Respiration Flashcards
What is respiration?
Process where energy stored in complex organic molecules is used to make ATP, occurs in living cells
What is energy?
Potential is storage, kinetic is energy of movement, moving molecules have KE that allows them to diffuse down concentration gradient. Large organic molecules contain chemicals potential energy. Energy cannot be created or destroyed only transferred, has many firms
Which is an anabolic reaction?
Biochemical reactions where large molecules are synthesised from smaller ones
What is catabolic reactions?
Biochemical reactions where larger molecules are hydrolysed to produce smaller ones
What metabolic processes require energy?
Active transport Secretion by exocytosis Endocytisis Synthesis of large molecules from smaller ones Replication of DNA and organelles Movement Activation of chemicals
What is a by product of catabolic reactions?
Release of energy as heat, useful as metabolic reactions controlled by enzymes, so temperature needs to be maintained
Where does energy come from?
Photoautotrophs use sunlight energy in photosynthesis to make large organic molecules that contain chemical potential energy, then available to others, respiration releases the energy, used to phosphorylate ADP to ATP, transfers energy to molecule
What is ATP?
Phosphorylated nucleotide, high energy intermediate in all cells, consisted of adenosine (adenine and ribose sugar) plus three phosphate groups. Can be hydrolysed to ADP and Pi releasing 30.6kj per mol, so energy available in small amounts, not wasted or damaging to the cell
What happens in the steps of respiration in terms of ATP
Energy released at each stage joins ADP and Pi to make ATP, it is continually hydrolysed and resynthesised, hydrolysis of ATP couples with synthesis reactions that require energy
What is a coenzyme?
Small non protein molecule that attaches to active site, just before or as substrate binds, take part in reactions and are changed, but recycled back to take part in faction again. Role is to carry chemicals between enzymes so link enzyme controlled reactions that are in a chain
What are the four stages of respiration?
Glycolysis
Link reaction
Krebs cycle
Oxidative phosphorylation
Where do stages of reputation occur?
Glycolysis in cytoplasm of cells
Link and kerbs in matrix of mitochondria
Oxidative phosphorylation in cristae of mitochondria
Last three must be under aerobic conditions
What is NAD?
Organic, non protein molecule that helps dehydrogenase enzymes carry out oxidation reactions, nicotiana mode adenine dinucleotide, made from nicotinamide, ribose, adenine and two phosphate groups. nicotinamide can accept hydrogen atoms, to become reduced, oxidised when it looses them
What is NAD?
Organic bin protein molecule that helps dehydrogenase enzymes carry jut co enzymes are needed to help the reactions, h combined with coenzyme, reduced, and they carry hydrogen atoms which are later split to protons and electrons, to the inner mitochondrial membranes where they are involved in oxidative phosphorylation to produce ATP, coenzymes then recycled
Where is NAD used?
Glycolysis, link reaction, Krebs cycle and in anaerobic pathways
What is Coenzyme A?
Made from panthothebjc acid, adenosine, three phosphate groups and cysteine
What is the role of CoA?
Carry acetyl(ethanoate) groups made from our hate in link reaction onto the Krebs cycle, can also carry acetate groups made from fatty acids or amino acids. Makes acetyl coenzyme A
Why are alcoholics deficient in NAD?
Dehydrogenation of alcohol by dehydrogenase enzymes (ethanol>ethanal>ethanoic acid) hydrogens released combined with NAD so less available for respiration
Why is NAD a nucleic acid derivative?
Contains ribose sugar, nitrogenous base adenine, and phosphate groups
What is glycolysis?
Is a metabolic pathway where each glucose molecule is broken down to two molecules of pyruvate, occurs in cytoplasm of all living cells and is common to anaerobic and aerobic respiration
What is stage 1 of glycolysis?
Phosphorylation
Glucose is hexose sugar, stable molecule and needs to be activated so can be split
ATP hydrolysed, phosphate group released attached to carbon 6 on glucose, the glucose 6P changed to fructose 6P, isomers. Another ATP is hydrolysed phosphate attached to C1 of fructose to make fructose 1,6 bisphosphate energy from hydrolysed ATP used to activate hexose sugar and stops it moving out of cell- hexose 1,6 bisphosphate. Two ATP molecules are used
What is stage 2 of glycolysis?
Each hexose molecule split into two molecules of triose phosphate
What is stage 3 of glycolysis?
Oxidation as two hydrogen atoms are removed with dehydrogenase enzymes, aided by coenzyme NAD, a hydrogen acceptor to give reduced NAD,
At this stage time I molecules if NAD reduced per molecule of glucose
Two molecule of ATP are formed, substrate level phosphorylation
What is stage 4 of glycolysis?
Four enzyme catalysed reactions convert each triose phosphate to molecule of pyruvate, 3c compound, two molecules if ATP made by substrate level phosphorylation
What are the products of glycolysis?
