Lecture 12: Unique Plant Structures Flashcards
Plant Cell = Cell Wall + ?
- Protoplast
What is the structure of the vacuole?
- An organelle surrounded by a single phospholipid bilayer membrane (tonoplast)
Mature plant cells typically have a ______ large vacuole
- SIngle
Where are vacuoles produced?
- They’re produced by the golgi associated endoplasmic reticulum
What is the function of vacuoles?
- Storage
- Breakdown of macromolecules
- Regulation of cell rigidity
- There is some organization
What is stored in the vacuole?
- Primary metabolites (growth-associated)
- Secondary metabolites (not growth-associated)
What primary metabolites can you find in the vacuoles?
- Sugars
- Inorganic ions
- Organic ions
- Oligosaccharides
- Lipids
- Proteins
- Amino Acids
Can water move freely across the tonoplast membrane?
- Yes
What secondary metabolites can you find in the vacuole?
- Molecules for defence
Produce toxic compounds not palatable to other organisms
- Molecules for signalling
Need to signal other organisms to attract them to come to them
What’re some examples of molecules for defence?
small latex containing vacuoles in rubber tree, screwing up insects mouth part
Calcium oxalate crystals make raphides found in some plant cell vacuoles. Needles can screw up digestive system.
Alkaloids - group of nitrogen containing bases, have toxic effects on animals, most commonly used drugs are alkaloids, cocaine, nicotine, morphine, codeine
What’re some examples of molecules for signalling?
- Vincristine / Vinblastine give the flower petals pretty colours to attract insects, also anti-cancer drug
- Anthocyanin pigments within vacuoles of petal cells attract pollinators and animals to disperse seeds
Why use cell cultures?
- More efficient than extracting from harvested materials
How do vacuoles breakdown organelles and macromolecules?
- Vacuoles are acidic and contain hydrolytic enzymes similar to the lysosomal enzymes of animal cells
How do vacuoles help keep the cell rigid?
- They contain a large amount of water and make up a large portion of the protoplast
- High conc. of solutes in vacuole result in water uptake
- Large pressure within cell because vacuole is pushing on cell wall
- Not enough water = decreased turgor pressure, wilting, leaves turn away from the sun
Where did plastids come from?
- Non-photosynthetic eukaryote
- Engulfing of photosynthetic prokaryote
- Kept within cell, chloroplast becomes semi-autonomous
- Ended up with a photosynthetic eukaryote
