Algal hysiology I. hotosynthesis I. hotosynthesis in algae II. Characteristics to distinguish algal divisions 1 2 SU : hotosynthetic Unit = Antennae rxn center Light reactions: solar energy is harvested and transferred into the chemical bonds of AT and NADH 3 4 1
Chloroplasts Thylakoid flattened vesicles or sacks; thylakoid membrane is where the pigments are Stroma space between inner membrane and thylakoids Granum (pl: grana) stacks of thylakoids yrenoid holds enzyme ribulose bisphospate carboxylase (Rubisco) used in Calvin cycle Calvin Cycle: C fixation from CO 2 to sugar using energy from AT and NADH 5 6 igment Location What light can be used for photosynthesis? 7 8 2
What light can be used for photosynthesis? AR = photosynthetically active radiation = 47 nm igments: rimary 1. Chlorophylls green pigments, embedded in thylakoid membrane. Chl a is the main player: used in all algae and land plants. Chl a absorbs light primarily in the blue and farred regions Must also deal with UV light (2832 nm); damage DNA, proteins Bcarotene, aromatic amino acids absorb UVB Reflects green why most plants appear green 9 1 What s wrong with this picture? What s wrong with this picture? 11 12 3
Algae have accessory pigments: Allow harvesting of light at middle wavelengths, then channel energy to Chl a Algae have accessory pigments: Allow harvesting of light at middle wavelengths, then channel energy to Chl a SU : hotosynthetic Unit = Antennae rxn center 13 14 Algal accessory pigments: How we measure photosynthetic rates (primary productivity): Carotenoids brown, yellow, or red pigments. Hydrocarbons with or without an oxygen molecule = carotenes and xanthophylls. 3. hycobilins red or blue pigments. Water soluble. Located on the surface of thylakoids in red algae, associated with proteins to form phycobilisomes Measure Oxygen release With electrodes using O 2 meter or Chemical titration Use Light and Dark Bottles Dark Bottles measure Respiration Light Bottles measure s Rs = Net photosynthesis Light Bottle O 2 Dark Bottle O 2 = Gross photosynthesis measured as O 2 /g/hr 15 16 4
How we study photosynthesis: E curve formally known as the s/i curve How we study photosynthesis: The E curve = photosynthesis= oxygen evolved or carbon fixed E= irradiance= measure of the amount of energy falling on a flat surface E curve= useful to compare the physiology of light harvesting pigments Light Intensity Light Intensity 17 18 How we study photosynthesis: The E curve 1. Light Intensity 1. E c = Compensation point: When photosynthesis equals respiration How we study photosynthesis: The E curve 1. I c = Compensation point: When photosynthesis equals respiration max = Maximum production 1. Light Intensity 19 2 5
How we study photosynthesis: The E curve 1. I c = Compensation point: When photosynthesis equals respiration max = Maximum production 3. hotoinhibition = Damage to photosystems due to high irradiance 1. Light Intensity 3. How we study photosynthesis: The E curve 4. 1. I c = Compensation point: When photosynthesis equals respiration max = Maximum production 3. hotoinhibition = Damage to photosystems due to high irradianc 4. Initial slope (alpha) = Indicative of photosynthetic efficiency 1. Light Intensity 3. 21 22 How we study photosynthesis: The E curve 4. 1. I c = Compensation point: When photosynthesis equals respiration max = Maximum production 3. hotoinhibition = Damage to photosystems due to high irradianc 4. Initial slope (alpha) = Indicative of photosynthetic efficiency 5. E k = Saturating irradiance 1. 5. Light Intensity 3. How we study photosynthesis: The E curve 4. 1. I c = Compensation point: When photosynthesis equals respiration max = Maximum production 3. hotoinhibition = Damage to photosystems due to high irradianc 4. Initial slope (alpha) = Indicative of photosynthetic efficiency 5. I k = Saturating irradiance 6. Gross photosynthesis = Total production 6. 1. 5. Light Intensity 3. 23 24 6
