BIO SCI 152 1st Edition Lecture 15Plant Form and Function I : Cells, tissues, meristems, basic ground plansLearning ObjectivesAfter suitable revision, you should be able to -- Name the characteristics unique to plant cells, things not found in plant cells - Name the 4 major cell types found in plant tissues - Name the 3 major types of tissues found in plants and recognizetheir functions - Name the cell types which make up xylem in gymnospermsversus angiosperms and describe their basic characteristics - Name the cell types which make up phloem and know their characteristics - Define meristem and name and locate the two main types of meristemsfound in plants - Explain the basic tissue regions found in roots, shoots and leaves - Identify differences between determinate and indeterminate growth VocabularyCell wall vessel elements DicotPlasmamembrane solutes MeristemVacuole xylem Meristematic tissueChloroplast Sieve tube elements Apical meristemPlasmodesmata Phloem Lateral meristemCytoplasm Companion cells PrimordialCellulose Totipotent Vascular cambiumLignin Epidermis Cork cambiumMiddle lamella Cuticle Tree ringsParenchyma Root hairs DendrochronologyCollenchyma Dermal tissueForensic plant anatomySclerenchyma Ground tissue Determinate plantFibres Vascular tissue growthStone cells/sclerids Vascular bundle Indeterminate plantTracheids Pits growthFig 4.7 Generalized plant cellsCell SizeCool Animation: http://www.cellsalive.com/howbig.htm40 um = 40 x 10-6 m 40 um = 0.00004 m or 0.04 mm 4/100th of a mm 250 cells fit in 1 cmGeneral Characteristics of Plant Cells• Cell walls – primary and secondary, middle lamella• Plasma membrane • Large vacuoles • Chloroplasts (plastids) • Starch grains canbe present • Plasmodesmata • Plant cells lack lysosomes and centriolesof animal cells Cell walls Fig. 4.7, 4.15• Primary cell wall –flexible, cellulose • Secondary cell wall – cellulose, lignin, other components • Middle Lamella –pectin-rich layer that cements together cell walls ofadjacent cells Plasmodesmata Fig. 4.7• cytoplasmic channels that pass through pores in primary and secondarycell walls • Plasmodesmata - small tubes joining plant cells • living bridges between cells allowing molecules to pass from cell to cell • Provide cell-to-cell communication Plant Cells page 510-511 of text 5 different types• Parenchyma • Collenchyma • Sclerenchyma • Vascular – xylem and phloemParenchymaLeast specialized plant cells ‘workhorse cells’- Primary walls thin and flexible, no secondary walls - Alive at functional maturity - Regeneration of more specialized cells in case of damage (Totipotent ‘stem cells’ of plants) - Functions? Collenchyma• Thick primary walls • Usually grouped in strands or cylinders • Can elongate and expand with stem and leaf growth • Alive at functional maturity • Function? Sclerenchyma• Thick secondary walls • Strengthened by lignin • Cannot elongate with growth • Often lack protoplasts at maturity – i.e. dead at functional maturityFibers - Long slender and tapering in bundles (Rope, flax) Sclereids – hard wood cellstructures Functions? In class exercise on cell types and functionsGroups of cells make up tissuesVascular TissueContinuous systems (root tips to leaf buds) Xylem cells, phloem cellsXylem and Phloem arranged together in vascular ‘bundles’ Fig. 24.8, 24.10Xylem - Tracheids and Vessel Elements (Sclerenchyma)water conducting cells – from roots to leavesdead ‘hollow tubes’ at functional maturitysecondary walls often deposited in spiral or ring patternsTracheids (Gymnosperms and Angiosperms) page 510Long thin cells with pits and tapered endsWater moves from tracheid to tracheid through the pits in the cell wallVessel elements (Angiosperms only)• Wider, shorter, thinner walled, less tapered than tracheids End walls perforated – form long tubes or pipes constructed ofvessel elements end to end Angiosperms have both tracheids and vessel elements Gymnosperms have only tracheidsPhloem Sieve tube members and companion cells‘Food’ conducting cells – fromleaves to roots but also to anywhere in plantIn chains like pipes joinedtogetherAlive at maturity althoughseive tube elements lack nucleus, ribosomes and vacuolesCompanion cells – alongside each sieve tube member• Plasmodesmata connect sieve tube member to companion cell • Companion cell nucleus serves sieve tube memberForensic Plant Anatomy http://myweb.dal.ca/jvandomm/forensicbotany/• Pollen – location associated with particular plants (e.g. marijuana pollencan link to drug operations) • Ecology – presence of new plant colonizers indicate soil disturbance • Anatomy – root growth, anatomy can determine disturbance and time of burial; plant cell types in victim stomach contents (sclerids, tracheids, vessel cells, silica bodies from grasses); wood fragments can be traced tofurniture or forest locations • Dendrochronology – determine age of wood (art fraud – picture frames,wooden musical instruments) e.g. Lindbergh kidnapping (1932) - wood anatomist matched wood from a floorboard in the home of the accused toa repaired ladder left at the crime scene Dermal tissue• Epidermis – single layer of tightly packed cells • Cuticle – waxy coating secreted by epidermisof leaves and stems to conserve water • Root hairs – specialized epidermal cells forwater and mineral absorptionGround Tissue Fig. 24.5• Fills space between dermaland vascular tissue • Predominantly parenchyma - may be some collenchyma and sclerenchyma • Photosynthesis, support, and storage - storage often starch grains in rootsand water in stem Meristematic TissueMeristems Fig. 24.6Two kinds in plants – Apical andLateral1. Apical - Responsible for primary growth - Found in roots and stems - At apex of terminal buds in stems Apical meristem of a shoot• Dome shaped • All types of tissues (epidermal, ground, vascular) are derived fromapical meristem • Leaf primordia flank apical meristem • Axillary buds develop from meristematic tissue at base of leaf primordiaLateral Meristems• Responsible for secondary(outwards) growth 2 types of lateral meristems: Vascular cambium– In stems and roots ofperennials and woodytrees – Increases tree girth – Forms xylem to inside,phloem to outside Cork Cambium –