Life Cycles Moro Pigments Flashcards
What is the primary pigment involved in the photosynthetic systems of both Cyanobacteria and algae?
Chlorophyll a
Where do the photosynthetic processes occur in eukaryotic organisms?
Inside the thylakoid membranes of chloroplasts.
In cyanobacteria, where are the photosynthetic complexes embedded?
In thylakoids free in the cytoplasm
What are the four multiprotein complexes responsible for the photosynthetic reaction in the thylakoid membrane?
- Photosystem II (PSII)
- Cyt b6f
- Photosystem I (PSI)
- ATP synthase
Name two types of pigments involved in photosynthesis
Chlorophylls and Carotenoids
Which chlorophyll types are usually found in some cyanobacteria?
Chlorophyll d and f.
What role do carotenoids play in photosynthesis?
They contribute to light-harvesting (=their role in photosynthesis)
also:
- producing large amounts of secondary caroteins is a mechanism for protection against different stressors (moslty in green algae)
- photoprotection mechanisms in red algae rely on carotenoids (LUT-, ZEA-, CX-group)
Which carotenoids are able to capture light in the green region of the spectrum (500-550 nm)?
Fucoxanthin, peridinin, and vaucheriaxanthin.
What is the VAZ cycle in Pheophyceae?
The biosynthesis cycle of xanthophylls that changes depending on light conditions.
What happens to the VAZ cycle when algae are exposed to high irradiances?
- biosynthesis of xanthophylls
- The cycle proceeds from violaxanthin to antheraxanthin to zeaxanthin
What pigment is responsible for the brown coloration of the thallus in Pheophyceae?
Fucoxanthin.
In which phyla are β,β-carotene and diatoxanthin most abundant?
Diatoms, Haptophytes, and Cryptophytes.
What is a unique feature of Dunaliella species (green algae) in high irradiances?
- Increase in β-carotene
- as compared to a xantophill cycle
What are the two types of secondary carotenoids synthesized by green algae?
- β,β-carotene and ketocarotenoids (e.g., Canthaxanthin)
- producing a large amount of secondary carotenoids is another mechanism for protection against different stressors
Which accessory photosynthetic pigments are largely present in Cyanobacteria, Rhodophyta, and Cryptophyta?
Phycobiliproteins.
Name the three main phycobiliproteins and their maximum absorption wavelengths.
- Phycoerythrin (570 nm)
- Phycocyanin (630 nm)
- Allophycocyanin (650 nm)
How does seawater affect light absorption compared to air?
- Seawater absorbs light more strongly, with blue light penetrating the farthest depths
- infrared and ultraviolet e.g. stop in the first cm of depth
What is the significance of accessory pigments in algae?
They allow algal growth at different depths by capturing light that chlorophyll cannot absorb.
What pigments are used for identification in cyanobacteria?
Chlorophylls a, b, d; Carotenoids like β,β-carotene and zeaxanthin; and Phycobiliproteins like phycocyanin and phycoerythrin.
Which chlorophyll allows cyanobacteria to utilize far-red light?
Chlorophyll d.
What is the function of the orange carotenoid protein (OCP) in cyanobacteria?
It acts as a sensor of light intensity and helps in photoprotection by quenching excess energy.
What is the major carotenoid in red algae species (Rhodophyta) that belong to the LUT group?
- photoprotective mechanisms rely on caroteinoids
- they play a key role in preventing damage
- the major carotenoid in red algae species (Rhodophyta) that belong to the LUT group is Lutein
What pigments are present in dinoflagellates of the DINO-1 group?
Peridinin, β,β-carotene, diadinoxanthin, and others.
Which group of dinoflagellates has a diatom endosymbiont?
DINO-3.
What are the three main profiles of carotenoid composition in Rhodophyta?
LUT group (main carotenoid is lutein), ZEA group (main carotenoid is zeaxanthin), XC group (main carotenoid includes violaxanthin or antheraxanthin).
What is the primary carotenoid in Porphyridium cruentum?
Zeaxanthin, belonging to the ZEA group.
Which xanthophylls are found in the LUT group of red algae?
Lutein
What makes dinoflagellates unique in terms of their pigment composition?
- They have likely incorporated various algal cells with different carotenoids into their bodies
- considering their pigments, they are the most differnet algal class
What type of endosymbiont is present in DINO-3 group dinoflagellates?
Diatom endosymbiont.
What pigment transformation occurs in the VAZ cycle under low irradiance?
Zeaxanthin to antheraxanthin to violaxanthin (ZAV cycle).
How do diatoms protect themselves under high irradiance conditions?
By converting diadinoxanthin to diatoxanthin.
What are secondary carotenoids, and when are they synthesized?
Carotenoids like β,β-carotene and ketocarotenoids (e.g., canthaxanthin) produced under environmental stress such as high irradiance or low nutrient availability.
Which cyanobacteria pigment allows the capture of infrared light, extending photosynthesis further into the infrared region?
Chlorophyll f
in responses to changes in light quantity and quality, cyanobacteria have evolved various regulation strategies, to adjust the functions of the PSI and PSII complexes.
These strategies include:
PBS stands for Phycobilisomes
What is non-photochemical quenching in cyanobacteria?
A mechanism to protect photosystems from excessive light using the orange carotenoid protein (OCP).
How do cyanobacteria use light quality to regulate the synthesis of phycobiliproteins?
By increasing phycocyanin synthesis under red light and phycoerythrin synthesis under green light.
What are the major carotenoids found in Rhodophyta species belonging to the XC group?
Violaxanthin or antheraxanthin.
