PLANT REPRODUCTION AND DEVELOPMENT

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CHAPTER 38

• PLANT REPRODUCTION AND DEVELOPMENT

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• ALTERNATION OF GENERATIONS
• SPOROPHYTE DIPLOID (PLANT)
• GAMETOPHYTE HAPLOID
• THE 2 GENERATIONS TAKE TURNS REPRODUCING EACH
  OTHER

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• MALE GAMETE
• POLLEN
• FOUND WITHIN THE SPORANGIA (POLLEN SACS WITHIN
  THE ANTHER)

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• FEMALE GAMETE
• OVULE FORMS WITHIN THE CHAMBER OF THE PLANT OVARY
  AND CONTAINS FEMALE SPORANGIUM
• THE MEGASPOROCYTE WITHIN THE SPORANGIUM OF EACH
  OVULE UNDERGOES MEIOSIS TO FORM 4 HAPLOID
  MEGASPORES (ONLY ONE WILL SURVIVE)
• THE REMAINING MEGASPORE UNDERGOES 3 MITOTIC
  DIVISIONS TO FORM 1 LARGER CELL WITH 8 HAPLOID
  NUCLEI
• MEMBRANES WILL SEPARATE THIS INTO A
  MUILTICELLULAR SAC. WITHIN THE SAC
• EGG AT ONE END FLANKED BY 2 OTHER CELLS
• OPPOSITE END IS FOUND 3 ANTIPOLAR CELLS
• POLAR NUCLEI (2) SHARE CYTOPLASM OF A LARGE
  CENTRAL CELL
• MICROPYLE-OPENING AT END

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• POLLINATION
• PLACEMENT OF POLLEN ONTO THE STIGMA OF THE CARPLE
  BY WIND, ANIMALS, INSECTS, SELF OR CROSS
  POLLINATION
• MONOECIOUS ANGIOSPERMS HAVE A MECHANISM TO
  PREVENT SELF-POLLINATION AS OPPOSED TO DIOECIOUS
  PLANTS THAT DO NOT

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• SELF INCOMPATIBILITY
• REJECTION OF POLLEN FROM THE SAME OR CLOSELY
  RELATED PLANT BY THE STIGMA
• THE POLLEN PRODUCES A CHEMICAL SIGNAL THAT IS
  DETECTED BY A RECEPTOR PROTEIN
• RECEPTOR WILL BIND TO A MEMBRANE KINASE
• KINASE WILL TRIGGER A SIGNAL TRANSDUCTION PATHWAY
• WHICH WILL ACTIVATE PROTEINS THAT WILL BLOCK THE
  FORMATION OF A POLLEN TUBE

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• DOUBLE FERTILIZATION
• UNION OF 2 SPERM CELLS WITH THE TWO CELLS WITHIN
  THE EMBRYO SAC
• LONG POLLEN TUBE DEVELOPS
• CARRY THE SPERM TO THE EMBRYO SAC
• SPERM IS DISCHARGED INTO THE SAC
• ONE SPERM WILL FERTILIZE THE EGG TO FORM A ZYGOTE
  AND THE OTHER WILL COMBINE WITH THE 2 POLAR
  BODIES TO FORM A TRIPLOID CELL THAT BECOMES THE
  ENDOSPERM (NUTRTION SOURCE FOR EMBRYO)
• MONOCOTS USE FOOD AFTER GERMINATION
• DICOTS EXPORT FOOD TO COTYLEDONS SO SEED HAVE
  NO ENDOSPERM

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• EMBRYOGENESIS
• AFTER GERMINATION APICAL MERISTEM AT THE ROOT
  AND SHOOT SUSTAIN PRIMARY GROWTH
• EMBRYO WILL CONTAIN
• PROTODERM
• PROCAMBIUM
• GROUND MERISTEM

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• 2 FEATURES ARE ESTABLISHED
• ROOT AND SHOOT AXIS ARE AT OPPOSITE ENDS
• RADIAL PATTERN OF THE PROTODERM

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• MATURE SEED STRUCTURE
• DICOT
• SEED COAT COVERING
• HYPOCOTYL BELOW THE POINT OF ATTACHMENT
  EMBRYONIC AXIS
• RADICLE EMBRYONIC ROOT
• EPICOTYL ABOVE THE COTYLEDON,
• PLUMULE TIP OF EPICOTYL HAS SHOOT TIP AND A
  PAIR OF EMBRYONIC LEAVES
• DICOT HAS A FLESHY COTYLEDON

