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