Indicate whether each of the following descriptions better applies to cellulose microfibrils (C) or pectins (P) in plant cell walls. Your answer would be a five-letter string composed of letters C and P only, e.g. CPPPP.
( ) It is made into a network by cross-linking glycans.
( ) It is particularly abundant in the middle lamella.
( ) Divalent ions such as calcium can cross-link it to form gels.
( ) It forms more homogeneous polymers.
( ) It contains many negatively charged galacturonic acid units.

Question

Indicate whether each of the following descriptions better applies to cellulose microfibrils (C) or pectins (P) in plant cell walls. Your answer would be a five-letter string composed of letters C and P only, e.g. CPPPP.
( )	It is made into a network by cross-linking glycans.
( )	It is particularly abundant in the middle lamella.
( )	Divalent ions such as calcium can cross-link it to form gels.
( )	It forms more homogeneous polymers.
( )	It contains many negatively charged galacturonic acid units.

Quizplus · Accepted Answer

In plant cells walls, cellulose microfibrils are homogeneous polymers that are cross-linked into a complex network by a heterogeneous set of cross-linking glycans. Pectins constitute a heterogeneous group of branched polysaccharides which are rich in galacturonic acid residues and are abundant in the middle lamella. They can turn into a semirigid gel by the addition of Ca²?.

Indicate Whether Each of the Following Descriptions Better Applies to Cellulose