5.7 Respiration Flashcards
What is Respiration?
Respiration is a chemical reaction which occurs in all living cells, releasing energy from glucose
Why do organisms need to Respire?
Provides energy for •DNA replication & cell division • Active transport • Movement • Metabolic reactions e.g. to form peptide bonds in protein synthesis.
What is Atp and its role?
Adenosine(adenine + ribose) Triphosphate that functions as an immediate energy source for reaction by hydrolysing and losing a phosphate group
What is the chain reactions involved to Completely hydrolyse 1 ATP?
30.5kJ 30.5kJ 13.8kJ
↑ ↑ ↑
ATP + H2O → ADP + H2O → AMP
↓ ↓ ↓
Phosphate Phosphate Phosphate
How is ATP formed?
ATP synthase catalyses the formation of ATP from ADP and the Inorganic Phosphate
What are some features of atp that make it suited to its job?
- relatively stable in solutions
- despite this is readily hydrolysed by enzymes
- Universal as appears in all living cells
- easily transported whilst in solution
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.
* 2,3,4 only happen with air(aerobic conditions)
What is Glycolysis?
the first step in Respiration that turns glucose into 2 pyruvates
Outline the steps of glycolysis?
- Phosphorylation of glucose to Hexose bisphosphate
- Hexose Bisphosphate split into Triose phosphate
- Triose phosphate oxidized to Pyruvate using NAD
* PRODUCTS per glucose: 2NADH & 2ATP per glucose
What is NAD?
a coenzyme that helps catalyses redox reactions by carrying protons or electrons
How are NAD different from NADP?
NAD for respiration
NADP for photosynthesis
What happens after pyruvate is formed?
with Oxygen present
enters mitochondrial matrix through active transport to enter link reaction
What happens after pyruvate is formed?
Anaerobic respiration
converted in cytoplasm to lactate(animals) or ethanol(yeast), NADH reoxidsed to continue glycolysis and
What happens during the Link reaction?
pyruvate is decarboxylated and dehydrogenated
pyruvate + NAD + CoA →
Acetyl CoA + reduced NAD + CO2
Steps of Link reaction?
1.Pyruvate oxidized to acetate + CO2
NAD reduced during process
2.Acetate combines with coenzyme A (CoA) to form Acetylcoenzyme A
What is the Krebs Cycle?
happen in the mitochondrial matrix where many enzyme catalysed reactions occur to makes products like the H+, NADH &FADH2 used for oxidative phosphorylation
What are the products of the Krebs cycle?
Per 1 Acetyl-CoA
• 1ATP by substrate-level phosphorylation • 2 CO2 from decarboxylation • FADH2 & 3(NADH & H+) (used in oxidative phosphorylation) * 1 Coenzyme a
Steps of Krebs cycle?
- acetyl Coenzyme A from link reaction releases acetyl group
- Acetyl group + OXALOACETATE → Citrate(6C compound)
- 6C compound oxidised to form a 5C compound & CO2, H reduces NAD
- 5C oxidised forms 4C compound & CO2, H reduces NAD , ATP formed
- 4C compounds, via dehydrogenation reduces FAD and NAD
- 4C regenerates Oxaloacetate
What is the Electron Transfer Chain (ETC)?
Series of carrier proteins embedded in membrane of the cristae of mitochondria.
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 proton gradient or released as heat.
- Oxygen acts as final electron acceptor
What is Oxidative Phosphorylation?
Formation of ATP using energy from the electron transfer chain, in the presence of oxygen (aerobic)
What are the final steps of Aerobic respiration?
Oxidative Phosphorylation
- NADH &FADH2 reoxidise and release the H+ ions(protons)
- Some energy released from the ETC is used to actively transport H+ ions (protons) from mitochondrial matrix into intermembrane space.
- H+ ions move down concentration gradient back into mitochondrial matrix via channel protein ATP synthase.
- ATP synthase catalyses ADP + Pi → ATP
What is Chemiosmosis, how is it relevant to ATP production?
The flow of protons down their concentration gradient across a membrane. When occurs through the protein channels associated with ATP synthase, they cause a conformational change that allows ADP and P to combine
Name the stages in respiration that produce ATP by substrate-level Phosphorylation.
- glycolysis
* Krebs cycle (aerobic/ requires oxygen)
What happens during Anaerobic respiration in animals?
only glycolysis continues, much less ATP produced
reduced NAD + pyruvate
→lactate + NAD (for further glycolysis)
What happens during Anaerobic respiration yeast and some plant cells?
Only glycolysis continues, much less ATP produced
Pyruvate is decarboxylated to form ethanal. Ethanal dehydrodgenated to ethanol oxidising NADH
What are the benefits of being able to respire Anaerobically?
- ATP production for vital metabolic processes continues despite lack of oxygen
- Production of ethanol/ lactate converts reduced NAD back into NAD so glycolysis can continue = maximum yield of ATP in the conditions
What is Respiratory quotient ?
CO2 produced/ O2 used
Can be used to determine:
• Respiratory substrate being used
• type of respirato goin on(anaerobic values are larger)
Name molecules that can be used as alternative Respiratory substrates
- (amino acids from) proteins
- (glycerol and fatty acids from) lipids
- disaccharides converted to monosaccharides changed to glucose
Why do different Respiratory substrates have different relative energy values?
Depends on the number of hydrogens in the structure which are oxidised to water
e.g. more hydrogens in a fatty acids than carbohydrate.
What a Respirometer?
apparatus used to measure the rate of respiration by measuring the rate of exchange between oxygen and carbon dioxide
Suggest how a student could investigate the effect of a named variable on the rate of respiration of a single celled organism
- Use respirometer (pressure changes in boiling tube cause a drop of coloured liquid to move
- Use a dye as the terminal electron acceptor for the ETC
What is the purpose of Sodium Hydroxide solution (Soda lime) in a Respirometer?
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
Describe the structure of a Mitochondrion
surrounded by double membrane.(inner, outer, inter)
folded inner membrane forms cristae: site of electron transport chain.
fluid matrix: contains mitochondrial DNA, respiratory enzymes, lipids, proteins, ribosomes
What are the RQ values for
Carbohydrates,lipids & Amino acids
- Carbohydrates = 1
- Amino acids = 0.8
- Lipids = 0.7
what are the steps of glycolysis
- Glucose Phosporlyated by 2 Atp
- Hexose Biphospate split into 2 Triose phosphate
3.Triose phosphate oxidised to Pyruvate
3* oxidation of 1 TP reduces 1NAD & forms 2 ATP
what could be the rection eqautionS for glycolysis
Glucose + 2 ATP → Hexose biphosphate + 2ADP
Hexose biphosphate → 2 Triose phosphate (TP)
2 TP+ 4(ADP+i) 2NAD → Pyruvate + 4ATP + 2NADH
