Chapter 9: Cellular Respiration Flashcards
What is the actual ATP yield per glucose?
29 ATP
What happens in cellular respiration?
Energy is harvested to regenerate ATP
What does food provide in biosynthesis?
The carbon skeletons necessary as well as energy to create molecules for the cell
Chemical formula for cellular respiration
C6H12O6+6)2–>6CO2+6H2O+Energy (ATP and heat)
Pyruvate processing formula
Pyruvate + coenzyme A + NAD+ –> Acetyl CoA + CO2 + NADH
What do electrons travel with?
A H atom
What is lactic acid fermentation used for in the food industry?
Make yogurt, cheese, and sauerkraut
Where do H atoms get passed before O2?
To NAD+ which becomes NADH with the H atom
How does ATP synthase work?
H+ ions flow through ATP synthase down their concentration gradient, bind to active sites and cause conformational change (rotor spins), and causes it to activate catalytic sites that generate ATP
What happens to glucose in glycolysis?
It gets split into 2 molecules of pyruvate
Glycolysis formula
Glucose + 2ATP + 2NAD+ –> 2Pyruvate + 4ATP(2net) + 2NADH
When are electrons stripped from glucose?
At key steps
What does brown fat allow for in hibernation?
Allows the oxidation of stored fuel to generate heat without buildup of ATP
How many steps are in the citric acid cycle?
8
Does glucose have to be the electron donor in anaerobic respiration?
No, other electron donors can be used
How is PE stored in food?
The arrangement of the electrons in the bonds
What type of fat do infants have a lot of and what does it do?
Brown fat. It helps them regulate body temperature
What does brown fat contain?
Cells full of mitochondria
Rxn 3 of pyruvate processing
Coenzyme A is added to form acetyl CoA
Where does glycolysis take place?
In the cytosol
Why do cells need building blocks?
For biosynthesis. They have to make their own molecules
What organisms use alcohol fermentation?
Some bacteria and yeast
Why do animals make respiration less efficient during hibernation?
Too much ATP would shut down respiration and hibernating animals need heat from respiration so making it less efficient keeps them alive
What are the two steps of oxidative phosphorylation?
Electron transport chain and chemiosmosis
How does the electron transport chain work?
Electron carriers alternate between reduced and oxidized states as they accept and donate electrons
How does oxidative phosphorylation generate ATP?
Adding Pi (free inorganic phosphate) to ADP
How are alcohol fermentation and lactic acid fermentation similar?
Lactic acid requires one less step; pyruvate does not get reduced to acetaldehyde and then reduced by NADH to ethanol. Pyruvate is directly reduced by NADH in lactic acid fermentation.
Why must cellular respiration be regulated?
Prevents the cell from wasting energy making something it already has
Rxn 2 of pyruvate processing
Remaining 2-carbon molecule is oxidized and NADH is formed
What is fermentation?
The process to generate energy without using oxygen or an electron transport chain
Is ATP produced in the electron transport chain?
No
What are the products of one cycle of the citric acid cycle?
2CO2, 1ATP (GTP), 3NADH, 1FADH2
Four steps of cellular respiration
- ) Glycolysis
- ) Pyruvate processing
- ) Citric acid cycle
- ) ETC and oxidative phosphorylation
What do some marine bacteria use as the final electron acceptor in anaerobic respiration?
The sulfate ion (SO4-2) to produce H2S instead of water
Rxn 1 of pyruvate processing
COO- is removed from pyruvate and given off as CO2
How many products are produced per glucose molecule in the citric acid cycle and why?
2x the amount of one cycle because one glucose makes 2 pyruvate and one pyruvate goes through the cycle to produce products
How are intermediates from glycolysis and the citric acid cycle used in biosynthesis?
They can be used as precursors for molecules the cell requires
What does glycolysis require as an input?
2 ATP
What would happen without the hibernation adaptation in animals?
ATP would accumulate since the animals metabolism is low and respiration would be shut down due to control mechanisms
What does ATP synthase do?
