Plant cell walls Flashcards
(12 cards)
1
Q
A
2
Q
biological roles of cell walls
A
- structural support
- cell adhesion
- protection
3
Q
the role of structural support in cell walls
A
- walls of mature tissues need to be rigid
- cells of growing cells need to be strong enough to withstand high pressure but flexible enough to allow growth
4
Q
the role of cell adhesion in cell walls
A
- cell walls are interface between cells
- middle lamellae hold cells together like bricks
- define cell shape
- plant cells without walls are always spherical
5
Q
the role of protection in cell walls
A
- protection from abiotic and biotic stress
- invading pathogens would enter cell wall, producing enzymes to break down the polysaccharides
- cell wall integrity sensors defend using signal transduction pathway, can synthesise more polysaccharides to plug hole
6
Q
what are cell walls made of
A
- cellulose
- hemicelluloses
- pectins
- lignin
7
Q
cellulose
A
- most abundant polymer on earth
- constructed of glucose
- chains of glucose joined together to form microfibrils
- very strong & load-bearing
- coils around cell
8
Q
hemicelluloses
A
- function to tether cellulose microfibrils together
- form a strong, load-bearing network
- wraps adjacently around cellulose to prevent from uncoiling
- variety of polysaccharide types
- main backbone w/ short side chains
9
Q
pectins
A
- variety of polysaccharide types
- all based on backbone of galacturonic acid
- form gel-like matrix which load-bearing polymers embed in
- seem have long, unbranched regions
- negatively charged, may be cross-linked with calcium cations
10
Q
what mutation cannot make pectin properly
A
quasimodo1
11
Q
lignin
A
- heterogenous phenolic polymer
- provides extra structural support to cell walls no longer growing
12
Q
cell wall diversity within
A
- fine-structures
- intra-molecular connections
- 3d architectures
