Functioning of Guard Cells

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Functioning of Guard Cells
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I. Guard Cells

• A. Function to balance water loss and need for
  photosynthesis
• 1. control diameter of stomata

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II. Guard Cell Structure

• A. Thicker cell wall toward center
• B. Cellulose microfibrils causes outward buckling
  when cell is turgid(full of water)

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III. Closing

• A. Cells lose water (become flaccid)

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IV. Opening

• A. Cells swell as water moves in by osmosis
• 1.stomate diameter increases

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V. Changes take place when K concentration changes

• A. Potassium from vacuole enters guard cell when
  opening
• 1. Active transport
• 2. Water enters by osmosis
• 3. Active transport of H helps drive K into the
  cell
• B. Potassium leaves guard cell when closing

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VI. Aquaporins proteins that regulate water
movement through membranes are involved
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VII. Light by increasing photosynthesis is
involved

• A. Creates more ATP for active transport

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VIII. Low carbon dioxide concentration causes
opening
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IX. Biorythms