What do dead cells lack?
nucleus, mito, chloroplasts, vacuole, cell membrane.
What are trichromes?
hairlike projections of cw of some epidermal cells
What are casparian strips?
gaskets like structures on outside of endodermal cells
3 types of ground tissue cells?
parenchyma collenchyma sclerenchyma
General cells: parenchyma characteristics?
least specialized of ground tissue cells, cubical to elongated cube in shape, generally thin walled w/o 2* walls large central vacuole, most metabolic activities present , generally retain totipotency, general background/space filling/ storage cells or PS cells
General cells:collenchyma details?
similar to parenchyma except thicker uneven 1 walls. lack 2walls, are arranged in strands or fibers, provide strength esp in young stems,(strings in celery) ,immature cells, often develop into sclerenchyma
Generalcells: sclerenchyma cells details?
1 and 2 walls w lignin, so stiff that plts can no longer grow in these ares, many actually are dead when mature, occur as bundle of fibers or sclereids
Sclerenchyma cells: Characteristics of the Bundle of fibers?
fibers are very long and thin with pointed ends, generally arranged in bundles of parallel fibers, e.g. hemp or flax fibers (woven into cloth or rope)
Sclerenchyma cells: Characteristics of the Sclereids ?
short, irreg in shape. may be highly lignified, e.g. shell of nuts, or in pear flesh
Xylem elements:What are some characteristics of tracheids?
allow transpiration, tracheids that are 1 and even 2 walls w lignin, (in areas of continued elongation 2* walls laid down in a spiral to allow stretch (eg palm) dead and hollow at maturity fiber shaped, overlap at ends with communicating pits to allow water conduction, also add strength, can have pits on side walls, conduct water upwards
Xylem elements: What are some characteristics of vessel elements?
shorter & wider than tracheids, 1 and thinner 2 walls w/ lignin dead and hollow at maturity, perforated ends walls, arranged end to end forming a water conducting pipe. also add length, pits on sides , conduct water upwards.
name of two phloem elements?
sieve tube members and companion cells
phloem elements: what are some characteristics of sieve tube members?
alive at maturity but may lack many of the functional organelles normally found (nucleus, mito, chlpsts) cells are lined up end to end and the ends are called sieve plates, sieve plates have plasmodesmata with communicating c.m. between adjacent cells. Func. Allow transport of phloem (sap)
phloem elements: what are some characteristics of companion cells?
all sieve tube members have 1 or more companion cells along side Companion cells have full metabolic abilities and is thought to "feed" and care for sieve tube member also thought to load phloem sap into s.t. member companions are small, flattened cells, have many plasmodesmata connecting it to its s.t. member cell.
What are the 3 general tissue types of plant tissue ?
dermis, fundamental (ground) tissue , vascular tissue
3 general tissue types: Characteristics of the dermis?
tissues that form the outermost cover of the plt body
3 general tissue types: Characteristics of the epidermis?
1* outer cover usually 1 cell layer thick of parenchyma cell type reflects func.
3 general tissue types: Characteristics of the epidermis of leaves?
thin to thick , relatively unspecialized cells ( except guard cells of stomata), covered on outside by cutin (waxy material) that forms the cuticle layer on the outside surface of epiderm. It waterproofs and airproofs the surface.
3 general tissue types: Characteristics of the epidermis of roots cells, protection, ?
generally thick (protection), unspecialized cells, with trichromes near root tips
3 general tissue types: Characteristics of the periderm
periderm is a 2 outer cover. takes place of 1 epidermis in regions of 2* growth, it is outer and dry layer of the "bark" true bark is "bark" + all of the tissues outside the vascular cambium
3 general tissue types: Characteristics of the fundamental (ground ) tissue
background tissue generally less specialized, looks like it just 'takes up space' but it generally has a function
3 general tissue types: Characteristics of the vascular tissue?
