Respiration Flashcards
4 stages of respiration?
Glycolysis, links reaction, Krebs cycle, oxidation phosphorylation
Equation for respiration
Glucose + oxygen —-> carbon dioxide + water (exothermic)
Structure of ATP?
Adenine base, 3 phosphate molecules bonded in a row to the pentose sugar
What is ATP used for?? 3 categories
Muscle contraction
Active transport
Biosynthesis (building molecules like proteins synthesis, DNA replication )
What are ATPase enzymes used for??
Used to catalyse the hydrolysis of ATP into ADP+Pi and energy
What is metabolism?
All the chemical reactions on going in a cell
What is a metabolite?
An intermediate in metabolic pathways eg pyruvate
Structure of mitochondria:
Double membrane
Stalked particles (ATP synthase) on cristae
folded projections of inner membrane/ Cristae
Matrix
Porins (protein channels in the outer membrane)
Where does the Krebs cycle take place?
Matrix
What are porins and stalked particles?
Porins are protein channels in outer membrane of mitochondria that let most small molecules in
Stalked particles are enzyme complexes of ATP synthase on the cristae
Benefit of compartmentation in respiration?
It keeps metabolites (products and reactants of each stage) separate as each stage occurs at a different location
Do Glycolysis, Krebs cycle and Electron transport chain occur in anaerobic conditions?
Glycolysis is anaerobic
Krebs cycle and electron transport chain are aerobic
How does glucose enter the cell and where from?
Facilitated diffusion through a specific carrier protein from the tissue fluid
How does insulin effect regulate the amount of glucose that enters a cell
The hormone controls the specific glucose carrier proteins in the membrane of the cell
Summary of glycolysis
Glucose -> phosphorylated glucose-> GALP (3C)->GP (3C, acid)->Pyruvate (3C)
Phosphorylation of glucose, how and why?
Adding a phosphate group to glucose
1) removes pure glucose, increasing the conc gradient, so pure glucose wants to diffuse into the cell from tissue fluid
2) activates the glucose for biosynthesis
How is GALP formed?
Glucose +ATP -> phosphorylated glucose
PG + ATP-> 2GALP
Therefore Glucose + 2ATP -> 2GALP (3C)
What happens when GALP is oxidised?
Forms GP (glycerate 3 phosphate) an acid
This releases energy to form ATP and a H+ ion
The hydrogen is taken and carried to the electron transport chain by coenzyme NAD which gets reduced in the process (NADH)
What happens to GP?
GP is simply converted into Pyruvate (3C)
ATP is made
What is the reverse of glycolysis?
Gluconeogenesis (turning pyruvate into glucose)
What happens to pyruvate in the absence of oxygen?
Converted into lactate or ethanol
The link reaction links glycolysis to the Krebs cycle, but what happens in this stage?
Pyruvate enters mitochondrial matrix and is converted into Acetyl CoA
Describe the change of pyruvate in the links reaction, and what happens to the products
Pyruvate loses CO2 and H+
Forming an acetyl compound (2C) which binds to a coenzymeA forming acetyl coA
- CO2 diffuses by lipid diffusion into the tissue fluid and then blood -> out the lungs
- H+ is taken up by NAD becoming reduced
Summary of Krebs cycle
Acetyl coA binds with a 4C compound which is then broken down to reform the 4C compound releasing ATP, H+ and CO2
What is the name of the 4 carbon compound that binds with acetyl coA and what does it form?
Oxaloacetate
Forming citrate
What happens to the H+ made in the Krebs cycle
Taken up by FAD or NAD to the electron transport chain
How many integral proteins consist of the electron transport chain?
5
4- protein carriers and ATP synthase
Why is oxygen needed in the electron transport chain?
Oxygen is the final electron acceptor which also binds to Hydrogen to form water
Describe how the proton gradient is made in the electron transport chain:
- FADH and NADH bind to integral proteins releasing their H+ and electrons (becoming oxidised)
- Electrons pass along the chain of integral proteins in the inner membrane, exciting the proteins to move the Protons across the inner mitochondrial membrane by active transport forming a proton gradient
What is the purpose of FADH or NADH?
To shuttle H+ and electrons back and forth from the Krebs cycle to the electron transport chain
How is ATP made from the proton gradient in electron transport chain?
As 4 protons travel down the conc. gradient through the ATP synthase enzyme channel across the inner mitochondrial membrane they spin the globular head which generates 1 ATP
Why is the synthesis of ATP called oxidative phosphorylation?
Because in the ETC oxygen (the final electron acceptor) is used to phosphorylated (add a phosphate group) to ADP
What is chemiosmosis?
Storing energy by creating a proton gradient across a membrane
Summary of oxidative phosphorylation:
1) NADH oxidised releasing H+ and e- returning to Krebs cycle
2) electron passes along the chain of proteins exciting them
3) Oxygen combines with hydrogen and the electron to form water
4) the energy of the electron is stored as a proton gradient and then used to make ATP
Why is Oxygen needed for respiration to work?
Oxygen accepts electrons and H+ to form water
- without oxygen electrons don’t leave the ETC so no NADH can unload any H+
- so there’s no NAD at Krebs cycle as bottle neck of NADH at ETC
- Without coenzymes NAD the enzymes in Krebs cycle and glycolysis don’t work
How many ATPs does anaerobic respiration make?
2
What co enzyme is needed for glycolysis?
NAD
How is reducing pyruvate into lactate an advantage?
This oxidises NADH and therefore regenerates NAD so more glycolysis can occur generating 2 ATP
What happens in anaerobic respiration in animals and bacteria?
Pyruvate is reduced into lactic acids
NAD is regenerated to be reused in glycolysis
How does anaerobic respiration lead to cramp?
Produces lactic acid which lower pH in muscle slowing down enzymes causing cramp and fatigue
What are the differences between anaerobic respiration in plants and humans?
Plant: produces ethanol and CO2, irreversible reaction
Human: produces lactate, reversible (can be oxidised back in pyruvate)
Similarities between anaerobic respiration in plants and animals
Reduction of pyruvate oxidises NADH into NAD to repeat glycolysis
Explanation of anaerobic respiration in plants from pyruvate:
Pyruvate is reduced into ethanol and CO2
This oxidises NADH regenerating NAD for glycolysis
Another name for anaerobic respiration in plants?
Fermentation
How many ATP are made in complete respiration
32
What is substrate level phosphorylation?
When ATP molecules are made directly by enzymes in glycolysis or Krebs cycle
