Lecture 4- Energy Metabolism Flashcards
What are the two main categories of chemical reactions?
Catabolism and anabolism
Define catabolism
Metabolic reactions break down molecules/extract energy
Define anabolism
Metabolic reactions synthesize building blocks to produce new molecules
Define photosynthesis
Plants use light energy (sun) to produce carbohydrates from CO2 and H2O
Define chemical energy
Energy contained in the bonds between atoms of a molecule
Our bodies extract energy in the form of _____?
ATP
What are the byproducts of glucose?
CO2 and H2O
What are the two high energy electron shuttles?
NAD+ and FAD
What 2 carriers carry high-energy electrons to the electron transport chain in cellular respiration
NADH and FADH2
How many steps does the complete breakdown of CO2 and H2O take?
How much ATP is generated?
30 steps
30 ATP
When completely oxidized, what does each glucose molecule yield?
CO2, H2O, and ATP
What are the 4 paths that cells can extract energy from carbs through?
- Glycolysis
- Pyruvate to acetyl CoA
- Citric acid cycle
- Electron transport chain
Which step(s) take place in the cytosol and which take place in the mitochondria?
Glycolysis- cytosol
Pyruvate to acetyl CoA, Citric acid cycle, Electron transport chain- mitochondria
What is glucose made of?
What does glucose split into?
Six carbon atoms
Two three-carbon pyruvate molecules
Does glycolysis require oxygen?
No, the process can be anaerboic
How much ATP is required in Glycolysis? How much is produced?
Uses 2 ATP and produces 4 ATP
Net ATP=2
Where are high energy electrons transferred to in Glycolysis?
What is this converted to?
NAD+
NADH
What 2 things can pyruvate be converted to?
Acetyl CoA or lactate
What determines the fate of what pyruvate converts to?
Oxygen supply
If oxygen is lacking, what does pyruvate convert to?
Lactate
Why does the body use lactate instead of acetyl CoA?
Makes ATP faster from lactate molecules that liver cells convert back to glucose
If oxygen is readily avaible, what does pyruvate convert to?
Acetyl CoA
When pyruvate is converted to acetyl CoA, how many carbons are lost?
2 carbons through CO2
Each pyruvate loses one carbon through CO2
Is the process of pyruvate to acetyl CoA reversible?
NO, acetyl CoA cannot exit via the mitochondrial membrane- must enter citric acid cycle in mitochondria
What is the first step in the citric acid cycle?
Hint: what 4 carbon structure combines with the conversion of pyruvate
4 carbon Oxaloacetate combines with 2 carbon acetyl CoA to form 6 carbon citrate (citric acid)
What is the second step of the citric acid cycle?
Hint: the carbons from the conversion of pyruvate combine with the input of cellular respiration
2 carbon atoms from acetyl CoA combine with O2 to form CO2
What are the products of the citric acid cycle?
-1 GTP which can produce 1 ATP
-3 NADH which go to ETC
-1 FADH2 which goes to ETC
-Oxaloacetate is regenerated
How many times does the citric acid cycle occur?
Twice. One glucose molecule produces 2 acetyl CoA molecules which each go through the citric acid cycle
How does the electron transport chain function?
NADH and FADH2 deliver high energy electrons that will travel along the ETC and give up energy to power the production of ATP
Where does the electron transport chain take place?
Inner mitochondrial membrane
What will happen is oxygen cannot accept energy depleted electrons and hydrogens?
ATP production will stop and halt body functions which leads to death
How is an electrochemical gradient formed in the ETC?
Electrons move down the chain from high to low energy/release energy. Some energy is used to pump H+ ions out of matrix/into inter membrane space
How is ATP synthase powered in the ETC?
H+ ions flow down the gradient
How many ATP molecules can be produced per glucose molecule?
25 ATP
What enzyme breaks lipids into glycerol and fatty acids?
What happens to the glycerol?
What happens to the fatty acids?
Lipase
-Glycerol goes to glycolysis due to carbon
-Fatty acids undergo betaoxidation to be made into acetyl CoA
What is betaoxidation? Where does it take place?
Breakdown of fatty acids into acetyl CoA in the mitochondria
What substance transports fatty acids across the mitochondrial membrane?
Caritine
Although the body prefers to use carbs and fats to make ATP, when would the body elect to use proteins?
During a period of starvation. Body breaks down proteins and extracts ATP from amino acids
What is deamination and why does it ocurr?
Body cannot break down amino group. Deamination removes amino group and is excreted in urine
What happens to the carbon skeleton that does not undergo deamination?
-Enter catabolic pathway
-R-groups determine where it enters and affects the amount of ATP produced
What is the respiratory quotient (RQ) and how is it calculated?
-Index of which nutrient is being used by the body to make ATP
-Calculated by the volume of CO2 exhaled divided by the volume of O2 used
What are the RQ values for carbohydrates, protein, and fat?
Carbs = 1.0
Protein = 0.8
Fat = 0.7
Why is the RQ value larger for carbs compared to fats/amino acids?
Carbs can use anaerobic and aerobic pathways. Don’t require O2 so the denominator is less. Fats/carbs mostly use aerobic pathways so denominator is larger, making RQ value smaller
What is creatine made of?
Where is it synthesized and stored?
Where is it excreted?
Amino acids
Synthesized in liver
Stored in muscles
Excreted in urine
When is creatine phosphate beneficial?
First 10 seconds of activity
Better for anaerobic work outs like weightlifting
Why does the RQ value decrease significantly after 60 seconds of activity?
- Glucose levels are depleted and must rely on fats/proteins
- Intensity of activities decreases with lactic acid build up
What are the various metabolic pathways used by the body to make ATP?
Carbs: Glycolysis, acetyl CoA, citric acid cycle, ETC
Fats: Beta-oxidation
Proteins: Deamniation
What is common between the breakdown of carbs, fat, and proteins? What is different?
-Citric acid chain and ETC for all three
-Deamination for proteins
-Beta-oxidation for fats
What is the connection between metabolism and respiration?
O2 is the final electron acceptor and CO2 is produced when pyruvate converts into acetyl CoA and also during the citric acid cycle. All carbons are used from carbs, proteins, or fats
What fuels does the body use for different types of physical activities?
-Carbs/fats at rest (-10-0)
-Followed by creatine phosphate for initial burst of activity (0-10 secs)
-Continues with carbs for anaerobic (10-60 secs) until body reaches fatigue and returns to fats/aerobic breakdown (60+ secs)
Why does the RQ values indicate the type of activity and substrate used to make ATP?
The type of substrate used during different activities will affect the RQ value
Carbs-1.0, proteins-0.8, fats-0.7
Which of the following metabolic pathways is unique to the catabolism of fat?
Glycolysis
Citric acid cycle
Electron transport chain
Beta oxidation
Beta oxidation
Which of the following substrates would be used by the body to make ATP, if you reeled in a fish and the whole process took about 5 seconds?
Fats/carbs
Creatine phosphate
Carbohydrates
Creatine phosphate
Mike has an RQ value of 0.8 and this may indicate?
-He is mainly metabolizing glucose
-He is using creatine phosphate
-He is mainly metabolizing proteins
-He is mainly metabolizing fats
-More than one answer is correct
More than one answer is correct
-Mainly metabolizing proteins (0.8)
-Using creatine phosphate for initial burst
