Chapter 11: Biosynthesis of Cell Components

Photosynthetic electron transfer

energy derived from sunlight energizes electrons in the oigment chlorophyll

the transfer of energy to ATP and NADPH

what does the movement of electrons through an ETC result in during photosynthetic electron transfer?

Carbon fixation

the ATP and NADPH molecules produced during the light reactions serve as energy sources to drive the synthesis of glucose

chloroplasts

where do both light and dark reactions occur?

Photosynthesis

the conversion of sunlight energy into chemical energy by living organisms

generation of organic molecules from atomospheric CO2

end product of photosynthesis

Chloroplasts

organelles found in plant cells and eukaryotic algae that conduct photosynthesis

thylakoids

two membranes plus a 3rd membrane system in the chloroplasts

chlorophyll

photosynthetic pigment within chloroplasts

stroma

the space inside the chloroplast

thylakoid space

the space inside the thylakoids

electrons

during photosynthesis H2) is split into 1/2O2 and 2 H+ by a water-splitting enzyme releasing...

electrons are energized by sunlight and then move through an ETC in the thylakoid membrane

what happens to the electrons released from H2O in photosynthesis

H+ gradient forms across thylakoid membrane

what happens as the electrons move through the ETC in photosynthesis?

synthesize ATP

what is the energy in the H+ gradient used for in photosynthesis?

NADP+ which is reduced to NADPH

what is the final electron carrier in photosynthesis and what is it reduced to?

photosystems of the thylakoid membrane

where is chlorophyll found?

all but green

what visible wavelengths does chlorophyll absorb?

decentralized electron cloud

where is energy absorbed by electrons in chlorophyll?

jumps from chlorophyll to chlorophyll within the photosystem

where does the energy go once abosrbed in chlorophyll?

Chlorophyll Ila

the most abundant pigment in plants

central photosynthetic reaction center

central chlorophyll molecules

antenna

3 parts of the photosystem

contains the central chlorophyll molecules and antenna

structure of the photosystem

accept and donate electrons

what does the central chlorophyll molecules do?

harvest sunlgiht energy

what do the antenna chlorophyll molecules do?

sunlight

what excited the electrons in each antenna chlorophylls into an unstable high-energy state?

the two central chlorophylls in the reaction center

what finally traps the energy that is going from chlorophyll to chlorophyll?

energized electrons

the two central chlorophylls in the reaction center donate the energy in what form to the ETC?

electron carriers of the ETC

where do the special pair of chlorophylls in the reaction center of both photosystems I and II donate their energized electrons to?

plastocyanin

where does photosystem I accept electrons from?

water

where does photosystem II accept electrons from?

electrons in the special pair of chlorophylls in the reaction center

where is the energy absorbed by the antenna chlorophylls in photosystem II transfer it to?

ETC: first to plastoquinone and then the cytochrome bf complex

where do the pair of chlorophylls in the reaction center donate the energy?

water-splitting enzyme

extracts electrons from H2O to replace the electrons donated by photosystem II

cytochrome bf complex

an H+ pump that uses energy of the electrons to pump H+ into the thylakoid space

plastocyanin

what carries the electrons to photosystem I?

ATP and NADPH generated during light reactions

what is used to synthesize glucose in the dark reactions in the stroma

the calvin cycle

example of a dark reaction

carbon fixation

what is the first reaction of Calvin cycle?

CO2 is added to each of 3 molecules of Ribulose 1,5-biphosphate to yield 3 molecules of a 6-C unstable intermediate

what happens during the first reaction of Calvin cycle?

RuBP carboxylase

what is carbon fixation catalyzed by

2 3-C molecules

what do the intermediates of each split into during carbon fixation?

6 molecules of 3-Phosphoglycerate (3C) and carbon into the living world

what are the products of carbon fixation?

2 molecules of glyceraldehyde 3-phosphate

what is the output of carbon fixation?

glucose

what are the 2 molecules of glyceraldehyde 3-phosphate used to synthesize?

