Bio 1B, Organismal Biology (UC Berkeley, Baldwin) questions and answers

3 domains of life

eukaryotes, bacteria, archaea

Eukaryotes

possesses membrane-bound nucleus and organelles

include protists, animals, plants, and fungi

Bacteria

highly diverse group, representing every major mode of nutrition and metabolism

Archaea

Halophiles

live in highly saline enviroments

Thermophiles

Live in very hot envrioments

Methanogens

Live in anaerobic guts

Photo-autotroph

capture energy from light

cyanobacteria

capable of photosynthesis

Autotroph

generate frood from inorganic carbon

Heterotroph

fees on organic substances

algae (tree of life)

generally used to refer to all of the disparate assemblages of photosynthetic organisms except for the land plants (polyphyletic)

Land Plants (tree of life)

polyphyletic

Fungi (tree of life)

clade, more closley related to animals than land plants

-seen in posterior flagellum sharec by animals and fungi

-share a common ancestor ~1 billion years ago

Characteristics of Fungi

-unicellular and multicellular

- large reproductive structure (top)

- eukaryotes (have nucleus and mitochondria)

- bodies are non-motile (can't move)

- multicellular fungi are filamentous (hyphae making up mycelium)

- hyphae: tubular filaments of high surface area/volume ratio(enhances absorption)

- cell walls are present, contain chitin

- store carbon as glycogen

- life cycle includes spores

Hyphae

tubular filaments of high surface ares/volume ratio

5 major clades of fungi

Chytridiomycota

Zygomycota

Glomeromycota

Ascomycota

Basidiomycota

Chytridomycota

diverge early in history, motile spores and gametes

- responsible for massive amphibian decline (chytromiotis)

Zygomycota

produce tough,resistant resting structure in which several spores are produced

- includes common bread mold

- moslty asexual production, until reasources get scarece then do sexual reproduction

- makes gamete then sexual hyphae travel to gamete, fuse together to get zygosporangium

- Pilobolus: asexual sporangia produce majority of spores, can be explosivley ejected

Glomermycota

cardiovascular mycorrhizal fungi are associated with 80-90% of plant families

- may have been key to the success of land plants

Ascomycota

most diverse group in terms of recognized species

- sac fungi, highly diverse, w/ destructive sacs (asci) in which sexual spores are formed

- asci often borne in fruiting bodies

- ex. Truffles, yeasts

- good relationship with tree roots

Bassidiomycota

club fungi (~30,00 species described)

- mushrooms, puff balls, brackets are among different fruiting bodies of this group

- fruiting bodies are often produced at leading edge of radiation mycelium, where resources are richest (creating fairy ring)

- ex. The Humongous Fungus: mycelia are main bulk of fungal body, may cover vast area

Deuteromycota

imperfect fungi

asexual

difficult to determine relationships based on morphology if sexual fruiting bodies are absent

Mycorrhizal associations

mutalism between fungi and plant roots. fungus obtains organic nutrients from the plant, the plant benefits frm enhanced uptake of water and other nutrients

Ectomycorrhizal fungi

form a dense network of hyphae that cover a plant's roots and extend into the soil but do not enter the root cells

Arbuscular mycorrhizal fungi

extend hyphae through the cell walls of root cells and contact the plasma membrane

Lichen

Association between fungus and a unicellular photosynthetic green alga or cyanobacterium

-3 general categories: foliose (leaf), fruticose (branched), crustose (flaky crust)

Other fungi and plant mutualisms

Fungi commonly live in plant leaves

- help plants resist pathogens, repel herbivores, improve tolerance to extreme environments

Meiosis

Beginning with a diploid cell, 1 round of DNA replication and crossing-over between each pair of chromosomes, followed by 2 rounds of cell division (independent assortment in 1st); results in 4 cells, each with half the nuclear-genetic content of original cell --- and recombined chromosomes (1n)

Haploid

1 set of chromosomes (1n)

Fertilization

fusion of gametes (haploid, 1n) to form a zygote (diploid, 2n)

