Plant cell biology Flashcards
What are the unique features of plants
Vacuole, chloroplast and cell wall
Chloroplasts
Double membrane, inner membrane system and have their own genome
Use light and CO2 to produce sugar and oxygen
Inside of chloroplase
thylakoid, geranium and stroma
Stroma
Carbon fixation enzymes, chloroplast DNA, ribosomes
Inner membrane
Chloroplast import and export machinery
Thylakoid space
Light capturing system
ATP synthase
Photosynthesis
Red light is absorbed by chlorophyll which cleaves water by generating oxygen, 4 protons
Electron is transferred across membrane pumping 1 proton
Electron is further excited in PSI
Electron is transferred onto NADP+ = NADPH
Carbon fixation
Calvin cycle to turn CO2 into 2 phosphoglycerate
Export into cytosol - glycolysis to make glucose and fructose and to convert pyretic acid
Maintained in storm - inverted glycolysis, conversion into start thats stored in chloroplast
Why are plants green?
absorbs blue and red light
Why are plants not black?
Chlorophyll evolved from green algae, absorbing more light creates heat that plants have to deal with, absorbing all light would be what we would engineer
What organelles do proplastids produce?
Chloroplast, amyloplast and Chromplasts and these turn into etioplast
Chloroplast photo relocation movement
Photoreception: plant blue light photoreceptors perceived light
Signal transduction calcium signaling
Movement - motor dependent movement of chloroplasts
Sliding theory of cytoplasmic streaming
A mobile endoplasm moves against a stationary ectoplasm the force is generated by myosin motors that move along actin cables (bundles of F-actin)
Plant cell wall
Primary wall is flexible and secondary wall is formed in fully developed cells
Cellulose with alpha and beta glucose, hydrogen bonds between glucose polymers
Plant vacuole
Generates outward pressure that is counter balanced by the cell wall
variation in cell wall ridgitiy direct cell expansion
Secondary cell wall
What keeps the plant upright?
balance of turgor pressure and opposing cell wall
Secondary cell wall
rigid and cellulose fibrils show a high degree of order, microfibrils are aligned costing in the same direction and form layers
How is high ordering of microfibrils achieved?
Cellulose synthase enzyme complex forms a rosette in the plant plasma membrane - cesA forms a pore in the membrane where the gluten chain is extruded into the wall
Interact with microtubules which guide the cellulose synthase complex
Plasmodesmata
GFP diffuses through the plant tissue
GFP expressed in the phloem diffuses into the root via plasmodesmata
Connect adjacent plant cells, allow free passage of small molecules
How are plant cells connected?
cytoplasmic bridges
What reveals cell-cell contact?
Plasmolysis
Structure of plasmodesmata
large proteins, mRNA and viral genomes
Mitosis
Cortical interphase microtubule array concentrates in the middle of the cell
The nuclear envelope breaks down and a spindle is formed
Cytokinesis is accompanied by de novo synthesis of plasma membrane and cell wall
array of microtubules guides and supports the formation of the cell plate
Microtubules guide secretory vesicles to forming the plate
Vesicles of cell plate form cell wall in interior, give rise to primary cell wall
Plasmodestmate are spared in the primary wall
Cell plate expands until it fuses at the cortical division zone
Cytokinesis
Microtubules form a plant specific array
How do cell plates form?
Fusion of vesicles, microtubules deliver secretory vesicle that fuse to give rise to the cell plate
Starts in the middle of the cell and expands until the plate is formed
ER crosses the cell plate
Where are plasmodesmata formed?
during cytokinesis
