Bio 1B Unit 3 :)

Autotrophs

generate their own food from inorganic molecules

Heterotrophs

Comsume food produced from other organisms

Chemotrophs

Energy comes directly from chemical reactions

Phototrophs

Energy comes from light

Binary fission

after doubling in size, single cell splits into two daughter cells (asexual by prokaryotes, not equivalent to mitosis)

Archaea

prokaryotes; generally extremophiles with anaerobic metabolisms

Bacteria

prokaryotes; very diverse, use basically all metabolism methods

Stromatolites

layers of rock that form from prokaryotes binding together thin films of sedimented minerals

Methanogens

anaerobic archaea, release methane and water as byproducts of metabolizing CO2 and H2

Cyanobacteria

In ocean, caused oxygen revolution by doing organic photosynthesis and producing oxygen, at first not noticible because it reacted with iron, but then caused mass die-off of anaerobic bacteria

First Eukaryotes

Archael ancestor gains a nucleus, Anaerobic respiration

Origin of Mitochondria

Endosymbiosis of bacteria capable of aerobic respiration, Aerobic respiration

Origin of Plastids

Endosymbiosis with cyanobacteria, Aerobe, autotroph!

Microbiome

refers to all microorganisms found in a given well-defined habitat

Horizontal transmission

microbiome acquired from environment

Vertical transmission

microbiome passed down directly from parent to offspring

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

• microbes that grow in long, thread-like chains of cells attached end-to-end

• Allows spatial separation of nitrogen fixation (anaerobic) from photosynthesis (aerobic)

• Unicellular organisms coming together, NOT a multicellular organism

• Do binary fission, NOT mitosis

Biofilm

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

Heterocysts

specialized, nitrogen-fixing cells formed by certain filamentous cyanobacteria (like Anabaena and Nostoc) under nitrogen-limiting conditions

Quorum Sensing

a bacterial communication process that allows bacteria to detect and respond to population density through chemical signaling with autoinducers

Autoinducers

small, signaling molecules produced and secreted by bacteria to communicate and monitor their population density

Protists

outdated term for all eukaryotes outside traditional kingdoms

Fungi

Decomposers/fermenters, convert sugars to CO2 and alcohol

What substance is in fungal cell walls?

chitin

Absorptive Nutrition

a process where organisms obtain nutrients by directly absorbing small, simple molecules from their environment, often after breaking down organic matter externally with secreted enzymes

fungi break down a substance most bacteria cannot

lignin (in wood)

Fungi store carbon as:

glycogen

Plants store carbon as:

starch

hyphae

long, branching, thread-like filaments that constitute the main vegetative structure of fungi, known as mycelium

Problems for fungus to solve:

1. Finding nutrition when non-motile

2. Directing growth without central information processor

3. Moving resources great distances

Fungal growth is:

indeterminate - no defined end structure

Cytoplasmic streaming

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

spores

single cells capable of growing into an adult organism

Arbuscular Mycorrhizal Fungi

• penetrate root cells and create structures called arbuscules

• Provide the roots water and mineral nutrients, get sugars and lipids in exchange

Ectomycorrhizal Fungi

• Form nets around the whole root and cell surfaces within root but do not enter cells

• Provide roots water and mineral nutrients, get sugars in return

Mycelial Applications

• Mycofabrication

• Mycoremediation

Meiosis

• production of haploid cells from a diploid cell over two rounds of cell division (2n → 1n)

• cuts copies of chromosomes in half

Haploid

cells with one copy of each chromosome (n)

Diploid

cells with two copies of each chromosome (2n)

Fertilization

• union of haploid gametes to produce a diploid zygote cell (1n → 2n)

• doubles copies of chromosomes

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

Haplodiplontic

• the life cycle type with both multicellular haploid and diploid phases

• Plants

• Multicellular algae

Diplontic

• life cycle where the multicellular phase is 2n (diploid)

• Animals

Haplontic

• life cycle where the multicellular phase is n (haploid)

• Fungi

• Unicellular algae

Mucuromycota

asexually reproduce, Mycelium forms sporangia with genetically identical spores

Unicellular yeasts

asexual reproduction, Haploid cells just bud off additional haploid cells

Multicellular ascomycetes

asexually reproduce, strings of spores called conidia form as hyphal tip structures

mycosis

a fungal infection

Human fungal infection

Valley Fever

Algae

• NOT a polyphyletic group

• Photosynthetic organisms that are not land plants

• Not even confined to one domain

Primary endosymbiosis

• Cyanobacteria engulfed prokaryotic bacteria

• Two membranes

Secondary endosymbiosis

• Different for various groups, symbiosis with a eukaryotic alga, gained endosymbiosis and became obligate together

• More than two membranes

Unicellular Only

• Cyanobacteria

• Diatoms

• Dinoflagellates

Unicellular or Multicellular

• Brown algae

• Red algae

• Green algae

Algae Ecological Groups

• Unicellular → phytoplankton

• Multicellular —> seaweeds

Diatoms

• Unicellular

• Unique glass-like cell walls made of silica embedded in an organic matrix

• 25% of global NPP!

