AqBot: Flagella and Intro to Reproduction

What are 3 flagellar external features?

scales, hairs, and spikes

• Describe flagellar scales

• What organisms are they present in?

• What are the 5 flagellar scale shapes

• Normally a continuation of cell body scales

• Present in Heterokontophyta, Haptophyta, and Chlorophyta

• Hexagonal, square, limuloid (has rod scale or rod structure on the outside for support), spider web, rod

• What are flagellar hairs known as?

• List and describe the 2 forms of flagellar hairs

• aka Mastigonemes

• 2 types

  • Tubular - tripartite (base, tubular shaft, and terminal filaments)

  • Non-tubular - simple; slender and flexible

generally describe Euglena mastigonemes

Euglena has complex tubular flagella hairs, a tubular shaft is present

• Describe flagellar spikes

• What is there function?

• What organisms are they present in?

• described as a “peculiarity”

• unknown function

• only present on male gametes of a few brown algae

• What are the 4 main types of flagellar internal features?

• Why are flagellar internal features important?

• Axoneme, paraxial rod, transition zone, and root system

• Flagellar internal features are complex and are used to distinguish b/w similar looking plankton groups

• What’s the purpose of axoneme?

• Describe its makeup.

• USE = generates movement of flagella

• 9 + 2 pattern = contains central pair (where “2” comes from) and has 9 microtubule doublets linked by dynein arms (where “9” comes from)

How does the axoneme move?

the dynein arm will move along the microtubule of one doublet causing the flagella to bend, then the other dynein follows creating undulation

• What’s the purpose of the paraxial rod?

• What is the paraxial rod known as?

• What organisms are they present in?

• USE = provides support for the flagella; in the form of a complex lattice structure parallel to the axoneme/flagella

• aka Paraflagellar Rod (PFR)

• present in Heterokonts, Euglenophytes, and Dinophytes

• Describe the transition zone

• How many types of transition zones are there?

• an axoneme constant b/w different algae; varies greatly, so it’s a useful indicator of phylogenetic relationships

• 5 transition zones types each having secondary variations

Describe the Type 1 transition zone

• simplest

• 1 basal plate present

Describe the Type 2 transition zone

• No basal plates

• Has a plug

Describe the Type 3 transition zone

double plate system of complex plates which are stacked on each other

Describe the Type 4 transition zone

• 1 basal plate

• contains transitional helix

Describe the Type 5 transition zone

stellate pattern

• Define the root system

• What are the 2 attachment forms?

• Extends from basal bodies. Underlays plasma membrane or projects into cell contacting organelles

• Cruciate and broad-band

what is the flagella structure of Euglena?

• canal is rigid

• mastigonemes

• contractile vacuoles can affect flagella

describe the flagella in dinoflagellates.

in their cingulum they have a transverse flagella and a longitudinal flagella comes out of posterior

• describe the flagella in Cryptophyta

• USE of flagella

• flagella are asymmetrical

• creates unique movement that is spiral like due to the short and long flagella

Describe the flagella of stramenopiles which includes Heterokontophyta and brown algae.

• Flagella comes in two forms which work together

  • whiplash - hairless so naked, pushes/propels the algae forward

  • tinsel - mastigonemes so has hairs, pulls or rows the algae using the increased surface area from the hairs

Why is physics important in algae movement?

its important to know how to move fluid as density increases from freshwater => saltwater => cytoplasm => diatom frustules or chrysophyceae scales => haptophyta coccoliths

• what was the analogy of phytoplankton swimming through water?

• what is the physics behind this analogy?

• phytoplankton moving through water is like fish/humans swimming through molasses

• Reynolds number (= inertial force/viscous force) is low for phytoplankton as inertia is low and viscosity is high for organisms the size of phytoplankton

what are the 6 adaptions for the movement of phytoplankton?

• forward stroke of flagella entails slinging itself forward which is different than reverse

• asymmetric cells advance by spinning along axis using its 2 unequal flagella

• symmetric cells don’t spin or rotate

• longitudinal flagella is propelling and steering flagellum

• transverse flagella propulsion

• flagellar hairs in Euglena increase thrust which creates helical waves, additionally Euglena secretes mucus and has inch worm motion for further propulsion

what is the general pattern of swimming/gliding speeds of the different phytoplankton?

the more complex the phytoplankton got, the faster they were able to move. Takes cyanobacteria 4 weeks to move 1 cm and takes dinoflagellates 20 seconds to move 1 cm

what are other adaptations present in phytoplankton that aid in swimming?

• buoyancy control = internally hold water or air via contractile vacuole or gas vacuoles

• reducing/increasing drag = hairs can slow down phytoplankton; the plankton can become more streamlines; mucus outer covering makes moving easier

describe the pattern of population growth of unicells

lag phase => exponential growth (aka log growth) where constant splitting occurs => stationary phase where the maximum population is reached and reproduction stops => decline occurs possibly due to end of life cycle or decrease in nutrients

• define binary fission

• what are the 4 different forms and what organisms does it correlate to?

• simplest form of asexual reproduction in which the parent divides into 2 equal and identical parts

• Longitudinal = Euglena is classic example. Transverse = Paramecium. Irregular = amoeba. Oblique = Ceratium

• What occurs during fragmentation?

• What organisms does it occur in?

• Why is it dangerous?

• filaments (or noncoenobic colonies, like Volvox) which can break into two-several pieces, each capable of developing into new individuals

• Occurs in cyanobacteria and macroalgae

• Causes introduced spp. to become invasive bc very efficient in reproducing through fragmentation

• what occurs during the resting stage, what is it influenced by?

• what does it look like in Cyanobacteria, Diatoms, and other planktons?

• this is a temporary stage in the intermediate part of the life cycle used for survival to stop reproducing until the environment is suitable again. Influenced by environmental triggers like desiccation, temperature, and nutrient limitations

• Cyanobacteria has akinetes. Diatoms have resting spores, resting cells, and auxospores. Hypnospores, hypnozygotes, and statospores

• Describe the reproduction in Cyanobacteria

• Define Hormongonia

• Define Baeocytes

• asexual reproduction ONLY

• Akinetes (spores) develop thick cell walls, can survive months in harsh conditions like freezing and desiccation, in favorable conditions the akinetes with germinate into vegetative cells

• Hormongonia are present in truly filamentous cyanobacteria in which they break off, glide away, and develop into a new filament

• Baeocytes are similar to the endospores produced inside the cell, undergo multiple divisions w/in protoplasm, release via cell bursting open to mature