Related Experiment Video
Updated: Aug 15, 2026
05:54
Autofluorescence Imaging to Evaluate Red Algae Physiology
Published on: February 17, 2023
Prochlorophyta - a matter of class distinctions
1Scripps Institution of Oceanography, University of California (San Diego), La Jolla, CA, 92093-0202, USA, rlewin@ucsd.edu.
Photosynthesis Research
|October 26, 2005
Summary
Photosynthetic prokaryotes like Prochloron, Prochlorothrix, and Prochlorococcus contain chlorophylls a and b. Despite initial classification as Prochlorophyta, molecular data suggest they are aberrant cyanophytes.
Area of Science:
- Microbiology
- Phycology
- Photosynthesis research
Background:
- Prochloron, Prochlorothrix, and Prochlorococcus are photosynthetic prokaryotes containing chlorophylls a and b or divinyl-chlorophylls a and b.
- These organisms were initially classified as a new algal sub-class, Prochlorophyta, due to the absence of blue and red bilin pigments.
Purpose of the Study:
- To re-evaluate the taxonomic and phylogenetic placement of Prochloron, Prochlorothrix, and Prochlorococcus.
- To investigate the evolutionary relationship between these organisms and ancestral green-plant chloroplasts.
Main Methods:
- Analysis of pigment composition (chlorophylls a, b, divinyl-chlorophylls a, b).
- Phylogenetic analysis using molecular biology data.
Main Results:
- All studied organisms are confirmed as photosynthetic prokaryotes.
- Molecular data do not support a close phylogenetic relationship to ancestral green-plant chloroplasts.
Conclusions:
- The classification of Prochloron, Prochlorothrix, and Prochlorococcus as Prochlorophyta is questionable.
- These organisms are best considered aberrant forms of cyanophytes based on current molecular evidence.
Related Concept Videos
01:21Green Algae
Green algae, also referred to as chlorophytes, are different from red algae in having the chloroplasts containing chlorophylls a and b, which give them their distinct green hue. However, they lack phycobiliproteins, preventing them from developing the red or blue-green pigmentation seen in red algae. In terms of photosynthetic pigment composition, green algae closely resemble plants and share a close evolutionary relationship with them. Taxonomically Green algae belong to Phylum Chlorophyta in...
01:19Other Algae
The group Stramenopiles include some phototrophic microorganisms. Members of this group possess flagella covered in numerous short, hairlike extensions, a feature that inspired the group's name, derived from the Latin words for "straw" and "hair." Some of the main categories of Stramenopiles include diatoms, golden algae, and brown algae.Diatoms are unicellular, photosynthetic eukaryotes, with over 200 known genera. They play a key role in the planktonic communities of both marine and...
01:15Diversity of Protists I
Excavata is a diverse group of protists that includes both chemoorganotrophic and phototrophic species, with some thriving in anaerobic environments. Among the key groups within Excavata are diplomonads and parabasalids, which are flagellated protists that lack mitochondria and chloroplasts. These microorganisms typically inhabit anoxic environments, such as the intestines of animals, where they exist either symbiotically or as parasites, relying on fermentation for energy production. Some...
01:27Diversity of Protists III
Rhizaria are a diverse group of unicellular protists characterized by their threadlike cytoplasmic extensions known as pseudopodia. These structures aid in both locomotion and feeding, giving Rhizaria an amoeboid appearance. Their amoeboid morphology once led to taxonomic confusion, but molecular phylogenetics has clarified their evolutionary placement and emphasized their shared use of pseudopodia despite divergent lineages.This clade comprises diverse lineages such as Chlorarachniophyta,...
01:23Red Algae
Red algae, also known as rhodophytes, are primarily found in marine environments, though some species inhabit freshwater and terrestrial ecosystems. These organisms exist in both unicellular and multicellular forms, with some multicellular varieties reaching macroscopic sizes.As phototrophic organisms, red algae contain chlorophyll a; however, their chloroplasts lack chlorophyll b. Instead, they possess phycobiliproteins, which serve as major light-harvesting pigments, similar to those found in...
01:28Overview of Algae
The kingdom Archaeplastida encompasses red and green algae, along with land plants. Unlike other protists with chloroplasts that arose through secondary endosymbiosis, only red and green algae originated from primary endosymbiotic events. This diverse group of eukaryotic organisms contains chlorophyll and performs oxygenic photosynthesis.Algae exist in various forms, from large brown kelp in coastal waters to green scum in puddles and stains on rocks or soil. Some species are responsible for...