BIOL 1625 Module 2

Fixation

truning an inorganic form into a organic form or a form usuable to life, carbon fixation: rubisco, nitrogen fixation: nitrogenase

rubisco

evolved before oxygen, won’t work in the prescnece of oxygen

nitrogenase

evolved before O2, won’t work in prescence, no eukaryotic cell can fix nitrogen

importance of carbon

1. versatile atom - can form many different kinds of molecules

2. organic chemistry is the study of carbon containing molecules

3. organic molecules are almost always produced by biological organisms

4. even simple carbon compounds can have huge consequecnes on life and the planet. CO2 and CH4

What are processes in the biological carbon cycle?

photosynthesis and respiration

David keeling

keeling curve, CO2 rise

phytoplancton

floating plants

zooplankton

floating animals

diatoms

large, eukaryotic photoautotrophs with glass shells, fix CO2- release O2

coccolithophores

large, eukaryotic photoautotrophs with carbonate shells, carbonae shells sink to bottom, can’t form shells with too much CO2 in ocean

carbon cycle

uptake and release of CO2 gas

nitrogen cycle

uptake and release of N2 gas

reactions preformed on prokaryotes

1. fixation

2. nitrification

3. denitrification

4. mineralization

fixation

bonding hydrogen to nitrogen to create ammonia

nitrification

bonding oxygen to nitrogen creating nitrate or nitrite

denitrification

removing oxygen bonds from nitrite to create N2

mineralization

deamination of protein resulting in ammonia

nitrogen cycle

eutrophication

excess nutrients enter waterways, fertilizer runoff from agriculture

nitrogen fixation

carried out by prokaryotes (bacteria and archaea), not eukaryotes

what ends snowball earth?

volcanoes, meteorite,

when did eukaryotes evolve?

after snowblal earth 1

How did snowball earth 1 end?

water vapor from meteorite was added to the atmosphere from melting ice changed, increase in greeenhouse gasses

endosymbiotic theory

origin of mitochondria and chloroplasts, englufed from cyanobacteria

1. mitochondria and chloroplasts have circular bacteria

2. they manufacture their own ribosomes

3. they replicate independently by binary fission

mitochondria

1. evolved from bacteria: proteobacteria

2. all eukaryotes mitochondria

3. aerobic = they use oxygen to generate ATP

Protists

a eukaryotic organism that is not an animal, plant, or fungus

How did chloroplasts evolve? 3 Hypothesis

1. common ancestor of all algae contained chloroplasts, chloroplasts were lost over lineages

2. multiple gains of cyanbacteria and converson to chloroplasts seperately in each superkingdom

3. Transfer of chloroplasts from one superkingdom to the others

Origin of Eukarya Hypothesis : 2

1. an ancient eukaryote engulfed a bacterium, which becamee the first mitochondrion. Predicts that there were ancient eukaya without mitochondria

2. an archaeal cell, engulfed a bacterium, which became the first mitochondrion. Predicts that some archaea are capable of endocytosis

Woese’s Tree of Life

Predicts that ancient ancestors of Eukarya had already diverged from the Archaea before they had mitochondria

Loki’s Tree of Life

Predicts that Eukarya evolved recently as one group within the Archaea, hydrothermal vents

Third hypothesis of Eukarya

Fusion of Archea and bacteria

Branded Iron Formations

dramatic sedimentary rocks that indicate repeated episodes of iron oxidation, before oxygen

Red Beds

only occur when the atmosphere has modern levels of oxygen, after great oxidation event

Autotroph

makes organic compounds from CO2

Heterotroph

need to consume organic compounds

phototrophs

energy from sunlight

chemotrophs

energy from chemical compounds

Anoxygenic photosynthesis

1. electron donor usually comes from reduced sulfer compounds such as hydrogen sulfide,

2. does not produce oxygen

oxygenic photosynthesis

1. electron donor comes from water.

2. electron flow non-cyclic

3. orginiated from cyanobacteria

4. uses two types of photosystems

5. produces oxygen

Green sulfur bacteria

1. They use light and hydrogen sulfide gas to make their own carbon compounds from CO2.

2. Instead of producing O2, they produce sulfur.

purple sulfer bacteria

Use sulfur-based photosynthesis.

light

particle (photon) + wavelength

pigements

1. molecules capable of absorbing certain wavelengths in order to protect cells from damage

2. to capture energy

Photosystems

clusters of chlorophyll molecules that capture photons

1. light-harvesting complexes

2. reaction-ceneter complex

chlorophyll

They form a complexes photosystem 

what do reaction centers do?

generate ATP and NADPH

cyclic phosphoralation

proteins accept and transfer electrons and while generating ATP

Type 2 reaction centers

(Q-type reaction centers, Q= quinones)

Type 1 reaction centers

FeS-Type reaction centers, Fd= ferredoxin

cyanobacteria

1. Fused both reaction centers

2. linear photosynethsis

3. Instead of cyclic photophosphorylation, cyanobacteria split water and generating electrons to produce both ATP and NADPH. Creating O2 biproduct.

chloroplasts - 2

1. An ancestral green algal cell acquired a cyanobacteria,

2. have genomes which are genetcial identical to cyanobacteria

ecological habitat expanision

The rise of O2 also leads to a rise in O3, opening up new shallow water and land habitats

stratospheric ozone

1. provides UV protection

2. enables life on land

biological soil crust

communities of cyanobacteria, green algae, lichens, and other microbes were probable the original terrestrial ecosystems

Greenhouse gas

heat trapping gas

biological carbon

stored in plants and algea

snowball earth hypothesis

global glaciations associated with big changes in the Earth’s carbon cycle.

