respiration Flashcards
Why can single cells respire anaerobically constantly? [3]
It produces toxic waste products which are expelled from the cell
- Protected by slime capsule
- Multi-cellular organism would have toxic waste accumulate in body
Cellular Respiration [2]
- Releases energy
- Takes place in all organisms all the time
How does Cellular Respiration work? [2]
- Food molecules are broken down to release energy
- Requires oxygen provided by exchange surface and vascular system in multi-cellular organisms
Breathing [2]
- Ventilation
- Provides oxygen and removes carbon dioxide
Aerobic Respiration [2]
- Requires oxygen
- Releases a relatively large amount of energy
Anaerobic Respiration [2]
- Respiration without oxygen
- Releasing a relatively small amount of energy
Aerobic Cellular Respiration [2]
- Humans respire mainly sugars (some amino acids and fatty acids)
- Net release of free energy (up to 38 ATP molecules)
Respiration Equation
Glucose + oxygen > Carbon dioxide + water + energy
Overview of the 4 stages of Respiration
Glycolysis
- Glucose splits into pyruvate
The link reaction
- Pyruvate is oxidised into acetate
The Krebs cycle
- Electrons are stripped off the acetate
The electron transport chain
- The energy in the electrons is used to produce ATP
What is NADH? [3]
- Respiration involves the removal of electrons from glucose molecules
- The energy in the electrons makes ATP
- NADH is an electron carrier
Where does each stage of Aerobic Respiration take place?
Glycolysis - Cytoplasm
Link Reaction & Krebs Cycle - Matrix
ETC - Inner membrane of mitochondria
Glycolysis [4]
- Substrate level phosphorylation
-2 ATP molecules add 2 phosphate groups to glucose - glucose phosphate splits into two triose phosphate (3C) molecules
- both TP molecules are oxidised (reducing NAD) to form 2 pyruvate molecules (3C)
- releases 4 ATP molecules
Link Reaction [4]
- Reduced NAD and pyruvate are actively transported to matrix
- pyruvate is oxidised to acetate (forming reduced NAD)
- carbon removed and CO2 forms
- acetate combines with coenzyme A to form acetylcoenzyme A (2C)
Krebs Cycle [2]
- Acetylcoenzyme A combines with 4C molecule to produce a 6C molecule - enters cycle
- oxidation-reduction reactions
produces :
6 reduced NAD
2 reduced FAD
2 ATP 4 carbon dioxide
Electron Transport Chain [10]
- NADH and FADH2 from glycolysis, link reaction and Krebs cycles are used
- A series of electron carriers are found in the cristae
- Electrons move from the hydrogen atoms carried by NADH and FADH2
to the first electron carrier - The electrons pass along the chain of carrier molecules, in a series of
oxidation-reduction reactions - As they move, energy is released
- This energy causes active transport of protons (H+) across the membrane into the mitochondrial inner membrane space
- This creates a chemiosmotic gradient
- Protons must move through ATP synthase
- As the protons diffuse through the ATP synthase, ATP is created from ADP and Pi
- The protons combine with the electrons and also oxygen to form water
- Oxygen is the final electron acceptor
Anaerobic Respiration [3]
- Occurs in the cytoplasm
- Aim is regenerating NAD
- NAD reduced in glycolysis so must be converted back to NAD to continue glycolysis
Anaerobic Respiration in plants and some microorganisms
Pyruvate + NADH → ethanol + carbon dioxide + NAD
Anaerobic Respiration in Animals
Pyruvate + NADH → lactate + NAD
Process of Anaerobic Respiration [3]
- Glycolysis
- NAD+ Regenration creates lactate and allows NAD+ to be used again in reaction
- Only releases 2 ATP, while aerobic reaction produces 38
Starvation [5]
- We obtain most of our energy by respiring food we have eaten recently
- Carbohydrate is our primary source of energy + small amounts of fat and protein
- Carbohydrate runs out after about a day
- Fat can only be respired when some carbohydrate
is still available - Must respire protein
Can lose 50% of protein before death occurs
How can Lipids be Respired? [3]
Hydrolysed to glycerol and fatty acids
Glycerol - phosphorylated and
converted into TP (then enters glycolysis)
Fatty acids - converted into 2C molecules, then acetyl CoA (then enters Krebs)
How can Proteins be Respired? [3]
- amino group removed from the amino acids,
- enter the chain depending on the carbon content
- 3C into pyruvate;
4C & 5C into Krebs
intermediaries
