Biosynthesis

Question 1

Most chemolithotrophs and phototrophs are

Answer 1

-autotrophs that use CO2 as carbon source

Question 2

the calvin cycle in chemolithotrophs and phototrophs

Answer 2

-used in phototrophic bacteria, most chemolithotrophic bacteria, algae and some arachae
-not the only way to fix CO2
-costs a lot of ATP and NADPH
-6CO2 added to 6 Tc molecules
-6 of these 36 are dran off through fructose-6-phosphate for biosynthesis

Question 3

enzyme for carboxylation step in the calvin cycle

Answer 3

-RuBisCO

Question 4

calvin cycle photo

Answer 4

Question 5

Nitrogen fixation why do we need to do it

Answer 5

-N2 is very stable and therefore metabolically useless for most organisms
-some organisms produce nitrogenase
-SOME BACTERIA AND ARCHAEA
-NH2 more useful that can be used for N for building nitrogen molecules

Question 6

nitrogenase

Answer 6

-converts N2 to NH3
-comprised of two proteins - dinitrogenase and dinitrogenase reductase
-use complex Fe/Mo cofactors

Question 7

Diazotrophs

Answer 7

-bacteria and archaea that can fix nitrogen
-cyanobacteria, rhizbia, some archaeal methanotrophs

Question 8

process of nitrogen fixation

Answer 8

-electrons transferred to N2 (N2 reduced) to generate two NH3
-electrons come from metabolite (pyruvate), passed to flavodoxin, to dinitrogen reductase to dinitrogenase to N2 to produce NH3
-activation/reduction of triple bond very energetically demanding - requires adding 6e - 2 ATP per electron therefore 16ATP per 2 NH3 produced

Question 9

nitrogen assimilation

Answer 9

-in many instances, inorganic nitrogen sources such as NH3 used to build nitrogen containg molecules
-requires ATP and reducing power
-glutamate dehydrogenase aand glutamine synthase are key enzymes for this - efficiently incorporate NH3 even at low levels
-glutamine/glutamate then act as nitrogen donors to produce many other key nitrogen containing molecules in the cell

Question 10

nitrogen assimilation photo

Answer 10

Question 11

common pathways used for anabolism and catabolism photo

Answer 11

Question 12

gluconeogenesis

Answer 12

-producing glucose
-basically the reversal of glycolysis-uses many of the same steps in reverse
-Glucose-6-phosphate is activated to produce many important molecules

Question 13

activated Glucose-6-P

Answer 13

-activated by addition of nucleotide diphosphates such as ADP glucose, UDP glucose
-activate form can produce LPS, NAM/NAG, and storage molecules like glycogen and starch

Question 14

Amino Acid biosynthesis

Answer 14

-Carbon skeletons can come from intermediates of the citric acid cycle or glycolysis
-often a parent AA is produced - precursor to producing others
-in some cases, there are multiple pathways for producing a given AA (redundancy key for flexibility)

Question 15

lipid biosynthesis

Answer 15

-FA bult 2C at a time by adding Malonyl CoA (3C) to growing chain - CO2 released as biproduct
-ACP = Acyl carrying protein is the holder of substrates for FA syntehsis
-Acetyl coA used to make malonyl CoA, this then used to make malonyl ACP
-Fatty acids can be added to glycerol backbone to produce membrane phospholipids

Question 16

nucleotide biosynthesis

Answer 16

-pentoses and nucleobases are the building blocks for nucleotides
-pentose phosphate pathway
-very complex
-Purine and pymidaines made using different pathways
-intermediates include IMP for purines and orotate (pyrimidines)
-ribonucleotides produces first

Question 17

pentose phosphate pathway

Answer 17

-nucleotide biosynthesis
-pentose phosphate pathway geenrates ribose 5-P from glucose 6-P
-Ribose-5-P can then beused to make ribonucleotides
-this pathway also generates NADPH and a range of important carbon skeletons

Question 18

what converts riboncleotides into deoxyribonucleotides

Answer 18

-ribonucleotide ruductase for DNA synthesis