Aerobic Respiration and Mitochondria Flashcards
What is metabolism? What are the three main purposes of metabolism?
metabolism is the set of life-sustaining chemical transformations within the cells of organisms.
conversion of food/fuel to energy
- catabolic reaction = breakdown
conversion of food/fuel to building blocks for proteins, nucleic acids and some carbohydrates
- anabolic reaction = formation/building
elimination of nitrogenous waste
Why is ATP a good source of energy? How can it be used?
ATP
- has adenine = nitrogenous base
- ribose = pentose sugar
- 3 phosphate molecules
ATP reacts with water and is hydrolysed
- forms ADP and Pi = phosphate is lost at each hydrolysis via cleavage
- reaction is reversible due to high phosphorylation potential
What are sources of energy other than ATP?
phosphoenolpyruvate
1,3-bisphosphoglycerate
creatine phosphate
- energy storage found in the muscle
How can the stages of aerobic and anaerobic respiration be split into anabolic and catabolic reactions?
anaerobic stages
- breakdown of larger molecules into smaller molecules
= glycolysis of glucose into pyruvate
- small molecules are converted into simple units that play a large role in metabolism
= pyruvate is converted to acetyl CoA
aerobic - oxygen is involved
- production of ATP from oxidation of acetyl CoA, tricarboxylic acid cycle, oxidative phosphorylation
What are the stages in metabolism?
glycolysis
- takes place in the cytosol of the cell
- breakdown of glucose into pyruvate = 3 steps
link reaction
- pyruvate transport into the mitochondrion
- converted into acetyl CoA
TCA = tricarboxylic acid cycle
- acetyl CoA enters the TCA cycle
- produces NADH + FADH2 (electron carriers), GTP
ETC = electron transport chain
- NADH and FADH2 enter the ETC
- causes transport of hydrogen ion across the membrane and oxidation of oxygen into water
ATP synthase
- H+ concentration gradient created is used to produce ATP via ATP synthase
Where does glycolysis take place? What are the steps in glycolysis?
glycolysis takes place in the cytosol of the cell
step 1
- phosphorylation = glucose is phosphorylated into glucose-6-phosphate and is catalysed by hexokinase. uses ATP
- isomerisation = glucose-6-phosphate is transformed from a 6 carbon ring to its isomer 5 carbon ring. it goes from glucose-6-phosphate to fructose-6-phosphate. is catalysed by phosphoglucose isomerase
- phosphorylation = fructose-6-phosphate is phosphorylated into fructose-1,6-phosphate. is catalysed by phosphofructokinase. uses ATP
step 2
- fructose-1,6-phosphate is split into isomers glyceraldehyde-3-phosphate and dihydroxyacetone phosphate
- from 6 carbon structure to 3 carbon structure. switch between 3 carbon forms is catalysed by triose phosphate isomerase
- two products means everything happens twice
step 3
- oxidation + phosphorylation = glyceraldehyde-3-phosphate forms 1,3-bisphosphate glycerate. forms NADH and H+. is catalysed by glyceraldehdye-3-phosphate dehydrogenase
- substrate level phosphorylation = 1,3-bisphosphate glycerate forms 3-phosphoglycerate. is catalysed by phosphoglycerate kinase. forms ATP
- intramolecular transfer = transfer of phosphate molecules from one carbon to another forms 2-phosphoglycerate. is catalysed by phosphoglyceromutase
- enolase reacts with 2-phosphoglycerate to form phosphoenolpyruvate. is dehydrated in the process
- phosphoenolpyruvate is catalysed by pyruvate kinase to form pyruvate. forms ATP
What is the link reaction? Where does it take place?
the reaction is the process in which pyruvate enters the mitochondria and is converted to acetyl CoA
- pyruvate enters the mitochondria via a transport protein
- pyruvate loses carbon dioxide = we breathe it out
- pyruvate reduces NAD+ to NADH and H+
- pyruvate gains the Coenzyme A molecules and forms acetyl CoA
acetyl CoA is a 2 carbon chain
What is the TCA cycle? Where does it take place?
TCA cycle is the tricarboxylic acid cycle. It takes place in the mitochondria
- acetyl CoA (2C) enters the cycle
- acetyl CoA goes through a cycle of forming a C6 molecule, then a C5 molecule, then a C4 molecule. the C4 then binds with acetyl CoA again to form the C6 molecule.
- forms 3 NADH, 1 FADH2 and 1 GTP = all x2 because of the 2 molecules of pyruvate formed from the 2 isomers in glycolysis
= 6 NADH, 2 FADH2 and 2 GTP - releases 2 molecules of carbon dioxide
What is ETC? Where does it take place?
ETC is the electron transport chain = oxidative phosphorylation. It takes place in the mitochondria
electron carries NADH and FADH2 enter the cycle.
- NADH is oxidised to donate a pair of electrons at the first protein complex
- FADH2 is oxidised to donate a pair of electrons at the second protein complex
- electrons released are transported to coenzyme Q.
- as electrons travel through the ETC, they lose energy. this energy is used to pump H+ ions into the intermembrane space from the matrix and creates a concentration gradient
- complex Q transfer the electrons and they bind to cytochrome c.
- binding of electrons to cytochrome c transports the electrons back into the matrix
- electrons oxidise oxygen and hydrogen to form water
What is ATP synthase and chemiosmosis?
ATP synthase is a rotor within the the membrane
- the lower half in the high pH matrix and the upper half in the low pH intermembrane space
- the rotor within the membrane spins clockwise when H+ flows past it down the concentration gradient
- as the rotor (upper half) spins the rod (pole) extending into the knob (lower half) also spins and activates the catalytic sites
- there are three catalytic sites with three conformation = open, loose and tight
it is loose when ADP and Pi are joining. it is tight when ti catalysis the formation of ATP. it is open when it releases ATP
What are the overall products of respiration?
ATP?
NADH?
FADH2?
32 ATP overall
for one molecule of glucose
- glycolysis = 2 ATP used and 4 produced = 2 overall produced
- link reaction = no ATP
- TCA = 2 GTP/ATP
glycolysis = 2 NADH link = 2 NADH TCA = 6 NADH
glycolysis = 0 FADH2 link = 0 FADH2 TCA = 2 FADH2
NADH = 2.5 ATP FADH2 = 1.5 ATP
What is the cori cycle?
cori cycle is also known as the lactic acid cycle
- is a metabolic pathway
- lactate produced by anaerobic glycolysis in muscles and is then transported to the liver and converted to glucose, which then returns to the muscles and is cyclically metabolized
muscle
- glycolysis = glucose to pyruvate to lactate
- produces ATP
liver = detoxified
- gluconeogenesis = lactate to pyruvate to glucose
- requires ATP
What are the different metabolic pathways for pyruvate?
aerobic pathway
- pyruvate enters the TCA cycle and undergoes further oxidation via the ETC to produce ATP
- loses carbon dioxide
anaerobic pathway 1
- pyruvate is converted into lactate during strenuous activity
- lactic acid causes cramping
- NADH is oxidised to NAD+
anaerobic pathway 2 = only in yeast and microorganisms
- pyruvate loses carbon dioxide and forms acetalaldehyde
- acetaldehyde is fermented into ethanol
- NADH is oxidised to NAD+
