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Flashcards by Zoe Mitchell, updated more than 1 year ago
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Created by Zoe Mitchell
almost 8 years ago
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| Question | Answer |
| What is the need for the cellular respiration? | Releases energy in organic molecules and immediately used to synthesise ATP from ADP and Pi to drive biological processes. |
| What biological processes are driven by ATP? | Active transport Endocytosis and exocytosis Cell division DNA replication Movement |
| Explain the structure of ATP | ATP is a phosphorylated nucleotide consisting of adenine, five carbon sugar ribose and three phosphate groups. |
| How does ATP release energy? | when it is hydrolysed |
| Which cells are mitochondria present in? | all eukaryotic cells |
| Length of mitochondria | 2 - 5 um |
| Name 4 features of mitochondria | inner & outer phospholipid membrane make up the mitochondrial envelope Cristae Intermembrane space Mitochondrial matrix |
| What makes up the mitochondrial envelope? | Inner and outer phospholipid membrane |
| cristae | inner highly-folded mitochondrial membrane which contain electron carriers and ATP synthase enzymes |
| intermembrane space | space between the inner and outer mitochondrial membranes |
| mitochondrial matrix | fluid-filled inner part of mitochondria where the link reaction and Krebs cycle takes place |
| What does the mitochondrial membrane contain? | mitochondrial ribosomes, mitochondrial DNA, enzymes for the link reaction and Krebs cycle, coenzymes NAD and FAD and oxaloacetate |
| oxaloacetate | 4C compound that accepts acetyl group from the link reaction |
| Draw a mitochondrion | |
| glycolysis | first stage or respiration which converts glucose to pyruvate, which occurs in the cytoplasm |
| NAD | nicotinamide adenine dinucleotide, a coenzyme . Each NAD can accept two hydrogen atoms to become reduced NAD. |
| Role of NAD in glycolysis | a coenzyme which help dehydrogenase enzymes to oxidise triose phosphate by removing the hydrogen atoms. Each NAD can accept two hydrogen atoms to become reduced NAD. |
| Role of reduced NAD in aerobic resiration | Reduced NAD carriers protons and electrons from glycolysis, to cristae so they can be used in oxidative phosphorylation. |
| 3 stages of glycolysis | Phosphorylation of glucose to hexose bisphosphate Lysis of hexose bisphosphate to triose phosphate Oxidation of triose phosphate to pyruvate |
| Explain phosphorylation in glycolysis | 1st stage of glycolysis. ATP is hydrolysed and the released phosphate group is added to glucose making hexose monophosphate. Another ATP is hydrolysed and the released phosphate group is added to hexose monophosphate making hexose bisphosphate. |
| Hexose bisphosphate is made during the first stage of glycolysis. What happens next? | Hexose bisphosphate is split into two molecules of triose phosphate |
| What happens to triose phosphate in glycolysis? | Triose phosphate is oxidated to become pyruvate. Dehydrogenase enzymes remove hydrogens from triose phosphate and 2 molecules of NAD accept the hydrogens and become reduced NAD. Four molecules of ATP are produced from ADP and Pi. |
| Products of glycolysis for 1 glucose molecule | 2 ATP (4 produced, but 2 needed for the initial phosphorylation step) 2 reduced NAD 2 pyruvate |
| Draw a diagram to explain glycolysis. | |
| Where does the link reaction occur? | mitochondrial matrix |
| Where does glycolysis occur? | cell cytoplasm |
| What is the reaction after glycolysis in aerobic respiration called? | link reaction |
| Explain the link reaction. | Pyruvate is decarboxylated and dehydrogenated, catalysed by pyruvate dehydrogenase enzyme, producing 1 molecule of carbon dioxide, combining 1 molecule of coenzyme A with the acetyl group making acetyl CoA and reducing NAD to reduced NAD |
| Role of acetyl CoA | carries the acetyl group from the link reaction to the Krebs cycle |
| For every molecule of glucose, what does the link reaction produce? | For every molecule of glucose, two molecules of pyruvate produce 2 CO2, 2 red NAD and 2 acetyl CoA in the Link reaction. |
| Draw a summary diagram of the link reaction | |
| What happens in aerobic respiration after the link reaction? | Krebs cycle |
| Where does the krebs cycle occur? | mitochondrial matrix |
| Explain the krebs cycle. | Acetyl group (2C) combines with oxaloacetate (4C) to produce citrate (6C) Citrate (6C) is decarboxylated and dehydrogenated to form a 5C compound, 1 molecule of CO2 and 1 molecule of red NAD The 5C compound is decarboxylated and dehydrogenated to form a 4C compound, 1 molecule of CO2 and i molecule of red NAD The 4C compound undergoes substrate-level phosphorylation, producing 1 molecule of ATP The 4C compound is dehydrogenated to form a different 4C compound and 1 molecule of red FAD The 4C compound is dehydrogenated to form red FAD and oxaloacetate. |
| For every molecule of glucose, the krebs cycle produces ....... | For every molecule of glucose, the Krebs cycle produces 6 red NAD, 2 red FAD, 4 CO2 and 2 ATP |
| Draw a diagram of the Krebs cycle | |
| Oxidative phosphorylation | the last stage of aerobic respiration which involves the formation of ATP using energy released in the electron transport chain and in the presence of oxygen |
| Where does oxidative phosphorylation occur? | In the mitochondria |
