Lecture 1 Flashcards
How does single cell develop into a complex multicellular plant and how do you get differences between plant forms (diversity)?
What are the common features in the development of plant and animals
they both depend on:
- ) cell growth and multiplication (cell expansion, cell division)
- ) cell differentiation
- ) morphogenesis
Define cell expansion
cell enlargement
Define cell division
increase in cell number
Define cell differentiation
specialization of cells to acquire specific functions
Define morphogenesis
creation of form
What are the essential differences between the development of plant and animal cells
- ) no cell migration in plants
- rigid cell wall, fixed position - ) Ongoing growth & morphogenesis
- at plant meristems - ) May be differences in permanence of differentiation; plants can change organs they make as time goes on; totipotent
- ) plants and animals evolved multicellularity independently
Define totipotent
having the ability to differentiate into all cell types
What controls plant development
co-ordinated program of gene expression and cell signalling that regulates cell division and expansion, cell differentiation and morphogenesis
true or false; plant body is laid down by cell growth and differentiation at meristem
true
What abiotic factors affect plant growth
light temperature nutrients drought pests
What are meristems
undifferentiated cells capable of cell division, but also of differentiation
Where does the word meristem come from and what does it mean in that language
Greek
meristos
means divisible
What are the 3 types of meristems
SAM ; shoot apical meristem
RAM; root apical meristem
Lateral meristems ( in woody plants)
true or false; ongoing growth and morphogenesis at plant meristems
true
What is the difference between vegetative shoot apical meristem and reproductive shoot apical meristem
vegetative apical meristem produces leaves
reproductive apical meristem produces flowers
what are the three developmental shifts that a plant undergoes throughout their lifetime
juvenile
adult vegetative
adult reproductive
Define apoptosis
programmed cell death
true or false; mature xylem cells function as conducting vessels, but are dead as they have no cytoplasm or nucleus
true
true or false; the symmetry of cell division is important
true
why are asymmetric cell divisions important
crucial for establishing axial polarity (top and bottom of plant)
what happens when incorrect asymmetric division occurs
mutant plants occur
What is a gnom mutant
ball shaped
lacks leaves and roots
plane a cell division does what
increased length
plane b of cell division does what
increased girth
plane c of cell division does what
cell into next row (cortex); inside the cell
What are preprophase bands
bands of microtubules
- orientation of preprophase bands of microtubules determines the plane and symmetry of cell division
What is the cell plate
where cell will divide
What determines the direction of cell expansion (one direction)
controlled by the orientation of cellulose microfibrils in the cell wall
What drives expansion
driven by turgor pressure of K+ ions into the cell; forces water inside the cell
What are important for determining plant form
plane and symmetry of cell division
what controls the orientation of the cellulose microfibrils in the wall
controlled by microtubules inside the cell
what are ‘left’ mutants of Arapidopsis
have altered cellulose microfibril angles
Why do ‘lefty’ arabidopsis mutants occur
have amino acid changes in the tubulin gene (tubulin makes the microtubules)
What do the microtubules control
- control plane of cell division
- direction of cell enlargement
What does it mean by leaf primordium
the first trace of an organ
What happens when growth of leaf primordium is unregulated
doesn’t make a leaf, it makes an undifferentiated tissue called CALLUS
what determines the size and shape of a leaf
differential growth:
- total number of cell division cycles (more cells meaning more leaves)
- relative orientation and distribution of cell divisions and cell expansions
- relative timing of cell cycle arrest
