exam 1 slides 3 and 4 Flashcards
Cellulose is made up of
- Carbohydrate (C,H,0)
– Monomer = glucose
– Repeating glucose subunits
– Beta linkages between glucose monomers
what is diifrent from cellulose and starch ( cellulose)
-Found in plant cell walls
* Repeating glucose monomers
* Beta linkages
* Not digestible by humans
starch=
amylose
how is starch diff from cellulose
-Not found in plant cell walls
* Repeating glucose monomers
* Alpha linkages
* Amylase in humans breaks
down starch
Plant Cell Wall have what 3 things
microfibrils
macrofibrils
pectins
microfibril
bundles of cellulose molecules
macrofibrils
ropelike twists of microfibrils
what does pectin do for plant cell walls
Pectins hold the microfibrils together
All plant cells have what type of walls
primary cell wall
what are primary cell walls
-The first formed cell wall
* Not particularly rigid
-Quite porous (like a sponge)
means not selectively permeable (water and dissolved substances flow through easily
A) Primary Cell Wall function
-Cells can continue to grow and divide if they have primary walls only (no secondary walls
B) Secondary Cell Wall which cells have them and where are they located
-Some plant cells have secondary cell walls in
addition to primary cell walls
-In general, plant cells with secondary cell walls
cannot grow and divide any more
-Laid down to the inside of the primary wall by
a living cell (cell often dies afterwards)
anatomy of secondary plant cell wall
More rigid than primary wall
* No pectins
Lignin often deposited in
secondary cell walls
what are lignins
and how do yk it is lignin
and what does lignin do
– Stains red with phloroglucinol-HCl
– A complex polymer
– Decay resistant
– Adds rigidity
– Water proofing
– It restricts communication and is a barrier to
water flow
Middle Lamella
.The region where cells and cell walls are in
contact
* Contains pectin and cements cells together
* It is permeable to water and dissolved
substances
pits
what does it do
where is it located or when do cells have them
and what is it made of
-For cells with secondary walls, these are
regions where there is no secondary wall
• Just primary wall and the middle lamella
present
• Transport from one cell to the next occurs
through pits
• Water and dissolved substances pass easily
through pits
Pit membrane is made of =
Middle lamella plus the primary cell walls of the
adjacent cells
Plant Tissues
Groups of cells with similar functions
Main types of plant tissues:
Meristematic
Non-meristematic
Meristematic
Comprised of cells that are actively dividing or
retain the capacity to divide
Non-meristematic
Cells that are not actively dividing.
the three non-meristematic simple tissues
a. Parenchyma
b. Collenchyma
c. Sclerenchyma
Simple tissues
compromised of one cell type
complex tissues
compromised with more than one cell type
Parenchyma tissue made of what cells
parenchyma cells
paranchyma tissue
-what type of palnt cells are they found in
-anatomy
-does it stain if not or if so why
– Typical plant cell
– Thin primary wall
– No secondary wall
– The cell walls do not stain red with phloroglucinol-
HCl
function of parenchyma cells
-– The cells can grow and divide but that is not their
main role
-Photosynthesis in chloroplasts
-Storage
-E.g. Starch stored in amyloplasts in potato
parenchyma cells
what is specialized for Photosynthesis in chloroplasts in parenchyma cells
Chlorenchyma is parenchyma specialized for
photosynthesis
Collenchyma tissue=collenchyma cells
-anatomy
-does it stain if not or if so why
-how do yk it is that type of cell
-main example
-secondary wall or primary wall???
Unevenly thickened primary walls
– No secondary cell wall
– The cell walls do not stain red with phloroglucinol-
HCl
– The cells are thickened in the corners because the
primary walls are thickened in the corners
– Can be somewhat square-shaped
– E.g. Celery stalks (petioles)
Functions of Collenchyma Cells
-Provide support in regions that are actively
growing or could still be actively growing
* Provide support in regions where there is still
flexibility
c. Sclerenchyma tissue = sclerenchyma cells
-anatomy
-does it stain if not or if so why
-how do yk it is that type of cell
-main example
-secondary wall or primary wall???
– Have primary and secondary walls
– Skleros
– Contain lignin
– The cell walls stain red with phloroglucinol-HCl
Skleros
hardned
Types of Sclerenchyma
1.Fibers
2. Sclereids
-Asterosclereids
fibers
-how do they look
-are they living or dead
-function
-does it stain
– They are longer than they are wide
– They are typically dead
– They end up having a lumen where the cytoplasm
was
– A large portion of the secondary wall is
strengthened with lignin
– The cell walls stain red with phloroglucinol-HCl
– Important for strength and support
- Sclereids
-how do they look
-are they living or dead
-“function”
-does it stain
-They are typically dead
– They have a lumen where the cytoplasm was
– A large portion of the secondary wall is strengthened
with lignin
– The cell walls stain red with phloroglucinol-HCl
– They are either isodiametric
* E.g Pear stone cells
– or of various shapes
* E.g. Asterosclereids
isodiametric
= of equal diameters all
around
Roles of Sclereids
– Main roles are mechanical support and protection
* May help to deter herbivory e.g. asterosclereids
* In seed coats of many species e.g. legumes
* The tough endocarp layer of coconuts
Asterosclereids
May Deter Herbivores
Asterosclereids in Water Lily Leaves
Keep the leaves tough yet pliable and able to
withstand forces of waves
