BSCI exam 2

Hadean eon

Hadean eon

first ocean

Archean eans

origin of life

Proterozoic eon

first photosynthetic organisms; first eukaryotes

Cambrian

explosion of diversity of multicellular forms

ordovician

radiation of marine invertebrates, first land plants

silurian

first vascular plants

devonian

first seed bearing plants; first jawed fish; first arthropods

carboniferous

large swamps of coal

permian

giant insects and amphibians; diverse ray finned fish

triassic

conifers dominant land plant; frog and reptile diversity

jurassic

dinosaurs; pterosaurs and rayed finned fish diversity, first flowering plant

cretaceous

flowering plant diversity, animals diversity on land sea

tertiary

radiation of mammals; climates cool and grasslands increase

quaternary

evolution of homo

mesozoic era includes

triassic, jurassic, cretaceous

Cenozoic era includes

tertiary, quaternary

Paleozoic era includes

cambrian, ordovician, silurian, devonian, carboniferous, permian

what eons are in the hanerozoic

Paleozoic, mesozoic, cenozoic

alveolates

unicellular, key feature being alveoli, phototrophic lineages being dinoflagellates, secondary endosymbiosis, heterotrophic lineages are ciliates, and apicomplexans

alveolates lineages

dinoflagellates, apicomplexans, ciliates

stramenopiles

uni and multicellular, key feature: 2 unequal flagella, phototrophic is diatoms and brown algae, heterotrophic oomycetes, secondary endosymbiosis

stramenopiles lineage

diatoms, oomycetes

rhizarians

unicellular, key feature: produce shells, phototrophic some cercozoa, heterotrophic foraminifera, radiolarians, rest of cercozoa, secondary endosymbiosis

rhizarian lineages

cercozoa, foraminifera, radiolarians

excavates

unicellular, have flagella, phototrophic: euglenoids, heterotrophic: parabasilids, diplomonads, secondary endosymbiosis

excavate lineages

euglenids, parabasilids, diplomonads

plants

uni and mulitcellular, key feature: photosynthetic, phototrophic lineages: red and green algae, land plants, primary endosymbiosis

amoebozoans

unicellular, key feature: amoeba like with pseudopods, heterotrophic: loboseans, plasmodial and cellular slime molds

groups of plants

bryophytes, pteridophytes, gymnosperms, angiosperms

bryophytes key groups

liverworts, mosses, hornworts

all bryophytes have

stomata (except liverworts), need water for fertilization, gymnosperm

pteridophytes key groups

club mosses, horsetails, ferns

all pteridophytes have

stomata, need water for fertilization, and roots, sporophyte

gymnosperm key groups

conifers, ginkgoes, cycads

all gymnosperms have

stomata, tracheids and roots, pollen, seeds, sporophyte

angiosperm key groups

flowering plants

all angiosperms have

stomata, tracheids and roots, pollen, seeds, double fertilization, sporophyte

key eukaryotic traits

flexible cell membrane (lost cell wall), complex cytoskeleton, nuclear membrane, digestive vacuoles, endosymbionts (mitochondria and chloroplast), sexual reproduction (mitosis and meosis)

what are the 8 major groups of eukarya?

alveolates, stramenophiles, rhizarians, excavates, plantae, amoebozoans, fungi, animals

which lineage of eukarya does not have nuclei?

excavates lineages: diplomonads and parabasalids

2 hypotheses for the origin of mitochondira

late origin, excavates split off before the origin of mitochondria, early origin, mitochondria arose at beginning but lost in excavates

What is proven through evidence?

single origin of mitochondria before excavates separate because genes found in nuclear genomes

excavates are usually

anaerobes and are parasites

how did secondary endosymbiosis occur:

green algae: transferred to the ancestor of euglenids and chlorarachniophytes

red algae: transferred to the ancestor of the chromalveolates

ancestrally how did organisms replicate

binary fission

steps for binary fission

replication of DNA from parent cell —> segregation of DNA —> cell splitting into 2

in binary fission what is shared

plasmids which contains genes for antibiotic resistance or pathogenicity

haploid

only one of each chromosome

diploid

two of each chromosome

sex

exchange of genetic material

reproduction

making more cells

meiosis

division of 1 diploid cell to generate 4 haploid cells

fertilization

fusion of 2 haploid gametes to form the diploid zygote

diplontic life cycles

organism is diploid and the gametes are the only haploid stage

haplontic life cycle

mature organism is haploid and the zygote is only diploid stage

haplo-diplontic life cycle

organism spends time in both haploid and diploid stages

isogamy

the gametes are the same size

anisogamy

two gametes are different sizes

oogamy

egg is larger and sperm is smaller

is both gametes are mobile it is best to be

isogamous

some asexual reproducing organisms can turn sexual reproducing during times of stress because

mating locus encodes a transcription factor driving gene expression

which of the following is a key eukaryotic trait that facilitated cell movement?

