Chapter 3 Flashcards
GLycolysis generates
It generates a NET 2 ATP and 2 NADH, and 2 pyruvate molecules that can enter the citric acid cycle for more ATP synthesis
Please note that glycolysis DOES MAKE 4 ATPs total however it had to use up 2 to prepare the 6 carbon ring for cleavage (gotta spend some to make some)
bond between the phosphate in ATP are ________: their hydrolysis is accompanied by a large decrease in free energy
high energy bonds
for ATP hydrolysis delta G is how much (kcal/mol)?
-12kcal/mol
Alternatively, ATP can be hydrolyzed to AMP plus
pyrophosphate (PPi)
the pyrophosphate is then rapidly hydrolyzed, and the total free- energy change is about ____ that from hydrolysis of ATP to ADP
twice
ATP hydrolysis can drive other reactions? True or false?
true
The first step in glycolysis is ______ (delta G =3.3 kcal/mol)
but it is coupled to ATP hydrolysis (delta G = -7.3 kcal/mol) making delta G (-4 kcal/mol)
unfavorable
remember that the first step in glycolysis is unfavorable. This is why you have to spend 2 ATPs in the begging to make 4 ATPs (aka net gain of 2 ATPs)…. however it can be coupled with ATP hydrolysis and this is what makes the reactions still able to occur
Glycolysis reaction equation: complete it:
glucose+ATP —.>
glucose-6-phospate+ADP
energy yielding reactions within the cell are coupled to ____
ATP synthesis
energy-requiring reactions are coupled to ___
ATP hydrolysis
the complete oxidation breakdown of glucose to CO2 and H2O yields a large amount of energy:
delta G = -686 kcal/mol
complete the reaction for the oxidative breakdown of glucose:
C6H12O6 +O2 —>
6CO2+6H2O
to harness the free energy, glucose is oxidize in a series of steps coupled to
ATP synthesis
The first step of generating ATP is __________ please describe it
glycolysis
occurs in all cells in the absence of oxygen; it can provide all the metabolic energy of anaerobic organisms
glycolysis results in the breakdown of glucose into pyruvate, with a net gain of 2 ATP
The first part of the pathway consumes energy
the enzymes that catalyze these reactions are important regulatory points; when there is an adequate supply of ATP, glycolysis is inhibited
glycolysis also converts two molecules of the coenzyes
NAD+ to NADH…
NAD+ acts as an oxidzing agent that accepts electrons
NADH must be recycled by serving as an electron donor for other oxidation-reduction reactions
in ___ the NADH is reoxidized to NAD+ by the conversion of pyruvate to lactate or ethanol
anaerobic conditions
in ________ the NADH donates electrons to the electron transport chain
aerobic condtions
glycolysis takes place in the
cytosol
in eukaryotic cells, pyruvate is then transported in to __________ where it is completely oxidized
mitochondria
pyruvate undergoes oxidative decarboxylation in the presence of _______________ forming____ generation of ______
in the presence of COENZYME A (COA-SH) forming ACETYL COA generation of 2NADH
______ enters the citric acid cycle
Acetyl CoA
in the citric acid cycle the 2 carbon acetyl group
combines with oxaloacetate (4 carbons) to yield nitrate (6 carbons)
in the citric acid cycle the remaining involve the 2 carbons of citrate
being completely oxidized to CO2 , where oxaloacetate is regenerated
2 carbons of citrate makes ??
2 CO2 1 oxaloacetate 1 GTP 3 NADH 1 FADH2
The complete oxidation of glucose makes what?
