biology 1B organismal biology

eukaryotes

cells with linear chromosomal DNA packed into a membrane-enclosed nucleus + contain membrane enclosed organelles

Prokaryotes

cells have no nucleus and no membrane-enclosed organelles + DNA contained in a circular chromosome and plasmids

autotroph

generate their own food from inorganic molecules

heterotrophs

consume food produced by other organisms

chemotrophs

energy comes directly from chemical reactions

phototrophs

energy comes from light

binary fission

how prokaryotes reproduce - double in size, single cell splits into two cells

archaea

extremophiles with anaerobic metabolisms, found in harsh anoxic environments (extreme salinity or temperature)

bacteria

diverse group, contain species that live by virtually every mode of nutrition and metabolism, some are parasites and pathogens, many play roles as decomposers and symbionts in animal guts

how did the life on earth begin?

atmosphere started as rich in N2, NH4, and CO2 but lacked O2. stromatolites formed no needing oxygenic photosynthesis. then cyanobacteria are present leading to the oxygen revolution which poisons the oceans with O2 toxic to anaerobes. this then increases the level of oxygen in the atmosphere and accumulates ozone which protects life from UV rays. eukaryotes are derived from archaea with a nucleus —> endosymbiotic theory

stromatolites

layered rocks that form from prokaryotes binding thin films of sedimented minerals together

cyanobacteria

photoautotrophs that capture light energy through oxygenic photosynthesis

microbiome

all microorganisms found in a given well-defined habitat; environment-dependent, in or on organismal host —> can be very important for development, nutrition, etc.

horizontal transmission

acquired from enviornment

vertical transmission

passed down directly from parent to offspring

human gut microbiome

acquired both through vertical and horizontal transfer, changed with age and diet

metabolite cross-feeding

interaction between bacterial strains in which molecules resulting from the metabolism of one strain are further metabolized by another strain

filamentous chains

in some cyanobacteria, some cells in chain will differentiate (becoming heterocysts), allows spacial separation of nitrogen fixation from photosynthesis

biofilm

a surface coating colony of one or more species of microbes that engage in metabolic cooperation

quorum sensing

if enough other microbes of the same type are nearby, a new density-dependent activity is induced

cells know when population reaches high density due to the concentration of secreted autoinducer molecules

fungi

unicellular or multicellular, chitin-rich cell walls, heterotrophs that engage in absorptive nutrition, store carbon as glycogen, multicellular fungi are non-motile and filamentous

hypha

single filament

mycelium

network of hyphae

mycelial networks

growth is indeterminate, swarms of very sensitive hyphal tips connected by massively parallel processing into one being, can be huge and ancient, hyphae can be specialized,

cytoplasmic streaming

a mechanism to distribute pressure, water, nutrients, organelles, nuclei

spores

single cells capable of growing into an adult organism

mycofabrication

making things out of fungi

mycoremediation

basically shrooms

meiosis

production of haploid cells from a diploid cell over two rounds of cell division

fertilization

union of haploid gametes to produce a diploid zygote

sporogenesis

the process of spore formation

gametogenesis

the process of gamete formation

gametophyte

haploid organism that produces gametes by mitosis

sporophyte

diploid organism that produces spores by meiosis

mycosis

fungal infection, pathogens of amphibians and insects

ecological group

set of taxa that share common ways of life, often in a community context; may or may not overlap with phylogenetic relatedness

diatoms

unique glass-like cell walls made of silica embedded in an organic matrix, diatom deposits accumulate on the ocean floor; used for water filtration, polish and toothpaste

dinoflagellates

have two flagella —> one makes them spin, some transitioned to heterotrophy others mixotrophs; blooms produced toxins that are toxic to fish and can poison humans; symbiosis of corals with zooxanthellae

brown algae

marine algae, keystone species like kelp

red algae

economically important, absorb blue light bc it penetrates to lower depths

green algae

freshwater and seawater, closest relatives to the plant kingdom

lichens

ecological group, combo of at least one heterotrophic fungus with one phototrophic eukaryotic alga or a cyanobacterium

photobiont provides sugar and microbiont provides moisture, shelter, UV protection and minerals

reproduction of lichens

together and asexually via fragmentation and soredia; alone and sexually producing their own fruiting body

soredia

bundle of fungi and algae

pros of plants coming ashore

light is unfiltered by water, more accessible carbon dioxide in air than dissolved in water

cons of plants coming ashore

staying hydrated/ preventing desiccation, acquiring and distributing water, building support, fertilization

phyllids

(in bryophytes) thin leaf-like growth that absorb water through direct contact with ground or trapped moisture (pre-leaves)

rhizoids

(in bryophytes) long tubular single cell or filaments that do some water/nutrient uptake but mainly function to anchor plant (pre-roots)

