Question

I have a strain of Arabidopsis with a mutation in a gene that encodes an enzyme that removes methyl groups from cell wall polysaccharides (it is called a methylesterase). I extracted the cell walls of this strain to get three fractions. The first fraction was obtained by extracting with steam and hot water, the second fraction was obtained by extracting with 2 M NaOH, and the final fraction was the residual, insoluble cell wall fraction. Name the type of cell wall polysaccharide (using broad terminology) extracted with each specific treatment. When compared with extractions from wild type plants, which fraction from the mutant plant will show differences in its polysaccharide content? (1/2 pt each) Steam & hot water fraction = ___________________; 2 M NaOH fraction = _____________________ Insoluble fraction = ________________; Mutant fraction with differences from WT = _______________

Answer 1

In Steam and Hot water fraction pectins were least abundant.

In NaOH fraction the hemicellulosic fraction is most abundant (H30 and H70). Hemicellulosic might help in increasing rigidity to combat stress.

Insoluable final fraction will have cellulose rich in glucose.

Methylesterase acts on pectin thus the mutated form will have effect on pectin cocentration thus the fraction, steam and hot water will have altered concentration of pectins. Thus mutant frction will differ from Hot water fraction

Hence answere would be 1. PECTIN

2. HEMICELLULOSE

3. CELLULOSE

4. Pectin in hot water fraction