Life Cycle of Plants

-gametogenesis

-pollination

-fertilization

-embryogenesis

-germination

-vegetative development

-reproductive development

ovule

-protective womb like structure in which egg is fertilized inside og

Embryogenesis

-development continues inside the ovule; ends w/the maturation of ovule into a seed

seed

-structure that contains embryo and a supply of nutrients surrounded by a protective coat

*embryo may remain in nongrowing state inside seed for monts/yrs/centuries**

germination

-embryo resumes growth to form seeding

(only when conditions are favorable)

3 vegetative organs developed by organogenesis 

-roots, leaves, stems

vegetative organs

non-reproductive portions of the plant body

most dramatice different btwn plant/animal development is found during which stage?

-gametogenesis

in plantes gametes ar produced by MITOSIS that occurs in haploid cells produced by MEIOSIS

pollen grains

-diploid cell undergoes meiosis to form haploid cell which then divides via mitosis to give rise to tiny, multicellular structure

embryo sac

-diploid cell inside ovule divides by meiosis, producing 4 daughter cells (ONLY 1 SURVIVES)

-->survivng cell divides via mitosis several times producing tiny, multicellular sturcures

-inside a haploid cell; differentiates into an egg

-->cell and maternal cell (2 haploid nuclei)

alternation of generations

-life cycle invovleing alternation of multicellular haploid state (gametophye) w/a multicelllular diploid stage (sporophyte)

In most plants

How does pollen attach to stigma

protein-protein interactions

if protein-protein interaction btwn 

pollen and stigma successful then what?

-pollen tube begins to extend from the pollen

grain down to the stigma towards the egg

carpel

-femal reproductive organ in flower

-consists of stigma (pollen adheres)

-style (what pollen grains move through)

-ovary (houses the ovule)

How does double fertilization occur?

 -pollen tube reaches base of carple

-->second sperm cell exit pollen tube

-->pass through wall of ovule

-->enter embryo sac

-one sperm fuses w/egg to form diploid zygot

-other fuses w/ cell that has 2 maternal haploid nuclei to form a triploid (3n)

endosperm

-triplolid cell that divides via mitosis

-provides proteins, carbs, fats/oils required for development, seed germination, early seedling growth

(ANALOGOUS to yolk in animals)

embryogenesis

-takes place inside ovule as seed mature

analogous to cleavage, gastrulation, and organogenesis in animals

apical-basal axis

-due to asymmetrical cell division

-apical = tip

-basal = base/foundation

radial axis

-extends from interior out to exterior

-visible difference between interior/exterior cells

cotyledons

-embryonic leaves

-connected to developming root by the hypocotyl

hypocotyl

-stem like structure that connects cotyledon to developing root

shoot

-cotyledons and hypocotyl

-becomes the abovegroupd portion of body

-shoot system functions in photosynthesis and reproduction

roots

-form belowgroup portion

-root system anchors individual 

&

functions as water/nutrient gatherer

shoot apical meristem

root apical meristem

-fan form all aerial portions (including reproductive structures)

-can form all underground structures

meristem

-tissue consisting of undifferentiated cells that divide repeatedly into daughter cells

(some become specialized)

-analogous to stem but can differentiate into a wider variety of cells

3 embryonic tissues

-epidermis

-ground tissue

-vascular tissue

Epidermis

-outer covering of specialized cells that protects the individual

ground tissue

-insdie epidermal layer

-mass of cells that may later differentiate into cells that are specialized for photosyntheis, food storage etc

Vascular Tissue

-in center of plant

-will eventually differentiate into specialized cells that transport food and water btwn roots and shoots

apical mutants

-lacked the first leave/cotyledons

central mutants

-lacked embryonic stem or hypocotyls

basal mutants

-lacked both hypocotyls and roots

monopteros

-encodes transcription factors that regulates the activity of target genes

-activated by signals from auxin

-responsible for mutants

auxin

-cell-to-cell signal moleclue

-produced in shoot apical meristen

-transported toward basal parts

-forms concentraiton gradient

where is meristematic tissue located

-@ each tip in the shoot and @ tips of root systems

-individual capable of growing in any direction above/below ground depending on the conditions

what is located just below meristem

-daughter cells are produced by mitosis and cytokinesis in meristem initially differentiate into epidermal/groud/vascular tissues

-->eventually cells differentiate into more specialized type

3 axis in a leaf

1-proximal-distal axis = toward/away from main body

2-lateral = runs from middle leaf towards margins

3- adaxial-abaxial = upper/lower

Phantastica

PHAN

-critical in setting up adaxial/abaxial axis of leaves

-has DNA binding domain and acts as reg transc factor

-trigger expression of genes that cause cells for form upper surface of leaves and suppress transcription of genes required for forming lower leaf structure

when does flowering and gametogenesis occur?

-when SAM converts from vegetative development to reproductive development

-meristematic cells can give rise to reproductive organs of plants and eventually to sperm/eggs

What signals for reproductive development

-proteins sense nights shorter and temps more favorable

-->triggers production of signals that convert SAMs from vegetative develop to reproductive develop

floral meristem

-when SAM is converted from vegetative to reproductive developemnt

-contain reproductive organs NOT vegetative structure

-produces a flower

4 organs floral meristems produce

-sepals

-petals

-stamens

-carpels

sepals

-located around the outside of the flower

-provide proction as the organ develops

-attract pollinators

petals

-inside sepal

-circular arrangement

-enclose the male and female reproductive organs

-colored to help advertise reproductive organs

stamens

pollen producing organ

-located in whorl inside petals

carpels

-center of entire structure

-egg producing reproductive organ

(ovules located at the base)

what causes mutants

-homeotic transformation that occured

ABC model

-each of the 3 genes involve expressed in 2 adjacent whorls

-total of 4 different combination of gene products can occur

-each of four combinations trigger development of floral organs

A protein

causes cell to form sepals

A + B protein combination

-sets up formation of petal

B + C protein combination

-cells produce stamens

C protein

produces carpels

why no AC combination

-a protein inhibits production of C protien and vic versus

Which proteins expressed in which whorls?

A-outer 2

B-middle 2

C-inner 2

MADS box

-all 2 genes contained a segment that coded for long sequece of 58 a.a. (MADS box)

-binds to DNA

-floral genes encode reg transc factors that bind to enhancer/other reg sequences and trigger expression of genes required for sepal, petal, carpel, stamen formation