conducts fluids ex phloem and xylem
Characteristics of the idea that form follows function?(FFF)
form follows function. plts must grow,makefood,conduct water and photosynthate,reproduce,protect themselves from desiccation, dont fall over Various plt tissues are distributed where they will do their job best. roots and stems have a lot of conductive tissue to conduct and also give strength
What is thought about angiosperms in evolution?
flowering plants, the most widespread and successful plts type at this time in evolution.
characteristics of angiosperm: monocots?
one cotyledon leaf veins run parallel, vasc bundles scattered, fibrous roots , flowers parts in threes. ex grasses like wheat, palm, lily
characteristics of angiosperm: monocots roots?
absorb and conduct water and minerals (xylem, dermis) anchor plt (xylem,dermis,ground tissue) store food (ground tissue) and conduct food(phloem) generally fibrous in monocots (to increase surface area) to abs water efficiently. outside to in root tissue arrangement. cortex is made of ground tissue.
characteristics of angiosperm:monocot root epidermis?
often with trichromes (root hairs for abs, found back from the root tip as they are scraped off with growth) little cuticle near tip, more on mature root shaft some mucin near tip
characteristics of angiosperm: function of cortex in monocot root?
strength & storage (can store starch or become lignified to give strength) loosely packed parenchyma cells, clls connected by plasmodesmata (important in C mobilization)
characteristics of angiosperm: monocot endodermis?
the separating layer between the vascular cylinder and the cortex. cells different from cortex in that they are tightly packed and have Casparian strips. (physiologically isolates stele from rest of root)
characteristics of angiosperm: whats in the monocot stele?
central region that contains vasc. tissue, pericycle, bundles of 1 xylem , bundles of 1 phloem , pith
characteristics of angiosperm stele: monocot pericycle?
directly inside endodermis is a lateral meristem & gives rise to lateral roots in monocots
characteristics of angiosperm stele: monocot bundles of 1* xylem in stele
arranged around periphery like #s on a clock
characteristics of angiosperm stele: monocot bundles of 1* phloem
arranged between the xylem bundles
characteristics of angiosperm stele: monocot pith
ground tissue of stele
characteristics of angiosperm stems: monocot stem epidermis?
has a thick cuticle to prevent water loss
characteristics of angiosperm stele: monocot stems ground tissue?
for strength, storage or space filling, loosely packed parenchyma or more sturdy sclerenchyma
characteristics of angiosperm stele: monocot stems vascular bundles are composed of... and found...?
composed of both xylem (more central) and phloem (more peripheral) bundles are scattered in the ground tissue but are more prevalent near the epidermis bundles may have fiber caps
characteristics of angiosperm : Eudicot characteristics?
2 cots , leif veins netlike, vasc. bundles arrangement in stem tap root flower parts in 4 or 5's e.g. roses, avocados, peas, oaks
characteristics of angiosperm eudicot: eudicot roots?
generally tap roots, to go for deeper water
characteristics of angiosperm: eudicot root epidermis?
often with trichromes(root hairs for abs, found near root tip mostly, as they are scraped off with growth) little cuticle near tip, more on mature root shaft
characteristics of angiosperm:root cortex eudicot?
ground tissue(storage or space filling) thick layer, loosely packed parenchyma cells , cells connected by plasmodesmata can store/transport starch this layer can be replaced as the stele enlarges (in 2* growth) as seen in most perennial eudicots occasionally lignified
characteristics of angiosperm: eudicot roots endodermis... physiologically barrier to what and has what?
actually inner layer of cortex different in that tightly packed tissue has casparian strips physiologically isolates stele from rest of root
characteristics of angiosperm:eudicot root stele?
central contains vasc. tissue
characteristics of angiosperm stele:eudicot roots pericycle?
directly inside endodermis lateral meristem, in eudicots gives rise to lateral roots and 2* vasc. tissue
characteristics of angiosperm stele:bundles of 1* xylem eudicot roots what is the overall arrangement?
