Question

A tetrose has asymmetric carbon atoms in the D and L configuration in the second and third positions, respectively. What is the respective configuration of the tetrose?

a. β

b. L

c. α

d. DL

e. D

What lectin selectively binds to the endothelium?

a. E-selectin

b. P-selectin

c. hemagglutinin

d. L-selectin

e. erythropoietin

Some viruses gain entry into specific cells by:

a. attaching to ion channels.

b. cleaving the glycosidic bonds and altering protein shapes.

c. adding moieties of sialic acids to membrane proteins.

d. binding to glycoproteins on the cell surface that are unique to specific cells.

e. changing permeability of membranes.

Answer 1

Que : A tetrose has asymmetric carbon atoms in D and L configaration in the second and third position respectively, what is the respective configuration of the tetrose?

ans: b. L

• A monosaccharide tetrose is given D configuration if OH group is right of last stero center while L configuration is given OH is to the left of last stereocenter carbon.

Que: what lectin selective binds to the endothelium?

ans: d.L-selectin

• Selectin are the cell surface lectin that have ability to evolved to mediate the adhesion of WBC to endothelial cells.
• While L selectin act as a homing receptor for lymphocytes to enter into secondary lymphoid tissues via endothelial venule.
• Which facilitate adhesion of the embryo to the site of invasion on the surface epithelium of the endometrium.

Que: some viruses gain entry into specific cells by:

ans: ​​​​​​d. Binding to glycoproteins on the cell surface that are unique to specific cells.

• Viruses are enter into host cells occurs by attachment of the glycoprotein to cell surface receptors.
• Viruses gain entry into cells by memberane fusion Which is mediated by viral memberane glycoprotein whose having affinities for their receptor on the host cell.