Biology Chapter 5: Cell Metabolism
2 photosystems
"Z scheme", noncyclic electron transport
glycolysis has ___ steps
10
____ NADPH and ____ ATP for 1 glucose
12;18
cyclic electron transport only uses photosystem _____ and produces_____
1; ATP
in glycolysis ____ molecules of ATP consumed per glucose molecule metabolized
2
the citric acid cycle products
2 CO2 3 NADH 1 FADH 1 ATP/GTP
the final products of glycolysis
2 pyruvate, 2 ATP, 2 NADH
About ________ molecules of ATP can be produced for each fully oxidized glucose
32
____ molecules of ATP made by substrate level phosphorylation per glucose in glycolysis
4
_____ turns of the calvin cycle needed for one molecule of glucose
6
citric acid cycle has ___ reactions
8
The Calvin Cycle (dark reactions)
A set of reactions converting CO2 into carbohydrates
Energy for anabolic processes is supplied by
ATP
What happens in carbon fixation? (Calvin Cycle)
CO2 added to 5-C backbone ribulose 1,5 bisphosphate (RuBP) ribulose bisphosphate carboxylase/oxygenase (rubisco) catalyzes the reaction a 6-carbon molecule results, which quickly breaks down into two 3-carbon molecules (3-phosphoglycerate; 3PG)
pyruvate oxidation products
CO2, NADH, and Acetate (acetate then bound to coenzyme A (CoA))
The figure shows the metabolic relationships between molecules in a cell. Which is a viable path that a carbon atom could take as it moves through metabolic pathways in a cell?
DNA → purine → amino acid → acetyl CoA → fatty acid → triglyceride
How is photosynthesis in plants most directly connected to building macromolecules?
Dark reactions generate monomers for condensation reactions in polysaccharide synthesis
Which of the following are the correct inputs of cellular respiration?
Glucose and oxygen
What happens in regeneration of RuBP? (Calvin Cycle)
The CO2 acceptor, RuBP is regenerated from G3P 5/6 of the glyceraldehyde 3 phosphate from reduction goes in to replenish RuBP when glucose accumulates it is linked to form starch, a storage carbohydrate
When purified cytochrome oxidase is exposed to cyanide, the cyanide binds reversibly and with high affinity to the enzyme's active site. What will be the likely outcome if mitochondria are exposed to high levels of cyanide?
The cyanide will prevent movement of electrons along the electron transport chain.
photons can be _____ by a molecule, adding energy to the molecule-move to an excited state
absorbed
Which statement about ATP is true?
The hydrolysis of ATP to ADP and Pi is an exergonic reaction.
When a suspension of algae is incubated in the presence of light and CO2and then transferred to the dark, the reduction of 3-phosphoglycerate (3PG) to glyeraldehyde-3-phosphate (G3P) is blocked. This reaction stops in the dark because
The reaction requires ATP and NADPH
When the human body is subjected to prolonged starvation, cells use up all available glucose first, including glucose bound up in glycogen. When all glucose has been depleted, cells use lipids as a fuel source, and when lipids have been depleted, cells use proteins as a fuel source. Throughout these shifts to new fuel sources, the enzymes of glycolysis and the citric acid cycle remain present and active in the cells. Which statement explains the constancy of these enzymes under conditions of starvation?
These enzymes continue to be needed since catabolism of lipids and proteins leads to intermediates that are oxidized through these pathways.
in cyclic electron transport you do not need
an electron donor (you use the same electron repeatedly)
photosynthesis is a major _____ pathway
anabolic (building)
In water, red light is fully absorbed at about 15 meters (m), orange light is fully absorbed at about 30 m, yellow light is fully absorbed at about 50 m, and blue light is fully absorbed at about 100 m. Based on this information, one can predict that many aquatic photosynthetic organisms will primarily use which color of light?
blue
3 components of calvin cycle
carbon fixation, reduction and sugar production, regeneration of RuBP
ATP is needed for ______ pathways
carbon-fixation (in photosystem 1)
cellular respiration is a major _____ pathway
catabolic (breaking down)
carbon skeletons (molecules with covalently linked carbon atoms) can enter
catabolic or anabolic pathways
5 principles governing metabolic pathways
chemical transformations occur in a series of intermediate reactions that form a metabolic pathway each reaction is catalyzed by a specific enzyme most metabolic pathways are similar in all organisms many metabolic pathways are compartmentalized each metabolic pathway is controlled by enzymes that can be inhibited or activated
in plants ______ absorbs light energy
chlorophyll
energy-transforming reactions are often _____; an _____ reaction can be used for an _____ reaction.
coupled; exergonic; endergonic
glycolysis takes place in the
cytosol
chemiosmosis
diffusion of protons across a membrane which drives the synthesis of ATP
NAD+/NADH is an _____ ______ in redox reactions
electron carrier
What happens in reduction and sugar production? (Calvin Cycle)
electrons and ATP needed to reduce phosphoglycerate; 1/6 of glyceraldehyde 3 phosphate(G3P) goes on to form glucose
The reduction of NAD+ is highly
endergonic
redox reactions
energy transfer through the transfer of electrons (aka oxidation reduction reactions)
When chlorophyll absorbs light, it enters an _____ state then rapidly returns to _____ state, releasing an excited _____
excited; ground; electron
Oxidation of NADH is highly
exergonic
hydrolysis of ATP is
exergonic (release energy)
Metabolic pathways can be controlled through the availability of enzymes and modulation of their catalytic activities. Enzyme availability can be regulated via _______, while enzyme activity is commonly regulated via _______.
gene expression; allosteric activation and inhibition
Oxidation occurs in a series of small steps in three pathways
glycolysis pyruvate oxidation citric acid cycle
If a cell is fed a large supply of fatty acids, what might you expect to happen? Fill in the blanks.Oxidation of fatty acids through the citric acid cycle will ___________ until ATP builds up and _____________ citrate synthase, diverting fatty acids into storage molecules such as ______________.
