Cellulose Flashcards
What is Pectin?
Hydrophilic gel-forming component.
It is composed of heterogeneous polysaccharies
__________ ____ form the main backbone of pectin and is important for its hydrophiilc properties.
Galacturonic acid
What type of ion help pectin form a network by ionic bonds?
Ca2+
What is hemicellulose primarily made of?
Five carbon sugars
What are two common hemicelluloses?
Xyloglucan
Glucuronoarabinoxylan
Wat is the primary role of hemicelluloses?
cross-link cellulose microfibrils on cell walls
What are the four steps of the life of a polymer?
Synthesis
Deposition
Assembly
Modification
What is the self-assembly model?
Isolated celluloses can be dissolved in strong solvents, and stable fiber can be formed spontaneously. i.e., manufacturing of rayon
What is the enzyme mediate assembly model?
Xyloglucan endoglucosylase can cut xyloglucan and add a new xyloglucan molecule in vitro
What are the components of the primary cell wall?
Cellulose
Hemicellulose
Pectin
What are the additional non-carbohydrate components?
Lignin - more abundant in secondary cell walls
Structural proteins - focus only on expansion protein
What is the precursor of lignin monomers?
Amino acids
What is creep?
The irreversible extention of cell walls which occurs by slippage of cell wall polymers relative to one another
What are the two types of glucose polymer structures?
Starch or amylose (alpha glucose form)
Cellulose (beta glucose form)
What bond tightly packs cellulose to form a microfibrils?
Hydrogen bonding
How thick are are cellulose?
1-10 nm width
What dose using SEM and freeze-fracture help you to examine?
What did they discover using SEM?
Surface topology
Rosette patterns
What dose using SEM and freeze-fracture help you to examine?
What did they discover using SEM?
Surface topology
Rosette patterns
Lignin is ____ and ____ linked with polysaccharides
Intertwined
covalently linked
What is the casparian strip model?
CASP1 protein organizes membrane proteins at the casparian strip
What protein suggests that lignin is not randomly deposited.?
ESB1 (enhanced suberin 1 protein)
Certain orientation occur when this protein is present. It is essential for proper lignification
What are two important considerations for cell wall expandability?
Tip growth (growth at the apical dome) Important for root hairs and pollen tubes)
and diffuse growth (equal directions). Most cells in multicellular plants grow by diffuse growth
What is the role of MT in cellulose microfibril
It dictates the orientation of newly deposited cellulose microfibrils.
What are the two observations relevant to cell wall expansion?
1) Cell wall loosening is enhanced at acidic pH
2) Drug fusicoccin treatment on plants enhanced cell wall loosening. Fusicoccin is known to activate H+ ATPases on PM
What is the instrument used to experimentally measure cell wall expandability
What is the instrument used to experimentally measure cell wall expandability