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• MONOCOT
• SCUTELLUM LARGE SURFACE AREA TO ABSORB
  NUTRIENTS FROM THE ENDOSPERM
• COLEORHIZA COVER ROOT
• COLEOPTILE COVERS SHOOT
• OVULE DEVELOP INTO SEED
• OVARY DEVELOPS INTO FRUIT
• PROTECTS THE SEED
• AID IN SEED DISPERSAL
• FLESHY PART IS FORMED FROM THE FUSION OF BASE OF
  THE FLOWER
• APPLE CORE IS THE TRUE FRUIT

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• TRUE FRUIT
• RIPENED OVARY
• POLLINATION TRIGGERS HORMONAL CHANGES WHICH CAUSE
  THE OVARY TO GROW
• WALL OF OVARY THICKENS TO BECOME PERICARP
• FRUIT SET FLOWER TURNING TO A FRUIT WHICH
  PARALLELS THE SEED DEVELOPMENT
• MOST PLANT THE FRUIT DEVELOPS UPON FERTILIZATION
• PARTHENOGENESIS A PLANT WHERE FRUIT DEVELOPS
  WITHOUT FERTILIZATION

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• FRUITS
• SIMPLE SINGLE OVARY OF 1 FLOWER (CHERRIES)
• AGGREGATES MANY OVARIES OF 1 FLOWER
  (BLACKBERRIES)
• MULTIPLE MANY OVARIES OF MANY FLOWERS
  (PINEAPPLES)

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• FLESHY FRUITS
• RIPEN DUE TO HORMONAL INTERACTIONS
• CELL WALL DIGESTED BY ENZYMES THAT WILL SOFTEN IT
• ORGANIC ACIDS AND STARCH ARE CONVERTED TO SUGAR,
  WHICH CAUSE AN ODOR CHANGE AS WELL AS SWEETEN THE
  FRUIT
• ATTRACTION OF ANIMALS

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• EVOLUTIONARY ADAPTATIONS
• SOME SEEDS GERMINATE AS SOON AS THEY REACH A
  SUITABLE ENVIRONMENT
• SOME HAVE SPECIFIC ENVIRONMENTAL CUES THAT ARE
  NEEDED IN ORDER TO BREAK DORMANCY
• DORMANCY
• SLEEPING OR RESTING, PREVENTS GERMINATION
• IMPORTANT ADAPTATION FOR TERRESTRIAL CONDITIONS
  WHICH MAY VARY MORE THAN AN AQUATIC ENVIRONMENT
• INCREASES SUCCESS WHEN GERMINATION DOES OCCUR

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• SEED TO SEEDLING
• IMBIBITION WATER ABSORPTION
• CAUSE THE SEED TO SWEEL AND RUPTURE
• CREATE METABOLIC CHANGES IN THE EMBRYO TO RESUME
  GROWTH
• STORAGE MATERIALS ARE DIGESTED AND NUTRIENTS USED
  FOR EMBRYONIC GROWTH

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• RADICLE EMERGES FIRST
• THEN THE SHOOT TIP BREAKS THE SOIL
• A HOOK FORMS IN THE HYPOCOTYL AND GROWTH PUSHES
  HYPOCOTYL ABOVE GROUND
• LIGHT STIMULATES THE HYPOCOTYL TO STRAIGHTEN
  WHICH RAISES THE COTYLEDON AND EPICOTYL
• LEAVES BECOME GREEN
• LIGHT IS TH ECUE TO TELL THE SEELDING IT HAS
  BROKEN GROUND
• SEEDLING SMALL S SURVIVE

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• VEGETATIVE PROPAGATION
• FRAGMENTATION SEPARATION OF A PARENT PLANT INTO
  PARTS THAT ARE ABLE TO FORM NEW PLANTS
• APOMIXIS (DANDELION) DIPLOID CELL WHICH CAN
  GIVE RISE TO AN EMBRYO. OVULES MATURE INTO SEEDS
  WHICH ARE DISPERSED. SEEDS ARE CREATED WITHOUT
  MEIOSIS OR FERTILIZATION

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• AGRICULTURE
• CLONES FROM CUTTINGS
• CALLUS THE END OF THE SHOOT, ADVENTITIOUS ROOTS
  ARE ABLE TO DEVELOP
• GRAFTING
• STOCK ROOT SYSTEM
• SCION GRAFTED TWIG
• WINE INDUSTRY (GRAPES)
• SEEDLESS FRUITS