Mitosis

mitosis is a process involving 1 round of DNA replication and 1 round of cell division, without recombination (normally), and resulting in 2 cells with DNA content and genetic constitution identical to one another and to the original parent cell. Mitosis can happen in haploid cells or in diploid cells or in both

-process responsible for growth (cellular replication) of a multicellular organism from a spore or from a zygote

Animal life cycle

Only haploid stage is gametes (sperm, eggs), fertilization occurs just after meiosis, with no mitosis in between meiosis and fertilization, mitosis occurs after fertilization, meiosis leads to production of gametes

Fungi life cycle

the only diploid stage is the zygote; meiosis occurs after fertilization is complete, with no mitosis in-between fertilization and meiosis.

-mating tyoes rather than distinct males or females

-no swimming gametes, no need for free-standing water 0

Plant life cycle

mitosis (resulting in production of a new individual organism) occurs after meiosis (resulting in a haploid organism)

and

after

fertilization (resulting in a diploid organism)

, so that two different kinds of organisms (one haploid and one diploid) alternate within the same life

cycle of a single species.

In sexual life cycles

spores and gametes are both haploid, unicellular reproductive cells --- but a spore germinates directly to form a new

haploid organism (involving mitosis) whereas a gamete fuses with another gamete to form a (diploid) zygote

Oomycota

water molds

-no longer considered fungi (unlike fungi, water molds have diploid hypae as well as small sperms nad large non-motile eggs)

Endosymbiosis

Process of incorporation of one organism within the cell

of another. A multi-step process: 1st step -- early eukaryote (with

cytoskeleton) engulfed prokaryote that became the mitochondrion.

Evidence for theory of endosymbiosis

- Size: size and internal structure of mitochondria and plastids similar to putative closely related bacteria

- Replication: mitochondria and plastids reproduce by binary fission, like bacteria (if plastids in cells are destroyed, they will not regenerate)

- Ribosomes: inside mitochondria and plastids are more similar to bacterial ribosomes than to those outside in the cytoplasm of a eukaryotic cell

- Antibiotics: some bacteriostatic antibiotics that target protein synthesis in bacteria are also toxic to organellar ribosomes but not those of eukaryotic cytoplasm

- Genomes: mitochondria and plastids have genomes separate from the nuclear genomes. Mitochondria and plastid genomes are circular and genetically similar to those of some bacteria

primary endosymbiosis

The engulfment of a cyanobacterium by a larger eukaryotic cell that gave rise to the first photosynthetic eukaryotes with chloroplasts.

secondary endosymbiosis

A process by which protist diversity is hypothesized to have evolved from a symbiotic association that arose when an autotrophic eukaryotic protist was engulfed by a heterotrophic eukaryotic protist.

Major Groups of Algae

Unicellular

1. Blue-green bacteria

2. Dinoflagellates

3. Euglenoids

4. Diatoms

5. Golden Algae

Multicellular (some or all)

6. Brown Algae

7. Red Algae

8. Green Algae

Blue-green bacteria

-cyanobacteria: unicellular but commonly occur as filaments; some occur in terrestrial in addition to aquatic habitats

- filamentous cyanobacteria have specialized cells where nitrogen fixation takes place

- though diverse, only one lineage gave rise to plastids of other algae (endosymbiosis)

Dinoflagellates

- external armor of cellulose plates with 2 flagellae, one encircling their body like a belt, causing them to spin through water

- blooms are responsible for red tides and toxins

Euglenids

- photosynthetic taxa acquired chloroplast from unicellular green alga( 2ndary endosymbiosis)

- most are still heterotrophic(engulf prey)

- have unique flagellum and storage polysaccharides

Diatoms

- most diverse and ecologically important algae

- may account for 25% of Earth's primary productivity

- cell walls of hydrated silica in organic matrix, like 2 halves of a petri dish

- marine and freshwater

- sink after they die → removing carbon from ecosystem and helping reduce atmospheric carbon dioxide

- animal-like life cycle (only gametes are haploid)

- mostly reproduce asexually

Golden Algae

- unicellular or colonial

- closely related to diatoms or brown algae, appear to descend from the same ancestor that engulfed red algae

