67. Which of the following statement isincorrect:-Pg-131, easyA) The ratio of proteins and lipids variesconsiderably in different cells.B) In erythrocytes; it has approximately52% proteins and 40% lipids.C) On the basis of ease of extractionmembrane proteins are of extrinsic andintrinsic type.D) None of the above68. The improved model of the structure of cellmembrane was proposed by:-Pg-132, easyA) Messelson & StahlB) Schleiden & SchwannC) Anton von LeeuwenhoekD) Singer and Nichloson69. The quasi–fluid nature of lipid enables:-Pg-132, easyA) Flip–flop movement of proteins withinthe lipid bilayer.TG: @Chalnaayaaar

The difference in lipid and protein composition between the membranes of the endomembrane system is largely determined byGroup of answer choicesthe physical separation of most membranes from each other.the function of the Golgi apparatus in sorting membrane components.the modification of the membrane components once they reach their final destination.the transportation of membrane among the endomembrane system by small membrane vesicles.the synthesis of lipids and proteins in each of the organelles of the endomembrane system.

An improved model of the structure of cell membrane was proposedby Singer and Nicolson (1972) widely accepted as fluid mosaic model(Figure 8.4). According to this, the quasi-fluid nature of lipid enableslateral movement of proteins within the overall bilayer. This ability to movewithin the membrane is measured as its fluidity.

Membrane proteins contribute roughly 50% of the total mass of the membrane, but there are about 50 times more lipid molecules than there are protein molecules in cellular membranes. This is because  of the size difference between protein and lipid molecules.  of the density of the lipid membrane due to the strong hydrogen bonds between lipid molecules.  of the density of the lipid membrane due to the hydrophobic and hydrophilic ends of lipids.   the ration of lipid to protein molecules allows transmembrane proteins to be imbedded in the lipid bilayer.

Which of the following is least likely to be part of a cell membrane?Group of answer choicesphospholipidstransport proteinsproteoglycansglycoproteins

Evaluate the following statements about the functional structure of cell membranes. A. All body cells have an unequal distribution of charged ions on the inside and outside of the membranes TRUE/FALSE B. Molecules that are small enough and soluble in lipids can easily diffuse across the cell membrane TRUE/FALSE C. Immune cells take up bacteria and cellular debris directly into the cytoplasm using membrane 'pseudopodia' in order to destroy them TRUE/FALSE D. When channels for a particular ion are opened the ion is able only to go in or out of the cell membrane in the direction of the chemical concentration gradient TRUE/FALSE E. The resting membrane potential can be determined by using the Nernst equation for Ca2+ distribution TRUE/FALSE