| What structures does oxidative phosphorylation involve and where are they? | Takes place in the mitochondria, involving electron transport chains and ATP synthase enzymes which are both embedded in the inner mitochondrial membranes |
| Chemiosmosis | flow of protons, down their concentration gradient, across a membrane, through a channel associated with ATP synthase |
| Explain oxidative phosphorylation. | 1. Red NAD and red FAD deliver hydrogen atoms to the electron transport chain and are reoxidised 2. Hydrogen atoms are split into protons and electrons 3. Electrons pass along a chain of electron carriers which releases some energy 4. Protons are pumped across the inner mitochondrial membrane into the inner membrane space 5. Protons accumulate in the intermembrane space and a proton gradient forms. 6. Protons diffuse down concentration gradient through protein channels associated with ATP synthase enzymes, which allows ADP and PI to combine to form ATP. This is chemiosmosis. 7. Oxygen combines with electrons from the electron transport chain and protons from ATP synthase channel to form water |
| First step of oxidative phosphorylation | Red NAD and red FAD deliver hydrogen atoms to the electron transport chain and are reoxidised |
| What happens to the hydrogen atoms in oxidative phosphorylation once they leave red NAD and red FAD? | split into protons and electrons |
| Once hydrogen is split into protons and electrons in oxidative phosphorylation, what happens to the electrons? | Electrons pass along a chain of electron carriers which releases some energy |
| Once hydrogen is split into protons and electrons in oxidative phosphorylation, what happens to the protons? | Protons are pumped across the inner mitochondrial membrane into the inner membrane space. Protons accumulate in the intermembrane space and a proton gradient forms. Protons diffuse down concentration gradient through protein channels associated with ATP synthase enzymes, which allows ADP and PI to combine to form ATP. This is chemiosmosis. |
| What is the final stage of oxidative phosphorylation? | Oxygen combines with electrons from the electron transport chain and protons from ATP synthase channel to form water |
| Explain chemiosmosis in oxidative phosphorylation. | 4. Protons are pumped across the inner mitochondrial membrane into the inner membrane space Protons accumulate in the intermembrane space and a proton gradient forms. Protons diffuse down concentration gradient through protein channels associated with ATP synthase enzymes, which allows ADP and PI to combine to form ATP. This is chemiosmosis. |
| 1 molecule of glucose in oxidative phosphorylation produces .... | 28 molecules of ATP |
| Draw a table of the stages of aerobic respiration, what the products are in each stage and how many ATP molecules this makes. | |
| 1 molecule of glucose theoretically produces ____ ATP molecules | 32 |
| Why isn't the yield of ATP as high as the theoretical yield for aerobic respiration? | some ATP used to actively transport pyruvate into mitochondria some ATP used to transport red NAD (made during glycolysis) into mitochondria some protons may leak out through outer mitochondrial membrane |
| Explain why aerobic respiration can't occur without oxygen. | Oxygen can't accept electrons at the end of oxidative phosphorylation and protons diffusing ATP synthase channels can't combine with oxygen. Concentration of protons in matrix increases and reduces proton gradient across inner mitochondrial membrane. Oxidative phosphorylation stops. Red NAD and red FAD are able to donate electrons to the electron transport chain. Krebs cycle and link reaction stops |
| Can glycolysis occur without oxygen? | yes, red NAD generated (during oxidation of triose phosphate to pyruvate) has to be reoxidised in a different way other than the electron transport chain. |
| How can red NAD be reoxidised without aerobic respiration? | Fungi & plants use the ethanol fermentation pathway Mammals use the lactate fermentation pathway |
| What are the anaerobic respiration pathways? For which organisms? | Fungi & plants use the ethanol fermentation pathway Mammals use the lactate fermentation pathway |
| Explain what the products are of anaerobic respiration and which stage of respiration they came from. | Anaerobic respiration only produce a net gain of 2 ATP. Neither ethanol or lactate fermentation produce ATP, but they allow glycolysis to continue which produces net 2 ATP per glucose |
| Explain the ethanol fermentation pathway. | Pyruvate from glycolysis is decarboxylated producing 1 CO2 and ethanal, catalysed by pyruvate decarboxylase enzyme. Ethanal accepts hydrogen atoms from red NAD forming NAD and ethanol, catalysed by ethanol dehydrogenase enzyme. Ethanal is reduced and red NAD is oxidised. |
| Explain the lactate fermentation pathway. | Pyruvate accepts hydrogen atoms from red NAD to form lactate, catalysed by lactate dehydrogenase. Red NAD has been oxidised and therefore glycolysis can continue to make ATP. |
| Draw a diagram to explain the lactate fermentation pathway. | |
| Draw a diagram to explain the ethanol fermentation pathway. | |
| Explain what happens to the lactic acid in your muscles after anaerobic respiration. | Lactate causing the muscles to lower in pH. If too much lactate is produced, it is removed from the mucles to the liver, via the bloodstream. When more oxygen is present, lactate is converted to pyruvate which may enter the Krebs cycle via the link reaction or it is recyled to glucose by gluconeogenesis. |