arranged most often in the shape of the cross
characteristics of angiosperm stele:arrangment of bundles of 1* phloem in eudicot roots?
arranged between the "spokes" of xylem bundles
characteristics of angiosperm:pith in eudicot roots?
little to none in eudicot
characteristics of angiosperm:what is eudicot stems epidermis way to prevent water loss?
single layer with thick cuticle prevents water
characteristics of angiosperm:eudicot stems cortex?
storage space filling PS thick layer of loosely packed parenchyma cells if PS then will usually lack endodermis
characteristics of angiosperm:Eudicot stems bundles of xylem and phloem combined positioning?
bundles arranged around periphery like #s on a clock or may be in a central vasc. stele may have fibrous caps.
In the center a pith of parenchyma (also found between bundles) or empty space
plant growth patterns general?
plts grow in 3D they grow in length (1 growth, both up and down) and they grow in width (2 growth, they become thicker) only
monocot plt growth pattern?
in general monocots live only one year and therefore grow only up and down 1 growth only
eudicot plt growth pattern?
many eudicots grow for more than one yr and therefore need to grow up and down and laterally (1 and 2 growth)
meristems definition and some characteristics?
undifferentiated cells that are able to continually divide mitotically. no other tissues are able to add cells to the plt body. therefore the sites of meristem are the only points at which the plt grows, meristems make all new plt tissue
where are the five places that meristems are found?
1* shoot apex (apical meristem)
leaf axis (axial meristem)
root tip ( root apical meristem)
produce increases in length and occur in the youngest parts of the plt. 2* vasc. cambium: tree rings
cork cambium produces bark increases in width 2* growth and occur in the older parts of the plt, mostly of perennial eudicots
characteristics of root cap of meristems?
a thick cover or zone of cells that protect the deeper meristem. secretes a polysac slime mucigel that lubricates the interface between the root tip and the abrasive soil
growth zones in roots?
3 overlapping regions of growth, zones are found behind the root cap,zones are _____ sharp boundaries , zones are based on cell____ (slide 46)
first zone in root growth?
zone of cell division, contains a ball like root apical meristem, provides dividing cells to the root tip and the three1 meristem tissues in young plts. the three 1 meristem tissues rise as 3 cylinders from the root apical meristem
zone of cell division gives rise to what three 1* meristem tissues?
procambium~~vasc. tissues of stele
characteristics of second zone in root growth?
zone of cell elongation, longest zone where cells elongate elongation is what pushes the root tip through the soil, is accomplished by the cell increasing in length by more than 10x and by the 1* meristems adding cells to the zone.
characteristics of third zone of root growth?
zone of maturation region where the cells complete their differentiation into adult tissues root hairs(extensions from the cells, used to increase surface area) can be formed here.
how does 2* root growth in meristems add to the plant?
growth that widens the root it adds 2 width and vasc tissue
2* growth in root occurs from the...?
vasc cambium, VC is a 2 meristem in the shape of a cylinder VC produces 2 xylem to inside and 2 phloem to outside VC retains meristematic cells so that it can continue to divide as 2 growth occurs the cortex degrades and is lost. only 2 tissues are left
growth from VC? X=xylem P=phloem
VC VCX VCXP VCXXP VCXXPP 1* shoots
1* shoots: Apical meristem characteristics?
apical meristem found at tip of shoot increases height only dome shaped mass of initials at the terminal bud give rise to the three 1* meristems protoderm dermis
ground tissue to cortex procambium to vasc. tissues of stele meristems elongate downward in cylinders, as in roots
1* shoots: purpose of leaf primordia?
enclose the delicate apical meristem
meristems 1* shoots:characteristics Axillary bud meristems?
flanked by leaf primordia at a node give rise to lateral branches, new axillary bud meristems arise from the three 1* meristem tissues left behind by the apical meristem as it grows as cells elongate and mature between the buds and apex, the internodes are formed, vasc. tissue arises from the procambium.
how are vasc tissues organized in shoots?
