AQUABOT EXAM 2 cyanobacteria, nutrients, and photoreceptors

Type 1 Photoreceptors

single layer

Who has type I photoreceptors

chlorophyta, ochorophyta, cryptophyta, haptophyta, and dinoflagellates

Type 2 photoreceptors

multilayered membrane structure of photoreceptive protein

Who has type 2 photoreceptors

Euglenophyta & Ochrophyta (Chrysophyceae)

Type 3 photoreceptors

very specialized ocelloid - lens, cornea, and retinal body help with light detection and finding prey (as close to an eye as you can get)

Who has type 3 photoreceptors

Dinoflagellates (Warnowiales)

Phototaxis

response to direction and intensity of light (+ toward light, - away)

Photophobia

response to rapid change in light intensity (swim backward / dart around)

Gliding

move along the surface

How does an increase in Ca2+ affect flagella “beats”?

increases the speed

How does a decrease in Ca2+ affect flagella “beats”?

slows the speed

_____ changes membrane potential, which changes _____ coming into the cell

Rhodopsin, Ca2+

Which of the following adaptations allows cyanobacteria to outcompete the other species particularly in freshwater environments?

all of them

Cyanobacteria can produce _____ that can affect your nervous system, kidneys, and promote tumor growth

cyanotoxins

What species of cyanobacteria is responsible for the Lake Taihu blooms?

microcystis

_____ is the final product of nitrogen fixation

glutamine

_____ refers to a system with low levels of nutrients

oligotrophic

Nitrogen fixation is a very energy-intensive process requiring 16 ATPs to complete

True

An organism capable of fixing atmospheric nitrogen is called

diazotroph

what is the enzyme that catalyzes nitrogen fixation

nitrogenase

What species is known for spinning when hit with light

Volvox

How to volvox react to light

the flagella on the side that the light hits slows down and the others continue to glide, causing it to spin

location of _____ prevents light from coming in certain directions from reaching receptors

eyespots

Usually contain carotenoids

eyespot

photosensitive proteins that provide a “solid-ish” structure

Rhodopsin

Swimming behavior that has sharper adjustments for trajectory control

Asymmetical

Swimming behavior that has a more smooth control of trajectory

symmetrical

_____ have physiological signal transmutations in their photoreceptors

Chlyamydomoans

Light driven proton pumps that use retinal to transport H (creating a chemical gradient to synthesize ATP) and is adapted to low iron

rhodopsin

higher end of the spectrum (510 nm max) creates a photophobic response — won’t cross light/dark

Rhodopsin A (CSRA)

Lower end of the light spectrum (470 nm max), saturates at low light intensity, creates a phototaxis response (toward or away from light)

Rhodopsin B (CSRB)

Phototaxis of spirogyra

will align toward blue light (positive phototaxis)

gliding movement along filaments

filaments form parallel bundles, curve, form larger mats

Orange-red lipid droplets (eyespots) characteristics

color is from beta-carotene or derivative

anterior portion of the cell

flagellar swelling in transition zone between canal and reservoir

don’t like bright lights (negative phototaxis in bright lights, positive in dim)

Light during dark periods causes phototaxis

false

Features of dinoflagellate eyespots

many different types

lipid globules in cytoplasm

lipid globules in plastid-like structure

complex eyespots (ocelloids)

Phototaxis can occur in dinoflagellates without eyespots

true

Characteristics in cryptophyta eyespots

present in some genera

lipid granules inside chloroplast envelope

positive phototaxis in SOME species

Environmental factors that affect phytoplankton

light, nutrients, HABs

What are the big nutrients that affect phytoplankton

nitrogen (N2, NH4+, NO3-, NO2-, and organic)

phosphorus (PO4, organic P)

silicon

iron

Ca2+, K+, S, Na+, Cl-, and Mg2+

Of the big nutrients, which ones are important for diatoms, dinoflagellates, and coccoliths?

silicon and iron

which nutrients act as fertilizers

nitrogen (nitrate, ammonium, and organic)

phosphorus (inorganic/organic)

silicon

iron

What is the Redfield ratio?