Two molecules of ATP- 4 made but 2 used
Two molecules if reduced NAD
Two molecules of pyruvate, actively transported into mitochondrial matrix for link reaction, not in anaerobic conditions
What happens to hydrogens removed from triose phosphate?
Accepted by NAD to reduced NAD, cried indirectly to inner mitochondrial membranes and used to generate more ATP in oxidative phosphorylation
Which stage is ATP used?
Stage 1, to activate glucose, two molecule used.
Where is ATP produced?
Stage 3 and 4, 4 molecules made by substrate level phosphorylation, but 2 net production
Where is NAD used?
Stage 3, oxidation of triose phosphate
At which stage are isomerise enzymes used?
Stage 1, glucose 6P to fructose 6P
How does the fact that all living things use glycolysis support evolution?
Pathway evolved s long time ago in early life forms, remained in all cell types as new species formed
What is the sequence of molecules in glycolysis?
Glucose Glucose6phosphate Fructose6phosphate Hexose1,6biphosphate Triose phosphate Intermediate Pyruvate
What are mitochondria?
Organelles found in eukaryotes cells, sites of the link reaction, Krebs cycle and oxidative phosphorylation, aerobic stages
Describe the structure of mitochondria
Envelope
Inner membrane folded into cristae to increase SA
Intermembrane space separate compartments in mitochondrion
Matrix, gel consisting of mixture of proteins, lipids and looped DNA and ribosomes
Where are mitochondria found?
Metabolically active cells have more mitochondria, usually longer in muscle cells, denser cristae to house more electron transport chains, and more ATP synthase enzymes. Lots in liver cells, can be moved around by cytoskeleton, or positioned near areas of high ATP demand such as synaptic knob
How does matrix allow mitochondria to carry out its function?
Enzymes for reactions Molecules if coenzyme NAD Oxaloacetate, for link reaction Mitochondrial DNA to code for mitochondrial enzymes Mitochondrial enzymes for proteins
How does outer membrane allow mitochondria to carry out its function?
Channel proteins that allow passage of pyruvate molecules
How does inner membrane allow mitochondria to carry out its function?
Differ f lipid composition so impermeable to small ions
Folded into cristae for SA
Electron carriers and ATP synthase embedded
What arête electron carriers in the inner membrane?
Enzymes associated with co factor that can accept and donate electrons, fe can be reduced and oxidised, they are oxidoreductase enzymes, some have coenzymes that pumped protons from Madrid into Intermembrane space, membrane impermeable so protons accumulate
What are ATP synthase enzymes?
Large and protrude from inner membrane until matrix, stalked particles, that allow protons to pass through them down proton gradient into matrix, chemiosmosis, which generates proton motive force, yo Phosphorylated ADP to ATP.
Coenzyme FAD
Coenzyme FAD is reduced in Krebs cycle, bound to dehydrogenase enzyme in inner membrane,?hydrogens pass back into mitochondrial matrix, not across membrane
What is the link reaction?
Converts pyruvate to acetate, NAD is reduced
What happens to pyruvate after glycolysis?
Transported across envelope into the matrix, changed th two carbon acetate
What happens in the link reaction?
Decarboxylation and dehydrogenation of pyruvate to acetate,
2 pyruvate +2NAD + 2CoA»_space; 2Co2 + 2 redNAD + 2 acetylCoA
What enzymes catalyse link reaction?
Pyruvate dehydrogenase, removed pyruvate
Pyruvate Decarboxylase, removes carboxyl group that become CO2
Coenzyme NAD accepts hydrogen atoms
CoA accepts acetate to carry it to Krebs cycle
What is the Krebs cycle?
Oxidised acetate to Co2 . NAD and FAD are reduced, ATP made by substrate level phosphorylation in mitochondrial matrix
What is produced by Krebs cycle?
Two molecules of ATP
3 reduced NAD
1 reduced FAD
Describe steps of Krebs cycle
Acetate offloaded fron coenzyme A and joins with 4C oxaloacetate to form 6C citrate
Citrate Decarboxylase and dehydrogenase a to form 5C, carbon dioxide removed, hydrogen accepted by NAD
5 carbon compound Decarboxylase and dehydrogenase a ti 4C, reduced NAD
4 C changed into another 4C, ADP Phosphorylated to ATP
4C changed into another 4C, hydrogen removed to reduce FAD
4C dehydrogenase to oxaloacetate, NAD produced
What is the sequence of molecules in Krebs cycle?
Oxaloacetate + acetate Citrate 5C and Co2 and NAD 4C and Co2 and NAD 4C and ATP 4C and FAD Oxaloacetate and NAD
How many cycles per glucose?
2, as two phruvate made
What is oxidative phosphorylation?
Formation of ATP by adding phosphate group to ADP presence of oxygen, which is final electron acceptor
What is involved in final stage of reputation?
