Module 5.6 - Respiration Flashcards
Stages of aerobic respiration? (4)
- Glycolysis
- Link reaction
- Krebs cycle
- Oxidative phosphorylation
Ways of cell respiration? (2)
- Glucose respiration
- Organisms can also break down complex organic molecules which can be respired
Glycolysis? (5)
- A reaction series
- Takes place in cytoplasm of cells
- Splits one molecule of glucose (has 6Cs) into two smaller molecules of pyruvate (has 3Cs)
- Is the first stage of both aerobic and anaerobic respiration
- Doesn’t require oxygen to take place
Two stages of glycolysis? (5)
- Phosphorylation
- Oxidation
- ATP is used to phosphorylate glucose to TP
- TP is oxidised releasing ATP
- There’s a net gain of 2 ATP
Phosphorylation? (3)
- Glucose is phosphorylated - add 2 phosphates from 2 of ATP
- Creates 1 of hexose bisphosphate and 2 of ADP
- Hexose bisphosphate is split up into 2 of TP
Oxidation? (6)
- TP is oxidised and forms 2 of pyruvate
- NAD is reduced and forms 2 of NADH
- The same H+ oxidised from TP is used to reduce NAD
- 4 ATP are produced
- 2 ATP is used up in stage one
- Total net gain of 2 ATP
What happens to NADH and the two pyruvate molecules? (2)
- NADH is used in oxidative phosphorylation
- The two pyruvate molecules are actively transported into matrix of mitochondria for link reaction
Link reaction? (7)
- A reaction series
- Takes place in mitochondrial matrix
- Pyruvate is decarboxylated
- NAD is reduced by taking a hydrogen from pyruvate
- Pyruvate turns into acetate
- Acetate is combined with coenzyme A (CoA) to from acetyl coenzyme A (acetyl CoA)
- No ATP is produced
How is pyruvate decarboxylated? (1)
- One carbon atom is removed from pyruvate in the form of CO2
How many times does the link reaction and Krebs cycle take place? (3)
- Link reaction and Krebs cycle happen twice for every glucose molecule
- 1 of glucose enters glycolysis, 2 of pyruvate form
- For 1 of glucose, 2 of acetyl coenzyme A go into the Krebs cycle
For every 1 of glucose? (4)
- 2 of pyruvate form
- Two CO2 are released as a waste product of respiration
- Two of NADH are formed
- 2 of acetyl coenzyme A go into the Krebs cycle
Krebs cycle? (3)
- Involves a series of oxidation-reduction reactions
- Takes place in the matrix of the mitochondria
- Krebs cycle happen twice for every 1 of glucose
How is citrate formed? (3)
- Acetyl group from acetyl CoA combines with oxaloacetate to form citrate
- Catalysed by citrate synthase
- Coenzyme A goes back to the link reaction to be used again
How does the 6C citrate molecule convert to a 5C molecule? (3)
- Decarboxylation occurs - CO2 is removed
- Dehydrogenation occurs - hydrogen is removed
- The hydrogen is used to form NADH
How does the 5C citrate molecule convert to a 4C molecule? (6)
- 5C molecule is converted to a 4C molecule
- Intermediate compounds form
- Decarboxylation and dehydrogenation occur
- One of reduced FAD and two of NADH formed
- ATP is produced
- Citrate turns into oxaloacetate
How is ATP produced in the last step of the Krebs cycle? (1)
- The direct transfer of a phosphate group from an intermediate compound to ADP
Substrate-level phosphorylation? (1)
- When a phosphate group is directly transferred from one molecule to another
What are the products from one Krebs cycle and where do they go? (6)
- 1 coenzyme - reused in the next link reaction
- Oxaloacetate - regenerated for use in the next Krebs cycle
- 2 CO2 - released as a waste product
- 1 ATP - used for energy
- 3 NADH - to oxidative phosphorylation
- 1 reduced FAD - to oxidative phosphorylation
Oxidative phosphorylation? (3)
- Process where the energy carried by electrons is used to make ATP
- Uses the products of the previous stages - NADH and FADH
- Takes place in the inner mitochondrial membrane
Where is the energy carried by electrons from? (1)
- From reduced coenzymes NAD and FADH
Steps of oxidative phosphorylation? (10)
- NADH and FADH are oxidised to NAD and FAD
- H atoms are released from NADH and FADH
- H atoms splits into protons (H+) and electrons (e-)
- The electrons move along electron transport chain
- Electrons lose energy at each carrier
- The lost energy is used by electron carriers to pump H+ from mitochondrial matrix into intermembrane space
- The concentration of protons is higher in intermembrane space than in the mitochondrial matrix
