Bio 202 Unit 2 Exam

when did earth form

4.6 bya

had very little O2

reducing conditions in early earth

reducing conditions favored the synthesis of organic compounds.

to be reducing, atmosphere contains high methane and ammonia 

some debate over if atmosphere was actually reducing 

first organic compound

may have been near deep sea vents or volcanoes

meteorites may have been another source of organic compounds

synthesis of macromolecules

monomers link to form polymers- process is v slow without enzymes

also faster when concentrated on sand, clay, or rock

protocols

lipids can form vesicles with a lipid bilayer

clay can speed up process

vesicles exhibit simple reproduction + metabolism

self replicating RNAs

first genetic material likely RNA

ribozymes catalyze many reactions in modern cells

RNA may have been a template for DNA

fossil dating methods 

1. Sequence of fossils in sedimentary rock strata

2. radiometric dating (gives absolute dates)

3. radiocarbon dating

radiometric dating

isotope half life can be the time required for half the parent isotope to decay→ shows absolute dates

radiocarbon dating

can date older fossils

isotopes with longer half lives cab date tock layers above and below the fossil

Pre Cambian Period

1) 3.5 by a cell life emerged

2) 2.5 bya: oxygen becomes permanent fixture in the atmosphere

3) 1.8 bya eukaryotes orginaite

4) 1.3 bya: multicellur euakatyotes orginicate 

oldest known fossil

stromatolites→ rocks formed by the accumulation of sedimentary layers on bacterial mats 

oxygen revolution

resulted in prokaryotic groups becoming extinct

survived→ adapt to use aerobic cellular respiration

→ restricted to anaerobic habitats

→ developed tolerance to some O2

• ultimate created the ozone layer (O3)→ ozone shield

endosymbiont theory

mitcochonria and plastids were formerly small prokaryotes living within larger host cells

evidence:
- they have their own genomes that are circular

-the organelles transcribe and translate their own DNA

-grow/ replicate outside of the cell cycle

origin of multicellular eukaryotes

1.3 bya

ediacaran biotia (600 myo)→ larver and more diverse soft bodied animals

Paleozoic Era

542-251 mya

1. Cambrian: sudden appearance of fossils similar to animal phyla

Eras

precambrian, Paleozoic, mesozoic, Cenozoic 

periods in Paleozoic era

1. Cambrian: First appearance of many major animal phyla (e.g., arthropods, mollusks).

2. Ordovician: colonization of land by fungi, plants & arthropods

3, Silurian: early vascular plants

4. Devonian: “Age of fishes”; 1 st tetrapods & insects

5. Carboniferous: 1 st seed plants; “forests”; amphibians dominant

6. Permian: radiation of reptiles & insects

Mesozoic Era

(251-65 mya)

1. Triassic and Jurassic: dinosoucres, gymnosperms are dominant plants 

2. cretaceous: flowering plants Aris 

Cenozoic era

65 mya to now

Paleogene

Neogene

Quaternary

-mammals, birds, insects

flowering plants dominant

Historical extinctions/ radiations

• boundaries between eras = mass extinction events

permian extinction

250 mya

96% of all marine species

insects and terrestrial life gone

due to high volcanic activity

resulted in large emission of CO2

Cretaceous Extinction 

65 mya 

50% of Marine species went extinct and terrestrial plants and animals and dinos

partially caused by meterioite impact in Yucatan Peninsula which altered climate and oceanic circulation 

Pleistocene Extinction

10,000 years ago

ice ace mammals gone

prob receding of ice sheets

adaptive radiation

evolution of diversity adapted species from a common ancestor

can follow

mass extinctions

evolution of novel charactertics

colonization of new regions

effect of developmental genes

changes In sequence can equal major changed in body form

heterchrony 

change in the rate or timing of developmental events 

impact body shape 

alter reproduction developmental timing 

homeotic genes

control placement and organization of body Parts

hox genes: info abt animal development position

prokaryotic traits genome

Genome: prokaryotes have 1 circular chromosome, smaller than eukaryotic

Small rings of DNA → called plasmids

resource use efficiency

small cell size allows more cell surface area per unit volume

allows greater rate of food absorption

can convert food resourced into more biomass via rapid reproduction→ binary fission

nutritional flexibility/ metabolic diversity

ASK

where is cellular respiration is carried out 

cellular resp + photosynthesis is in specialized infolding of the plasma membranes 

prokaryotic metabolism + O2

obligate aerobes: require O2 for cell resp

obligate anaerobes: NO O2, use fermentation + anaerobic respiration

facultative anaerobes: survive with or without O2

motility

flagella act like boat propellor s

capable of chemotaxis→ moving to/away from a substance

transformation

prokaryotic cell can take up and incorporate DNA from its environment

transduction 

movement of genes between bacteria by viruses 

conjugation

process where genetic material is transformed from 1 prokaryotic cell to another

donor cell attached to recipient by a plus, then pulls other cell closer to transfer DNA