increase; inhibits; triglycerides
The _______ of the mitochondrion contains the proteins making up the _______ that carry out electron transport.
inner mitochondrial membrane; respiratory chain
catabolic and anabolic pathways are ______
integrated
Glycolysis
is a reduction-oxidation process.
one of the main function of photosynthesis
is to supply electrons for carbon fixation
Photosynthesis involves 2 pathways
light reactions convert light energy into chemical energy carbon-fixation (light independent) reactions use ATP and NADPH along with CO2 to produce carbohydrates
antenna sysytems
light-harvesting complexes of arranged pigments
the most oxidized state has the ______ free energy
lowest
_____ is regenerated in the last step
oxaloacetate
electrons for noncyclic electrons come from the
oxidation of water
2 common reaction types in metabolic pathways
oxidation-reduction and substrate-level phosphorylation
Cellular respiration is primarily the _____ of ______, organic molecules
oxidation; reduced
Chl* gives the excited electron to an acceptor and becomes _____ to Chl+
oxidized
in cellular respiration glucose is being
oxidized
During photosynthesis in green plants, water is
oxidized to O2 in the light.
in the citric acid cycle, organic molecules are _____ and NAD+ is _____
oxidized; reduced
chemiosmosis converts ________ energy of a proton gradient across a membrane in the ______ energy in ATP.
potential; chemical
The _______ ______ can also be used to produce heat
proton gradient
alcoholic fermentation
pyruvate is converted to ethanol
lactic acid fermentation
pyruvate is converted to lactic acid
energy in the reducing agent is transferred to the
reduced product
The conversion of malate to oxaloacetate in the citric acid cycle takes place with the conversion of NAD+ to NADH. In this reaction, NAD+ is
reduced.
Which of the choices properly completes the following sentence? The generation of an H+gradient across the mitochondrial inner membrane ________ energy that is provided by ________. The synthesis of ATP is coupled to the ________ flow of H+down the gradient.
requires; oxidation-reduction reactions; exergonic
Fermentation
results in the formation of lactic acid or ethanol.
photons can _____ (bounce off) of _____ (pass thorugh)
scattered; transmitted
Where does the Calvin cycle take place?
stroma of the chloroplast
reduction
the gain of 1 or more electrons
oxidation
the loss of one or more electrons
the more reduced a molecule is...
the more energy is stored in its bonds
beta oxidation
the process of Converting fatty acids to Acetyl-CoA
The chemiosmotic generation of ATP is driven by
the proton motive force.
primary production
the synthesis of organic compounds from atmospheric or aqueous carbon dioxide
a photosystem spans
the thylakoid membrane in the chloroplast; it consists of antenna systems and a reaction center
the main role of acetyl CoA
to donate its acetyl group to the four-carbon compound oxaloacetate, forming the six-carbon molecule citrate, initiating the citric acid cycle
the citric acid cycle operates ______ for every glucose molecule that enters the glycolysis
twice
More free energy is released during the citric acid cycle than during glycolysis, but only 1 mole of ATP(aka GTP)is produced for each mole of acetyl CoA that enters the cycle. Most of the remaining free energy produced during the citric acid cycle is
used to reduce electron carriers.
Which type of metabolic reaction is an example of a process that does not require coupling to ATP hydrolysis?
β-oxidation of fatty acids
Activities such as amino acid synthesis and active transport in plant cells are powered by
ATP from glycolysis and cellular respiration.
products of noncyclic electron transport
ATP, NADPH
The energy currency of cells is
ATP.
_____ and _______ _______ link catabolism, anabolism, and photosynthesis
ATP; reduced coenzymes (NAD+/NADH)
accessory pigments
Absorb wavelengths between red and blue and transfer some of that energy to the chlorophylls
the citric acid cycle starts with ____; acetyl group is oxidized to ______
Acetyl CoA; two CO2
A suspension of yeast supplied with glucose as its source of energy was transferred from an aerobic environment to an anaerobic one. The yeast must expend the same amount of energy to survive in both environments. Which result would you predict for the rate of glucose utilization and the rate of ethanol production after the transfer?
Both glucose usage and ethanol production would increase.
Triglycerides are major energy storage molecules. Which statement about the complete oxidation of triglycerides to CO2 and water and the oxidation of glucose to CO2 and water is true?
Both the complete oxidation of triglycerides and that of glucose use acetyl CoA as an intermediate.
Which statement about the citric acid cycle is true?
It takes place in the mitochondrial matrix.
______ can be reduced to form ______, which can then be oxidized to form _____
NAD+;NADH;NAD+ (NAD+ is oxidized form, NADH is reduced form)
Which of the following statements regarding the coupled reactions shown in the figure is false?
NAD+acts as a reducing agent.
oxidative phosphorylation transfers energy from
NADH to ATP
What do plants use NADPH for?
NADPH supplies the electrons (as H atoms) to reduce CO2 to carbohydrates
____ is the final electron acceptor in the respiratory chain
O2
The figure shows allosteric regulation of glycolysis and the citric acid cycle. If a cell is fed a large supply of fatty acids, which outcome can be expected?
Oxidation of fatty acids through the citric acid cycle will be stimulated until ATP builds up and inhibits citrate synthase, diverting fatty acids into storage molecules such as triglycerides.
At which catabolic step is the greatest quantity of ATP produced?
Oxidative phosphorylation
Why is oxygen important in the electron transport pathway and ATP synthesis?
Oxygen accepts electrons at the end of the electron transport chain to free the pathway for a new set of electrons.
The production of ethanol from pyruvate oxidation is an example of
a fermentation process in anaerobic respiration.
