Phytoplankton Diversity and Evolution

Question 1

Classification and taxonomy

Answer 1

Single celled 1um phytoplankton to 30m (kelp)
No tissue differentiation
Classification based on:
- Pigments
- Food storage products
- Variable cell wall composition
- Variable flagella position, length, form, number
- Other cellular features
- molecular analysis

Question 2

Evolution of oxygenic photosynthesis

Answer 2

Photosystems in oxygenic photosynthesis very similar to the photosystems found in S bacteria

Question 3

Prokaryotes and Eukaryotes

Answer 3

Cyanobacteria and Prochlorophytes
Euks:
Bacillariophyta - Diatoms
Dinophyta - Dinoflagellates
Crysophyta
Haptophyta
Cryptophyta
Chlorophyta - green algae
Euglenophyta

Question 4

Evolution of eukaryotic phytoplankton

Answer 4

Primary symbiosis of a cyanobacterium with an apoplastidic host, rise to chlorophyte and red algae.
Chlorophyte line, second symbioses –> “green” line of algae, predecessor of all higher plants.
Secondary symbioses in the red line with various host cells gave rise to all chromophytes, diatoms, cryptophytes and haptophytes.

Question 5

Prokaryotic cell

Answer 5

Photosynthetic apparatus in thylakoids

Question 6

Eukaryotic cell

Answer 6

Outer cell covering of cellulose, silica, protein, calcite or organic scales
Nucleus
Mitochondria
Golgi, form waste material and polysaccharide production.
Endoplasmic reticulum and ribosomes
Chloroplast
Pyrenoid: proteinaceous area of chloroplast, site of carbon dioxide fixation
Vacuoles
Flagella

Question 7

Cell walls

Answer 7

Silica in diatoms
Cellulose in dinoflagellates
Mucilage in Phaeocystis
Calcium carbonate in Coccolithophores

Question 8

Pigments

Answer 8

Range of pigments across primary producers and therefore colours
Energy of the absorved photon modifies the electronic structure of pigment molecules
Auxiliary pigments can capture and utilise different wavelengths:
- Biliproteins found in cyanophyta, Rhodophyta and cryptophyta
- Carotenoids
Chlorophyll and carotenoids are soluble in lipid type solvents
Biliproteins are soluble in water.

Question 9

Molecular phylogeny

Answer 9

Application of molecular methods to determine genetic diversity of organisms
Ribosomes are the sites of protein synthesis, have a slow evolutionary rate and are composed on two subunits, large and small
Prokaryotes 16S ribosomal RNA
Eukaryotes 18S ribosomal RNA
Ribosomal units can reveal phylogenetic relationships between bacterium types.

Question 10

Sampling

Answer 10

Nets:
- large volume of water in short time
- Good for collecting large organims
- more difficult to sample quantitatively and to target discrete depths.
CTD:
- Samples a smaller volume of water, 5 to 20L
- Good for tageting discrete depths and collecting smalll to medium sized organisms
- largest organisms may be under sampled.
CPR/VPR:
- Continuous plankton recorder
- Captures samples on a silk, the preserved for future analysis
- Video plankton recorder.
- Captures images of larger images in situ.

Question 11

Quantification

Answer 11

Light microscopy
Flow cytometry:
- individual cells counted and characterized according to optical characteristics
- Scatter (size)
- Chlorophyll a fluorescence and phycoerythrin fluoroescence

Question 12

Pigments, HPLC

Answer 12

Pigments extracted into solvent
Pigments separated by High Performance Liquid
Chromatography then quantified by fluorescence and absorption,