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Chapter 9

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What is the formula for cell respiration?
C6H12O6 + 6O2 --> 6CO2 + 6H2O + energy
What is ATP made of?
three phophate groups, ribose, and adenine
How does ATP work?
energy is released when ATP is hydrolyzed
Is the hydrolysis of ATP exergonic or endergonic?
exergonic - it gives off a lot of energy
What would happen if the energy from the hydrolysis of ATP was given off all at once?
the reaction would be so hot the cell would set on fire
The energy in ATP is found at which part of the molecule?
between the phosphate groups -- creates a lot of energy when broken
What are the stages of cell respiration?
glycolysis, transition, Krebs Cycle, and the electron transport chain
How is NADH formed?
when NAD+ is reduced by adding H+ and 2e- to create NADH
What is glycolysis?
the breakdown of glucose by enzymes
What goes into glycolysis?
glucose, 2 NAD+, 2 ATP, and 4 ADP
What comes out of glycolysis?
2 pyruvate, 2 NADH, 2 ADP, and a net gain of 2 ATP
Where does glycolysis occur?
cytosol
What is the major event that happens around step 5 of glycolysis?
the fructose-1,6-bisphosphate splits into two glyceraldehyde molecules and from then on everything happens twice
What happens in the transition step?
pyruvate is turned into acetyl co-enzyme A
What goes into the transition step?
pyruvate
What comes out of the transition step?
acetyl co-enzyme A, NADH, and CO2
What happens after glycolysis when there is no oxygen process?
it will transition on to fermentation rather than the Krebs Cycle
Where does the Krebs Cycle occur?
the matrix of the mitochondria
What goes into the Krebs Cycle?
2 acetyl co-enzymes A's, 6 NAD+, 2 FAD, and 2 ADP
What is the purpose of the Krebs Cycle?
produce the NADH
Describe feedback inhibition.
when there is enough product present, some product will go back to one of the enzymes in the process and inhibit production until more is needed
How are the steps of glycolysis carrried out?
each step has an enzyme specialized to carry out each step
How does feedback inhibition work in glycolysis?
when there is enough ATP produced, the enzyme phosphofructokinase that is supposed to be bound to fructose-1,6-bisphosphate is allosterically inhibited by an ATP molecule
Why is the Krebs Cycle a cycle and not just a process?
it begins and ends with the same product
What is the product that is both started with and ended with in the Krebs Cycle?
oxaloacetate
What happens to the carboxylic acids that are involved in the Krebs Cycle?
they become steadily more oxidized as the cycle continues, with citrate being the most reduced and oxaloacetate being the most oxidized
How many turns does the Krebs Cycle take for 1 glucose molecule?
2 turns
What are the products of the Krebs Cycle?
4 CO2, 6 NADH, 2 FADH2, 2 ATP
What is the purpose of the Krebs Cycle?
to generate the electron carrying molecules NADH and FADH2 that will aid in the production of ATP in the electron transport chain
Why do we breathe out CO2?
the Krebs Cycle produces CO2 as a waste product
How is the Krebs Cycle regulated?
when there is enough product present, either ATP, acetyl CoA, or NADH will go back to inhibit the Pyruvate Dehydrogenase enzyme
Where does the electron transport chain occur?
in the inner membrane of the cristae
What is the purpose of the electron transport chain?
harvesting the energy from NADH and FADH2 to generate ATP
What goes into the electron transport chain?
10 NADH, 2 FADH2, 32-34 ADP, O2
What comes out of the electron transport chain?
10 NAD+, 2 FAD, 32-34 ATP, H2O
What is the net intake of cell respiration?
1 glucose, 6 O2, 36-38 ADP
What is the net output of cell respiration?
6 CO2, 6 H2O, 36-38 ATP
Why do we need to breathe oxygen?
to pick up the electron that is being passed on through the electron transport chain and without it, cell respiration will not work
How does the electron transport chain work with membrane proteins?
electron carriers form protein complexes embedded in the inner membrane and electrons from NADH and FADH are passed along until joined up with oxygen and hydrogen to form water.
How is water formed from cell respiration?
hydrogen ions in the intermembrane space are pumped through the complexes using an electrochemical gradient and they are joined up with oxygen and the passed along electrons to form water
How does ATP synthase work?
it is an enzyme where the H+ ions move from high concentration to low concentration, forming a proton mode of force that causes the ATP synthase to start turning and generating ATP
What is the purpose of fermentation?
to allow cells to regenerate NAD+ and continue glycolysis
What goes into fermentation?
2 pyruvate, 2 ATP, and 2NADH
What comes out of fermentation?
lactate
Can fermentation sustain the human body?
no
What is the difference between human fermentation and yeast fermentation?
it will produce ethanol and CO2, and it can survive on fermentation for a longer amount of time
In muscle cells, fermentation produces _____.
lactate and NAD+
In fermentation _____ is reduced and _____ is oxidized.
A) lactate ... ethanol
B) lactate ... NADH
C) pyruvate ... NADH
D) NAD+ ... pyruvate
E) NADH ... lactate
C) pyruvate ... NADH
What is the correct sequence of steps in cellular respiration, starting with glucose?
glycolysis, pyruvate processing, citric acid cycle, electron transport, oxidative phosphorylation
How many NADH are produced by glycolysis?
2
In glycolysis, ATP molecules are produced by _____.
substrate-level phosphorylation
Which of these is NOT a product of glycolysis?
A) FADH2
B) NADH
C) pyruvate
D) ATP
A) FADH2
In glycolysis, what starts the process of glucose oxidation?
ATP
In glycolysis there is a net gain of _____ ATP.
2
At the end of cellular respiration, protons flow through a protein called _____, which drives the formation of ATP from ADP and inorganic phosphate.
ATP Synthase
In eukaryotes, the components of the electron transport chain are located in the ____.
inner mitochondrial membrane
Glycolysis is a series of ___ reactions that occurs in the _____ of cells.
A) fifteen; mitochondria
B) ten; cytoplasm
C) fifteen; cytoplasm
D) ten; mitochondria
B) ten; cytoplasm
Why is ATP production during cellular respiration characterized as indirect?
ATP is not produced directly by the ETC but instead via the proton gradient generated during electron transport through the ETC.
For each molecule of glucose processed during glycolysis, the net yield is ____.
two molecules of NADH, two of ATP, and two of pyruvate
Which answer best explains why organisms that have an ETC as well as fermentation pathways seldom ferment pyruvate if the electron acceptor at the end of the ETC is available?
A) The molecule formed by addition of an electron to pyruvate is toxic to the cell.
B) Fermentation is extremely inefficient because it is so slow.
C) Fermentation is extremely inefficient in terms of the number of ATP molecules produced for each molecule of glucose metabolized.
D) The ETC outcompetes fermentation pathways for use of the electron acceptor.
C) Fermentation is extremely inefficient in terms of the number of ATP molecules produced for each molecule of glucose metabolized.
What molecule is produced in the citric acid cycle as a by-product of glucose oxidation and is considered a waste product?
CO2
During cellular respiration ____
glucose is oxidized and there is net production of ATP
Which of these enters the citric acid cycle?
A) glucose
B) NADH + H+
C) pyruvate
D) acetyl CoA
E) G3P
D) acetyl CoA
In the citric acid cycle, ATP molecules are produced by _____.
substrate-level phosphorylation
Which of these is NOT a product of the citric acid cycle?
A) FADH2
B) acetyl CoA
C) NADH + H+
D) ATP
E) CO2
B) acetyl CoA
What is a significant advantage to the cell in having pyruvate dehydrogenase consist of a large, multi-enzyme complex?
metabolism can occur more rapidly