Chapter 12 - Respiration Flashcards
What are the carriers for respiration?
Called co-enzymes
NAD+ and FAD (oxidised form)
What is dehydrogenation?
Removal of high energy hydrogen (proton) as it contains electrons
Carried out by dehydrogenase enzymes
Where does glycolysis occur?
In cytoplasm of cells
What are the steps involved in glycolysis?
- Glucose is activated by phosphorylation using ATP, into glucose phosphate
- Glucose phosphate is hydrolysed into 2 triose phosphate
- Triose phosphate is oxidised by dehydrogenation using NADH
- Substrate level phosphorylation occurs whereby ATP is resynthesised
- This forms 2 pyruvate
Why is glucose converted to pyruvate in glycosis?
Transporters on mitochondrion membrane are only specific to pyruvate and not glucose
- glucose is too big to pass through
What is the model for answering an ‘evaluate’ question?
- for and against
- analyse every part of conclusion
- sample size/ range
- stats test done?
Where does link reaction and Krebs cycle take place?
In mitochondrial matrix
List steps involved in the link reaction and Krebs cycle
- Pyruvate is decarboxylated and dehydrogenated using NAD+ to from acetate
- Acetate then combines with co-enzyme A to form acetyl CoA
- Acetyl CoA combines with OAA to form citric acid- at this point coenzyme a has left acetate
- Citric acid is decarboxylated and dehydrogenated using NAD+ to form a 5 carbon molecule
- The 5 carbon molecules is decarboxylated and dehydrogenated using NAD+ to form a 4 carbon molecule
- The 4 carbon molecule undergoes decarboxylation and dehydrogenation using FAD and NAD+ and substrate level phosphorylation of ATP occurs to reform OAA
Where does oxidative phosphorylation occur?
Inner membrane of mitochondria
Describe the steps involved during oxidative phosphorylation
- From the Krebs cycle, NADH and FADH2 are formed
- NADH releases 2 electrons which go to the first protein of the electron transfer chain
- These electrons pass down the ETC via a series of redox reactions, releasing energy
- This energy powers proton pumps which pump protons via active transport from matrix to inter membrane space
- The terminal electron acceptor is oxygen, which combines with 2 electrons and 2 protons to form water
- The protons then pass through ATP synthase down their electrochemical gradient and release energy to phosphorylate ADP into ATP (x3)
What are the rules about NADH and FADH2 in oxidative phosphorylation?
NADH - goes to first protein in ETC so releases lots of energy. So more protons are pumped and therefore 3 molecules of ATP are made.
FADH2 - goes to second protein in ETC so releases less energy. So less protons are pumped and therefore only 2 molecules of ATP are made.
What occurs during anaerobic respiration in animals?
Glycolysis occurs but:
- NADH reduces pyruvate into lactic acid
- this allows the re-oxidation of NADH into NAD+ so glycolysis can carry on occurring
What occurs during anaerobic respiration in plants, yeast and fungi?
Glycolysis occurs but:
- pyruvate is decarboxylated forming CO2 and ethanal
- NADH reduces ethanal into ethanol
How can carbohydrate act as an alternative respiratory substrate?
E.g. glycogen
- the enzyme hydrolyses glycogen into alpha glucose
- this glucose can then be used in the first stage of glycolysis
How can lipids act as an alternative respiratory substrate?
Step 1 - enzyme hydrolyses lipid releasing fatty acids
- fatty acids then hydrolysed into a 2 carbon molecule
- 2 carbon molecule (acetate) is then used in link reaction and Krebs cycle
Step 2 - glycerol is phosphorylated using ATP into triose phosphate
- TP then used in glycolysis
How can proteins act as an alternative respiratory substrate?
PART 1
The polypeptide is hydrolysed by an enzyme to form many amino acids
- amino acids then deaminated (NH2 removed in liver)
- left is toxic ammonia (NH3) which then goes into urea to be excreted via urine
How can proteins act as an alternative respiratory substrate?
PART 2
The remaining keto acid:
- If has 2 carbons - is acetate so goes to link reactions to bind with coenzyme A
- If has 3 carbons - is pyruvate so enters link reaction
- If has 4/5 carbons - acts as a intermediate in Krebs cycle
What is the equation for respiratory quotient?
RQ = Volume of CO2 given off / volume of O2 taken in
How can RQ ever be greater than 1?
When anaerobic respiration is taking place as CO2 is produced whilst there being no O2 taken in
Why does the dye move to the left in the respirometer?
- Organism is respiring aerobically so it is absorbing oxygen
- Any CO2 produced is absorbed by potassium hydroxide
- Volume of gas in tube decreases
- Pressure in tube decreases
- So dye moved to the left
What is the function of the syringe in a respirometer?
Used to reset the dye by pushing it back to the right using air
What is the equation for rate of respiration?
Distance / time = cm min-1
What is the equation for volume of CO2 consumed?
Pie r^2 x distance travelled / time = cm3 min-1
What is the equation for (volume of CO2 consumed or rate of respiration) per gram of organism?
Either equation / mass of organism = cm3 min-1 g-1
Why is apparatus left for 10mins before the respirometer experiment is done?
- to allow pressure changes to occur
- to equilibrate the temperature
- to allow rate of respiration to stabilise
What is the compensation point? What do plants need to do more of?
The point at which photosynthesis and respiration are occurring at the same rate
- plants need to be doing photosynthesis more
ALGAL BALLS DEMO
What is hydrogen carbonate indicator used for?
To supply a source of oxygen