In bundles with 1 xylem towards the center and 1 phloem to the outside
2* growth in meristems shoots?
only some woody dicots do this, add width to stem or roots 2 tissues often crush and replace 1 tissues most commonly starts in 2nd year of growth
Vasc tissues in 2* growth in shoots?
VC is a lateral meristem , produces 2 xylem("wood") to inside produces 2 phloem to outside 2phloem and 2xylem can be found in vasc. bundles or vasc. layers VC can also make parenchyma between bundles"xylem and phloem rays" VC is not thick layer and can be lost to growth of the cork cambium VC adds X (&P) each yr, giving rise to wood "rings" Most increase in girth is due to this process.
Vasc tissues in 2 growth Cork Cambium?
In trees that have bark, a cork cambium is found CC is another lateral meristem develops outside of 2* phloem, in the cortex CC adds cork to the outside only. This is the outermost layer in a woody eudicot like an oak tree, cork is what you think of as "BARK" yr by yr the cortex is destroyed and replaces by cork When the cortex is gone, cork cambium arises from phloem initials (meristematic stem cells of the phloem) the outer layer of cork is constantly sloughed off
Definition of Bark?
2*phloem + Cork cambium + cork
Why do plts need water five reasons?
transport nutrients wastes and chem signals within and between cells biochem rxns require water. water gives plts physical strength to remain upright (esp. in annuals)
turgor gives up plts physical strength to grow (hydrostatic pressure is used to expand cell walls) provide e's for PS
3 Type of fluid transport in plts?
bulk flow in phloem (sap containing PSthate)
transpiration in xylem (h2O and minerals) diffusion over short distances
diffusion across cm,freely permeable to what?
freely permeable to gases and alcohols, but not much else. cm are not freely permeable to charged or polar molecules, ions, medium and large sized molecules, but life requires that these types of molecules cross the cm. :
Mechanisms by which large or charged/polar molecules can pass the cm?
endocytosis and exocytosis passive diffusion ( facilitated diffusion. by protein channels for ions) active transport
What is passive diffusion of water/ions
diffusion of water through the memb. is mostly(?) by specific passive diff proteins called aquaporins. 1 is hypertonic and 1 is hypotonic ions, molecules are via ion channels/gated ion channels. specific passive protein channels embedded in cm or specific active transport proteins
how isactive transport of ions or molecules conducted via?
via carrier proteins/pumps/active transport proteins, specific, able to jump against a gradient, energy requiring
examples of active transport
proton pump , pumps protons outside the cell, using up ATP in the process, co-transport protein:2 different molecules or ions are exchanged across a memb. this is a stoich. relationship. ATP required. ,
example of co-transport
sucrose/proton pump ( a strong proton gradient drives the transport of sucrose)
movement of water across a cell memb in response to [solute] gradients
How is osmosis different in plts than animals?
once a plt cell is full the cm exerts pressure on the cw and cw pushes back and restricts inflow. therefore osmosis alone cannot be used to predict water movement in plt cells
Define ψ or psi or water potential?
expresses the combo of pressure potential and osmotic potential, by definition a container open to atm and containing pure water is defined as ψ =0MPa
how is ψ used?
to describe the water movement in plants
ψ high water potential characteristics?
relatively low solute & or high pressure: i.e."relatively lots of water"
characteristics ψ low water potential?
relatively high solute & or low pressure: i.e. "relatively little water"?
ψ unit of measurement?
water open to atm with solute causes ψ to...?
water open to atm, with solute has a lower water potential than zero its negative, any 0.1M solution=-0.23MPa , lower #= lower water pot, meaning less water or more solute , water with less solute has higher water potential = a less negative #.
Pure water water potential
What does pressure do to ψ?
pure water under a household pressure in a tap is MPa=.25Mpa i.e. more water in smaller area and higher water pot.
can you achieve a positive ψ using only solution?