How we study photosynthesis: The E curve 4. 6. 7. 1. Light Intensity 1. I c = Compensation point: When photosynthesis equals respiration max = Maximum production 3. hotoinhibition = Damage to photosystems due to high irradianc 4. Initial slope (alpha) = Indicative of photosynthetic efficiency 5. I k = Saturating irradiance 6. Gross photosynthesis = Total production 7. Net photosynthesis = Gross production Respiration 3. How we study photosynthesis: The E curve 4. 6. 7. 1. 5. Light Intensity 1. E c = Compensation point: When photosynthesis equals respiration max = Maximum production 3. hotoinhibition = Damage to photosystems due to high irradiance 4. Initial slope (alpha) = Indicative of photosynthetic efficiency 5. E k = Saturating irradiance 6. Gross photosynthesis = Total production 7. Net photosynthesis = Gross production Respiration 3. 25 26 How we measure photosynthetic rates (primary productivity): Important Considerations: Temperature Saturating Light? Background gasses run blanks Ambient primary productivity by phytoplankton when using seawater Nutrients Other methods CO 2 measurement (by ph) C 14 isotope tracers Infrared gas analysis II. Algal characteristics for distinguishing divisions: 1. igments Storage products 3. Cellular/plastid structure 4. Motility (e.g. / flagella) 5. Life history 27 28 7
Algal pigments: 1. Chlorophylls green pigments, embedded in thylakoid membrane. Chl a is the main player: used in all algae and land plants. igments Chl: Carotenoids: hycobilins: Carotenoids brown, yellow, or red pigments. Hydrocarbons with or without an oxygen molecule = carotenes and xanthophylls. 3. hycobilins red or blue pigments. Water soluble. Located on the surface of thylakoids in red algae, associated with proteins to form phycobilisomes Chl: Carotenoids: hycobilins: Chl: Carotenoids: hycobilins: 29 3 II. Algal characteristics for distinguishing divisions: 1. igments Storage products 2 forms: alpha 1,4 linked = starches (Chlorophyta, Rhodophyta) Storage products 3. Cellular/plastid structure 4. Motility (e.g. / flagella) 5. Life history beta 1,3 linked = sugars (Ochrophyta) (e.g. floridean, amylopectin, amylose starches) 31 (e.g. laminarin, chrysolaminarin, mannitol) 32 8
Storage roducts: Starches: II. Algal characteristics for distinguishing divisions: 1. igments Sugars: Storage products 3. Chloroplast structure 4. Motility (e.g. / flagella) Starches: 5. Life history 33 34 Chloroplast structure Chloroplast Structure: Membranes: Thylakoids: Membranes: Thylakoids: Membranes: Thylakoids: 35 36 9
II. Algal characteristics for distinguishing divisions: To have or not to have. 1. igments Storage products 3. Cellular/plastid structure 4. Motility (e.g. / flagella) 5. Life history.flagella 37 38 Flagella: II. Algal characteristics for distinguishing divisions: 1. igments Storage products 3. Cellular/plastid structure 4. Motility (e.g. / flagella) 5. Life history 39 4 1
Algal life histories vary Fertilization Algal life histories : Terminology to know and love Spore (mitospore, meiospore): Gamete: Vegetative Reproduction Mitosis Sporophyte: Gametophyte: Haplontic: Meiosis Diplontic: 41 Alternation of Generations: Heteromorphic: Diplohaplontic Haplodiplontic Isomorphic: 42 Algal Life Cycles Three main patterns: 1) Haplontic 2) Diplontic 3) Alternation of Generations Isomorphic Heteromorphic Algal Life Cycles Three main patterns: 1) Haplontic 2) Diplontic 3) Alternation of Generations Isomorphic Heteromorphic 43 animallike life history 44 11
Algal Life Cycles Three main patterns: 1) Haplontic 2) Diplontic 3) Alternation of Generations Isomorphic Heteromorphic Algal Life Cycles Three main patterns: 1) Haplontic 2) Diplontic 3) Alternation of Generations Isomorphic Heteromorphic 45 haplodiplontic 46 Algal Life Cycles Three main patterns: 1) Haplontic 2) Diplontic 3) Alternation of Generations Isomorphic Heteromorphic Life cycles: diplohaplontic 47 48 12
Example: Fucus Example: Ulva 49 5 Example: Nereocystis 51 13