Lec03 - Plant Cells and Plant Tissues.doc

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22 Apr 2012
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Plant Cells and Plant Tissues I
Slide One – basic stem -> elaborate adaptations
Cacti stem is the organ of photosynthesis
oAlso organ of water storage
Potatoes are not roots but modified stems
Slide Two – basic leaf -> elaborate adaptations
Do things other than photosynthesis
Leaves modified into tendrils that are used to crawl up other plants
Modified leaves (venus fly trap) catches flies
Pitcher plant creates a flask like structure with digestive enzymes and water to
catch insects
Slide Three – basic roots -> elaborate adaptations
Many vegetables we eat are storage roots (starch sugars etc)
Swamp cedar send roots into air to get air and carbon dioxide
Invasive roots that are sent into the ground from the branches of trees
Slide Four –
Slide Five
Slide Six – plant cells and plant tissues (real lecture starts here)
Undifferentiated cells: meristems
Differentiated cells
Slide Seven – difference in growth between plants and animals
Giant Sequoia (tree has indeterminate growth)
Humans have determinate growth
Slide Eight – indeterminate plant growth
Stem cells in humans are totipotent (meristematic) cells in plants
A differentiated cell will give rise to the same cell
A totipotent cell will give rise to different cells
Slide Ninedeterminate plant growth
Totipotency into specific cells
From there, the specific cells give rise to the same cells, but run out of
totipotent cells
Slide Ten – factors limiting growth
Limiting external factors aside, the giant sequoia would continue growing and
growing
Humans have limited amount of stem cells resulting in determinate growth
Slide Eleven – undifferentiated plant cells: meristem
Group of meristematic cells
oBy dividing, give rise to more meristematic cells and specialized and
differentiated cells
Primary meristematic cells:
oShoot Apical Meristem
At the tip of the shoot
oRoot Apical Meristem
At the tip of the root
Slide Twelve
Secondary meristems
oDeveloped from primary meristems
Axillary meristem
To grow side buds or branches
Lateral Meristem
Increase girth of a plant
Lateral Root Meristem
To grow side roots
Adventitious Meristem
Used to grow leaves
Vascular Cambium (Cork Cambium)
Slide Thirteen – shoot apical meristem (SAM)
Leaf primordial protect shoot apical meristem
oSAM located at the very tip of the shoot protected by side leaves
(imagine a cabbage)
Slide Fourteen – root apical meristem (RAM)
Protected by (pealing cells of) root cap
oRAM is set back from the root cap and replaces the root cap as it is
damaged from extending into the ground
Slide Fifteen / Sixteen – comparative plant form and function
Differentiated cells
oSimple plant tissues
Tissue made of one cell type
oComplex plant tissues
Tissue made of more than one cell type
Slide Seventeen
Parenchyma
Collenchyma
Sclerenchyma
Slide Eighteen
Parenchyma
oMost common cell type
oAt maturity: