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Sporic life cycle: Occurs in ALL plants and but there is tremendous variation
Variation: Isomorphisic alternation of generations: the gametophyte and sporophyte are morphologically identical (sea lettuce)
Heteromorphism: the gametophyte and sporophyte are not identical
Can have dominant gametophyte (mosses) or dominant sporophyte (ferns - where gametophyte is freeliving)
Trees, shrubs, grasses, herbs are:: all dominant sporophyte - gametophyte is hidden
Zygotic Life cycles: most primitive type, some algae, protozoa and fungi
the ZYGOTE is the ONLY diploid cell
can go into resting stage or dormant stage and amke a zygospore
Process: zygote is one cell from teh fusion of gametes - diploid undergoes meiosis (NEVER mitosis)
there is no sporophyte or sporangia
spores undergo mitosis and produce gametes or gametophytes
Gametic life cycles: NO gametophyte stage
Cells in the sporophyte undergo meiosis and produce spores (equal to gametes)
Found in protists and all mammals
Gametophyte: haploid individual or stage of life that produces gametes in gamentangia by mitosis; do NOT undergo meisois
Sporophytes: diploid individuals or stage of life that produces haploid spores by meiosis, in the gametic life cycle spores are equal to gametes
Homosporous: all spores are identical
give rise to bisexual gametophyte
Heterosporous: production of two types of spores (gives rise to male or female gametes)
Isogamous: male and female gametes that are the same, flagellated and tend to be small
Anisogamous: still flagellated, one big and one small
Oogamous: one flagellated and have one egg (don't fuse, sperm has to find egg)
Haploid: a single set of genes
Diploid: has two copies of each gene, sporophites can be diploid or polyploid
Angiosperms: flowering plants
monocots: have grass like leaves (corn, onions)
dicots: have broader leaves
Dicots divided into two groups:: magnoliids and eudicots
Monocots and eudicots evolved from the magnoliids
Gamentangia in males and females: antheridia (male)
archegonia (female)
Calyx and corolla: collectively called the perianth
Carpels: evolved from infolded leaves with ovules on their margins
Is a carpel the same as a pistil?: They can be (when pistil is simple) a pistil can have one or many carpels
Superior ovary: when ovary is above the other flower parts
Hypogynous: corolla, stepals, stamens are hypogynous whe they are under the ovaries
Inferior ovary: it has fused with the receptical so it is below the other flower parts
Epigynous: flower parts are ABOVE the ovary
Hypanthium: tube like structure partially fused with petals, sepals and stamens
Perigynous: many ovaries inside
Perfect flowers: have both stamen and carpels
Imperfect flowers: lack either stamens or carpels (pistillate flower - lackes stamens, stamenate flower - lacks pistils)
Complete flowers: have all four whorls (petals, sepals, stamens and carpels)
Incomplete: missing one or more of the whorls
Example: Flower missing petals is...: perfect but incomplete
Imperfect flowers can have..: stamenate and pistillate flowers on teh same plant (monoecious)
Dioecious: imperfect flowers with stamenate and pistilate flowers on different plants
Infloresence: A group of flowers
Spike: flowers are directly ont he main stem
Simple umbrel: peduncle lower and pedicles all come out from one point
Catkin: have a peduncle which is hanging downwards (poplar, birch)
Megasporocyte: megaspore mother cell
produce a cell (not a spore)
Integuments: tissue surrounding gametophyte - develops into teh seed
Micropyle: opening into the ovule allowing things in
Funiculus: arm which is holding the ovule in place
Sporangeous cells: inside there are many microspore mother cells which undergo meiosis and produce microspores (2N)
Anthers: filled with tetrads of pollen grains, eventually splits open (dehisses) and releases the pollen --> doesn't release sperm but a tiny 2 cell gametophyte
After pollen grains are released: pollen grains then land on stigma --> the pollen germinates and grows a pollen tube
Pollen Grain: Male gametophyte
Exine: outer layer of pollen grain, highly sculptured, made from sporopollenin which is VERY decay resistant
How does pollen grain move to the stigma?: bees, winds, mammals
Once pollen tube lands on stigma..: pollen tube grows up the style - tube nucleus leads the way and sperm follow - pass through the micropyle - sperm enters
Self incompatable: dont want to be fertilized by pollen of the same plant
Double fertilization: 1) One sperm fuses wtih egg which produces a 2n zygote and grows into embryo
2) other sperm fuses with the 2 polar nuclei and produces a 3n endosperm nucleus
3N nucleus: undergoes division and produces multiple 3n nuclei and later forms the cell wall
Endosperm: develops into endosperm in monocots
Endosperm in monocots: endosperm present in the mature seed, it is storage for the germinative seed (corn), stores starch and protiens
Endosperm in dicots: endosperm usually gets used up during the seed maturation
Antipodals and synergids: serve no purpose
Differences in monocot and dicot seed development: coleoptile covers the SAM in monocot
scutellum in monocot transfers food from endosperm to embryo
Zygote: develops into the embryo
SAM and RAM: SAM - produces new nodes and internodes
RAM - at the end of every root there is a RAM
Ovule and ovary wall: ovule - develops into a seed (1 ovule = 1 seed)
ovary wall - develops into pericarp
1 ovary is equal to: one fruit
True Fruits: develop from ovary wall and consist of pericarp
False Fruits: develop from at least partly from non-ovarian tissue (accessory fruits) (strawberry)
Main tissue deveolops from hypanthium or receptical tissue
Achenes: has dry, indehiscent fruit
Aggregate Accessory: swollen fleshy receptacle with many dry fruits on surface
Simple Accessory: a single ovary enclosed in receptacle tissue
(pome)
Pome: have a papery endocarp by core (apple and pear)
Simple Fruits: Fruit develops from one or more ovaries in one flower
Aggregate Fruits: from many carpels in one flower but carpels are NOT fused (raspberry)
Multiple fruits: formed from carpels of several associated flowers (pineapple)
Fleshy simple fruits: pericarp is fleshy at maturity, tissues can be sugary, starchy or fatty
Drupe: endocarp hard and stoney, ovary superior, single seed (cherry)
Berry: Entire pericarp is fleshy (tomato)
Hesperidium: a type of berry with a leathery outer rind containing oils (orange)
Pepo: a type of berry with a thick outer rind with no oils (pumpkin)
Dry simple fruits: pericarp composed of dead cells
indehiscent: fruit wall dry and not opening at maturity
Nut: pericarp hard and stony, cup at base, acorn
Caryopsis: grains, single seed fully fused to pericarp, pericarp soft and thin
Achene: single seed only attached to pericarp at base (sunflower), pericarp soft and thin
Dehiscent: fruit splits open at maturity (legume)
Legume: one carpel, splits open at both sides (beans)
What happens to the seeds? Case 1: seeds can germinate while still on the mother plant (not common) (called viviparity)
Case 2: Seeds can dry down and dehydrate and are shed in a dry stat (called orthodox seeds)
Orthodox Seeds: start out 90% water and 10% dry matter, during maturation udergo dehydration and become 5-20% water and 80-95% dry matter, after they dry are shed tot he mother plant and can be quiescent or dormant
Case 3: Recalcitrant seeds - cannot be dried down or they lose their viability, must germinate sooner or they die (nuts)
Germination of Orthodox Seeds: Moist developing seeds --> dehydrate --> dry seeds --> quiescent or dormant
Quiescent: normal, dehydrated seed, when given water, oxygen and temperates will germinate (garden vegetable)
Dormant: dried down orthodox seeds, need certain special requirements to be fulfilled before they can germinate
Exogenous dormancy: dormancy imposed by factors OUTSIDe the embryo
Endogynous dormancy: dormancy due to internal factors in the embryo itself
Physical factors (exogynous): seed coat is impermeable to gases and water therefore cannot germinate because water can't reach embryo (can break down dormancy with scarification)
Chemical factors (exogynous): dormancy imposed by inhibitors present in the seed coat or present in the wall, break dormancy by washing away chemicals
Morphological (endogynous): the embryo itself is still not fully developed even though seed is shed off mother plant
Physiological (endogynous): some physiological block within the embryo itself that prevents germination (photodormancy - requires exposure to red light)
Photodormancy: most common in small seds because large seeds have more stored reserves than small - seeds MUST have sufficient reserves to germinate, grow and reach surface before they run out - small seeds germinate near surface after exposure
How do plants detect red light?: 1) Photosynthesis - using light as a source of energy (chlorophyll and carotenoids)
2) photomorphogenesis - using light as a source of information (phytochrome)
Phytochrome: involved in seeds needing light, exists in two photoreversible forms (Pr and Pfr)
Pr and Pfr: Pr - inactive - present in the dark
Pfr - active form, causes germination
Stratification: imbibe seeds in moist, usually cool conditions for weeks to months mimmiciing spring time or fall time
Apomoxis: apomatic seeds
- production of an embryo without fertilization (dandylions)
- no union of sperm and egg, clone of mother
Parthenocarpy: development of the fruit without seeds (seedless grapes)
Hypocotyl: first piece of stem above the roots but below the cotelydons
SAM: shoot apical meristem - where new cells are produced, most important part of the shoot