In what way does water potential influence water movement across the memb.?
water moves across a mamb from an area of high water pot to an area of lower water pot. always goes to area of lower ψ. when a cell is in osmotic equilibrium with the environment, the ψ will be equal in the cell and the environment
What is the2nd law of thermodynamics
in time all things go from ordered to random any increase in complexity must be offset by a concomitant decrease in complexity elsewhere
How is water pot. used to access the movement of water in a U shaped Tube before Equil?
water pot ψ = pressure pot + solute pot
Transpiration stream definition?
the abs. of water and minerals by roots, transport through out the plt body and evaporation through the leaves
Where does the transpiration stream occur?
occurs in xylem, which forms a continuous branched system of pipes from the roots to the leaves
What fact does transpiration rely on?
transpiration relies on the fact that water has the emergent property of cohesion(water sticks to itself very tightly) water from xylem evaporates through the stomata of leaves
What are the 3 major compartments for water?
1)vacuole: main water storage area and is well able to increase and decrease its volume.
2)cytoplasm (sol) compartment = symplast: less able to change its volume due to physiological requirements.
3)region outside the cm=apoplast: in reality outside the cell but not necessarily outside the plt
why is water attracted by roots?
water is attracted to roots because plt cell walls are polar due to a polar carbohydrate structure, active transport of mineral ions espK+ into root cells, therefore roots have a lower ψ than the surrounding normal ground water, all the low ψ leads to root pressure which pushes water upwards, but amt of root pressure possible pushes water up only a couple of meters. so there is a problem
How do plts transport xylem sap to the tops of trees?
transpirational loss of water leads to developing water deficits in the leaves. (i.e. a negative ψ p lowers the ψ in leaves water evaporates through the stomata)
2 mechanisms by which transpiration (xylem transport) is driven?
1)root pressure (positive pressure, therefore high ψ potential) pushes water up the roots.
2)transpiration pulls water to the top of the tree via water evaporation, cohesion of water and bulk flow
in some plts root pressure causes guttation in morning, before transpiration begins. most of water is abs through the rot hairs(cellular extensions from epidermal cells) or hyphae of mycorrhizal fungi
how can water be abs by the root cortex?
apoplastic, symplastic, or a combo of both
what happens after water is abs by the root hairs/hyphae
water travels through the cortex apoplast or symplast, water then reaches the endodermis, remember the endodermis is a hollow cylinder of tightly packed parenchmal cells. endodermal cells have a casparian strip: a gasket of suberin, like mortar around bricks, think of the endodermis as a brick wall with mortar(suberin) between the bricks
How is water "screened" and why?
before water can be apoplastic or symplastic, symplastic water passes through a cm, therefore it has been "screened" , apoplastic water has not passed through a cm and needing to be "screened", must pass into the cells of the endodermis before entering the stele. , Casparian strips act as a gasket, not allowing water to enter the stele before passing through a cm.
How does water enter cells of endodermis?
by osmosis, water enter cells of endodermis and is "screened". (i.e. enters symplast) , water then can continue to travel to the conductive tracheids and vessel elements of xylem of the stele. , remember that tracheids and vessel elements are dead and are therefore are part of the apoplast , so water once again wil pass from the symplast to the apoplast
What is xylem sap?
the liquid contents of the xylem is known as the xylem sap , xylem sap is dilute solution of water and minerals, but it has been screened by the cm of the root cells, water of the xylem sap is held together by cohesionand are very hard to pull apart, cohesion is the sticking together of identical compounds, in this case water molecules
what are the conductive cells of the xylem?
tracheids and vessel elements, both are continuous with each other via pits and perforated end plates, form the pipes of the stele
Transpiration is driven by?
water evaporating from the stomata , this creates a lower ψ in the stomatal space and this will create a draw on water below it in the xylem (this creates a tension on the water , as water sticks together due to cohesion).
