UC Berkeley Biology 1B Organismal Bio

Eukaryote

Cells with linear chromosomal DNA packed into a membrane-enclosed nucleus that contains membrane bound organelles

Prokaryotes

Cells that have no nucleus and no membrane-enclosed organelles. Instead, their DNA is contained in circular plasmids.

autotroph

organism that derives nutrition from inorganic substances - usually photosynthetic

heterotroph

organism that derives nutrition from organic substances - usually plant or animal matter

Chemotroph

energy comes from organic compounds

Phototroph

energy comes from light (not all phototrophs do oxygenic photosynthesis)

Anaerobic vs Aerobic

anaerobic: no oxygen

aerobic: oxygen

How do prokaryotes reproduce?

Asexually by binary fission (not equivalent to mitosis)

Archaea

extremophiles with anaerobic metabolisms

First evidence of prokaryotic life in the fossil record

Stromatolites which were photoautotrophs that lacked oxygenic photosynthesis

Cyanobacteria

photoautotrophs that capture light energy through oxygenic photosynthesis and have the ability to fix nitrogen

Oxygen Revolution

An increase in the level of oxygen in the atmosphere that led to an accumulation of ozone which protects life from UV rays. Prior to this oxygen oxidizes large amounts of iron causing it to precipitate out into the ocean.

Why was the passage of two Snowball Earth periods ~700 million years agoimportant for the expansion of multicellular eukaryotes on the planet?

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

3 multiple choice options

Even though they are more closely related to animals, fungi are more similar toplants in which of the following ways?

Reproduction by spores & Haploid generation can be multicellular

3 multiple choice options

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

Barriers between cells are incomplete or absent, facilitating movement of resources and cellular structures

3 multiple choice options

The Pacific golden chanterelle is a basidiomycete that is the state mushroom of Oregon and highly prized for its flavor. Which of the following is TRUE about its delicious fruiting body?

It was generated by mitosis following plasmogamy

3 multiple choice options

Which of the following have left humans more vulnerable to fungal pathogens?

Disruption of habitat for agriculture or construction, globalization of trade, immunosuppressive therapies, climate change

3 multiple choice options

Endosymbiont theory for the origin of eukaryotic organelles

1. Archaeal ancestor evolves a nucleus

2. Mitochondiron gained by endosymbiosis with host, a bacterium capable of aerobic respiration

3. Plastid gained by endosymbiosis with a cyanobacterium

Evidence for endosymbiosis

1. Inner membranes of organelle have enzymes and transporters homologous to those in plasma membranes of bacteria.

2. Similar ribosomes to bacterial ribosomes

3. Organelles have their own DNA on circular chromosomes

4. Organelles divide by binary fission like bacteria

Microbiome

Refers to all microorganisms found in a given well-defined habitat. Establish by horizontal transmission (acquired from environment) or vertical transmission (passed down from parent to offspring)

Human gut

1. acquired both through vertical and horizontal transfer which can in turn influence gut development

2. Changes with age and diet

How can prokaryotic cells work together?

Metabolite cross-feeding, filamentous chains, biofilm, and quorom sensing

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 cells in a chain will differentiate, becoming heterocysts which allows spatial separation of nitrogen fixation (anaerobic) from photosynthesis (aerobic).

Biofilm

A surface coating colony of one or more species of prokaryotes that engage in metabolic cooperation. Biofilm are mats of cells that secrete and become stuck to each other in amatrix of polysaccharides and protein.

Quorom Sensing

If enough other microbes of the same type nearby, a new density-dependent activity is induced. Population density detected by concentration of secreted auto-inducer molecules.

General characteristics of fungi

1. unicellular or multicellular

2. Chitin-rich cell walls

3. Heterotrophs that engage in absorptivenutrition by secreting enzymes to digestfood externally

4. Multicellular fungi are non-motile and filamentous

-single filament = hypha (plural =hyphae)

-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

1. Diploid phase dominates in animals, haploid phase dominates in fungi

2. In animals steps are as follow

- Diploid multicellular organism (2n)

- Undergoes meiosis (2n -> n)

- Produces gametes (sperm and egg cells) (n)

- Combine in fertilization to form zygote (n -> 2n)

Fungal life cycle

Note: No mitosis after fertilization

1. Haploid unicellular or multicellular organism produces gametes by mitosis

2. Gametes combine in fertilization to produce zygoteterm-148

3. Zygote undergoes meiosis to produce spores

4. Spores undergo mitosis to become haploid organism

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. Following this 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?