flexible cell membrane, complex cytoskeleton

How do we know that excavates once had mitochondria but lost them?

they have homologs to proteobacterial genes in their nuclear DNA, they have hydrogenosomes with double membranes

in chlamydomonas how does the mating type gene impact gamete formation?

expression of the gsp allele makes a positive mating type

paramecium have an unusual sexual cycle. Which of the following is the most similar to what you would expect for orgnaism’s that have more normal sexual reproduction?

the 2 cells exchange one haploid micronucleus

What is the main difference between the 2 different kinds of slime molds in their vegetative state?

plasmodial slime molds have many nuclei per cell, the cellular slime molds have one nuclei per cell

how does the mating type locus affect the zygote

expression of the gsp and gsm alleles makes a zygote which develops, and undergoes meiosis

in what eon was their visible life and fossil evidence for multicellular organisms

phanerozoic

during which period do 75% of all animals go extinct and the sea levels drop by 50m

silurian

multicellularity

cooperation among cells for “good” of organisms

five requirements for multicellularity

extracellular environments, division of labor, resource allocation, proliferation inhibition, programmed cell death

multicellularity evolved multiple times because

it is profitable for organisms

type of multicellular designs related to nutrition

photosynthetic, adsorptive organisms, ingestive organisms (animals)

convergent designs for photosynthetic organisms

flat leaves, tubular stems with roots

ingestive organisms have specialized tissues:

muscular- to move, nervous- to coordinate, digestive- to ingest

4 major multicellular clades

land plants, animals, fungi, brown alage

closest unicellular relative to land plants

green algae: charophytes

closets unicellular relative of animals?

choanoflagellates

closet unicellular relative for fungi

opisthokonts

closet unicellular relative for brown algae

unicellular stramenopiles (diatoms)

why would a choanoflagellate benefit from being reversible colonial

only spontaneously form rosette colonies in presence of bacteria

fungal bodies

mycelia, networks of branche hyphae

benefits of multicellularity

overcoming long distance diffusion, task division

multicellular organisms can reproduce by

budding (asexual) and producing a single celled spore or gamete (sexual)

gsp allele

encodes transcription factor for making + proteins in the + gamete

gsm allele

encodes transcription factor for making - proteins in the - gamete

low population size induces the expression of

gsp allele

the mating type locus encodes the integrates genetic machinery that

transformed cells into 2 gamete types, enable syngamy, and drives development of zygote, enables meiosis to form 4 haploid spores

do organisms need to have sex organs to have sex

no

what an organism needs to have to have sex:

form haploid gametes, union of haploid meiotic products to produce diploid, meiosis to form haploid stage again

most animals have what kind of sexual cycles?

diplontic sexual cycles

most unicellular organisms have what kind of sexual life cycle?

haplontic life cycle

how do multicellular organisms switch between sexual and asexual reproduction?

during warm months reproduction is parthenogenetic = cloning, during cold months or limited food, sexual morphs are made which produced resistant “resting eggs”

what is the surest form of evidence that life existed during a particular geological era?

find mineralized body parts that have fossilized

which types of organisms have a division of labor with regards passing down the genetic material

a diploid organisms with some cells undergoing meiosis

closets relatives to metazoans

choanoflagellates

likely sequence of events for the evolution of multicellularity starting from unicellularity

colonial cells —> linear filamentous cells —> branches filamentous cells —> parenchymatous cells

Where were animals fossilized following the Cambrian radiation 540 years ago

burgess shale

Why was it easy for plants to live in aquatic environment

bathed in nutrients, extensive internal transport not necessary, gametes offspring transmitted by water, no desiccation, supported against gravity

colonization of terrestrial environments:

early: plants evolved a new monophyletic lineage with novel adaptations for surviving on land. later: plants made terrestrial environment more survivable existing lineage of animals able to colonize