cells & tissues. apical meristems tips of roots and shoots tips of roots and shoots extension of...
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Apical MeristemsApical Meristems Tips of roots and shootsTips of roots and shoots Extension of plant bodyExtension of plant body InitialsInitials
One cell remains as initial – maintaining One cell remains as initial – maintaining meristemmeristem
Other cell is derivative – new body cellOther cell is derivative – new body cell
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Primary MeristemsPrimary Meristems
Multiple divisions before differentiationMultiple divisions before differentiation Partly differentiated tissuePartly differentiated tissue
Primary growthPrimary growth Extension of the plant bodyExtension of the plant body
Secondary growthSecondary growth Thickening of the plant bodyThickening of the plant body
Indeterminate growthIndeterminate growth Formation of new organs during their Formation of new organs during their
entire lifeentire life
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Growth, Morphogenesis Growth, Morphogenesis & Differentiation& Differentiation
Development – sum total of events that Development – sum total of events that form an organisms bodyform an organisms body Driven by geneticsDriven by genetics In response to environment: day length, In response to environment: day length,
light quality/quantity, temperature, gravitylight quality/quantity, temperature, gravity Development – 3 processesDevelopment – 3 processes
GrowthGrowth MorphogenesisMorphogenesis Differentiation Differentiation
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GrowthGrowth
Combination of cell division and Combination of cell division and elongationelongation Cell division alone only increases Cell division alone only increases
number!number! Most growth – elongation & Most growth – elongation &
enlargementenlargement
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MorphogenesisMorphogenesis
Primary event – expansion of tissuePrimary event – expansion of tissue Subdivided by cell divisionSubdivided by cell division Cell/tissue differentiation follow Cell/tissue differentiation follow
morphogenesismorphogenesis
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DifferentiationDifferentiation
Often begins while cell is still enlargingOften begins while cell is still enlarging Depends on gene expressionDepends on gene expression Ultimate fate positionalUltimate fate positional
Not dependant on cell lineageNot dependant on cell lineage DeterminationDetermination
Commitment to specific course of Commitment to specific course of developmentdevelopment
Competency Competency Ability of cell to develop in response to Ability of cell to develop in response to
specific signalspecific signal7
Internal OrganizationInternal Organization Cells Cells tissues tissues tissue systems tissue systems Tissue SystemsTissue Systems
GroundGround VascularVascular Dermal Dermal
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Tissue SystemsTissue Systems GroundGround
ParenchymaParenchyma CollenchymaCollenchyma Sclerenchyma Sclerenchyma
VascularVascular XylemXylem PhloemPhloem
DermalDermal Epidermis Epidermis periderm periderm
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Tissue SystemsTissue Systems Characteristic Distribution PatternsCharacteristic Distribution Patterns
Primary difference – vascular/ground Primary difference – vascular/ground tissuetissue
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TissuesTissues
Functionally/ structurally distinct Functionally/ structurally distinct cellscells
Simple tissues – one type of cellSimple tissues – one type of cell Ground tissuesGround tissues
Complex tissues – more than 1 type Complex tissues – more than 1 type of cellof cell Vascular tissuesVascular tissues Dermal tissuesDermal tissues
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Ground Tissues -- Ground Tissues -- ParenchymaParenchyma
Living at maturity Living at maturity Capable of cell divisionCapable of cell division Some have 2º cell wallsSome have 2º cell walls Adventitious rootsAdventitious roots Photosynthesis, storage & secretionPhotosynthesis, storage & secretion
““chlorenchyma”chlorenchyma” Movement of water and foodMovement of water and food
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Parenchyma – Transfer Parenchyma – Transfer CellsCells Increased surface areaIncreased surface area
Facilitates movement of solutes over short distancesFacilitates movement of solutes over short distances Intensive solute transferIntensive solute transfer
Common Common Associated with xylem/phloem of minor veins Associated with xylem/phloem of minor veins
CotyledonsCotyledons Leaves in herbaceous EudicotsLeaves in herbaceous Eudicots Leaf tracesLeaf traces
Reproductive tissues – placentae, endosperm …Reproductive tissues – placentae, endosperm … Glandular structures – nectaries, salt glands …Glandular structures – nectaries, salt glands …
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Ground Tissues -- Ground Tissues -- CollenchymaCollenchyma
Living at maturityLiving at maturity Discrete strands of elongated cells Discrete strands of elongated cells
Continuous cylinders in stems and Continuous cylinders in stems and petiolespetioles
Borders veins in Eudicot leavesBorders veins in Eudicot leaves Unevenly thickened, nonlignified cell Unevenly thickened, nonlignified cell
wallswalls Supports young growing organsSupports young growing organs
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Ground Tissues -- Ground Tissues -- SclerenchymaSclerenchyma
Continuous masses or small groupsContinuous masses or small groups Hard, lignified cell wallsHard, lignified cell walls Strengthening and supporting plant partsStrengthening and supporting plant parts FibersFibers
Long, slender cells Long, slender cells o strands or bundlesstrands or bundles
Bast fibersBast fibers Sclerids Sclerids
Variable in shapeVariable in shape Seed coats, nut shells, endocarpSeed coats, nut shells, endocarp
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Vascular Vascular TissueTissue
Xylem and Xylem and PhloemPhloem Conducts Conducts
water and water and nutrientsnutrients
