Download Original

Unique Features ofPlant Cells 4-4 notes
-
Plants have 3 unique things that animal cells do not: plastids, central vacuoles, and cell walls.
Plant Cells
*why do plants have different characteristics –cell wise? Well compare a human to a plant.
Plants make their own carbon-containing molecules directly from the environment
Through photosynthesis- they take carbon dioxide from the air and convert that from carbondioxide
&water into sugars.
Cell Wall
-
A rigid layer outside of the cell’s plasma membrane.
-
Contains carbohydrate cellulose, which is mixed in with proteins & other carbs that form the
stiff box around each cell.
o Pores in the cell wall allow water, ions, & some molecules to enter and exit
Primary and Secondary Cell Walls
-
Cellulose, main component of the wall, is made straight off the surface of the cell membrane by
enzymes that travel alongside the membrane.
How? THEY’RE guided by microtubules inside the cell membrane.
Primary cell wall depends on orientation of microtubules
o Rest of cell wall made by ER.
o When the cell stops growing, a secondary cell wall is made.- which is very strong, but
can no longer expand.
 Wood in tables and desks are billions of secondary cell walls- the cells inside
have just died and disintegrated.
Central Vacuole.
Plant cells have lots and lots of water
-
Central vacuole- large, fluid filled organelle that stores water and also enzymes, metabolic
wastes, and other materials.
o forms as other smaller vacuoles fuse together.
o Can make up 90% of cell’s volume & pushes all organelles into thin layer against plasma
membrane…. BULLY
When water is plentiful, the plant’s vacuole is filled. So it expands and stands upright. If
it lacks water,vacuoles lose water, cells shrinks and so the plant will wilt.
Other Vacuoles
-
Some vacuoles have toxic materials
o Acacia trees- have poison!
Plastids
*basically the fancy shmancy way of saying “plant cells”
They’re organelles that, like the mitochondria, have a double membrane and have their own DNA. 1)
Chloroplasts 2) chromoplasts 3) leucoplasts
Chloroplasts
-
These buddies use light energy to make carbohydrates from CARBON DIOXIDE AND
WATER WOOHOO
o
-
Thylakoids- flattened, membranous sacs in chloroplast that contains..
 CHLOROPHYLL - THE GREEN PIGMENT. Main molecule that absorbs the light
and captures energy for cell.
Found in not only plants but also many eukaryotic algae- ex. seaweed!! Yum.
Chloroplast DNA is very similar to that of some photosynthetic bacteria….
o Can only be reproduced by division of already existing chloroplasts.
o Scientists think that these are descendants of ancient prokaryotes incorporated into
plant cells through endosymbiosis, oohalalalala
Chromoplasts
-
Plastids that contain the colorful pigment
May or may not be part of photosynthesis
Ex .carrot root cells: chromoplasts filled with orange pigment (carotene)
Other Plastids
-
Others share general feature of chloroplasts… only differ in content.
Ex. amyloplasts store starch.
o They all come from PROPLASTID.
Comparing Cells
-they all have their similar features, like membrane, cytoplasm, ribosomes, etc. but they’re still
DIVERSSSSEEEEEEEEEEEEEEEE
-Pro vs. Euk and Animal vs. Plant!
Prokaryotes versus Eukaryotes
-
Proks- lack nucleus &membrane- bound organelles
o They have a nucleoid, where their genetic material is concentrated.
o Lack internal membrane system
Plant cells vs. Animal Cells
3 major unique differences
1. Plants have CELL WALLS
2. Plants have large CENTRAL VACUOLE
3. Plants have a variety of PLASTIDS, which are deff not in animal cells!
*plants neeed this to function!