Hypocotyl hook: to protect the SAM
De-etiolation: as the hook emerges above ground into surroundings PR is converted to PFR and this is the signal for the hypocotyl hook to straighten anad for the cotelydons to green up
Etiolated Seedlings: pale, yellowish due to carotenoid
seedlings grown in no light - an etiolated seedling devotes most of its time and energy to extension growth
Epigeous germination: cotelydons come above ground
1) cotelydons can come above ground and become leaflike (watermelons)
2) cotelydons can come above ground but they are purley storage organs so wither away and die
Hypogeous germination: the cotelydons stay where they are but shoot grows up to form EPICOTYL hook
Fruit in monocots: caryopsis - seed coat is fused to the fruit coat
De-etiolation in monocots: coleoptile stops growing and leaves grow green and emerge - comes from SAM
coleoptile then splits open and withers away
Purpose of coleoptile: provides a safe passageway for the leaf to push it's way up through the g ground
Shoot and Root: shoot - everything above the root shoot interface
root - everything below
Internode: the stem between nodes
Axillary buds: buds in the axils of a lead at nodes
they are resting or dormant SAMs waiting for the right signal to grow
Phytomere: repeating unit of shoot (internode, node, axillary buds, leaves)
Branch: just another shoot growing from a node, same as main stem
Primary plant body: built on repeating units called a phytomere
Plant body of monocots: built on the same plan as dicots except typically hvae very short stem with short internodes
How do plants grow?: 1) cell division at meristems to increase cell number
2)cell expansion to increase cell size
Meristems: groups of specialized cells that are more or less capable of continuous cell division
Primary Meristems: give primary plant body (basic stem, root and leaves)
Shoot Apical Meristem: Transitional meristems, protoderm, ground meristem, procambium
Root Apical Meristem: transitional meristems
Lateral meristems: give secondary growth, increase girth of stems and roots
Intercalanary meristems: meristem stuck between two nodes
Basal meristems: only found at the base of monocot leaves
Marginal meristems: around the outside of dicot leaves - makes new cells which expans
Initials and derivitives: initials - cells that divide
derivitives - cells that are produced
Differentiation: a process by which cells with the same genes become different from one another in terms of form and function
differentiation produces different cells and tissues
Tissues: groups of cells that form a structural or functional unit
Simple tissues: made up of only one type of cell (parenchyma)
Complex tissues: made up of MORE than one type of cell (dermal tissues)
Vascular Tissues (type of complex): invovled in long distance transport
Two types of vascular tissues:: Xylem- carries water and minerals from the root to the shoots
Phloem - carries water and sugars and some hormones from sources to sinks
Sources: sources of sugars either freshly made in leaves or stored
Sinks: reguions that are using/need sugars (either growing regions or where they are stored)
cotelydons are sinks during development and sources durin germination
Ground Tissue: everything between the vascular and dermal tissues
Basal meristem: leads to the growth of monocot leaves - makes new cells which undergoes cell expansion
Basal meristems located at the base of each leaf in monocot plants
What causes different leaf shapes: varying activity of marginal meristems
monocots do not have marginal meristems (because they are long and have a basal meristem and grows UPWARD vs. dicot leaves which grow WIDTH wise)
Vascular cambiums: occurs only in platns have secondary growth, not in monocots
Part of lateral or secondary meristems
Produces Phloem to the outside and xylem to the inside
Cork Cambium: only in dicots with secondary growth, produces cork cells to the outside (bark) and secondary cortex to the inside
Tunica-corpus model (model of how SAM works): have anticlinal and periclinal division
tunica - produces cell surface/epidermis
corpus - produces vascular tissues and ground tissues
when SAM is damaged mother cell produces new cells
Central mother cell zone: cells which rarely divide and are held in reserve
Periclinal division: division parelell to tissue surface -corpus
increases volume
Anticlinal division: increases SA
cells divide perpendicular to the surface
corpus and tunica
Plants can be chimeras: plants that have cells with different genes
occurs because plant growth is MERISTEMATIC
How do plants have cells with different genes?: if there is a mutation, all cells that derive from that cell are going to have a different gene - may show up in leaves, bud etc. depending on where in the SAM mutation occured