CO2 and ribulose 1,5-biphosphate

the 2 substrates of Ribulose biphosphate carboxylase (rubisco)

Rubisco

the most abundant enzyme on earth

3 CO2

input of the Calvin Cycle

glyceraldehyde 3-phosphate

output of the calcin cycle

6CO2 + 6H2O -> C6H12O6 + 6O2

overall balanced equation of glucose

Gluconeogenesis

an anabolic pathway that synthesizes glucose from pyruvate

1,3,10

what steps of gluconeogenesis are irreversible?

enzymes

gluconeogenesis and glycolysis use different _______ for the irreversible steps

ATP is high

when does glycolysis occur?

ATP low

when does gluconeogenesis occur?

free energy changed are very large

what makes steps 1,3,10 irreversible?

step 3

which step in glycolysis is the rate-limiting step?

energy is consumed

what happens during step 3 of glycolysis

phosphofructokinase

what catalyzes step 3 of glycolysis?

fructose biphosphate

what catalyzes the rate-limiting step of gluconeogenesis?

ATP acts as an allosteric inhibitor and ADP acts as an allosteric activator

during the regulation of phosphofructokinase (step 3 glycolysis), what do ATP and ADP serve as due to the enzyme used?

ADP acts as an allosteric inhibitor and ATP acts as an allosteric activator

during the regulation of ructose biphosphate in gluconeogenesis, what do ATP and ADP serve as due to the enzyme used?

de novo

salvage

what two ways are the subunits of nucleic acids synthesized as nucloside monophosphates?

de novo

long pathways that assemble the molecules from smaller components

salvage

recycling of nitrogenous bases; short pathways

gout

If HGPRT activity is deficient and hypoxanthine is instead converted to uric acid which precipitates as crystals in the joint of the big toe triggering...

accumulation of uric acid crystals in the mtatarsophalangeal joint due to HGPRT activity deficiency

what is gout caused by?

Lesch-Nyhan syndrome

a severe HGPRT deficency

ATP is hydrolyzed and atomospheric N2 is reduced to NH3

what happens during nitrogen fixation during the assimilation of nitrogen?

NADH or NADPH is oxidized and NO3- from soil is reduced to NH3

what happens during nitrate incorporation during the assimilation of nitrogen?

intermdiates of aerobic cellular respiration

Amino acids are reived from...

no

do all organisms have the enzymes necessary for the synthesis of all 20 amino acids?

dietary sources

where must essential AAs be obtained from?

humans

where are nonessential AAs be syntheisized from?

Phenylketonuria

a deficiency of the enzyme phenylalanine hydroxylase, which converts phenylalanine into tyrosine

phenyalanine is accumulated and is deaminated to phenylpyruvate

what occurs during phenylketonuria?

intellectual disability

what is caused in children due to phenylketonuria during their first yr of life?

screening og newborn children for elevated levels of phenylalanine and a low phenylalanine diet

prevention of phenylketonuria

nucleic acids

nucelotides form the macromolecule...

polysaccharides

simple sugars form the macromolecule...

polypeptides

amino acids for the macromolecule...

fats, lipids

fatty acids or other simple lipids form the macromolecule...

dehydration synthesis

macromolecules require the formation of bonds between the subunits by...

dehydration synthesis

condensation reactions that consume energy and yield water molecules

activated intermediate

in the synthesis of macromolecules, the porcesses requires what to be synthesized before the actual formation of the corresponding bond?

glycogen

example of polysaccharide in animals

starches and cellulose

example of polysaccahride in plants

formation of the glycosidic bond between simple sugars

what formation does the synthesis of polysaccharides involves?

nucleotide sugar intermediate

The synthesis of polysaccahrides is coupled with an energy yielding reaction causing the formation of what?

glucose

what is the starting molecule in the synthesis of polysaccharides?

phosphorylation of C6

step 1 of the synthesis of polysaccharides

glucose 6P

product of step 1 of synthesis of polysaccharides

isomerization

step 2 of the synthesis of polysaccharides

glucose 1P

product of step 2 of the synthesis of polysaccharides

condensation

step 3 of the synthesis of polysaccharides

UDP-glucose

product of step 3 of the synthesis of polysaccharides

reaction with UTP and release of pyrophosphate

what occurs during step 3 of the synthesis of polysaccharides?

formation of glycosidic bond

step 4 of the synthesis of polysaccharides

glucose is transferred from UDP to the growing polysaccharide chain

what occurs during step 4 of the synthesis of polysaccharides?

polysaccharide

product of step 4 of the synthesis of polysaccharides