How does transpiration, cohesion and tension all come together to accomplish the movement of xylem sap?
tension is generated by the draw of water upward and this will draw more water from the roots, cohesion and adhesion of water to the cell walls, also helps counteract the forces of gravity
Phloem and transport of phloem sap?
xylem moves fluid upwards from root to shoot only, good for moving water and minerals up into the plt from the ground , does not move PSthate , PSthate is made in the leaves and therefore must move from leaves down shoots and roots, called translocation and uses the phloem, moves PSthate both up and down in a plt
What does phloem sap contain?
up to 30% sucrose (derived from PSthate sucrose is the main form of transported C in plts) , symplastic minerals, hormones, dissolved organic compounds
what is the conductive cell in phloem?
conductive cell is the sieve-tube members. sieve-tube members are arranged end to end to make sieve tubes.
where are sieve plates in phloem?
they are at the end of s.t members and about adjacent s.t. member's sieve plates. fluid transport between adjacent st members is very efficient
where is plasmodesmata in phloem?
s.t. pores are lined with cm and the cm extend from one cell to the next, therefore there is free communication between cells. the phloem set up begins to blur the distinction between one cell and the next
characteristics of a sieve tube members in terms of the phloem structure?
s.t. members are alive at maturity but s.t. members support most internal organelles (they are mostly just cytoplasm on inside)
what does the companion cell do ?
each sieve-tube member has one or more companion cells along side of it to load phloem sap and care for the s.t. member, companion cells are small in diameter but long and spindle shaped with many ribosomes, comp. cells have a full complement of organelles, comp. cells are thought to provide the st member with normal cellular functions and food. in many plts, comp cell also load sugar into s.t. members
what is a sugar sink
any organ that is actively using or taking up sugar, therefore a sugar sink draws sugar from the phloem , meristems of roots and shoots , leaves, fruits.
what is a sugar source?
any organ that is actively making sugar by PS or is breaking down starch into sugar, therfore a sugar source moves sugar into the phloem, e.g. leaves, storage roots or stems, a sugar source will load sucrose into the phloem (symplastic or combo) mostly through active transport of sucrose into the s.t. members
What co-transport proteins of companion cells are used in loading of phloem from the sugar source?
ATPase and a sucrose H+ , ATPase in the cm pumps H+ to the apoplast, making the [H+] there high , the sucrose pump uses the chemiosmotic potential of the [H+] of the apoplast to co-transport sucrose into the companion cell from the apoplast
phloem sap to sugar sink whats the process?
bulk flow moves phloem sap to sugar sink, once the sucrose at the source is loaded in the phloem symplast, the ψ at that point in the phloem is low , water will move into the area of low ψ from outside the phloem , that increases the ψ pot. inside the phloem and water will start to flow away from that area towards an area of lower ψ (=bulk flow or pressure flow) , once the sugar in the phloem sap reaches the sugar sink, it must be unloaded
What happens once the phloem sap reached the sugar sink?
unloaded by the sucroseH+ transport protein and ATPase to sink cells , now V is lower outside the phloem (in the sink cells) so there is bulk flow of water through osmosis out of the phloem to xylem and sink , once there is increased water in the xylem bulk flow will start there as well and the water will be moved back towards the sugar source via the xylem
How is C stored and then mobilized?
C is stored as polysaccharides in granules in the chlpst of leaves or in plastids of parenchyma cells of storage roots or stems.
enzymes are utilized to either polymerized glucose into starch when sugar is plentiful, or , other enzymes depolymerize starch into glucose and then glucose is loaded into the phloem for transport to whatever the glucose is required.
What happens when C changes in C storage?
whether an organ is a sugar sink or source can change as demand for C changes , the demand may vary from season to season and even day to night in some cases.
How is water of the xylem sap held together?
cohesion: which is simply identical compounds sticking together