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• TEST TUBE CLONING
• PROTOPLAST CELL WALL IS REMOVED
• PROTOPLAST FUSION COUPLED WITH TISSUE CULTURE
• PARENCHYMAL CELLS GIVE RISE TO A CALLUS WHICH IS
  ABLE TO DIFFERENTIATE INTO AN ENTIRE PLANT

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• RISK AND BENEFITS
• MONOCULTURE LARGE LAND AREA WITH A SINGLE PLANT
• MAJOR FACTOR IN THE IRISH POTATO FAMINE (OOMCOTA)
• BENEFIT SPECIES SHOULD NOT BE WIPED OUT

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• DIFFERENTIATION GROWTH
• 3 PROCESSES WILL TRANSFORM A FERTILIZED EGG INTO
  A PLANT
• 1. GROWTH IRREVERSABLE SIZE INCREASE WHICH
  RESULTS FROM CELL DIVISION PLUS CELL ENLARGMENT.
  MITOSIS IN ROOTS AND SHOOTS MERISTEMATIC CELLS
• 2. MORPHOGENESIS FORM, DEVELOPMENT OF BODY
  SHAPE AND ORGANIZATION
• 3. CELLULAR DIFFENTIATION
• DIVERGENCE IN STRUCTURE AND FUNCTION
  (SPECIALIZATION)

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• CYTOSKELETON
• PLANT CELLS CANNOT MEOVE AROUND DUE TO THE
  PRESENCE OF A CELL WALL
• SO CELL GROWTH IS PERPENDICULAR TO THE PLANE OF
  DIVISION
• PREPROPHASE BAND MICROTUBULE RING THAT
  SURROUNDS THE NUCLEUS AND WILL CONTROL THE FUTURE
  PLANE OF CELL DIVISION
• ACTIN MICROFILAMENTS WILL HOLD THE NUCLEUS IN A
  FIXED POSITION UNTIL THE SPLINDLE FORMS AND
  DIRECTS FORMATION OF THE CELL PLATE

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• ORIENTI NG THE DIRECTION OF CELL EXPANSION
• IS MAINLY DUE TO WATER UPTAKE
• CELL WALLS BECOME LOOSE DUE TO WEAKENING OF THE
  CROSS LINKS BETWEEN POLYMERS IN THE CELL WALL
  WHICH WILL REDUCE TURGOR AND IT CAN NOW TAKE UP
  MORE WATER AND THE CELL WILL ELONGATE
• VACUOLES WILL COALESCE AND FORM A CENTRAL VACUOLE
  WITH LITTLE INCREASE IN WIDTH
• LOCATION OF CELLS WILL CAUSE A DIFFERENT TYUPE OF
  EXPANSION

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• CELL DIFFERENTIATION DEPENDS ON GENE EXPRESSION
  DUE TO SPECIFIC PROTEINS BEING SYTHESIZED

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• PATTERN FORMATION
• LOCATION AND ORGANIZTION
• DEVELOPMENT OF SPECIFIC STRUCTUES IN SPECIFIC
  LOCATION

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• POSITIONAL INFORMATION
• SIGNALS INDICATING A CELLS LOCATION RELATIVE TO
  OTHER CELLS IN AN EMBRYONIC MASS.
  DIFFERENTIATION AND ORGAN DEVELOPMENT OCCUR

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• CLONAL ANALYSIS OF SHOOT APEX
• MAPPING A CELLS LINEAGE
• HOW EARLY IS THE FATE OF A CELL DETERMINED
• CELL POSITION WILL DETERMINE WHAT TYPE OF A CELL
  IT WILL DEVELOP INTO

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• THE GENETIC BASIS OF PATTERN FORMATION
• DAYLENGTH AND HORMONES WILL TRIGGER CHANGES IN
  SHOOT TIP TRANSITION TO A FLORAL MERISTEM
• MERISTEM IDENTITIY GENES
• TRANSCRIPTION FACTORS THA HELP ACTIVATE GENES
  NEEDED FOR FLORAL MERISTEMATIC DEVELOPMENT

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• ORGAN IDENTITY GENES
• FUNCTION IN THE DEVELOPMENT OF A FLORAL PATTERN
• MUTATION SUB ONE TYPE OF FLORAL ORGAN FOR
  ANTOHER, THIS MAY CAUSE EXTRA SEPALS, PEDALS ETC.
• THE MODEL ORGANISM FOR PLANT GENETIC RESEARCH IS
  ARABIDOPSIS

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