1. after great oxidation event

2. 2 and 3 after multicellular organims appear,

Biomes

regions characterized by their enviroment conditions and their dominant vegetation types, defined by precipitation and tempature

Why are the tropics wet and deserts dry?

1. At equator, warm air rises, cools and releases rain

2. Around 30 N and 30 S latitude, dry air descends, warms up, and takes moisture away

3. Rising air = wet, 60 S and 60 N, 0 

4. Descending air = dry, 30 S and 30 N

what causes seaons?

the tilt of the earth

Tropic of Cancer

Solar radiation directly on the tropic of cancer, increase input and day length in Northern Hemisphere

Tropic of Capricorn

solar radiation directly falls on the tropic of Capricorn, with increased input and day length in the southern hemisphere

InterTropical Convergence zone

the area where the two hadley cells converge and cause large amounts of precipitation, changes in this produce seasonality in precipitation, rainy seasons and dry seasons at the equator.

Tropical Forests

1. 0 degrees

2. equator

3. wet, hot

Deserts

1. 30 degrees

2. Dry, hot

Boreal Forest

1. 60 degrees

2. wet, cold

3. taiga

4. high latitude coniferous forest

Tundra

1. 90 degrees

2. dry, cold

3. high-latitude cold grassland (no trees)

chaparral

shrubland with warm wet winters, hot dry summers

savannah

tropical grasslands

permafrost

1. soil that has been continuously frozen for >2 years.

2. Some has been frozen for millions of years 

3. Thawing will release CO2 and CH4

elevation

affects tempature and precipitation in a simialr way as latitude

Rain shadow effect

results in less rainfall at eqaul elevations on one side of the mountain versus the other

• Great Basin, Nevada, Utah, Arizona

Four great deserts of North America

1. The sonoran desert: winter rain, summer monsoons 

2. Chihuahuan desert: summer rain only 

3. Mojave desert: winter rain 

4. The great basin desert: winter rain and snow

After second snowball earth:

1. O2 levels increase, lead to ozone

2. provides protection of UV rays, allows algae into shallow water, invasion of land

Advantages to land

1. More light

2. Faster diffusion of CO2 in air than water 

3. No competition (at least at first)

Disadvantages to land

1. UV exposure 

2. Lack of water: desiccation 

3. Lack of water: Access to nutrients more difficult 

4. Need new dispersal methods that don’t require water 

5. Without water buoyancy, gravity is a serious constraint 

6. Temperature extremes

Cuticle

1. prevents water loss

2. watertight sealent, keeps CO2 out and H2O in

Liverwort

Air Pore: permanent openeing in epidermis - facilitates CO2 uptake but cannot regulate water loss, must live in wet spots and/or desiccation tolerant

Stomata

maximizes CO2 uptake while minimizing water loss is the evolution of stomata that open and close 

• High light + water supply: stomata open for business 

• Low light or low water supply: stomata close to save water 

• Stoma: singular, Stomata: Plural 

• ALMOST every land plant has stomata

stem cells

1. regions of cells division at tips of shoots and roots

2. growth at tips, search for water and light

3. inteterminate growth

4. meristems

sporophyte

diploid, spores

gametophyte

haploid, gametes,

why do plants need water

1. To supply electrons during oxygenic photosynthesis 

2. To expand their cells during growth 

3. To replace water lost from plant surfaces and stomata due to evaporation (transpiration). 98% OF WATER GOES HERE

4. To ensure the sperm gets to the egg

Transpiration

The water loss through the stomata into the atmosphere

What life cylce do land plants have?

• Alternation of generations: both diploid and haploid multicellular stages 

• Gametes - zygote - multicellular sporophyte - spore - multicellular gametophyte

Haploid multicellular haploid stage

gametophyte

Haploid multicellular diploid stage

sporophyte

What life cylce does green algea have?

Haplontic life cycle 

• Multicellular alga - gametes - zygote - haploid cells 

What advantage is there to being a tall plant? 

1. Dispersal of spores or other reproductive structures 

2. Less competition for light

Disadvantages of height

1. Need to develop rigid structure to support height = lignin 

2. Need to move water/nutrients farther above the ground = vascular tissue 

Lignin

1. complex polymer that imparts rigidity

2. Rigidity allowed the evolution of xylem, which required extremely long, rigid cells.

3. Doesn’t get broken down, turns into coal 

transport tissues in vascular plants

xylem and phloem

Carboniferous

when carbon dioxide dropped due to lignin locking in CO2

During the Carboniferous Period

1. Atmospheric CO2 levels from 10,000 to 1,000 ppm

2. Atmospheric O2 increased to 30-35%

3. Decomposition of dead plants was low (altered carbon cycle, turned into coal)

4. Animal flight first arose

5. Insects were larger than they are today