Cell wall structure Flashcards
what four components makes up a cell wall+ 5th in secondary cell walls
cellulose
pectin
hemicellulose
extention proteins
lignin (secondary cell walls)
what is the structure of cellulose
Cellulose are long straight chain fibers of glucose which together form microfibrils. these make up a majority of the cell wall.
what is the structure of lignin and where is it located
lignin is a complex polymer which restricts water flow. it is wrapped around microfibrils in the secondary cell wall.
How do components of the cell wall make it to the cell wall
rosettes make the cellulose microfibrils on the outside of the cellwall by adding glucose molecules together. They move parralel to cortical microtubing sitting on the cytoskeleton.
consitutive exocytosis brings pectin and hemicellulose from the Golgi via vesicles
Extention protein is brough in vesicles from the rER.
what is the structure of hemicellulose and pectin
hemicellulose: a straight chain of varrying polysaccharides with one kind of sugar backbone andvarying side chains. provides rigidity to the cell wall. and binds cellulose fibers together
pectin: A negativly charged branched chain molecule. binds to water giving a gel like propertie. acts like a glue
what are the functions of the cell wall
To create structure of the cell, esspecily when pressure is applied by protoplast
Restrict water flow into the cell
how is the direction of growth of the cell wall effected
the direction of cellulose will direct how the cell grows. grows in the same direction
why do cells stick together
the middle lamella which is located above the primary cell wall. Its comosition of mostly pectin causes it to be sticky
Why are vacuoles important to maintain shape
made from 1 semiperiable membrane,
enables water to enter via osmosis as it has a high solute concentration. makes up a majority of the protoplast pressing on the cell wall.
what happens when the cell is in a hypotonic isotonic and hypertonic solution
hypotonic: vacuole swells making a turgid cell
hypertonic: vacuole shrinks making a plazmolyzed cell
isotonic: no change to vacuole, flacid cell
what is the structure of the secondary cell wall
the secondary cell wall is made from multiple layers. each layer has microfibrils layed out in diffrent directions with more hemicellulose than pectin. Inbetween microfibrils there is lignin which adds strength and restricts water flow to secondary cell wall
secondary cell walls are made when?
in what kind of cells, and why in these cells?
Only made when a cell is matured.
Made in cells which support the plant, carry water. specalise in this as they are much thicker and stronger than regular cell walls.
what is the function on the plasmodesmata, and how it works
the function of the plasmodesmata is to enable communication between cells. the continuouse cell membrane forms, holes inbetween cells enabling the ER to be shared between neighbouring cells. they can exchange small molecules via plasmodesmata.
what type of cells would have more plasmodesmata
cells which are more acitive.
