu$ m

they reinforce cell membrane by -there cell membrane have sterols,which is unique as regulators of membrane fluidty durning changes in growth temprature in addition to sterols they also contains chloestrol like substance which help in maintaining rigidity of membrane. and mycopalsma is osmotically sensitive.

16- functions of bacterial plasma membrane

a-Acting as a permeability barrier for most of molecules.

b-Serving as the location for the trnasport of molecules into the cell.

c-Also functions in energy conservation as the location about which proton motive force is generation.

d- important role in cell recognition,cell adhesion.

e- helps in DNA and cell wall synthesis

f-excretion of hydrolytic enzymes.

17-active transport means move against a gradient.

To move substance against a concentration or electrochemical gradient,a cell must use energy . Active transport mechanisms do just this,expending energy(often in the form of ATP) to maintain the right concentrations of ions and molecules in living cells.

active transport divided into two

A- Primary active transport- directly uses a source of chemical energy (eg ATP) to move molecules across a membrane against their gradient.eg sodium potassium pump

B- secondary active transport -uses an electrochemical gradient generated by active transport as an energy source to move molecules against their gradient,and thus does not directly requires a chemical source of energy such as ATP