6 Co2
4 ATP
10 NADH
2 FADH2
Note that makes a total of 38 ATPs because :
one FADH2 makes 2 ATPs
one NADH makes 3 ATPS
Give the total ATP yield of glycolysis
2 ATP+2NADH
Give total ATP yield for citric acid cycle
2ATP, 8 NADH, 2 FADH2
give total ATP yield for oxidative phophorylation
each NADH yields 3 ATP, each FADH2 yields 2 ATP
polysaccharides can be broken down to ___ which are metabolized by glycolysis and the Krebs cycle
sugars
oxidation of lipids yields (more or less) energy per weight of starting material
more energy
Fats are first broken down to ______ and ____
glycerol and free fatty acids
each fatty acids is joined to ___ yielding a ___ at the cost of one ATP
coenzyme A,,, fatty acyl CoA
The fatty acids are then degraded in a stepwise oxidative process, two carbons at a time. each round of oxidation also yields _____ NADH and _____ FADH2
one NADH
one FADH2
the acetyl coA then enters the ______. the net gain is ____ ATPs per molecules of 16 carbon fatty acid. (compared to net gain of 38 ATPs per molecule of glucose
enters the citric acid cycle
net gain of 130 ATPS per molecule
most of the energy from the breakdown of carboyhydrates or fats is dervided by ______ and ____
electron transport
oxidative phosphorylation
Electrons from NADH and FADH2 are transferred to O2 which is coupled to the formation of
34 ATP by oxidative phosphorylation
to harvest the free energy in a usuable formthe process is gradual as electrons pass through a series of carriers, which constitute the
electron transport chain
components of the ______ are organized into ____ complexes in the inner mitochondrial membrane
electron transport chain
four complexes
NOTE INNER MITOCHONDRIA MEMBRANE
NADH is produced in the krebs cycle in the ___ of the mitrochondria
matrix
electrons from NADH enter the electron transport chain at _____
complex I
electrons are transferred to _____ by Coenzyme _ (ubiquinone)`
(mitrochondria)
complex III by coenzyme Q
_____ then carries electrons to complex IV (______) where they are transferred to O2
(mitrochondria)
cytochrome c then carries electrons to complex IV cytochrome oxidase, where they are transferred to O2
Note the energy yielding electron transfers at each step are coupled to ATP synthesis
passage of electron through complexes I, III, and IV drives synthesis of ATP by
oxidative phosphorylation
the energy derived from _____ coupled to the generation of a _______ across the inner mitochondrial membrane
electron transport
protein gradient
electron transport through complexes I, III, and IV is coupled to the transport of protons out of the interior of the mitrochondrion, establishing a _______ across the mitochondrial membrane
proton gradient
In complex IV,
__ proton per pair of electron are pumed across
__ combine with O2 to form H2O in the matrix
thus ___ protons per pair of electrons are transported at each complex
2 protons
two
4 protons per pair of electrons
the proton gradient is an
electrochemical gradient
the phospholipid bilayer is impermeable to ions, so protons can cross the membrane only through ________________-
protein channels
both the ________ and the _______ drive the protons back into the matrix, they combine to form an _________ across the inner membrane
pH gradient and the electric potential
for an electrochemical gradient
protons can cross the membrane only through a ______________
protein channel
The protein channel allows energy in the electrochemical gradient to be harnessed and converted to ATP in complex V , also called __________
ATP synthase
ATP is generated as protons move with the concentration gradient through ______________ which is ____________
complex V
ATP synthase
ATP synthase consists of two components:
F0 forms a spinning channel through which protons pass
F1 spins and harvests the free energy by catalyzing the synthesis of ATP
_____ converts the energy of sunlight to a usable form of chemical energy
photosynthesis.
note it is ultimately the source of all metabolic energy in biological systems
What is the overall equation for photosynthesis
6CO2+6H2O—> C6H12O6+6O2
the process takes place in two stages: ___ reactions and _____ reactions
light and dark
light reactions: sunlight energy drives synthesis of ____ and ___ coupled to the oxidation of H2O to ____
ATP and NADPH
oxidation of H2O to O2
Dark reactions: the ATP and NADPH drive synthesis of carbohydrates from
CO2
in eukaryotic cells both light and dark reactions occur in what organelle?
chloroplast
sunligh is absorbed by ______ pigments, such as chlorophylls
photosynthetic
Absorption of light excites an ____ to a higher energy state, thus converting the energy of sunlight to the potential chemical energy
electron
the pigments are organized into _____ in the chloroplast membrane
photocenters
hundreds of pigment molecules absorb photons and transfer energy to _______________
reaction center chlorophyll
excited electrons are then transferred to an acceptor in the ______–
electron transport chain
in light reactions, energy from sunlight is used to split
H2O to O2
in light reactions, the resulting high energy electrons are then transported through a series of carriers and used to convert NADP + to _________
NADPH
in light reactions, the energy from the electron transport reactions also drive __________-
ATP synthesis
chloroplast have an internal membrane system, the _____________-
thylakoid membrane
the thylakoid membrane divides chloroplast into three internal compartments
stroma, intermembrane space, thylakoid lumen
four proteins complexes in the ___________ function in electron transport and synthesis of _____ and ________
thylakoid membrane,
synthesis of ATP and NADPH
photons of light energy are absorbed by photosystems __ and ___
photosystems I and II
in the first electron transport pathway:
at photosystem _____, H2O is split and the resulting electrons enter the transport chain
photosystem II
in the first electron transport pathway
photo-system _____ generates NADPH, which is required for converting CO2 to carbohydrates
photosystem I
in the first electron transport pathway:
photosystem ____and _______ complex generates a proton gradient that drives synthesis of ATP
Photosystem II and cytochrome bf complex
in a second electron transport pathway,
cyclic electron flow, light absorbed at photosystem ____ is used to ____ instead of NADPH
cyclic electron flow, ligh absorbed at photosystem I is used to generate ATP instead of NADPH
in a second electron transport pathway,
high energy electrons are transported back to the ____ complex and coupled to establishment of proton gradient
cytochrome bf complex
the energy in the proton gradient is almost entirely ______?
chemical
the thylakoid membrane is impermeable to other _____, particulary Mg+2 and Cl-
other ions
free passage of these ions neutralizes the voltage component of the _________
proton gradient
the difference in PH units between the stroma and the thylakoid lumen can be more then ?
