BIO 1B - ORGANISMAL BIOLOGY

eukaryote

cells with linear chromosomal DNA packed into a membrane enclosed nucleus with membrane bound organelles

prokaryotes

cells with no nucleus or organelles; DNA in circular plasmids

autotroph

organism that creates its own food; photosynthesis

heterotroph

organism that can’t make its own food; must consume other forms of nutrients

chemotroph

gets energy from organic compounds

phototroph

gets energy from light

• not all phototrophs do oxygenic photosynthesis

anaerobic

no oxygen

aerobic

oxygen

how do prokaryotes reproduce

asexually through binary fission

archaea

extremophiles with anaerobic metabolisms

first evidence of prokaryotic life in the fossil record?

stromatolites: photoautotrophs that lacked oxygenic photosynthesis

cyanobacteria

photoautotrophs that capture light energy through oxygenic photosynthesis; can fix nitrogen

oxygen revolution

cyanobacteria began releasing large amounts of free oxygen into Earth’s oceans and atmosphere

• wiped out anaerobic life forms

• created an ozone layer

• created aerobic respiration forming complex multicellular life

why was the passage of two snowball earth periods (700 mya) important for the expansion of multicellular eukaryotes on the planet?

weathering of continental rock made key nutrients more available in the oceans

how are fungi similar to plants?

• reproduction by spores

• haploid generation can be multicellular

what organisms are fungi most closely related to?

animals

how are multicellular fungal bodies adapted for their nutrition and ecology?

barriers between cells are incomplete or absent allowing movement of resources and cellular structures

what’s true about the pacific golden chanterelle?

• basidiomycete

  • generated by mitosis after plasmogamy

what leaves humans more vulnerable to fungal pathogens?

• disruption of habitat for agriculture or construction

• globalization of trade

• immunosuppressive therapies

• climate change

endosymbiotic theory (symbiogenesis)

1. archaeal ancestor evolves a nucleus

2. the host, a bacterium capable of aerobic respiration, gains a mitochondrion through endosymbiosis

3. cyanobacterium goes through endosymbiosis and gains plastid

evidence for endosymbiosis

• inner membranes of organelle have enzymes and transporters homologous to those in plasma membranes of bacteria

• similar ribosomes to bacterial ribosomes

• organelles have their own DNA on circular chromosomes

  • organelles divide by binary fission like bacteria

microbiome

all microorganisms found in a well defined habitat established by transmission

horizontal transmission

acquired from environment

vertical transmission

passed down from parent to offspring

human gut

• acquired through vertical and horizontal transfer; can influence gut development

• changes with age and diet

how can prokaryotic cells work together?

• metabolite cross-feeding

• filamentous chains

• biofilm

• quorum sensing

metabolite cross-feeding

interaction between bacterial strains; molecules from one strain’s metabolism further metabolized by another strain

filamentous chains

cyanobacteria cells in a chain differentiate become heterocyst allowing spatial separation of nitrogen fixation from photosynthesis

biofilm

• mats of cells that secrete and become stuck to each other in a matrix of polysaccharides and protein

• coats surfaces and engages in metabolic cooperation

quorom sensing

a biological system of cell to cell communication that allows bacteria to track their population density and change their behavior in synchrony

general characteristics of fungi

1. unicellular or multicellular

2. chitin-rich cell walls

3. heterotrophs that engage in absorptive nutrition by secreting enzymes to digest food externally

4. multicellular fungi are non-motile and filamentous

5. single filament = hypha (plural = hyphae)

6. a network of hyphae (mycelium)

cytoplasmic streaming

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

generalized sexual life cycles

1. must include meiosis and fertilization

2. diploid phase dominates in animals; haploid dominates in fungi

3. in animals steps are as follows

   1. diploid multicellular organism (2n)

   2. undergoes meiosis (2n → n)

   3. produces gametes (sperm and egg cells) (n)

   4. combine in fertilization to form zygote (n → 2n)

fungal life cycle

1. haploid unicellular or multicellular organism produces gametes by mitosis

2. gametes combine in fertilization to produce zygote

3. zygote undergoes meiosis to produce spores

4. spores undergo mitosis to become haploid organism

* there’s no mitosis after fertilization

multicellular fungal life cycle

1. spores undergo germination and develop into the mycelium

2. asexual reproduction can occur to produce more spores

3. plasmogamy occurs where the cytoplasms of the spores fuse

4. then, there is a heterokaryon which is one mycellium with two distinct haploid nuclei types

5. this heterokaryon then fuses in karyogamy to form the diploid zygote

6. the diploid zygote undergoes meiosis to produce spores and restart the cycle

where does mitosis occur in the basidiocarp life cycle?

happens everywhere between meiosis and karyogamy; doesn’t during the diploid zygote phase

plant life cycle

1. sporophyte undergoes meiosis to produce spores

2. spores undergo mitosis to produce the haploid multicellular gametophyte

3. gametophyte undergoes mitosis to produce gametes

4. gametes combine in fertilization to form diploid zygote

5. zygote undergoes mitosis to produce sporophyte

in modern production of nori (porphyra yezoensis), what is grown on oysters?

diploids

in modern production of nori (porphyra yezoensis), what is grown on nets?

haploids

what is true about dinoflagellates and symbiosis?

the plastid in a dinoflagellate cell is derived from a secondary endosymbiosis event

what’s a correct matching of organismal groups and general nutritional modes?

diatoms and oxygenic photoautotroph

sporogenesis

the process of spore formation

gametogenesis

production of gametes

what’s the solution to the shift from water to wind based spore dispersal in fungi?

the fruiting body

what are basidiomycetes important features?

