Cellular Respiration Flashcards
Compare the structure of a chloroplast and a mitochondrion in relation to function [AHL].
8 marks
Similarities:
- both are double membrane organelles
- both contain DNA
- both contain ribosomes
- both have an electron transport chain
- both produce ATP by chemiomosis
- both contain ATP synthase /ATPase
Only Chloroplast:
- site of photosynthesis
- third membrane system / thylakoid membranes
- photosynthetic pigments/chlorophyll to absorb light
- light generated ATP production
- H+ gradient across thylakoid membrane
Only Mitochondrion:
- site of respiration
- ATP production by oxidation of organic molecules / fats / amino acids
- H+ gradient across inner membrane
Outline the process of glycylosis [AHL].
5 marks
- occurs in cytoplasm;
- hexose is phosphorylated using ATP;
- hexose phosphate is split into two triose phosphates;
- oxidation by removal of hydrogen; (do not accept hydrogen ions/protons)
- conversion of NAD to NADH (+H+);
- net gain of two ATP / two ATP used and four ATP produced;
- pyruvate produced at the end of glycolysis;
Draw the structure of a mitochondrion as seen in an electron microscope [Core].
5 marks
- outer membrane
- intermembrane space / outer compartment
- inner membrane
- matrix
- cristae
- ribosome
- naked / circular DNA
- ATP synthase
Explain how the structure of the mitochondrion allows it to carry out its function efficiently [AHL].
8 marks
- membranes to compartmentalise / separate from processes in the cytoplasm
- small size gives large surface area to volume ratio
- large surface area to volume ratio allows rapid uptake / release of materials
- matrix contains enzymes of the **Krebs cycle **/ matrix carries out Krebs cycle
- inner membrane invaginated / infolded / forms cristae to increase the surface area
- large surface area gives more space for electron transport chain / oxidative phosphorylation
- inner membrane contains ATP synthetase / ATPase / stalked particles that make ATP
- (narrow) gap between inner and outer membranes / intermembrane space ( must be stated or labeled)
- pH / H+ / proton concentration gradient rapidly established / steeper
- chemiosmosis therefore more efficient / chemiosmosis can occur
- inner membrane contains the electron transport pathway
- DNA present to act as genetic material
- ribosomes for protein synthesis
- some proteins do not need to be imported
Explain the reactions that occur in the matrix of the mitochondrion that are part of aerobic respiration [AHL].
8 marks
KREB’S CYCLE:
- pyruvate is decarboxylated/ CO2 removed
link reaction/ pyruvate combined with CoA/ ethanoyl/acetyl CoA formed
- pyruvate is oxidized/ hydrogen removed
- reduction of NAD/ formation of NADH + H+
- whole coversion called oxidative decarboxylation
Krebs cycle
C2 + C4 —> C6
C6 —> C5 giving off CO2
C5 —> C4 giving off CO2
hydrogen atoms removed collected by hydrogen-carrying molecules (NADH, FADH2)
ATP formed by substrate level phosphorylation
oxygen accepts electrons/ oxygen combines with hydrogen
total yield per ONE GLUCOSE of Krebs cycle =
4 CO2,
6 NADH + H+,
2 FADH2,
2 ATP (directly produced)
6 NADIA for respiration. 2 fibola
Explain the process of aerobic respiration [AHL].
8 marks
- by glycolysis, glucose is broken down into pyruvate (two molecules) in the cytoplasm
with a small yield of ATP/ net yield of 2 ATP
and NADH + H+/ NADH
link reaction:
- aerobic respiration in the presence of oxygen
pyruvate converted to acetyl CoA
Krebs Cycle:
- by **oxidative decarboxylation **/ NADH and CO2 formed
fatty acids / lipids converted to acetyl CoA
acetyl groups enter the Krebs cycle (accept acetyl CoA)
Krebs cycle yields a small amount of ATP/ one ATP per cycle and FADH2/ FADH + H+/ NADH /NADH
ETC:
+ H+/ reduced compounds/ electron collecting molecules
these molecules pass electrons to electron transport chain (reject donates H+)
oxygen is final electron acceptor/ water produced
electron transport chain linked to creation of an electrochemical gradient
electrochemical gradient/ chemiosmosis pwers creation of ATP
through ATPase/synthase/synthetase
Outline the role of oxygen in providing cells with energy [AHL].
6 marks
- needed for aerobic (but not anaerobic) resp./simple equation for aerobic resp.
- used in oxidative phosphorylation
- **oxygen accepts electrons **at the end of the ETC
- also accepts protons to** form water** / water formed using oxygen
- allows more electrons along the ETC
- allows NAD to be regenerated / reduced NAD to be oxidised
- allows ATP production
- allows a **high yield of ATP **from glucose in respiration / 32-38 instead of 2
Explain how chemiosmosis assists in ATP production during oxidative phosphorylation [AHL].
9 marks
- occurs during aerobic respiration;
- oxidative phosphorylation occurs during the electron transport chain;
- hydrogen/electrons are passed between carriers;
releasing energy; - finally join with oxygen (to produce water);
- occurs in cristae of mitochondria;
- chemiosmosis is the movement of protons/hydrogen ions;
- protons move/are moved against their concentration gradient;
- into the space between the two membranes;
- protons flow back to the matrix;
- through the ATP synthase/synthetase (enzyme);
energy is released which produces more ATP/combines ADP and Pi;
Explain the similarities and differences in anaerobic and aerobic cellular respiration [Core].
8 marks
- aerobic requires oxygen and anaerobic does not utilize oxygen
Similarities: 3 max
- both can start with glucose
- both use glycolysis
- both produce ATP/energy(heat)
- both produce pyruvate
- carbon dioxide is produced
- (both start with glycolosis) aerobic leads to Krebs’ cycle and anaerobic leads to fermentation
differences: 5 max
Differences
Anaerobic:
- (fermentation) produces lactic acid in humans
- (fermentation) produces ethanol and CO2 in yeast
- occurs in cytoplasm of the cell
- recycles NADH (NAD+)
Aerobic cellular respiration:
- pyruvate transported to mitochondria
- further oxidized to CO2 and water (in Krebs cycle)
- produces a larger amount of ATP (36-38 ATP)/anaerobic produces less ATP (2)
- can use other compounds / lipids / amino acids for energy
Describe the central role of acetyl (ethanoyl) CoA in carbohydrate and fat metabolism [AHL].
5 marks
- acetyl CoA enters Krebs cycle
- glucose / carbohydrates converted to pyruvate in glycolysis
- pyruvate enters mitochondria
pyruvate converted to acetly CoA
by oxidative decarboxylation / hydrogen and CO2 removed - fats enter mitochondria
- fats oxidised to acetyl CoA / oxidation of fatty acids / fats converted to acetyl CoA