Examples of Mutations: Blackberry: wild blackberries are VERY thorny but cultivated are thornless but revert in exceeding years
How do blackberries revert?: thornless have a mutation in the tunica (which produces epidermal cells that make thorns), mutation is not in the corpus
If tunica is damaged the corpus produces new tunica that does not have the mutation
Mutations in the corpus: if have a mutation int eh corpus may never see it unless the tunica is damaged
What is the advantage of rarely dividing mother cells?: unlikely to develop a mutation
Suckers: do NOT arise from axillary buds,arise adventitiously (occuring in an abnormal way or area - never grow into healthy normal plant)
Where do flowers and inflorescences come from?: SAM and axillary buds can be converted into floral meristems by signals (like daylength)
Floral meristems: produces flowers and inflorescences
Photoperiod: tells plants when to flower, measure of daylength
Cell expansion: cells expand in two ways
1) tip growth
2) diffuse growth
Tip growth: unusual
occurs in root hairs, pollen tubes
new material is added into the ends
How do root hairs grow?: grow as extensions of dermal tissues
grow by adding new material to the tip
Diffuse growth: 99.9% of plants
cell wall expands similar to a balloon
For diffuse growth to occur:: requires turgor (pressure within the cell)
need cellular microfibrules to slide past each other to allow the cell wall to expand
need low pH in cell wall to allow cellulose to slide past each other
Where is diffuse growth occuring?: anywhere plant organs are increasing in size (just behind the SAM, internode, behind RAM)
Middle lamella: material that holds adjacent cells together
made of pectins
Pectins: complex polysaccharide made from many sugars linked together
Galacturonic acid: main sugar in pectins
has a carboxyl group that makes in negatively charged
Divalent cations: (have two charges) (Mg++)
go in and make pectins stick together and form a gel
if remove divalent cations middle lamella will fall apart
Middle lamella and fruit ripening: includes action of pectinases (enzymes which digest pectins)
Primary Cell Wall: consists of cellulose microfibrils imbedded in a matrix of pectins, hemicellulose and glycoproteins
Properties of Pectins: very strong but flexible, but needs turgor to assume it's shape
turgor comes from the cytoplasm
has lots of spacing - very permeable to ions, water and small molecules
Cellulose: polysaccharide made from thousands fo glucose molecules linked by B1-4 bonds which animals cannot break
Cellulose microfibril: take 60-80 cellulose molecules held together with H bonds
very strong, cannot be stretched, layed down in patterns
How is the PCW synthesized?: cellulose synthase complex makes entire microfibril at one time - adds glucose to end of 60-80 glucose molecule and celllulose microfibril grows
*as the microfibril grows the cellulose synthase moves back*
What governs the orientation of the cellulose microfibril synthesis?: on underside of plasma lipid bilayer there are microtubules of the cytoskeleton which act like a railway directing movement of rosettes
Rosettes: 5 proteins subunits in cellulose synthase complex
What controls direction that cell grows?: orientation of cellulose microfibrils - the orientation of the newer innermost layer of cellulose microfibrils
Synthesis of Pectins and Hemicelluloses: made in teh golgi - move by vescicles to PM - fuse with PM and release contents into PCW
Acid Induced Growth: at pH of 4-5 cellulose H bonds holding it to hemicellulose are loose and cellulose can slide past each other
When will cellulose slide past?: when there is sufficient internal turgor pressure
Where does the low pH in PCW come from?: proton pumps in plasma membrane pump out H ions get a hydrogen ion gradient and low pH outside cell allowing cellulose to slide past each other
What activates proton pumps?: hormones like auxins which will cause cell expansion
Plasmadesmata: direct cytoplasmic connections from one cell to the other
PM of one cell linked to PM of another
What does plasmadesmata go through?: Goes through plasma membrane, cell wall, middle lamella
Why plasmodesmata?: Small substances can pass directly (without passing through PM) from one cell to another
they are basically communication junctions
Desmotubule: extension of the ER tubules from one cell to another
small molecules can more through the plasma desmata
Gate mechanism: made of proteins that control waht goes trhough (only amino acids, smaller proteins, sugars, viruses, NOT cellular organelles)
Secondary Cell walls: much thicker that PCW
usually in 2-3 layers
lignified
rigid and IMPERMEABLE
Lignin: complex polyphenolic which is rigid and impermeable and stains red with phloroglucenol
Differences between PCW and SCW?: PCW= flexible, strong, very permeable
SCW= regid, strong, immpermeable
Pits: small areas with no SCW to allow for exchanges of gases, sugars, etc