3 Ph units
the total free energy stored across the thylakoid membrane is similar to that stored across the inner mitochondrial membrane? (true or false)
true
for each pair of electrons transported, ______ protons are transferred at photosystem II and _____ protons at cytochrome bf complex
2 protons are transferred at photosystem II
2-4 protons at cytochrome bf complex
since ___ protons are needed for synthesis of 1 ATP each pair of electrons yeilds ___ to ___ ATP
4 protons are needed for synthesis of 1 ATP
each pair of electrons yields 1 to 1.5 ATP
cyclic electron flow yields____ ATP per pair of electrons
1 ATP per pair of electrons
in the dark reactions,
the ATP and NADPH produced in the light reactions drive _________ from _________-
reactions drive synthesis of carbohydrates from
Co2 and H2O
one molecule of Co2 at a time is added to a cycle of reactions, the ______ cycle which leads to the formation of carbohydrates
calvin cycle
the calvin cycle consumes________ for each glucose produced
18 ATP and 12 NADPH
____ electrons are needed to convert each molecule of NADP+ to NADPH
two electrons
these electrons come from the conversion of ____ to ____
H20 to O2
energy from the breakdown of organic molecules (catabolism) drives synthesis of other components in the cell (true or false?)
true
____ pathways involve oxidation of organic molecules coupled to generation of ATP and reducing power (NADH)
catabolic pathways
____________ pathways use ATP and reducing power (NADH or NADPH) for the production for new organic compounds
anabolic or you can call it biosynthetic pathway
an example would be dark reactions`
in animal cells,
glucose synthesis (____________) usually starts with ??????????
gluconeogenesis
this can usually start with:
- lactate (from anaerobic glycolysis)
- amino acids (From breakdown of protiens
- glycerol (from breakdown of lipids)
plant cells can synthesize glucose from _______
fatty acids
in seed germination: energy stored as fats must be converted to carbohydrates for growth of the new plant. This is why it is important that plant cells can synthesize glucose from fatty acids. (true or false)
true
in ________ pyruvate is converted to glucose
gluconeogenesis
Gluconeogenesis is not simply the reversal of glycolysis pathways, it requires more energy to drive the pathway in direction of _______
biosynthesis
glucose is stored in the form of ___________
starch and glycogen
the dehydration reaction that ______ is energetically unfavorable, and must be coupled to an energy yielding reaction
this is accomplished by the use of __________
joins two sugar molecules
nucleotide sugars as intermediates
glucose is phosphorylated, then reacts ________, yielding _________
glucose is phosphorlyated the nreacts with UTP (uridine triphosphate) yeilding UDP glucose
____ glucose is and activated intermediate that then donates its glucose to a growing polysaccharide chain
UDP- glucose
proteins and nucleic acids contain ______. different organisms use different sources of _____
nitrogen
some bacteria uses atmospheric N2 by a process called _______, in which N2 is reduced to NH3. ATP is required
nitrogen fixation
most bacteria, fungi and aplants can use ____ which is common constituent of soil, by reducing it to NH3
nitrate NO3-
all organisms are able to incorporate _____ into organic compounds
ammonia
NH3 is incorporated during synthesis of the amino acids _____________
glutamate and
glutamine
these amino acids then donate amino groups to other amino acids, which are derived from intermediates in glycolysis and the citric acid cycle
bacteria and plants can synthesize all ____ amino acids
20
humans and other mammals can make only about half of the required _______, the remainder must be obtained from dietary sources
amino acids
synthesis of protiens also require energy? (true or false?)
true
unlike polysaccharide synthesis, amino acids are incorporated into protiens in a ____ order, specified by the order of nucleotide bases in a gene
unique order
what type of RNA acts as a template for protien synthesis?
messenger RNA, mRNA
each amino acid is attached to a specific __________ molecule in a reaction coupled to ATP hydrolysis
transfer RNA (tRNA)
__________ then align on the mRNA template, and each amino acid is added to the peptide chain is also coupled to the hydrolysis of _________-
the aminoacyl-tRNAS
hydrolysis of ATP and GTP
nucleotides can come from dietary sources or from nucleic acid break down or be synthesized from ____________
carbohydrates and amino acids
synthesis of starts with ________. different pathways lead to synthesis of purine and pyrimidine ribonucleotides
ribose-5 phosphate