• zygote forms in the basidium prior to meiosis

• basidia line the gills of the fruiting body

how are the life cycles of multicellular fungi different?

• asexual reproduction

• there are hyphal tips that look the same but express different mating types instead of binary gametes

• fertilization is actually a two step process that includes plasmogamy and karyogamy

plasmogamy

fusion of cytoplasm to become a heterokaryon

heterokaryon

one mycelium with two distinct haploid nuclei types in each cell (n+n)

karyogamy

fusion of haploid nuclei sharing a cytoplasm to make a diploid zygote

steps of fertilization in fungi

1. plasmogamy

2. karyogamy

saprobe

organism that eats dead/decaying matter

parasite

organism that takes from a host; usually causing harm to host while it benefits

mitosis

cell division that creates 2 daughter cells with the same number of chromosomes

meiosis

cell division that creates 4 daughter cells (gametes) that have half the number of chromosomes of the parent cell

haploid

having a single pair of unpaired chromosomes

diploid

having two complete sets of chromosomes, 1 from each parent

gamete

mature haploid male/female germ cell that can combine with opposite gender to create a zygote

sperm

a haploid male gamete

egg

a haploid female gamete

spore

a haploid reproductive cell that gives rise to a gametophyte

fertilization

the process in which a male and female gamete fuse to form a diploid zygote

zygote

a diploid cell formed by the fusion of two haploid gametes

embryo

the part of a seed that will develop into a plant; forms from a zygote

sporangium/sporangia

a receptacle in which asexual spores are formed

sporophyte

the asexual and diploid generation in the alternation of generations of plants which produces haploid cells through meiosis; the result of fertilization occurring

gametophyte

the haploid generation in the alternation of generations of plants that produces haploid cells through mitosis; dominant in bryophytes

antheridium/antheridia

non flowering plant’s male sex organ

archegonium/archegonia

non flowering plant’s female sex organ

haplodiplontic life cycle

alternation of generations between two distinct forms; pattern of reproduction for many plants

haplontic life cycle

life cycle where the haploid stage is multicellular → formation of diploid cell → zygote undergoes meiosis and forms haploid cells

diplontic life cycle

diploid stage is multicellular and results in formation of haploid gametes through meiosis; when haploid gametes fuse, zygotes form

rhizoid

a filamentous outgrowth on the underside of the thallus that help anchor the plant and conduct water

sporophyll

a leaf that bears sporangia, usually with sori on the underside

sorus/sori

a cluster of spore producing receptacles on the underside of a fern frond

megasporangiate strobilus

a female cone in gymnosperm, holding megasporangia

megasporophyll

a sporophyll that bears megaspores (they develop into female gametophytes)

megasporangium

structures in which megaspores are formed

megasporocyte

a diploid cell where meiosis occurs and creates 4 haploid megaspores

megaspore

a spore that develops from a heterosporous plant species that develops into a female gametophyte

megagametophyte

a female gametophyte created by a megaspore

microsporangiate strobilus/strobili

a male cone in a gymnosperm, holding microsporangia

microsporangia/microsporangium

structure where microspores are formed (a pollen cone)

microsporophyll

a sporophyll that bears microspores (they turn into male gemtophytes)

microsporocyte

diploid cell that undergoes meiosis to form 4 haploid microspores

microspore

a spore from a heterosporous plant species that develops into a male gametophyte

pollen

a structure consisting of a male gametophyte enclosed within a wall

microgametophyte

male gametophyte formed by microspores

pollen tube

a structure that forms after germination of the pollen grain to the part of a seed plant containing ovules; required for fertilization

cotyledon

an embryonic seed leaf

seed

adaptation of terrestrial plants consisting of an embryo packaged along with a store of food in a protective coat

integument

layer of sporophyte tissue that contributes to the structure of the ovule of a seed plant

seed coat

a tough outer covering of a seed formed from the outer coat of an ovule; encloses and protect the embryo and endosperm in flowering plants

monocotyledon

member of a clade of flowering plants with 1 cotyledon; endosperm starts as a liquid with loose nuclei and then becomes starchy solid that provides nutrition for embryo

eudicotyledon

member of a clade of flowering plants that have 2 cotyledons; in most endosperm is taken up by growing embryo and stored in the cotyledons

flower

a specialized shoot with up to four sets of modified leaves with structures for sexual reproduction

inflorescence

a group of flowers tightly clustered together

sepal

modified leaf that helps enclose and protect a flower bud before it opens

modified leaf of a flowering plant, usually colorful to attract pollinators

stamen

the pollen-producing reproductive organ of a flower with an anther and a filament

anther

the terminal pollen sac of a stamen, where pollen grains with sperm-producing male gametophytes form