- freshwater and marine

Brown Algae

- marine algae, include kelps

- occur in intertidal zone and in deep water

- keystone taxa in aquatic ecology

Red algae

- mostly seaweeds, often reddish from pigments that mask green color of chlorophyll

- can live in water up to 850 ft deep

- closely related to green algae

- reddish pigments absorb light in blue/green wavelengths, which penetrate deepest in water

Gree Algae

- unicellular → multicellular

- close relatives to land plants

- occur in wide range of habitats

- ex: "watermelon snow" unicellular Chlamydomonas nivalis had red pigments

Alternation of generations

having a multicellular organism in the haploid phase of the life cycle and a multicellular organism in the diploid phase of the life cycle

Vascular plant innovations

- dominant sporophyte generation: allowed for complex genetic expression and buffering of mutations

- well developed cuticle (waxy outer covering)

- vascular tissue (xylem and phloem): specialized conducting tissue for water and inorganic and organic nutrients, allows for large plant bodies

- tracheids (lignified xylary conducting cells): rigid, decay-resistant conducting tissue

- Branched sporophyte

- roots: allow for efficient uptake of water and nutrients from deep in the soil, and anchorage

moss life cycle

fern life cycle

one type of gametophyte bearing both types of gametangia (antheridia, which

produce sperm, and archegonia, which produce eggs).

-requires free-standing water

- sporophyte is the dominant generation

sorus

cluster of sporangia in ferns. Shape, location and presense of indusium are important in identification of different taxa of ferns

Heterospory

production of 2 different types of spores, which become unisexual gametophytes

- promotes protection of the vulnerable gametophyte generation and allowed for evolution of seeds and pollen in plants seeds

Angiosperm life cycle

Gymnosperm life cycle

Sporophyte is dominant

Contains male and female cones

Gametophyte is completely dependent on sporophyte structures; female in ovulate cone, male develops in pollen

Pollen (and seeds) dispersed by wind

Gymnosperms

include all seed plants except the flowering plants

angiosperms

flowering plants

Flower Morphology

Carpels

a modified leaf that contains immature seeds= ovules

Generally have 3 parts:

- the stigma, a sticky surface where pollen is recieved and germinates

- the style, pollen tubes grow down through to reach ovules

- the ovary, the chamber containing the ovules

Mechanisms against selfing

-Self-Incompatibility (SI)

- Monoecious or Dioecious angiosperms

-spatial separation

-separation in time

Self-incompatibility (SI)

a genetically based system that allows plants to recognize pollen that shred one or both alleles of the "s" gene and to prevent those male gametophytes from reaching the ovules

- many plants have lost this

Monoecious angiosperms

individual plant has to types of flowers; flowers with stamens but no functional carpels AND flowers with one or more carpels but no functional stems

Dioecious angiosperms

individual plants has only one type of flower; flowers with stamens but no functional carpels OR flowers with one or more carpels but no functional stamens

- generally incapable of selfing

Bee pollination

flower colors: blue or yellow

- flower sent: various

- often have patterns and guidelines

- often have landing platform

Moth pollination

- color: whitish

-visible under low-light

- sweet

- no landing platform

- narrow nectar tubes

Butterfly pollination

- color: colorful (bright colors)

- sent: present (often sweet)

- have a flat surface

- narrow nectar tubes

Bird Pollination

- color: colorful, often reddish

- scent: none

- produce relatively large amounts of nectar

- thick, rigid parts

- ones that use hummingbirds do not have landing platforms

Bat Pollination

- color: white or pale

- scent: fruity or musky

- both pollen and nectar

- often large and tough

Fly pollination

- deceit pollination

- color: reddish and light spotted (often fleshy textured)

- scent: rotten

Wind Pollination

-No attractants or rewards

- flowers either pistillate or staminate

- petals are small or absent

- anthers open in dry weather

- enlarged stigmatic surface

- pollen dry, with smooth surface

Bee Orchids

deceit pollinatiors, look and smell like a female bee