• Diatom deposits accumulate on the ocean floor

• Uplifted fossil deposits are harvested as diatomaceous earth

diatomaceous earth

a key gritty component of toothpaste, metal polishes, and water filtration systems

Dinoflagellates

• Have two flagella, one of which is a spiral that can make them spin (dinos = whirling)

• Some of them have transitioned to heterotrophy; others are mixotrophs that can switch back and forth between modes of acquiring nutrition

red tides

Dinoflagellate blooms produce toxins that leave massive fish kills and, when concentrated by mollusks, can poison humans

Brown Algae

• Marine algae including kelps

• Kelps are keystone species of intertidal and deepwater

• Can grow up to 200 ft long

Red Algae

• Often red because their pigments are tuned to absorb blue light and reflect red light because only the former penetrates to lower depths

• Can come in diverse colors and forms though

• Economically important (ie. nori, dulse)

Green Algae

• Closest relatives to the plant kingdom

• Very diverse forms and life cycles from unicellular to colonial to multicellular

• Found in freshwater and seawater, and even in high elevation snow fields

phycocolloids

polysaccharide compounds that prevent drying out (desiccation)

Algal Solutions to Climate Change

• Plastic replacements

• Cattle feed, fish food, vineyard food

• Production of biodiesel

Nori

• Known as “gambler’s grass” among fisherman because some years were booms and others were busts

• Study done with oysters that solved this

Lichens

• Combo of at least one heterotrophic fungus (the mycibiont) with one phototrophic alga or cyanobacterium (the photobiont)

• Both species take on a form completely distinct from how they would grow individually

• Neither the mycobiont or the photobiont that lichenize are monophyletic

• Capacity to lichenize has evolved many many times

Photobiont

• phototrophic alga or cyanobacterium

• provides sugars (and fixed nitrogen if cyanobacterium)

Mycobiont

• heterotrophic fungus

• provide moisture, shelter, UV protection, and minerals obtained from dust or leached from substrate

• Secrete acid like usnic acid

Gamates

unicellular, haploid (sperm, egg)

Zygote

unicellular, diploid (formed by fertilization)

Embryophytes

make embryos (haplodiplontic), clade of plants (all land plants)

Sporangia

spore container

• top of moss stem

• In sori on ferns

Sporocyte

cell that makes spores (2n cell, thing that performs sporophyte phase)

Sporophyll

leaf that makes spores

When fungi hyphae touch:

• Plasmogamy: fusion of plasma membranes, cell becomes n+n, two unfused nuclei

• Karyogamy: fusion of nuclei, go from two haploid nuclei two one diploid nuclei

• Then undergoes meiosis and produces haploid spores

Soredia

bundle of fungus and algae

Benefits of Coming Ashore

• Light is unfiltered by water

• More accessible carbon dioxide in air than dissolved in water

Challenges of Coming Ashore

• Staying hydrated: water evaporates quickly in air, raising danger of desiccation (drying out)

• Acquiring then Distributing Water: By not being available to all cells directly, need a water distribution system

• Building support: without water, no buoyancy, need rigid support

• Fertilization: How will motile gametes meet up for reproduction

Bryophytes

Mosses, liverworts, hornworts

Key Observations

1. “leafy “ structures pressed close to the moist soil are gametophytes

2. Stem-like structures are rising up are or contain sporophytes -> attached and dependent on gametophyte for nutrition, not free-living

Phyllids

• Thin leaf-like growths that absorb water through direct in contact with ground or trapped moisture

  • NOT LEAVES; those come later

Rhizoids

• long tubular single cell or filaments that do some water-nutrient uptake but mainly function to anchor plant

  • NOT ROOTS; those come later

  • Also associate with arbuscular mycorrhizal fungi

cuticle

waxy, permeable layer that keeps a plant hydrated on land

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

sporopollen

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

Key Life cycle innovations

1. Rhizoids and phyllids

2. Gametangia

3. Retained embryos

4. Waterproofed sporophytes and spores

Features that unite vascular plants

• Solutions to problems 2+3: Development of an increasingly complex vascular system to conduct water from soil through the plants specialized cells and tissues to transport water, sugars, and nutrients (tracheids, xylem, and phloem)

• Sporophyte gains roots

• Lignification of stem vascular tissue increases functional strength

• Sporophyte gains leaves with veins

Gametophyte Generation of seed-free vascular plants

• Free-living, small, and water absorbing

• Non-vascular with some rhizoids

• Gametangia

• Water-dependent dispersal by flagellated sperm

Sporophyte Generation of Seed Free Vascular Plants

• free living!

• Still have embryo retention by maternal gametophyte

• But now the sporophyte is not nutritionally dependent on gametophyte

• Roots

• Vascularized leaves and stems

• Sporophylls: leaves that form sporangia

• Sorus: clustered groups of sporangia (plural sori)

Hornworts

• Form symbiotic associations with cyanobacteria to fix nitrogen

• Can be early colonists and soil formers

Liverworts

Stalks with umbrella are the gametangia (still haploid), and short sporophytes develop on them

Mosses

• Most common in moist forests and wetlands

• But can also be incredibly tolerant of desiccation, more so than any other plant. Some can lose 98% H2O

• Chemicals called phenolics in moss cell walls protect them from UV radiation in desert or at high altitudes