Plant cell biology Flashcards
How do animals acquire their multicellular state?
from cell division and sticking together and failing to separate
Name the 3 difference between a plant cell to an animal cell?
- contains a vacuole
- contains chloroplasts
- the cell wall sits outside the cell membrane
difference in Golgi bodies between plants and animals?
1 Golgi is found in animal cell whereas lots of Golgi bodies are found in a plant cell
Name the main 2 roles of the cell wall?
structure and protective layer
What forms the shape of plant cells?
water in the vacoule
Name the 4 main components that make up the cell wall
water
cellulose microfibrils
hemicelluloses
pectin
what other 2 components modify teh cell wall architecture?
glycoproteins and enzymes
What are the 3 main functions of hemicelluloses?
- act as a linker between cellulose microfibrils
- form hydrogen bonds with microfibrils
- limit the extensibility of teh cell wall
Name the 2 locations where pectin can be found?
primary cell wall and middle lamella
What are the 2 functions of pectin?
- soack up water
- gives wall flexibility and resits compression
How much percentage of cell walls is water?
65%
Where is cellulose synthesised?
Plasma membrane
How does the cell remain its shape?
- the cell wall
- protoplast
- round shape due to turgor pressure
How is the cell wall remodelled during growth?
- bonds between cellulose fibrils loosened
- more water enter the vacuole
- crosslinks cleared + rebuilt by enzymes
- expansins disrupt H+ bonds between cellulose and hemicellulose
What is cell expansin hugely important in?
plant development
What is the 2 main roles of secondary cell walls?
structure
evolution of large plants
why don’t plant cell shave intermediate filaments?
they have a cell wall instead to provide a strong framework
What are microtubules?
big structures made up of tubulin units which assemble together into big hollow filaments
What is actin filament?
actin molecules polymerised together which regulates polymerisation
How do microtubules and cellulose synthases work together?
- cellulose synthases rub along microtubule tracks
2. microtubule motors may propel the cellulose synthases along
Where is plasmodesmata found?
- in pit fields
- found in clusters
- in areas with least turgor pressure
What is the purpose of the space in the plasmodesmata?
It enables molecules to move through the plasmodesma through the endoplasmic reticulum or through the cytoplasmic route
How do plasmodesmata allow plant communication?
= small molecules pass through the cytoplasmic sleeve
= substances move through the symplast between cells without ever having to go effectively outside
What molecules can pass through the plasmodesma?
smaller molecules like nutrients and growth regulators
What proteins can’ pass through the plasmodesma?
-larger molecules like proteins and mrna
Name 3 things that regulate the size of plasmodesmata
- plant viruses
- plant developmental state of cells
- environmental and physiological signals
What does it mean that guard cells are simplistically isolated?
- they are not connected to the plasmodesmata
Why are guard cells simplistically isolated>
to maintain turgor pressure so solutes can’t ge in
Name teh hormone that controls growth
Gibberellin (GA)
What is the phragmoplast?
a plant cell specific structure that forms during late cytokinesis
Where does cell division take place in plants?
in specialised areas called meristems
How is phragmoplast size and position regulated?
kinesin and overlapping microtubules
How do microtubules govern the direction of cell expansion?
by affecting cell wall biosynthesis
How do microtubules govern the orientation of cell expansion?
regulated by environmental and developmental signals
What is the main driver of growth in tip growing cells?
actin
