Respiration Flashcards
Why do organisms need to respire
Produces ATP
AT against concentration gradient
Metabolic reactions
Muscle contraction
Describe the structure of a mitochondrion
Surrounded by double membrane
Folded inner membrane forms Cristae, sire of electron transport chai.
Fluid matrix: contains mitochondrial DNA, respiratory enzymes, lipids and proteins
Name the 4 main stages in aerobic respiration and where they occur
Glycolysis: cytoplasm
Link reaction: mitochondrial matrix
Krebs cycle: mitochondrial matrix
Oxidative phosphorylation: via electron transfer chain: membrane of Cristae
Outline the stages of glycolysis
Glucose is phosphorylated to hexose bisphosphate by 2 ATP
Hexose bisphosphate splits into 2TP
2 x TP is oxidised to 2 x pyruvate
Net gain: 2 reduced NAD and 2 ATP
How does pyruvate from glycolysis enter the mitochondria
Active transport
What happens during the link reaction
Oxidation of pyruvate(3C) to acetate(2C): decarboxylation and 2 H atoms (used to reduce 1 x NAD)
Acetate combines with coenzyme A to form acetyl coenzyme A
What is the summary equation for the the link reaction
Acetyl Co A+reduced NAD+co2
What happens in the Krebs cycle
Series of redox and enzyme controlled reactions that produces:
ATP by substrate level phosphorylation
Reduced coenzymes
CO2 from decarboxylation
Acetyl coA (2c) reacts with oxaloacetate (4c).
Cycle regenerates oxaloaceteate
Outline the stages of the Krebs cycle
Acetyl coA delivers an acetyl group in the cycle. 2C acetyl group combines with 4 carbon oxaloacetate to form 6c citrate
6c undergo dehydrogenation giving off reduced NAD and decarboxylation = c. 5 carbon compound formed
Undergoes further dehydrogenation and decarboxylation, regen 4c
What is the electron transport chain
Series of carrier proteins embedded in membrane of the Cristae mitochondrial of mitochondria
Produces ATP through oxidative phosphorylation via chemiosmosis
What happens in the ETC
Electrons released from reduced NAD and Fad undergo successive redox reactions
Oxygen acts as final electron acceptor
How does chemiosmosis produce ATP during aerobic respiration
ETC helps with the active transport of H+ ions from mitochondrial matrix into inter membrane space
H+ ions move down concentration gradient into matrix via channel protein ATP synthase
ATP synthase catalyses ADP+ pi-> ATP
Describe the process of phosphorylation and dehydrogenation
Removal of hydrogen atoms to form two pyruvate molecules
Adding a phospahte to glucose = hexose bisphosphate
Explain how NAD acts as a coenzyme in glycolysis
NAD coenzymes accept the removed hydrogens = 2 reduced NAD
Describe the process of dehydrogenation and phosphorylation
Removal of hydrogen from triose phopshate molecules to form pyruvate and reduction of NAD/ formation of reduced NAD
P- addition of phosphate group to a glucose molecule forming hexose bisphospahte
Explain how NAD act as a coenzyme in glycolysis
NAD accepts hydrogen and is reduced during the formation of pyruvate, supplies hydrogen to enzyme involved in later stage of respiration
Explain the meaning of substrate level phosphorylation
Addition of phosphate group to ADP for the formation of ATP
Outline the importance of dehydrogenation and phosphorylation in glycolysis
Dehydrogenation - hydrogen removed in breakdown of glucose, required at a layer stage
Phosphorylation- addition of phosphate groups destabilise large molecule
Explain why the removal of carbon dioxide in the link reaction is called oxidative
Hydrogen is also removed, removal of hydrogen oxidises pyruvate
Name one organic compound and one inorganic compound produced in the link reaction
Acetyl group and carbon dioxide
Suggest why glycolysis occurs in the cytoplasm but not in the mitochondrial matrix
Enzymes required are in the cytoplasm
Glucose molecule too large to move into mitochondrion
No transport proteins for pyruvate
Compare the structures of ATP and NAD
ATP- three phosphate groups, one ribose, one nitrogenous base
NAD - 2 phosphate groups, 2 ribose, two nitrogenous bases
Explain why ATP can be considered a co enzyme
It links reaction
Energy is releases as a result of the activity of one enzyme and used by another enzyme
Suggest why the Krebs cycle is termed aerobic
Hydrogen needs to be removed for cycle to continue, hydrogen removes using NAD/FAD and reduced
Oxygen required for electron transport
Explain why hydrogen have to be actively pumped across the membrane from the matrix and return to the matrix but diffusion through ATP synthase
Actively pumped to increase concentration gradient, energy required as moving from low to high concentration
Explain why the electrons released from reduced FAD lead to the synthesis of less ATP than the electrons released from reduced NAD
Reduced NAD releases electrons to carriers at the START of the ETC
Reduced FAD releases electrons to carriers AFTER the start of the etc
FAD electrons transported a shorter distance so fewer protons are actively transported
Describe why alcoholic fermentation can be described as having more in common with aerobic respiration than with fermentation E
ETC present in some types of anaerobic respiration , aerobic respiration include presence of ETC, no ETC present in lactate fermentation
Explain why the build up of lactic acid eventually stops muscle contraction when we experience fatigue
Increase in lactic acid -> decrease in pH
muscle contraction depend on enzymes, decreasing pH denatures protein
No longer functional
Outline the benefits to RBC and cardiac muscle of different types of respiration they undertake
RBC adapted to carry oxygen, lack of mitochondria means more space for haemoglobin, increased oxygen transport
Outline the respiratory pathway of a triglyceride
Triglyceride is broken down into fatty acids and glycerol, fatty acids undergo beta oxidation forming acetyl groups, acetyl groups are taken into Krebs cycle by coenzyme A, glycerol is converted to pyruvate which undergoes oxidative phosphorylation
Describe the difference between a respirometer and a spirometer
Both measures oxygen uptake/carbon dioxide releases, so rate of respiration, respirometer is modified spirometer usually for smaller organism