Archaea Domain

eukaryotes and archaea are more closely related to each other than bacteria

euryarchaeota→ domain archaea

includes halophiles + methanogens

halophiles

require high salinity 

methanogens

strict anaerobes→ poisoned by O2

live in herbivore guts, swamps, wastewater treatment plants

crenarchaeota→ domain archaea

includes thermacidophiles→ thrive in hot/ acidic environments

many archaea are not extremophiles 

gram positive bacteria

layer of peptidoglycan traps crystal violet

postitive = purple

incredible diversity

ex: staph, strep, actinomycetes

gram negative bacteria

thin layer of peptidoglycan between 2 membranes

doesn’t turn purple

capsule (part of gram positive bacteria)

sticky layer of protein outside cell wall, helps cells adhere to substrate or stick together in groups 

endosphere (part of gram positive bacteria)

type of resistant cell that can remain viable in harsh conditions for centuries

cyanobacteria domain bacteria

‘blue green algae”

photosynthetic→ responsible for addition of oxygen to early earth’s atmosphere ‘

chloroplasts likely evolved from this

spirochetes domain bacteria 

helical shape 

some are free living, others are parasitic 

filaments allow for a quince “corkscrew” style of locomotion→ useful to propel through viscous matter

chlamydias domain bacteria

parasites, only live within animal cells

no cell wall, very small'

ex: clamidiya

proteobacteria domain bacteria

gram negative bactiea

• e coli

• h pylori

mitochronia likely originated from subgroup of proteobacteria

all protests are

eukaryotes

they are in their own kingdom

variety of nutritional modes

photoautotrophs→ make their own food

heterotrophs→ must acquire food from another source

mixotrophs→ combine photosynthesis + heterotrophic

structure of cells

protists are single celled organisms

1 cell must carry out the basic functions

importance of protistan producers 

multicellular algae and phytoplankton form the major base of aquatic food webs 

protists are primarily

aquatic

protistan diversity stems from

endosymbiosis

primary endosymbiosis + secondary endosymbiosis

excavata

diplomonads, parabasalids, euglenozoans

diplomonads

rely solely on anaerobic pathways 

low O2 environments 

highly reduced mitochondria 

EX: Giardia 

Parabasalids

flagellated anaerobes

animal parasites

euglenozoans

presence of spiral crystalline rod inside flagella

euglenids→ commonly found in pond water, photosynthetic 

kinetoplastids→ single large mitochondria , some are free living others are parasitic 

SAR clade

Stramemophiles, Alveoates, Rhizarians 

Stramenophiles

have “hairy” flagellum with smooth flagellum

diatoms, brown algae, oomycetes

diatoms

unicellular algae with glass like cell walls

members of marine + FW phytoplankton

“pillbox” structure→ withstand pressure

brown algae

largest and most complex algae

mulitcelluar→ most are marine

common on temperate coasts with rocky substrate

oomycetes

water molds, white, rusts, downy mildews 

tiny filaments that resemble fugal hyphae 

distant from fungi 

alveolates

dinoflagellates

apicomplexans

cilliates

have alveoli (small membrane- bound sacs) just underneath the plasma membrane

help stabilize the cell and or function in ion balance

dinoflagellates

abundant components of marine and FW phytoplankton

2 flagella located in grooves that run the circumference of the cell

dinoflagellate “blooms” create red tides in coastal waters

some endosymbiotic species live within coral

apicomplexans

animal parasites

have intricate life cycles w sexual and asexual stages requiring different hosts

Plasmodium→ causes malaria

ciliates

use cilia to move and feed 

have 2 nuclei (Diff set of genes in each)

normal reproduce asexually via binary fission 

eat bacteria or smaller protists 

rhizarians

most are amoebas with threadlike pseudopodia

radiolarians

forams

cercozoans

radiolarians

unicellular

planktonic in the ocean 

foraminerferans

have a porous shell of CaCO3

live in marine

and FW systems

cercozoans

highly diverse protists

very common in marine, FW, in soil

parasitic or predators-< important for plants/ plant health

archeoplastida

red algae, chlorophytes, charophytes, plants( not a protist)

red algae 

red color comes form the pigment phycoerythrin 

common in tropical oceans 

inhabit very deep waters 

green algae

found in aquatic habitats worldwide- also damp soil

chloroplast structure/ pigments→ similar to land plants

have complex life cycles

2 groups: chlorophytes + charophytes

unikonta

have 1 flagellum

amoebozoans + opisthokonts

amoebozoans

different amoebas with lobe or tube shaped pseudopodia

includes: tublinids, slime molds, entamoebas

tubulinids 

basic amoebas 

common in soil and aquatic environments 

active predators 

entamoebas

unicellular parasites of animals

slime molds

plasmodial slime molds + cellular slime molds

produce fruiting bodies that aid in dispersal

resemblance to fugi bc convergent evolution

“amoeba” body form is only present during part of their life cycle

plasmodial slime molds

neon colored

decomposers

“acellular” body is 1 giant mass of bytoplams + many nuclei

cellular slime molds

feeding stage consists of solitary amoeba 

when food is scare, form and aggregate that functions for reproduction 

phytoplankton

unicellular algae, microscopic

seaweed

mulitcellular

different groups have different pigment types

all have chlorophyll A

different accessory pigments

• carotenes (orange) → brown seaweed

fleshy (soft) or calcareous (hard) bodies

paper chromatogny

way to separate the combination of pigments

seaweed is not a 

plant

seaweed structure

thallus→ entire body

blade→ “leaves”

stipe→ “stem”

holdfast→ holds in bottom but doesn’t function like roots

brown algae

live in temperate regions

intertidal non-kelps

and subtitle kelps

interstitial brown algae

rockweed→ has bumps/ spores on blades

sea palm

pneumatocysts 

“airballs” that help seaweed float 

subtotal kelp

pacific giant kelp

feather boa 

elkhorn kelp

giant kelp

fastest growing organism

forms offshore habitats

economic importance

elkhorn kelp

brown algae 1 large pneumatocyst

long stipe

inertial green algae

sea lecture + dead man’s fingers

tropical green algae

can be calcified

calcareous algae→ contains calcium carbonate

ecological equivalents 

similar algae in different geographic areas 

intertidal red algae

can be fleshy

• filamentous

• blades

calcareous

• crustose

epiphytic

crustose

grows like a sheet over hard surfaces

resistant to waves + grazing animals

conceptacles

bumps on segments were reproductive spores are shed into the water