Electron carriers in inner membrane, folded into cristae, increasing SA, reduced NAD FAD are deoxidised when they donate hydrogen to electron carrier, split into protons and electrons
First electron carrier is NADH, coenzyme Q reductase
Protons go into solution in matrix
What is the role of electron transport chain?
Electrons passed among carrier and then donated to molecular oxygen the final acceptor
What is chemiosmosis?
Diffusion of ions through partially permeable membrane, flow of protons m, genararoon of ATP, in respiration
How does chemiosmosis occur in mitochondria?
Electrons flow along transport chain, energy released used by coenzymes if carriers that pump protons across to Intermembrane space, builds Ho proton gradient, potential enemy build up in Intermembrane space as hydrogen ions cannot diffuse across, but can flow through ion channels associated with ATP synthase, flow is chemiosmosis
How does oxidative phosphorylation happen?
Protons flow through ATP synthase, drive rotation part of enzyme to join phosphate to ADP, electrons passed from last electron carrier to molecular oxygen, final acceptor, hydrogen ions also join it to produce water
How much ATP is made before oP?
2 in glycolysis, 2 in Krebs
How much made in oxidative phosphorylation?
FAD AND NAD provide eke find to chain, and hydrogen from NAD for proton build up, FAD stay in matrix, used to generate water. 10 molecules of ATP can produce 26 mil of ATP
Yield should be 30 ATP
Why is yield of ATP less than theoretical?
Some protons leak across mitochondrial membrane, so less for proton motive force
SomeAto used to actively reasons pyruvate into mitochondria
Some used to bring hydrogen from NAD in glycolysis into mitochondria
How does low pH in Intermembrane space support the chemiosmosis theory?
Indicates high concentration of protons
How does more negative potential in matrix side of inner membrane support the chemiosmosis theory?
Indicates electrochemical gradient, more positive in membrane so matrix more negative
How does no ATP made in mitoblasts support the chemiosmosis theory?
No outermembrane so no Intermembrane space for proton buildup
How does no ATP removed in headpiece removed from stalked particles support the chemiosmosis theory?
No ATP synthase, so no phosphorylation can take place
How does no ATP made with oligomycin support the chemiosmosis theory?
Blocks flow if protons through synthesis
What is anaerobic respiration?
Release if energy from substrates in the absence of oxygen
What happens when there is no oxygen?
Oxygen is final electron acceptor, so if no oxygen, electron transport chain cannot function, so Krebs cycle and link reaction also stop, only anaerobic process is glycolysis as source of ATP, so red NAD has to be reoxidised so it can keep operating
What is anaerobic respiration in animals?
Lactate fermentation, pyruvate is hydrogen acceptor, reduced to form lactate, reduced NAD is reoxidised, so can accept more hudrogen from glucose and glycolysis can continue
Catalysed by lactate dehydrogenase
What happens to the lactate?
Carried away in blood from muscles to liver, converted back to pyruvate when oxygen is available, can enter Krebs cycle via link reaction , or may be recycled to glucose and glycogen.lactate causes reduction in pH that reduces enzyme activity in muscles
What is anaerobic respiration in fungi?
Pyruvate converted to ethanal by Decarboxylase enzyme,
First each loses a CO2 molecule, to ethanal, then it accepts hydrogen from NAD, to form ethanol, catalysed by ethanol dehydrogenase. NAD can now go back to glycolysis
What is yeast?
Facultative anaerobe, can live without oxygen, however will die if concentration of ethanol builds up to 15%, but rate of growth faster in aerobic conditions, so oxygen initially used in brewing
Why is aneroid respiration in animals was wasteful?
Lactate can be recycled back to pyruvate, ethanol not recycled or respired
What is a respiratory substrate?
An organic substance that can be used for respiration
How is majority of ATP made?
Produced during oxidative phosphorylation when protons flow though channel associated with ATP synthase on inner mitochondrial membrane, the more protons, the more ATP is made, more oxygen required to respire that substrate
What is generally respired?
Carbohydrates, stored as glycogen in animals, actual trill of ATP is 30 per mole, remaining energy released as heat
How are proteins respired?
Deamination if amino acids, to make Keto acid, can changed to glycogen or passed into Krebs cycle or converted to pyruvate, respired when starving, fasting or exexsrcise, proteins hydrolysed to amino acids, more hydrogens that carbohydrates
How are lipids respired?
Triglycerides hydrolysed by lipase to fatty acids and glycerol, can be converted to glucose and respired. Fatty acids cannot be, lots of hydrogens present, combined with CoA, requires ATP hydrolysis, complex transported to matrix, broken down to twoC acetyl groups, reduced NAD and FAD formed, acetyl can enter Krebs cycle to generate 3NAD and 1 FAD per molecule. NAD reoxidised at electron transport chain
What are the energy values?
Carbs 15.8
Lipid: 39.4
Protein 17