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Vascular Tissues -- XylemVascular Tissues -- Xylem Conducts waterConducts water
Also conducts mineralsAlso conducts minerals SupportSupport Food storageFood storage
1º growth – procambium1º growth – procambium 2º growth – vascular cambium2º growth – vascular cambium Dead at maturity Dead at maturity
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Vascular Tissues -- XylemVascular Tissues -- Xylem Trachery elementsTrachery elements
Tracheids Tracheids Vessel elementsVessel elements
May have wall pitsMay have wall pits
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A-C – vessel elementsD – tracheidE-F -- fibers
Xylem – Vessel ElementsXylem – Vessel Elements
Vessel elements – perforation plateVessel elements – perforation plate End rimsEnd rims
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Xylem -- TracheidsXylem -- Tracheids
Less specializedLess specialized No perforationsNo perforations Seedless vascular plants & Seedless vascular plants &
Gymnosperms Gymnosperms Only water conducting cellsOnly water conducting cells
Less efficient because of lack of Less efficient because of lack of perforationsperforations
Safer because of pit membranesSafer because of pit membranes Stop air bubblesStop air bubbles
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Xylem -- TracheidsXylem -- Tracheids
Variety of 2º wall thickeningsVariety of 2º wall thickenings During elongation – spiral or annularDuring elongation – spiral or annular Allow for extension after differentiationAllow for extension after differentiation
Programmed cell deathProgrammed cell death Only cell walls retainedOnly cell walls retained
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Xylem – Miscellany Xylem – Miscellany
Parenchyma – stores stuffParenchyma – stores stuff Vertical strandsVertical strands In rays -- 2º xylem In rays -- 2º xylem
FibersFibers Storage and supportStorage and support May be livingMay be living
ScleridsSclerids
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Vascular Tissue -- Vascular Tissue -- PhloemPhloem
Principal food-conducting tissuePrincipal food-conducting tissue Not just sugars!Not just sugars! Long distance signaling moleculesLong distance signaling molecules
1º or 2º growth1º or 2º growth Sieve elements – principal conducting cellsSieve elements – principal conducting cells
Sieve areas connecting adjacent sieve Sieve areas connecting adjacent sieve elementselements
Sieve cells – only phloem tissue in Sieve cells – only phloem tissue in gymnospermsgymnosperms
Sieve-tube elements – only angiospermsSieve-tube elements – only angiosperms
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PhloemPhloem
Sieve CellsSieve Cells Narrow pores Narrow pores Uniform sieve areasUniform sieve areas
Sieve-tube elementsSieve-tube elements Sieve PlateSieve Plate
o Some areas Some areas larger pores larger pores
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PhloemPhloemSieve CellsSieve Cells
Narrow pores Narrow pores Uniform sieve areasUniform sieve areas
Sieve Tube ElementsSieve Tube Elements
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Sieve ElementsSieve Elements Living at maturityLiving at maturity DifferentiationDifferentiation
Trachery elements – complete breakdownTrachery elements – complete breakdown Sieve elements – partial breakdownSieve elements – partial breakdown
o Breakdown of nucleus, loss of ribosomes, Breakdown of nucleus, loss of ribosomes, Golgi & cytoskeletonGolgi & cytoskeleton
o Remainder distributed along wall → plasma Remainder distributed along wall → plasma membrane, SER, some plastids & membrane, SER, some plastids & mitochondriamitochondria
P-protein – except in some monocotsP-protein – except in some monocots
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Sieve-tube ElementsSieve-tube Elements Companion Cells – Companion Cells –
specialized parenchymaspecialized parenchyma Same mother cellSame mother cell Deliver stuff to sieve-tube Deliver stuff to sieve-tube
elementselements Hormones, proteins, ATP, Hormones, proteins, ATP,
etc.etc. Life support system for Life support system for
STESTE Companion cell dies when Companion cell dies when
sieve element cell diessieve element cell dies
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Gymnosperm Sieve CellsGymnosperm Sieve Cells
Associated with albuminous cellsAssociated with albuminous cells Have nucleus, etc.Have nucleus, etc. Similar function to companion cellsSimilar function to companion cells Also dies when sieve element cell diesAlso dies when sieve element cell dies
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Dermal TissueDermal Tissue
Epidermis – outermost layerEpidermis – outermost layer Variable functionally & structurallyVariable functionally & structurally
Unspecialized or specialized!Unspecialized or specialized! Guard cellsGuard cells Trichomes Trichomes
Protects plantProtects plant cuticlecuticle
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Epidermis – Guard CellsEpidermis – Guard Cells Contain chloroplastsContain chloroplasts Regulate stomatal openingRegulate stomatal opening
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Epidermis -- TrichomesEpidermis -- Trichomes Root hairsRoot hairs Increased reflection of radiation Increased reflection of radiation
lower tempslower temps Lower water lossLower water loss
Absorption of water and mineralsAbsorption of water and minerals Secretory functionsSecretory functions Protection against herbivory Protection against herbivory Carniverous plantsCarniverous plants
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PeridermPeriderm 2º protective tissue2º protective tissue
Replaces epidermis in Replaces epidermis in 2º growth2º growth
Cork (phellem) → Cork (phellem) → nonlivingnonliving
Cork cambium Cork cambium (phellogen)(phellogen) Cork – outer surfaceCork – outer surface Phelloderm -- innerPhelloderm -- inner
Phelloderm – living Phelloderm – living parenchyma tissueparenchyma tissue
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Periderm -- LenticelsPeriderm -- Lenticels Loosely arrangedLoosely arranged Gas exchange across the corkGas exchange across the cork
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