106C:16N:1P

What are the 5 steps in nitrogen fixation (in order)

nitrogen fixation, nitrification, assimilation, ammonification, denitrification

What happens in the first step of nitrogen fixation?

atmospheric nitrogen (N2) is pulled in and converted to ammonia (NH4) or ammonium (NH3)

What happens in nitrification?

NH3/4 is used or converted to nitrite (NO2)

What happens during assimilation?

NO2 (nitrite) is converted to NO3 (nitrate)

What happens during ammonification?

NH3/4 and NO3 is consumed or released

What happens during denitrification?

low oxygen coverts NO3 to N2

What are the steps of the phosphorus cycle?

weathering, assimilation, decomposition (and release into sediment)

N fixers take up ____ and make ____

unusable nitrogen, usable

What was the Mississippi phosphate/Chevron incident

Mississippi phosphate was dumping a bunch of chemicals into the water. They made mound of P and liquid waste. In 2014 their facility exploded and were fined by the EPA. MP went bankrupt and left the mounds of waste, then a hurricane washed all of it into the gulf. It is now a superfund site by the EPA and they just put big tarps over all of it and called it good.

Eutrophic

high in N and P

Mesotrophic

moderate nutrients

Oligotropic

low nutrients (nutrients in - out = 0)

What happens in nitrogen fixation in phytoplankton?

Nitrogenase breaks the N2 triple bond and makes NH4

• NH4 is added to 2-oxoglutarate and makes glutamate

A second NH4 is added to glutamate, with additional ATP

• glutamine synthetase forms glutamine

primary nitrogen carrier and signaler

glutamine

All known nitrogen-fixing organisms are

prokaryotes

Thickened cells in cyanobacteria

heterocyst

layers of heterocyst cells (3)

fibrous, homogenous, and laminated

inner cytoplasmic membrane of heterocysts

plasmalemma

connects heterocyst to vegetative cell

pore channel

thickened cell walls _____ atmospheric gases, creating a _____ environment internally

restrict, anoxic

keystone organism that fixes up to 50% of nitrogen in the ocean

trichodesmium

smallest phytoplankton (0.5-2 micrometers) that photosynthesize during the day and fix nitrogen during the night

synechococcus

Distribution of cyanobacteria

costal and marine environments

non-acidic hot springs

terrestrial environments

freshwater environments

hot or cold

Who are the key players

microcystis, gomphosphaeria, lyngbya, oscillatoria, planktothrix (non-nitrogen fixing)

anabaena, aphanizomenin, cylindrospermopsis, nodularia (nitrogen fixing)

what are the common cyanobacertial HAB species (the big 5)

Microcystis aeruginosa

Anabaena circinalis

Anabaena flos-aquae

Aphianizomenon flos-aquae

Cylindrospermopsis raciborskii

what do alkaloid neurotoxins do

they block transmission of signals between neurons or neurons to muscles

Prochlorococcus

small, low in water column (blue light) — unique case

Common habitats for microbial mats

hypersaline ponds, hot springs, shallow marine coastal zones, intertidal zones, and cold nutrient poor environments (Antarctica)

What hepatotoxins are produced by cyanobacteria

microcystins, nodularins, and cylindrospermopsin

what chemicals that can increase tumor growth are produced by cyanobacteria

microcystins and lipopolysaccharides (GI system)

what neurotoxins are produced by cyanobacteria

alkaloids, anatoxins (very fast death factor), and saxitoxins

How do cyanotoxins get into people?

contact with skin (minor symptoms like rash), inhaling water droplets, swallowing water with cyanobacterial toxins

Features of lake Taihu (pre-cyanobacteria)

supplies water for 20 million people, fishery (crab, carp, eels, and shrimp), known for its beauty, 3rd largest lake in china

Post HAB features of lake Taihu

drinking water crisis, cyanobacteria blooms 100s of km² in size

Actions needed for lake T

reduction of N, P, and toxic chemicals

sewage treatment plants

non point source runoff

increase water reuse

Common freshwater cyanobacteria species

microsystis, anabaena, lyngbya, and oscillatoria

Why can cyanobacteria outcompete other species

not as light limited, high affinity for N and P, can regulate buoyancy, and have a higher temperature optimum for growth/photosynthesis