Uses energy of the H+ gradient to power ATP synthesis
What happens during alcohol fermentation?
Pyruvate gives off CO2 and becomes acetaldehyde which is reduced by NADH to make ethanol and NADH is oxidized and NAD+ is replenished. In essence, pyruvate is reduced to ethanol
How are amino acids used in biosynthesis?
They can be incorporated into the cells own proteins
4th step of cellular respiration
Oxidative phosphorylation
What type of rxn is cellular respiration?
Exergonic
What does anabolic mean?
Requires energy
What does the inner membrane of brown fat contain?
An uncoupling protein which allows H+ to flow back down their gradient without generating ATP
How do old mitochondria contribute to a lower yield of ATP?
As they get older they become leaky and less efficient
How is ATP generate in glycolysis?
An enzyme transfers a phosphate group from a substrate molecule to ADP instead of using Pi
What does acetyl CoA have?
A high PE
What is deltaG equal to in cellular respiration?
-685kcal/mol of glucose
Are H atoms transferred directly to O2?
No
What has happened to glucose at the end of the citric acid cycle?
It has been fully oxidized
What is the theoretical yield of ATP per glucose?
38 ATP
What is the proton motive force?
A gradient of H+ ions in the innermembrane of a cell created during chemiosmosis by the exergonic flow of electrons
How many rxns are in glycolysis?
10
Why can’t cells just switch to fermentation when you are completely deprived of oxygen (suffocated)?
Fermentation wouldn’t be able to supply enough ATP
What happens to the metabolism of animals in hibernation?
It drops to levels just needed for survival
Where do carbohydrates enter cellular respiration?
Before glycolysis. Right at the start
Step 3 of cellular respiration
Citric acid cycle (Krebs/TCA cycle)
What are NADH and FADH2?
Electron carriers
How is the flow of electrons used in chemiosmosis?
Exergonic flow of electrons is used to pump H+ across the membrane into the intermembrane space
What is chemiosmosis?
The second part of oxidative phosphorylation that uses the diffusion of H+ ions down their electrochemical gradient to generate ATP
What do high levels of ATP cause in a cell?
They inhibit an enzyme in early glycolysis
What type of rxn is the electron transport chain and why?
Exergonic because as electrons move through it they are losing energy
Why is cellular respiration aerobic?
It requires oxygen pull the electron off of the end of the electron transport chain
How do the types of fermentation differ from each other?
They produce different end products
Does alcohol fermentation occur in humans?
No
What type of rxns take place in the citric acid cycle?
Redox
What does biosynthesis require?
Energy. It is anabolic
What is alcohol a product of in alcohol fermentation?
A waste product of the yeast or whatever organism went through alcohol fermentation
Where does pyruvate processing take place?
Mitochondria
How is energy harvested in cellular respiration?
In a stepwise manner
How do the four steps of cellular respiration tie together?
The product of one becomes the reactant of the next
What causes the discrepancy between the theoretical and actual yields of ATP?
The proton motive force is used for other work that isn’t flowing through ATP synthase to generate ATP
Step 2 in cellular respiration
Pyruvate processing
What happens to the rest of the energy from glucose that isn’t transferred to ATP?
It is released as heat
What is alcohol fermentation used to create?
Beer, wine, liquor, and bread
What are the two common types of fermentation?
Alcohol and lactic acid
What does AMP do in cellular respiration regulation?
Stimulates phosphofructokinase in glycolysis. Go
What are some substances that can be used as the final electron acceptor in anaerobic respiration?
NO3-, CO2, S, Fe, and uranium
Two main pathways of cellular respiration
Aerobic respiration and anaerobic respiration (fermentation)
How does pyruvate get in the mitochondria?
Transport protein
What happens to CoA and oxaloacetate in the citric acid cycle?
They are recycled
Do NADH and FADH2 enter the electron transport chain at the same place? What does this cause?
No they enter at different places. This causes less energy for ATP synthesis when electrons come from FADH2
How many calories are in a gram of carbohydrate? In a gram of fat?
