plant cell biology Flashcards
what are chloroplasts
plant specific organelles that use light and carbon dioxide to produce oxygen and sugar
chloroplast are surrounded by a
double membrane
chloroplasts have..
their own genme
thylakoid
membrane compartment that surrounds the lumen
granum
stack of thylakoid
stroma
matrix of the chloroplast
stroma contains
- carbon fixing enzymes
- chloroplast DNA
- ribosomes
inner mem. contains
chloroplast
0-import and export machinery
thylakoid space
-light capturing system and ATP synthase
how much sun light absorbed
1%
28%
of the energy is chemically bound
why are plants green
-chlorophyll absorbs blue and red light–> green plants do not use a large part of the visible spectrum
photosynthetic electron transfer- light dependent reaction
- red light is absorbed by chlorophyll which cleaves water thereby generating: 1 O2, 4 protons and 1 electron
- e- is transferred across the mem. which pumps 1 proton across the membrane
- the electron is further excited in the Photosytem I
- Electron is transferred onto NADP+ resulting in NADPH
- Proton gradient is utilized to generate ATP
how do chloroplasts and mitochondria cooperate
chloroplasts use sunlight t produce oxygen and sugar, which the mitochondria use to produce ATP to power the cell. this produces water and CO2 which is then used by the chloroplasts.
chloroplasts
photosynthesis
amyloplasts
starch storage
chromoplast
colouring
chloroplasts are
motile organelles and this helps them avoid photo damage
when there is strong light
the chloroplasts go to the outside of the cell
when there is weak light the chloroplasts
are equally distributed around the cell
3 steps of the chloroplast photo relocation
1) photoreception: plants blue light photoreceptors perceive the light (phototropins)
2) signal transduction- calcium signalling
3) chloroplast movement: motor dependent movement of chloroplasts (myosin and kineins)
which ion is used in signal transduction during photo relocation
calcium
what occurs independent to chloroplast movement
cytoplasmic steaming
cytoplasmic streaming depends on
energy and requires F-actin
what does cytoplasmic streaming support
tip growth of pollen tubes
cytoplasmic streaming in Nitella spec.
distributes nutrients and organelles- fastest directed transport at 50-100 um/s
cytoplasmic streaming occurs
around the vacuole
How doescytoplasmic streaming occur
myosin XI walk to organelle along the actin filament
a mobile endoplasm moves against
a stationary exoplasm
which mysosins do plants contain
XI, XIII and VIII
plasmodesmata
plants are connected via cytoplasmic bridges, allowing free passage of small molecules –> proven by GFP diffusing through plants
how many plasmodesmata connects cells
1000-10,000
what molecules do plasmodesmata slow passage of
ions, water, sugars, amino acids and even some larger proteins
plasmodesmata can be regulated or even closed by..
local formation of callose
what widen the plasmadesmara
movement proteins
during cytokinesis , microtubules form
a plant specific array
cell plate formation starts in the
middle of the cell
what crosses the cell pasta
endoplasmic reticulum
when are plasmodesmata formed
during cytokinesis
mitosis and cell division
o Cortical interphase microtubule array concentrate in the middle of the cell
o The nuclear envelope breaks down and a spindle is formed
o Cytokinesis is accompanied by de novo synthesis of plasma membrane and cell wall
o An array of microtubules (the phragmoplast, 1) guides and supports the formation of the cell plate (2)
o The microtubules guide secretory vesicles (3) to forming the cell plate
