MICROM 301 CHAPTER 6

the pigments of photosynthetic organisms capture

radiant energy

pigments that function as electron donors in the photosynthetic process, emitting high-energy electrons that are then passed to an ETC are called

reaction-center pigments

in photosynthesis, the protein complexes located within photosynthetic membranes that contain pigments are responsible for capturing radiant energy are called

photosystems

plants, algae, and several groups of bacteria harvest the radiant energy of sunlight and then use it to power the synthesis of organic compounds from CO2 in a process called

photosynthesis

photosynthetic organisms use the light-dependent reactions to accomplish

- generate ATP via photophosphorylation - generate reducing power

pigments that make up a complex that acts as a funnel, capturing light energy and transferring it to the reaction-center pigment are called

antennae pigments

anoxygenic photosynthetic bacteria like the purple bacteria and green bacteria may use any of the following as electron donors for reducing power

- organic compounds - hydrogen sulfide (H2S) - hydrogen gas (H2) - BUT NOT WATER

Other sources of energy for microbes besides glucose

- fatty acids - lipids - proteins - monosaccharides - disaccharides - polysaccharides

pigments that increase the efficiency of light capture by absorbing wavelengths not absorbed by other pigments are called

accessory pigments

amino acids are grouped

by structurally related families that share common biosynthesis pathways

process by which chemolithoautotrophs and photoautotrophs incorporate CO2 into organic compounds

carbon fixation

process used by chemolithotrophs to produce organic carbon compounds to fulfill their carbon needs (unlike organisms that use organic molecules to fill both their energy and carbon needs)

carbon fixation

to generate 1 molecule of the 6-carbon sugar fructose, how much energy and reducing power is consumed?

18 ATP and 12 NADPH+H+

glutamate synthesis especially important for bacteria

it provides a mechanism for incorporating nitrogen into organic material

in photosynthesis, the reactions that capture radiant energy and convert it into chemical energy in the form of ATP are called the

light/light dependent reactions

prokaryotes that extract electrons from inorganic energy sources and pass them to an electron transport chain to generate a proton motive force that is used to make ATP is called

chemolithotrophs

location of photosystems in organisms

cyanobacteria- embedded in the membranes of thylakoids located within the cells plants & algae- in thylakoids located in the stroma of the chloroplast purple bacteria- in extensive invaginations of the cytoplasmic membrane green bacteria- in chlorosomes attached to the inner surface of the cytoplasmic membrane

in order to form lipids, how are fatty acids and glycerol synthesized

fatty acid chains are assembled from 2-carbon acetyl groups from the transition step and glycerol from glycolysis

non-cyclic photophosphorylation

generates both ATP and NADPH and uses both Photosystem II and Photosystem I

cyclic photophosphorylation

generates only ATP by cyclic electron flow using only photosystem 1

starch and cellulose are both polymers made up of the monosaccharide

glucose

fats are broken down by lipases into

glycerol and fatty acids

hydrolysis of the polymers of glucose releases subunits that can enter directly into the central metabolic pathway of what to be oxidized?

glycolysis

in terms of their metabolism, prokaryotes are

highly diverse with respect to compounds they use for energy but remarkably similar in their biosynthetic processes

chemolithotrophs fall into 4 general groups

hydrogen bacteria- H2, gas sulfur bacteria- H2S iron bacteria- Fe2+ nitrifying bacteria- NH2, HNO2

purines and pyrimidines are synthesized

in distinctly different manners

synthesis of aromatic amino acids (tyrosine, phenylalanine, tryptophan) requires what type of metabolic pathway?

multi-step, branching pathway

proteins are hydrolyzed by proteases, enzymes that break what kind of bonds between amino acid subunits?

peptide

pigments involved in photosynthesis

- are located in protein complexes called photosystems - the colors we observe are due to the wavelengths reflected by the pigments - capture energy of light - different types include chlorophylls, bacteriochlorophylls, and accessory pigments

the calvin cycle can be viewed as having three essential stages

1) CO2 is added to ribulose 1,5 biphosphate (RuBP) 2) ATP and NADPH are used to reduce 3-phosphoglycerate (3PG) to glyceraldehyde 3-phosphate (G3P) 3) ribulose 1,5-biphosphate (RuBP) is generated

cyanobacteria and photosynthetic eukaryotic cells have how many distinct photosystems?

2

in the synthesis of aromatic amino acids (tyrosine, phenylalanine, tryptophan), the first step is the formation of a 7-carbon compound. How is this first step regulated in E.coli?

3 different enzymes can catalyze this step; each has a different allosteric site inhibited by one of the three amino acids