Tuesday, September 9, 2014

Plant Cell Wall Lab

In this lab we explored various anatomical features of plant cell walls.

Mitosis & Cytokinesis
Not going to repost that, I did this last year and it is still beautiful: Mitosis post
Here's another great pic of a cell plate and phragmoplast on the edges I got today though:

Cytokinesis in plants is a rather involved process since a new middle lamella must be made, followed by primary wall and sometimes secondary wall.

Primary pit fields
This is a TERRIBLE picture taken of a picture shown to me on another camera.  But you can kind of see the primary wall and the thinner parts that indicate the primary pit fields (pointer is on the thicker part of the primary cell wall).

More primary pit fields from a more 3D outside view of the cell (this is from #6 of the lab).

The cell walls are stained pink and you can see that there are lighter/ white spots on it.  That's where the wall is thinner, so those are the primary pit fields.

By definition, plasmodesmata are only in primary cell walls, and they are channels between adjacent cells, through which the cytoplasm of each cell is continuous.  These occur more often in primary pit fields where the membrane is thinner, but they can happen anywhere in the primary wall.

You can also see these in the tomato cells we looked at last week:

Intercellular Air Spaces
These get formed often at the edges of cells as they are dividing, and are important to gas exchange for the plant. (#6)

Secondary Cell Wall
Here you can see the distinction between the secondary wall and the compound middle lamella (which includes middle lamella and 2 adjacent primary walls).

Just a picture to orient- vascular bundle, and the bundle cap at the top.
The lighter lines between all the cells are the compound middle lamella, the darker parts are secondary cell wall.

These are pear stone cells, and they have many long simple pits running through their secondary cell walls.  I thought they look rather similar to plasmodesmata, but the distinction is plasmodesmata are ONLY in primary walls, and pits are ONLY in secondary walls.  (Lab #9)

Bordered pits
Bordered pits from above look like little donuts.  Here there are a whole bunch in some dense pine wood.  These types of pits are common in water conducting cells, and they act to help prevent clogs from air bubbles. (Lab #11)

Stained microscope slides are pretty.  That is all.

Stay curious.

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