4 calories/gram of carbohydrate
9 calories/gram of fat
Why does a gram of fat produce 2x the ATP generated from a gram of carbohydrate?
Many more electrons can be pulled off of a fat because it has so many H atoms
What percentage of the potential energy of glucose is transferred to ATP?
31%
What is the final electron acceptor?
Oxygen
What is really stripped from glucose?
H atoms
What do ATP and citrate do in cellular respiration regulation?
Inhibit phosphofructokinase in glycolysis. Stop
Step 1 of cellular respiration
Glycolysis
What happens in lactic acid fermentation?
Pyruvate is reduced directly by NADH to form lactate. NADH is oxidized and NAD+ is replenished
Does lactic acid fermentation occur in humans?
Yes
What must be broken down to release energy?
Food
When does lactic acid fermentation occur in muscle cells?
When the supply of oxygen can’t keep up with energy demand
Where do proteins enter cellular respiration?
Pyruvate processing, acetyl CoA, and the citric acid cycle
What is energy transferred from to in cellular respiration?
From food chem PE to ATP
How many rxns take place in pyruvate processing?
3
How many ATP are made in glycolysis?
4 made (2 net)
Where is the energy from glucose at the end of the citric acid cycle?
Most in NADH and FADH2 but some has been lost to heat
Where do fats and phospholipids enter cellular respiration?
Glycerol into glycolysis and fatty acids into pyruvate processing (acetyl CoA)
Where is ATP synthase located?
Mitochondrial inner membrane
How do the 8 steps of the citric acid cycle proceed?
They are each catalyzed by a specific enzyme
What other molecules can be broken down to release energy?
Other carbs, fats, and proteins can also be used
Where is the majority of ATP made in cellular respiration?
Oxidative phosphorylation
How does fermentation work?
It creates a metabolic pathway to regenerate NAD+ through the continuation of glycolysis when no oxygen is present. It is glycolysis + an extension of glycolysis. There is no electron transport chain
What does chemiosmosis generate?
Generates a gradient that is called the proton motive force that ultimately generates ATP
What drops electrons off at the electron transport chain?
NADH and FADH2
What would happen if glucose was oxidized all at once?
Too much energy would be lost. It would be too inefficient
Where does oxidative phosphorylation take place?
Inside the mitochondria
What happens to the pyruvate from glycolysis in pyruvate processing?
It is shuttled into the mitochondria
Citric acid cycle formula
Acetyl CoA + H2O + 3NAD+ + FAD –> 2CO2 + H2O + 3NADH + FADH2 + GTP(ATP)
How is cellular respiration regulated?
Follows principles of supply and demand. Main mechanism of control is feedback inhibition
What do animals do to the efficiency of cellular respiration in hibernation?
They reduce the efficiency of respiration
What is the difference between aerobic and anaerobic cellular respiration?
In anaerobic cellular respiration, O2 is not the final electron acceptor like it is in aerobic
What happens to O2 in cellular respiration
It becomes reduced and becomes water
How can anaerobic respiration be used to lower radiation in area high in radiation?
Organisms capable of using uranium as the final electron acceptor can be introduced to the area to lower the radiation
Does NADH or FADH2 generate more energy when it comes in the electron transport chain?
NADH generates more energy
ETC and oxidative phosphorylation formula
NADH + FADH2 + 1/2O2 + ADP + Pi –> ATP + H2O + NAD+ + FAD
What is the electron transport chain and where?
Collection of molecules embedded in the mitochondrial inner membrane
What happens to glucose in cellular respiration?
It becomes oxidized
What does oxygen do in the electron transport chain?
It is the final electron acceptor which also picks up 2 H+ ions to form H2O
What is happening when you are deprived of oxygen (suffocated)?
Oxygen is the final electron acceptor so if there is no oxygen, it can’t pull the final electron off the chain. This stops the process of producing ATP and a build up.
Why is it hard to lose weight with a large fat intake?
You have to burn 2x as many calories for each gram of fat
Where does the citric acid cycle occur?
Mitochondrial matrix (inside the inner membrane)