Happen everywhere between meiosis and karyogamy; doesn't occur 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), __________ are grown on oysters; and __________ are grown on nets.

diploids; haploids

3 multiple choice options

Which one of the following statements about dinoflagellates and symbiosis is TRUE?

The plastid in a dinoflagellate cell is derived from a secondary endosymbiosis event.

3 multiple choice options

Which one the following pairings of organismal groups and general nutritional modes are correctly matched?

Diatoms - Oxygenic photoautotroph

3 multiple choice options

What quality unites algae as an ecological group?

None of the above

3 multiple choice options

Sporogenesis

the process of spore formation

Gametogenesis

production of gametes

Solution to the shift from water to wind based spore dispersal in fungi.

The fruiting body

Basidiomycetes important features

1. Zygote forms in the basidium prior to meiosis

2. basidia line the gills of the fruiting body (basidiocarp which is the mushroom)

How are the life cycles of multicellular fungi different?

1. Asexual reproduction (can make spores without going through diploid zygote) - arbuscular mycorrhizial only reproduce asexually

2. There are hyphal tips that look the same but express different mating types instead of binary gametes

3. Fertilization is actually a two step process that includes plasmogamy (fusion of cytoplasm) and karyogamy (fusion of nuclei).

Steps of fertilization in fungi

1. Plasmogamy: Cytoplasms fuse to become a heterokaryon,one mycelium with two distinct haploid nuclei types in each cell or floating around (n + n).

2. Karyogamy: The different haploid nuclei sharing the same cytoplasm that fuse to make the diploid zygote

saprobe

organism that derives nutrition from dead or decaying matter

parasite

organism that derives nutrition from a host (another species), usually causing harm to the host to this organism's own benefit

mitosis

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

meiosis

cell division that creates 4 daughter cells (e.g. 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 is capable of uniting with another of the 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, usually a sperm and an egg

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 (esp. in ferns)

sporophyte

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

gametophyte

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

antheridium/antheridia

the male sex organ of non-flowering plants; creates sperm

archegonium/archegonia

the female sex organ of non-flowering plants; houses the egg

alternation of generations/haplodiplontic life cycle

the pattern of reproduction for many plants, involving a regular cycle between two distinct forms - usually one diploid (sporophytes) and one haploid (gametophytes)

haplontic life cycle

a life cycle in which the haploid stage is multicellular and results in the formation of a diploid cell; the zygote then undergoes meiosis and forms haploid cells

diplontic life cycle

a life cycle in which the diploid stage is multicellular and results in the formation of haploid gametes through meiosis; zygotes form when the haploid gametes fuse

rhizoid

a filamentous outgrowth on the underside of the thallus (e.g. in bryophytes) that help anchor the plant and conduct water

sporophyll

a leaf that bears sporangia, usually with sori on the underside (in ferns)

sorus/sori

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

megasporangiate strobilus

a female cone in a gymnosperm, holding megasporangia

megasporophyll

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

megasporangium

structures in which megaspores are formed

megasporocyte

a diploid cell in which meiosis occurs, creating 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 (a pollen cone)

microsporophyll

a sporophyll that bears microspores (which develop into male gametophytes)

microsporangium

structures in which microspores are formed

microsporocyte

diploid cell which 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 the ovules, required for fertilization

cotyledon

an embryonic seed leaf

seed

an adaptation of some 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 protects the embryo and endosperm in flowering plants

monocotyledon

a member of a clade of flowering plants that has 1 embryonic seed leaf or cotyledon; endosperm starts as a liquid with loose nuclei floating around and then becomes starchy solid which provides nutrition for embryo

eudicotyledon

a member of a clade of flowering plants that have 2 embryonic seed leaves or cotyledons; some maintain a separate endosperm until germination but 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, bearing structures for sexual reproduction

inflorescence

a group of flowers tightly clustered together

sepal

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

petal

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

stamen

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

anther

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

filament

the stalk portion of the stamen, the pollen-producing reproductive organ of a flower

carpel

the ovule-producing reproductive organ of a flower, consisting of the stigma, style and ovary

ovary

the portion of a carpel in which the egg-containing ovules develop, will become the fruit in angiosperms

ovule

a structure that develops within the ovary of a seed plant and contains the female gametophyte, becomes a seed

stigma

the sticky part of a flower's carpel which receives pollen grains

style

the stalk of a flower's carpel, with the ovary at the base and the stigma at the top

double fertilization

a mechanism in angiosperms where one sperm cell fertilizes an egg cell and another sperm fertilizes 2 polar bodies to create the zygote and endosperm