1.5 Cellular Respiration CS Flashcards
What are the four steps to aerobic cellular respiration?
- Glycolysis
- Pyruvate Oxidation
- Krebs Cycle
- Oxidative Phosphorylation
Aerobic Cellular Respiration
Phosphorylates ADP (adds ADP and phosphate group) into ATP by breaking down glucose through electron carriers (in oxidation and reduction reactions). The electron carriers deposits their electrons into electron transport chain. This deposit fuels chemiosmosis (process of moving protons to other side of membrane creating electrochemical gradients which is used to fuel ATP synthesis) to make chemical energy in form of ATP. (Exergonic)
What is the purpose of glycolysis?
To convert glucose into pyruvate
What are the products of glycolysis?
2 Net ATP and 2 Pyruvate Molecules
What type of phosphorylation occurs in glycolysis? What is this?
Substrate level phosphorylation
Process used to generate ATP to power glycolysis and every cycle other than electron transport chain. SLP transfers a phosphate group to ADP to make ATP.
What are the products and enzymes of glycolysis in ordered steps?
- Hexokinase phosphorylates glucose into glucose-6-phosphate using first ATP
- Isomerase (PGI) modifies glucose-6-phosphate into fructose-6-phosphate
- Phosphofructokinase uses second ATP to phosphorylate fructose-6-phosphate into Fructose-1, 6-biphosphate. (Important because PFK controls rate of glycolysis)
Where does glycolysis occur?
glucose enters the cytosol
What happens in pyruvate decarboxylation?
3 Carbon pyruvate molecules are shuttled from the cytosol into the mitochondrial matrix. After, pyruvate dehydrogenase complex (PDC) transforms pyruvate into acetyl-CoA by CoA binding to the acetyl-group.
What is the enzyme that carries out pyruvate oxidation steps?
Pyruvate dehydrogenase
What is another name for the Krebs Cycle?
Citric Acid Cycle
What happens in the Krebs Cycle?
Acetyl-CoA first joins oxaloacetate to form citrate then later oxaloacetate is regenerated to produce the key products.
What are the products of the Krebs Cycle?
CO2, ATP, FADH2, NADH
What is the purpose of oxidative phosphorylation?
The electron transport chain and chemiosmosis (ions moving down electrochemical gradients) work together to make ATP.
What is the first step of oxidative phosporylation?
Electrons pass from electron carriers (NADH and FADH2) to other carrier proteins in inner mitochondrial membrane.
What is the second step of oxidative phosphorylation?
After electrons are passed to carrier proteins, this generates an H+ gradient (hydrophillic tunnel) that provides ATP synthase energy. This energy allows protons (proton motive force) to flow down gradient to produce ATP.
What is the final electron acceptor in the ETC?
Oxygen is final electron acceptor. Oxygen combines with Hydrogen to form H2O.
What two electron carriers are oxidizes by the ETC?
NADH and FADH2
What does electron transport chain allow?
Allows us to generate substantially more ATP
What is ATP synthase?
A channel protein that provides hydrophilic tunnel to allow protons to flow down gradient.
What is chemiosmosis?
Movement of ions down their electrochemical gradient
What is the goal of chemiosmosis?
To use proton electrochemical gradient (also known as proton-motive force) to synthesize ATP
How does ATP synthase use the H+ gradient?
ATP synthase uses the H+ gradient for chemiosmosis (movement of ions down gradient) to allow the energy of hydrogen ions to flow down gradient across ATP synthase. This allows ATP to be synthesized and made.
What does the electron transport chain do?
It uses the flow of electrons to pump hydrogen ions and establish a concentration gradient.
The ETC is found in what 2 critical organelles?
- Mitochondria
- Chloroplasts
Where does ETC take place in the chloroplasts?
ETC takes place across thylakoid membrane in chloroplasts
ETC in mitochondria is located in where?
ETC in mitochondria is loacted in inner mitochondrial chain membrane
What are the two important enzymes in glycolysis?
Hexokinase and Phosphofructokinase (PFK)
Hexokinase
The first step of glycolysis that is an enzyme that uses first ATP to phosphorylate glucose to glucose-6-phosphate.
Why is hexokinase important?
Because once it phosphorylates glucose, it cannot leave the cell. It is irreversable.
Phosphofructokinase (PFK)
PFK adds the second phosphate (fructose 1-6 BIphosphate) using 2nd ATP.
Why is PFK important?
PFK commits the molecule to glycolysis and controls the rate of glycolysis.
What is aerobic cellular respiration?
Catabolic process use to breakdown glucose to make ATP. It requires oxygen as the final electron acceptor (accepts electrons after they’ve passed ETC)
What is anaerobic cellular respiration?
An anabolic process that does not require oxygen but produces less ATP.
Why does anaerobic cellular respiration rely on glycolysis?
It relies on glycolysis to convert pyruvate into different molecues in order to oxidize (cause chemical reaction with O2) NADH regenerating the NADH to oxidized NAD+.
Why is regenerating NAD+ important?
Regenerating NAD+ means glycolysis can continue to make ATP and run.
What is unique about glycolysis aside from other 3 steps of cellular respiration?
Glycolysis can run both aerobically and anaerobically.
What two processes require oxygen?
- Citric Acid Cycle
- Electron Transport Chain
What is the purpose of alcohol fermentation?
To convert the 2 pyruvate into 2 ethanol. To do this, pyruvate is converted to acetyladehyde + CO2. The acetyladehyde is then converted into ethanol in a process that oxidizes NADH to regenerate NAD+.
What is the final electron acceptor in alcohol fermentation?
Acetyladehyde is the final electron acceptor
What are examples of where alcohol fermnetation takes place?
Plants, fungi, and yeast
What cells utilize lactic acid fermentation? Why?
Muscle cells. Muscle cells use lactic acid fermentation during periods of intense exercise when aerobically produced ATP is quickly depleted and there is low oxygen availability. When there is low oxygen, muscle cells then default to lactic acid fermentation to prouduce energy anaerobically to meet tha energy demand.
What is the purpose of lactic acid fermentation?
To reduce 2 pyruvate to 2 lactate so NADH is oxidized back to NAD+ in the process so glycolysis can continue.
Lactate can be converted back to _______ in the ______ once a surplus of ATP is restored.
The Cori cycle helps to convert lactate back to glucose once oxygen and a surplus of ATP is restored and available again.
When glucose is low, what are other alternative sources of energy generation?
Other carbohydrates, proteins, and fats are used for energy to enter cellular respiration.
Why is gluconeogenesis important?
Because the body creates glucose in the liver from non-carbohydrate precursors like a glycerol molecule. That precursor makes new glucose through gluconeogenesis in the liver.
What cells store lots of glycogen?
Skeletal muscle cells and Liver cells
Why is glycogen stored in the skeletal muscles and liver?
Glycogen is stored in there when the body needs quick energy or when body needs glucose so glycogen is broken down to release glucose into bloodstream to be used as fuel.
What is the overview of cellular respiration?
Glucose is oxidized (combined with oxygen) through electron carriers to deposit their electron in the Electron Transport Chain. This fuels chemiosmosis (ions moving down proton gradient to make ATP) to generate chemical energy, ATP.
Is cellular respiration exergonic or endergonic?
Cellular respiration is exergonic because it is where energy is released and it does not require energy. It is spontaneous with negative gibbs free energy.
