Respiration Flashcards
Why do organisms need to respire ?
Respiration Produces ATP as an energy currency for:
- Active transport against concentration gradients e.g. to absorb nutrients from small intestine/soil
- Metabolic reactions e.g. to form peptide bonds in protein synthesis
- Muscle contraction
Release heat energy for thermoregulation
Describe the structure of mitochondria
Surrounded by a double membrane
Folded inner membrane forming the Cristae: Site of electron transport chain
Fluid matrix: Contains mitochondrial DNA, Respiratory enzymes,lipids,proteins
Name the 4 main stages in aerobic respiration and where they occur
- Glycolysis : Cytoplasm
- Link Reaction : Mitochondrial matrix
- Krebs Cycle : Mitochondrial matrix
- Oxidative Phosphorylation via electron transfer chain : membrane of cristae
Outline the stages of glycolysis
- Glucose is phosphorylated to hexose bisphosphate by 2x ATP
- Hexose bisphosphate splits into 2x triose phosphate (TP)
- 2x Triose Phosphate is oxidised to 2x pyruvate
Net gain of 2x reduced NAD & 2x ATP per glucose
Draw a flowchart to represent what happens during glycolysis
Refer to GoodNotes
How does pyruvate from glycolysis enter the mitochondria ?
Via active transport
What happens during the links reaction ?
- Oxidation of pyruvate to acetate.
Per pyruvate molecule : net gain of 1 x CO² (decarboxylation) & 2H atoms (Used to reduce 1xNAD) - Acetate combines with coenzyme A (CoA) to form Acetylcoenzyme A
Give a summary equation for the link reaction
Pyruvate + NAD + CoA —> Acetyl CoA + Reduced NAD + Co²
What happens in the Krebs cycle ?
series of redox reactions produces:
-ATP by substrate-level phosphorylation
-Reduced coenzymes
-Co² from decarboxylation
Begins when acetyl group from Acetyl CoA (2C) reacts with oxaloacetate (4C). Cycle regenerates oxaloacetate
Outline the stages of the Krebs Cycle
Refer to GoodNotes
What is the electron transfer chain (ETC) ?
- Series of Carrier proteins embedded in membrane of the cristae of mitochondria
- Produces ATP through oxidative phosphorylation via chemiosmosis during aerobic respiration
What happens in the electron transfer chain (ETC)
- Electrons released from reduced NAD & FAD undergo successive redox reactions
- The energy released is coupled to maintaining a proton gradient or released as heat
- Oxygen acts as final electro acceptor
How does chemiosmosis produce ATP during aerobic respiration ?
- Some energy released from the ETC is coupled to activate the transport of H+ ions (protons) from mitochondrial matrix into inter membrane space
- H+ ions move down concentration gradient into mitochondrial matrix via channel protein ATP synthase.
- ATP synthase catalyses ADP + Pi —> ATP
State the role of oxygen in aerobic respiration
Final electron acceptor in electron transfer chain
(Produces water as a byproduct)
Name the stages in respiration that produce ATP by substrate-level phosphorylation
- Glycoloysis (Anaerobic)
- Krebs Cycle (aerobic)
What happens during anaerobic respiration in animals ?
Only glycolysis is able to continue
Reduced NAD + Pyruvate —> NAD + Lactate
Lactate will bind with oxygen in the liver forming Glucose, to be used in glycolysis
What happens during anaerobic respiration in some microorganisms e.g. yeast and some plant cells ?
- Only glycolysis continues so much less ATP is produced compared to aerobic respiration
- Pyruvate is decarboxylation to from ethanal
- Ethanal is reduced to ethanol using reduced NAD to produce oxidised NAD for further glycolysis
Draw a low chart to show how ethanol is produced during anaerobic respiration
Refer to GoodNotes
What are the benefits of being able to respire Anaerobically ?
- ATP production for vital metabolic processes continue
- Production of ethanol/lactate converts reduced NAD back into NAD so glycolysis can continue = maximum yield of ATP in the conditions
Suggest how a student could investigate the effect of a named variable on the rate of respiration of a single-called organism
- Use respirometer (pressure changes in boiling tube cause a drop of coloured liquid to move)
- Use a dye as a terminal electron acceptor for the ETC
What is the purpose of sodium hydroxide solution in a respirometer set up to measure the rate of aerobic respiration?
Absorbs CO² so that there is a net decrease in pressure as O² is consumed
How could a student calculate the rate of respiration using a respirometer?
Volume of O² Produced or CO² consumed/time x mass of sample
Volume = Distance moved by coloured drop x (0.5 x capillary tube diameter)² x π
Name 2 types of molecules that can be used as alternative respiratory substrates
- Amino Acids from proteins
- Glycerol and fatty acids from lipids
What is the respiratory quotient (RQ) ?
RQ = carbon dioxide produced / oxygen consumed
Can be used to determine :
- Respiratory substrate being used (carbohydrates: 1.0, lipids: 0.8, proteins 0.9)
- If organism is undergoing anaerobic respiration (anaerobic values are larger)
Why do different respiratory substrates have different re;active energy values ?
Depends on the number of hydrogens in the structure which are oxidised to water e.g. the number of hydrogens is greater in fatty acids than carbohydrates