do NOT go through PCW
Where do we find plasmadesmata: concentrated in oval areas of thinner pcw called primary pit feilds
Where do pits occur?: occur in primary pit feilds
where there is lots of plasmadesmata cells do not put secondary cell walls
Three main types of cells in plant: parenchyma
collenchyma
sclerenchyma
Parenchyma: oldest and most primitive
has thin flexible pcw, never has scw, alive at functional maturity
Photosynthetic parenchyma: filled with chloroplasts
Spongy parenchyma: tend to have no chloroplasts, lots of amyloplasts
Collenchyma: has PCW that is thickened at the corners
alive at maturity
has thicker PCW that contains extra pectins (which form a gel and become glisteny white)
Plastic deformation:: living cells that can assume and maintain form in a growing leaf or stem
provide strengthening to living cells that can undergo changes later
Plastic deformation vs. elastic deformation: plastic - tends to stay in pulled shapes
elastic - goes back when pulled
Where are collenchyma founds?: young stems
young growign tissue
around edge
- main function of these are structural support
Sclerenchyma: any cell with a thick, lignified SCW
never found in primitve plants
Main Functions:: 1) support
2) protection
3) some involved in xylem transport
Two major categories: Mechanical sclerenchyma
conducting sclerenchyma
Mechanical: support and protection
1) sclereids - not elongated
2) fibre cells - like sclereids but elongated
Conducting: move water and nutrients from roots to shoots in xylem
1) trachids
2) vessel elements
SCW has...: cellulose
hemicellulose
lignin
not pectins!
Schlerenchyma: usualy dead at maturity
cells under programmed cell death
have mechanical scelerenchyma and conducting sclerenchyma
Sclereids: found in layers such as pericarp on nuts
also isolated in leaves and fruit tissue
Fibre cells: similar to sclereids except are elongated, can be up to several inches long
found in vascular bundles
Tracheids: found in angiospers and lower vascular plants
elongated, usually pitted on side wall and end walls
Vessel elements: hollow cylenders with perforated end walls
H2O moves freely from cell to cell
gymnoserperms have NO vessels
Three main tissue systems: ground, dermal and vascular
Dermal: exterior surface of root and shoot
1 layer thick often
not invovled in secondary growth
Types of cells: Ordinary epidermal cells - parenchyma
Guard cells - part of stomatal aparatus ( when they swell they make a pore)
Trichomes - hair cells
Trichome purpose: protection - some can inject toxins
absorbtion of nutrients
increases boundary area at leaves
shoot system of plant is coverered with: a cuticle - to reduce water loss
Cutin: polymer that is incredible water proof, thick in xerophytes
Waxes: waterproof and impermeable to gasses, resistant to enzymes and decay, reflect light
What leads to tissue systems?: dermal - protoderm
ground - ground meristem
vascular - procambium
Purpose of ground tissue: some photosynthesis, storage, support
Vascular tissues: xyleom and phloem
Xylem in Angiosperms (monocots and dicots): vessel elements, tracheids, fiber cells, parenchyma (only one living)
Xyleom in gymnosperms (conifers): tracheindss and NO vessels
parenchyma
no fibers
Phloem: Sieve elemetns (living cells)
Fiber cells
Companion cells or albuminous cells
Main difference between phloem and xyloem: in xyleom the conducting cells are dead and have thick lignified cell walls (woody)
in phloem conduction cells are living and have thin walled parenchyma (not woody)
Stele: a term used to descrie the vascular tissue in roots and stems but not leaves
Vascular cambium: has two areas (interfasicular and fasicular)
group of cells that has become meristematic and produce secondary xylem (to inside) and phloem (to outside)
Cork cells: regular in shape - no secondary cell wall
primary cell wall has SUBERIN
cells are dead
SUBERIN: very impermeable lipid making the cork layer
Does wood have living tissue?: yes - secondary pholoem and parenchyma
Lenticels: irregular, nonsuberized cells in areas that allow oxygen to enter, groups of cells
Layers of periderm: cork cells, cork cambium, and secondary cortex
Bark: Bark is equal to EVERYTHING OUTSIDE THE VASCULAR CAMBIUM
secondary phloem
secondary cortex
cork cambium
cork
When a tree has been girdled...: removes bark - secondary xylem is still present but the secondary phloem is gone or damaged - so there is no sugar transport and roots eventually die
New cork cambia:: established by the tree in response to cork splitting - in the secondary cortex or phloem
Ways to make new cork cambia: 1) make in ring - birch
2) uneven initiation (scale bark)
Wood is equal to: secondary xyloem
Two systems in wood: vertical system (axial system)
horizontal system (ray system)

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