Exam 2 - Lecture 11 Flashcards
what is photosynthesis?
energy from light is trapped and is converted to chemical energy
over half of the photosynthesis on earth is carried out by:
microbes
what are the two parts of pohotsynthesis?
- light reactions: light energy is trapped and converted to chemical energy
- dark reactions: energy from light rxns is used to reduce CO2 and synthesize cell constituents
match the following:
a. light rxns
b. dark rxns
- catabolism
- anabolism
a1. light rxns = catabolism
b2. dark rxns = anabolism
oxygen is generated and released in ___________ photosynthesis, but not ____________ photosynthesis
oxygenic, anoxygenic
what are the major light absorbing pigments in plants called?
chlorophylls
what do accessory pigments do?
they transfer light energy to chlorophylls by absorbing different wavelengths of light than the chlorophylls (example: carotenoids)
what are antennas? what do they do?
- highly organized arrays of chlorophylls and accessory pigments
- capture light transferred to a special reaction-center chlorophyll
what is a photosystem?
an antenna and its associated reaction-center chlorophyll
which photosystem is cyclic and which is non-cyclic?
- photosystem I: can be cyclic or non-cyclic
- photosystem II: non-cyclic
when photosystem I is cyclic, does it generate reducing power? how about non-cyclic?
- cyclic: ATP is made by cyclic phosphorylation, NO reducing power is produced
- non-cyclic: reducing power is produced (NADPH) and it works with PS II
when PS I and II work together, what do they make?
ATP and NADPH
when PS I and II work together, how is ATP made?
noncyclic phosphorylation
most anoxygenic phototrophs are strict ___________
anaerobes
what five bacterial phyla do anoxygenic phosphorylation?
- proteobacteria
- chlorobi
- chloroflexi
- firmicutes
- acidobacteria
- (doubt we actually have to know this)
what pigment do anoxygenic phototrophs use?
bacteriochlorophyll
how many photosystems do anoxygenic phototrophs have?
just one
how much reducing power do anoxygenic phototrophs produce?
they don’t produce any
is the ETC for anoxygenic phototrophs cyclic or non-cyclic?
cyclic
how can NADH be generated in anoxygenic photosynthesis?
electrons from PMF in cyclic ETC can be drawn off and “pushed” to NAD+
what molecule do chlorophyll-independent phototrophs use? what is it’s function?
- bacteriorhodopsin
- functions as a light-driven proton pump (without use of an ETC)
what are the principles governing biosynthesis?
- macromolecules are synthesized from a small number of small molecules
- many enzymes do double duty (amphibolic)
- some enzymes function only in one direction
- anabolism requires energy
- anabolic and catabolic rxns are physically separated
- catabolic and anabolic pathways use different cofactors
what are precursor metabolites? how many are there?
- carbon skeletons that serve as the major link between catabolism and anabolism; they serve as the building blocks in anabolism
- 12
what pathways generate precursor metabolites?
- glycolysis
- PPP
- TCA cycle
what important biomolecules are generated from the precursor metabolites?
- amino acids
- lipids
- DNA (purines and pyrimidines)
what is the purpose of the Calvin cycle? who uses it?
it’s used by autotrophs to fix CO2 (its also called the reductive pentose phosphate cycle)
where does the Calvin cycle take place in eukaryotes?
the stroma of chloroplasts
where does the Calvin cycle take place in cyanobacteria, some nitrifying bacteria, and thiobacilli?
carboxysomes
what are carboxysomes?
inclusion bodies that are sites for CO2 fixation (specifically)
what are the three phases of the Calvin cycle?
- carboxylation phase
- reduction phase
- regeneration phase
how many ATP and NADPHs are used in the incorporation of one CO2 molecule?
3 ATPs and 2 NADPHs
the carboxylation phase is catalyzed by the enzyme:
RuBisCO (ribulose 1,5-bisphosphate carboxylase aka ribulose bisphosphate carboxylase/oxygenase)
what reaction does RuBisCO catalyze?
the addition of CO2 to ribulose 1,5-bisphosphate (RuBP) to form two molecules of PGA (3-phosphoglycerate)
what takes place in the reduction phase?
- 3-phosphoglycerate is reduced into glyceraldehyde 3-phosphate
- this is basically inverse rxns of the Embden-Meyerhof pathway
what takes place in the regeneration phase?
RuBP is regenerate using glyceraldehyde 3-phosphate
how many times must the Calvin cycle take place to generate one 6-carbon molecule?
six times
in the Calvin cycle, what does this become?
6CO2 + 18ATP + 12NADPH + 12H2O +12H+
glucose + 18 ADP + 12Pi + 12NADP+
what is gluconeogenesis?
synthesis of glucose and related sugars from non-carbohydrate precursors
how many enzymes are shared between gluconeogenesis and glycolysis? how many are unique to gluconeogenesis?
- 7 enzymes shared
- 5 enzymes unique to gluconeogenesis
what two sugars are synthesized from gluconeogenesis?
- glucose and fructose
- other common sugars can then be synthesized from these two
several sugars are synthesized while attached to a ___________ ___________ (NDP) such as ____________ ____________ (UDP)
- nucleoside diphosphate
- uridine diphosphate
what is UDPG?
uridine diphosphate glucose
NDPs are important in the synthesis of _______________ like starch and glycogen
polysaccharides
what are the two carrier molecules utilized in peptidoglycan synthesis?
UDP derivatives and bactroprenol
what is the first step of peptidoglycan synthesis?
biosynthesis of UDP-NAG, which is then derived into UDP-NAM
how are amino acids added to the newly derived UDP-NAM?
non-ribosomal peptide synthesis; the amino acids are added sequentially and then the pentapeptide bridge is added to make UDP-NAM-pentapeptide
what is bactroprenol?
a 55 carbon lipid used to transport NAG-NAM-pentapeptide units across the cell membrane
where does bactroprenol attach?
NAM