solutions to staying hydrated

waterproofing —> waxy, permeable cuticle; protecting gametes and new sporophytes as they develop; make sporophyte and spores more waterproof for airborne life, multicellular sporangia

gametangia

new multicellular protective tissues where gametes form

antheridia

gametangia that produce sperm

archegonia

gametangia that produce eggs

embryo

the zygote (fertilized egg) is also retained in the archegonium and develops embedded in and dependent on nutrition from maternal tissue

sporopollenin

a polymer that prevents desiccation of charophyte zygotes to make plant spores also resistant to harsh environments and capable of dispersal by air

solution to acquiring and distributing water and building support (in bryophytes)

development of an increasingly complex vascular system to conduct water from soil through the plant specialized cells and tissues to transport water, sugars and nutrients (tracheids, xylem and phloem)

hornworts (bryophytes)

form symbiotic associations with cyanobacteria to fix nitrogen, can be early colonists and soil formers

liverworts (bryophytes)

stalks with umbrella are the gametangia and short sporophytes develop on them

mosses (bryophytes)

most common in moist forests and wetlands, tolerant of desiccation

microphylls

lycophyte leaves with a single unbranched vein; branching only occurs at shoot tip

megaphylls

leaves of monilophytes; potential for stem branching not limited to shoot tip

carboniferous period

plants greatly expand two carbon dioxide sinks; root acids weather continental rock → releases calcium and magnesium → react with CO2 and form minerals deposited in marine rocks; boggy soils highly water logged, stagnant, and anoxic → dead trees decay and become peat + covered by marine sediments they are converted to coal

azolla

fairy moss; aquatic and very reduced in form; symbiotic association with nitrogen-fixing cyanobacteria → makes home in pouches in leaves; became alaskan oil deposits

When does the rise of seed plants come?

about 250-280 mya when there was a big change in climate that drained the swamp → formation of Pangea; had its hayday in the Jurassic

reduction in gametophyte → less tissue protecting embryo from desiccation; evolution of seeds which protect the early sporophyte

what leads to the rise of seed plants?

cone

gymnosperm reproductive structure; anatomically akin to compressed fern fronds; produce seeds and pollen within

scales (of cones)

modified leaves with sporangia; 2n sporophytes

2

gymnosperms make __ types of spores each from a different type of sporangium

megasporangia

make megaspores that germinate to become female gametophyte

microsporangia

make microspores that germinate to become the male gametophyte

key innovations of pollen cones

microspores not dispersed; free-living male gametophyte moves by wind not water; megaspore is also not dispersed → retained on the sporophyte and protected

ovule

megasporangium surrounded by the protective structure that will become the seed coat; protects female gametophyte; nourishes the sporophyte embryo even after seed dispersal

integument

seed coat

pollination

the transfer of pollen to the part of a seed plant containing the ovules

3 major angiosperm innovations

flowers, endosperm, fruits

sepals

offer protection to the bud

petals

often bright, large and attractive to pollinators

stamens

fertile organs that bear pollen (male reproductive)

filament

stalk that bears the anthers

anthers

sac that contains the microsporangia where microspores form and germinate to become pollen (gametophyte)

carpels

sporophyll fused into a container within which the ovules are found (female reproductive)

pistil

single carpel or collection of fused carpels

stigma

sticky surface where pollen lands and pollen tube germinates

style

tract down which the pollen tube migrates to reach the ovules

ovary

protective container around the ovules

inflorescence

the flowering stalk

how does pollen fertilize the ovules?

sporophyte holds onto microspores in microsporangium → microspore germinates to become the pollen grain (male gametophyte) and is dispersed → the tube cell in the initial pollen grain becomes the pollen tube and the generative cell becomes TWO sperm cells → the pollen tube germinates on stigma and grows down style and two sperm travel down tube to ovule

inbreeding depression

deleterious recessive mutations are exposed in offspring, lowering fitness

capacity to partly or full self-pollinate is helpful at times when…

lower pollinator availability; high competition for pollinators; dispersal to new habitats; in crop breeding

what attracts pollinators?

floral scent; color and color patterning; nectar and pollen rewards; flower shape, size and number

coevolution

the joint evolution of two interacting species in response to selection imposed by the other

pollination syndromes

suites of plant traits that suggests coevolution with a particular group

what is the major difference between the angiosperm seed and the gymnosperm seed?

food supply; the angiosperm seed gains nutrients from the endosperm (3n) while the gymnosperm seed gains nutrients through the remaining female gametophyte tissue (n)

cotyledons

embryonic leaves

fruit

the mature ovary of a flower

pericarp

thickened wall of the fruit

abiotic mechanisms for seed dispersal

wind; water; active propulsion; whole plant movement

biotic mechanisms for seed dispersal

passively by adherence; passively by consumption; actively by nutrient provisioning

growth

increase in size of a tissue ; occurs by cell division and cell elongation

cell division

increasing cell number

cell elongation

increasing cell size