- Electrochemical gradient formed and chemiosmosis occurs
- Chemiosmosis drives ATP synthesis
- At the end of the transport chain H+, e- and O2 from the blood combine to form H2O
Electron transport chain? (2)
- Made up of three electron carriers
- Located in the inner mitochondrial membrane
Adaptation of the inner mitochondrial membrane? (2)
- Folded into cristae
- Increases the membrane’s surface area to maximise respiration
Intermembrane space? (1)
- The space between the inner and outer mitochondrial membranes
What enzyme is responsible for moving H+ move down the electrochemical gradient? (1)
- ATP synthase
How much ATP is formed at the end of aerobic respiration? (7)
- Glycolysis: form 2 ATP, produces 2 ATP
- Glycolysis: form 2 NADH, produces 5 ATP
- Link reaction: form 2 NADH, produces 5 ATP
- Krebs cycles (x2): from 2 ATP, produces 2 ATP
- Krebs cycles (x2): from 6 NADH, produces 15 ATP
- Krebs cycles (x2): from 2 FADH, produces 3 ATP
- 32 of ATP formed in total
How much ATP is formed from NADH and FADH? (2)
- NADH: 2.5 ATP
- FADH: 1.5 ATP
Anaerobic respiration? (4)
- Doesn’t use oxygen
- Doesn’t involve the link reaction, the Krebs cycle or oxidative phosphorylation
- Take place in the cytoplasm
- Starts with glycolysis
Types of anaerobic respiration? (2)
- Alcoholic fermentation
- Lactate fermentation
Lactate fermentation? (3)
- Occurs in mammals and produces lactate
- Reduced NAD from glycolysis transfers hydrogen to pyruvate to form lactate and NAD
- NAD can then be reused in glycolysis
Why can glycolysis continue when there isn’t much oxygen? (3)
- The production of lactate regenerates NAD
- Glycolysis needs NAD in order to take place
- So a small amount of ATP can be produced to keep some biological process going
Lactate? (2)
- Our cells have a high tolerance for lactate for a short period of time
- Too much lactate is toxic and is removed from the cells into the bloodstream
How is lactate removed from the bloodstream? (2)
- The liver takes up lactate and converts it back into glucose
- Gluconeogenesis
Where does alcoholic fermentation take place? (2)
- Yeast cells
- Plants
Alcoholic fermentation in yeast cells? (3)
- CO2 is removed from pyruvate to form ethanal
- NADH from glycolysis transfers hydrogen to ethanal to form ethanol and NAD
- NAD is reused in glycolysis
Why is the ATP yield from anaerobic respiration lower than aerobic respiration? (2)
- Anaerobic respiration only includes glycolysis
- Glycolysis only produces 2 ATP per 1 of glucose
Why is there only one energy releasing reaction for anaerobic respiration? (2)
- Krebs cycle and oxidative phosphorylation need oxygen
- So they can’t occur during anaerobic respiration
What can cells respire? (4)
- Glucose
- Carbohydrates
- Lipids
- Proteins
At what stage can proteins and lipids enter respiration? (1)
- At the Krebs cycle
Respiratory substrate? (1)
- Any biological molecule that can be broken down in respiration to release energy
Respiratory values of respiratory substrates (in kJ/g)? (3)
- Lipids: 39.4
- Proteins: 17
- Carbohydrates: 15.8
Why do lipids produce the most ATP when respired? (4)
- Most ATP made in oxidative phosphorylation
- Requires H atoms from NADH and FADH
- Means the respiratory substrates that has more H atoms make more ATP to be when respired
- Lipids contain most H atoms per unit of mass
Respiratory quotient (RQ)? (3)
- Volume of carbon dioxide produced when that substrate is respired, divided by the volume of oxygen consumed, in a set period of time.
- RQ = V. CO2 released / V. O2 consumed
- Tells you the what substrate is respiring and how its respiring
RQ of respiratory substrates? (3)
- Lipids: 0.7
- Proteins: 0.9
- Carbohydrates: 1
Why do lipids and proteins have a RQ value lower than one? (1)
- More oxygen is needed to oxidise fats and lipids than to oxidise carbohydrates
How can you determine what substrate is respiring and how it’s respiring from its RQ? (4)
- Under normal conditions RQ is between 0.7 and 1.0
- RQ: 0.7 to 1.0 shows some lipids and carbohydrates are respiring
- Protein isn’t normally used for respiration unless there’s nothing else
- High RQs greater than 1 show oxygen deficiency - anaerobically & aerobically respiration takes place
Why do plants have a low RQ? (1)
- CO2 released in respiration is used for photosynthesis
