bio 2d03

when did life emerge?

3.8 bya

what is the first major event of plant life?

non-oxygenic photosynthesis and origin of ancestors of cyanobacteria 3.8 bya

what is the evidence of photosynthesis?

more carbon dating of C12 in ancient rocks compared to C13

what is the second major event of plant life?

oxygenic photosynthesis 3.5 bya and widespread 2.2 bya

what is the evidence of current photosynthesis?

chemical evidence of cyanobacteria 2.7 bya and stromatolite fossils

what did stromatolites do?

protected early cyanobacteria from UV

what is the third major event of plant life?

evolution of eukaryotes 2.7 bya

what is the evidence of eukaryotes?

steroles found in rocks because they are only in eukaryotes

what is the fourth major event of plant life?

multicellularity 1.25 bya

what is the evidence of multicellularity

discovery of bangiomorpha fossils

what are the most important things for land plants?

ability to retain water and a way to fight against gravity to transport water

what is the evidence of early land colonizers

bryophytes, spores, and ancient fossils

what is a bryophyte?

nonvascular spore-forming land plant

what does lignin do?

provides mechanical support for water transport and minerals in xylem

what was the progenitor of seed plants?

progymnosperms

what does a stomata do?

increases gas exchange, maintains water flow, and provides evaporative cooling

what does low CO2 levels do to the stomata?

increases number of stomata to intake more CO2

types of gymnosperms

Cycads, Conifers, Ginkgoes, and Gnetophytes

types of angiosperms

monocots, eudicots/dicots, and magnoliids

what is the difference between monocots and eudicots?

monocots only have one cotyledon and eudicots have two

features of angiosperms

flowers, seeds have endosperm, xylem vessels

what plants have large gametophytes and small sporophytes?

bryophytes

what plants have large sporophytes and small gametophytes?

ferns and horsetails

what kind of plant life cycle do seed plants follow?

sporophyte enclosing female gametophyte and dispersed male gametophyte

what is different about somatic plant mutations compared to somatic animal mutations?

somatic plant mutations can be passed on to offspring

what is a benefit of alternating generations between sporophyte and gametophyte?

removal of deleterious mutations in haploid generation because they will not be able to survive to pass on their genes

general timeline of plant evolution

algae --\> bryophyte-like plant --\> development of lignin --\> vascular system --\> gymnosperms --\> angiosperms

what is a benefit of sequencing a genome?

gives better idea of the required genes to make a plant, develops techniques to monitor genes, identifies similarities among other organisms,develops our understanding of evolution

what does P450 enzyme do?

produces secondary metabolites such as anit-microbial and anti-herbivory molecules

what is a transposon?

discrete piece of DNA that moves from one region of the genome to another

what is a class I retrotransposon?

copies itself by producing mRNA, reverse transcriptase, and transposase to reverse transcribe the mRNA into DNA which inserts itself into another part of the genome

what is a Class II DNA transposon?

moves to another part of the genome without copying itself. may or may not leave a footprint that can cause mutations

what induces transposon movement?

stress to generate genetic diversity but it is only useful for organisms with lots of progeny

what are the reasons for transposons?

genomic parasites or adaptive advantage

functional redundancy

2 or more genes that do the same thing

ortholog

a gene in one organism that is similar to a gene in another organism because of descent from a common ancestor

Paralogs

duplication of genes within a species

synteny

order of genes in a genome that are conserved in closely related species

what tools help discover gene function

forward genetics, expression profiling, reverse genetics, manipulation of plant genes using transgenic technology

examples of expression profiling

microarrays and RNA sequencing

what is used to overexpress a gene

transgenic technology by adding a 35S promoter onto the gene and inserting the transgene into the genome
can also lead to the inhibition of a function if the gene is a negative promoter

what is used to suppress a gene

transgenic technology by adding a 35S promoter onto the antisense gene which hybridizes to the native gene, causing it to be cleaved.

how do you transfer transgenes into a plant?

using agrobacterium:1. create transgene by adding 35S promoter onto gene2. insert transgene into T-DNA3. transfer T-DNA into agro4. infect plant with agro5. gene of interest is transferred into the plant

what is endoreduplication?

DNA replication without nuclear cell division

what does endoreduplication do?

results in polyploidy (i.e. a cell with 4C undergoes 4 rounds of endoreduplication to get 32C)

why does endoreduplication occur?

to tolerant DNA damaging conditions and to increase cell size

True or False: Primary cell wall is laid down first

True

what does the primary cell wall do?

allow cell expansion and withstands turgor pressure

what is cellulose?

polysaccharide made of beta-glucose

what is pectin?

linear and branched sugar polymers made of galacturonic acid backbone and other sugars

what is the middle lamella?

pectin layer that cements adjacent plant walls together

what are junction zones?

calcium bridges between pectin polymers

what are microfibrils used for?

to resist turgor pressure and provide support for the plant

what proteins synthesis the primary cell wall?

CESA 1 and 3

what happens if CESA 1 and 3 proteins are mutated?

retarded growth phenotype (i.e. bulging caused by lack of resistance to turgor pressure)

what are temperature sensitive mutants used for?

to find mutations that only affect protein function at high temperature and allow them to survive for future studies

what proteins synthesis the secondary cell wall?

CESA4, 7, and 8

what are protoplasts?

plant cells without a cell wall

what is the difference between criss-cross and hooped microfibrils?

criss-cross grow in all directions while hooped grow perpendicular to the hoops

what do microtubules do in plants?

determine direction of cell expansion

What is confocal scanning microscopy?

scanning a thin layer of the cell

what are reporter genes and what are they used for?

visualize where the gene of interest is expressed in the cells (i.e. GFP)

what happens in Mor1 mutant plants?

no cell expansion so the plant is small

what are vacuoles and what do they do?

storage in a plant; stores and sequesters waste products, stores enzymes, pigments, and maintains turgor pressure

what is turgor pressure?

movement of water and solutes into the cell

what does turgor pressure do?

it gives plants shape and support

what is cell expansion?

osmosis to increase turgor pressure and the loosening of cell wall by reducing microfibril and pectin cross-links

what does the secondary cell wall do?

storage, strength, and water-proofing

what is suberin?

phenolic compounds linked to fatty acids, alcohols and waxes. allows secondary cell wall to be water-proof

where is lignin found?

secondary cell walls (i.e. xylem)

what does the xylem do?

transports water and minerals

why is the xylem good at water conducting?

perforation plates at the ends of the vessels

what happens if CESA7 is mutant?

secondary cell wall doesn't form properly, creating collapsed cells

what are some of the layers in woody plants?

primary ph and xy --\> ring of vascular cambium --\> secondary ph and xy --\> protective periderm/bark

examples of biofuels

bioethanol and biodiesel

what is bioethanol?

alcohol made by fermenting sugars and starches from cellulose

what is biodiesel?

oil obtained from chemically treated oil crops

why can't lignin be used for biofuels?

too tough

pros and cons of biofuels

Pros:Carbon neutralbiodegradablerenewable
Cons:less energy output than input to produceNeed large areas of land to grow

plasmodesmata

channels between cells for communication in plants

what are plasmodesmata used for?

used to coordinate cell development and growth and respond to pathogen attack

what is the cuticle and what does it do?

waxy layer on plants that reduces water loss and provides protection from pathogens and chemicals

what are the plant meristems?

shoot apical, root apical, and inflorescence

what does auxin do?

embryo development, trophic responses, and development of vasculature

what transports auxin?

PIN1 - ourAUX - in

what are the main processes of angiosperm seed development?

embryogenesis, production of endosperm, production of protective seed coat

what does the gnom mutant do?

prevents PIN1 protein from localizing creating a blob of cells

what does a plant embryo contain?

cotyledons, hypocotyl, radical, RAM, SAM

where are all the root stem cells?

quiescent centre

what does transverse division in ground tissue initial produce?

cortex/endodermis initial

how do plant cells specialize?

through signaling from neighbouring cells

what does the scr gene do?

produces a transcription factor necessary for longitudinal division of the cortex cell into cortical and endodermal cells

what are the SAM zones? what do they do?

central zone (CZ) - provide cells for other zonesperipheral zone (PZ) - produces leavesRib zone (RZ) - produces central tissues of stem

what zones divide quickly?

PZ and RZ

what do layers in plant cells do?

indicates what tissue types will arise in that region

what genes are involved with the inflorescence meristem?

LEAFY

what is the difference between indeterminate and determinate meristem?

indeterminate meristems give rise to multiple floral meristems while determine only give rise to 1

what proteins are required for flower development?

SEP and ABC proteins

Where does the female gametophyte develop?

carpel

where does the male gametophyte develop?

anther