| What happens to the lactate stored in the liver from anaerobic respiration when there is more oxygen present? | lactate is converted to pyruvate which may enter the Krebs cycle via the link reaction or it is recyled to glucose by gluconeogenesis. |
| Explain an experiment with yeast to investigate aerobic respiration? | Put a known volume and concentration of a substrate solution such as glucose into a test tube, along with a buffer solution. Put in a 25 degree water bath and leave to stabilise for 10 mins. Add a known mass of dried yeast to the test tube and stir for 2 mins. After it has dissolved, put a bung in the test tube with a tube to a gas syringe set to 0. Start the stop watch and every 30 secs record the volume of CO2 gas in the gas syringe. Repeat with a control where no yeast is present. Repeat 1-4 three times and calculate a mean rate of CO2 production. |
| Explain an experiment with yeast to investigate anaerobic respiration? | Put a known volume and concentration of a substrate solution such as glucose into a test tube, along with a buffer solution. Put in a 25 degree water bath and leave to stabilise for 10 mins. Add a known mass of dried yeast to the test tube and stir for 2 mins. After it has dissolved, put a bung in the test tube with a tube to a gas syringe set to 0. Trickle some liquid paraffin down the inside of the test tube so that a layer settles on the surface and stops oxygen getting to the solution beneath. Yeast will respire anaerobically. Start the stop watch and every 30 secs record the volume of CO2 gas in the gas syringe. Repeat with a control where no yeast is present. Repeat 1-4 three times and calculate a mean rate of CO2 production. |
| Explain how fatty acids can be used in aerobic respiration. | Fatty acids broken down to many molecules of acetate that enter the Krebs cycle via acetyl CoA |
| Explain how glycerol can be used in aerobic respiration. | Glycerol is converted to pyruvate and enters Krebs cycle via the link reaction |
| Explain how amino acids can be used in aerobic respiration. | Amino acids are deaminated and enter Krebs directly or may be changed to pyruvate or acetyl CoA |
| Explain how carbohydrates can be used in aerobic respiration. | carbohydrates undergo processes to turn into glucose which is then respiried |
| Explain how proteins can be used in aerobic respiration. | only occurs in situations such as fasting, starvation and prolonged exercise. Proteins from muscles can be hydrolysed and amino acids respired directly. Amino acids are deaminated and enter Krebs directly or may be changed to pyruvate or acetyl CoA |
| Can proteins be respired anaerobically? | No, only aerobically |
| Respiratory substrate | an organic substance that can be oxidised by respiration, releasing energy to make molecules of ATP |
| Are all respiratory substrate the same energy value? | Each respiratory substance has a different relative energy value |
| Put these in order of energy value, highest to lowest: protein, carbohydrate, protein | lipid protein carbohydrate |
| Why are lipids the highest energy value? | because the most ATP is made in oxidative phosphorylation, which requires hydrogen atoms from red NAD and red FAD. Lipids have the most hydrogen atoms per unit mass, so more molecules of ATP are made. |
| What order do our bodies respire respiratory substrates? | glucose glycogen (carbohydrate stores) fatty acids (in lipids) proteins (only in starvation conditions) |
| cardiac muscles only respire ____ | fatty acids |
| respiratory quotient | Respiratory quotient (RQ) is the volume of carbon dioxide given out in respiration to that of oxygen used. |
| formula for respiratory quotient | RQ = carbon dioxide produced / oxygen consumed |
| What does it mean if an organisms respiratory quotient is higher than 1? | If RQ is greater than 1, some anaerobic respiration is taking place, because more CO2 is produced than oxygen being consumed. |
| respiratory quotient of carbohydrates | always 1 |
| Respirometer | apparatus used to measure the rate of respiration of living organisms by measuring the rate for exchange of oxygen and carbon dioxide |
| Explain briefly how a respirometer works. | Soda lime (aka potassium hydroxide) absorbs any CO2 produced. The oxygen in the test tube is absorbed by the respiring organism. The volume of air in the test tube decreases and so the pressure decreases. The manometer fluid is drawn up the capillary tube. The distance the fluid has moved is used to work out the volume of oxygen absorbed. |
| Describe how to set up a respirometer | Set up apparatus as shown. Put the same mass of glass beads in the control tube as the mass of respiring organisms in the test tube Use the syringe to set the manometer at a known level Leave the apparatus for a set time (i.e. 20 mins) Measure the distance moved by the manometer fluid Distance moved X cross sectional area of capillary tube = volume of oxygen taken in Calculate volume of oxygen per min per gram |
| Draw a diagram of a respirometer. | |
| Explain how a respirometer can be used to investigate yeast respiration. | If the potassium hydroxide solution is omitted, and a suspension of yeast is put into one of the tubes, the evolution of carbon dioxide per unit time can be measured |
| Explain how a respirometer can be made more accurate and reliable results. | An oxygen sensor can be set up with a respirometer to measure the oxygen concentration inside the respirometer chamber at set time intervals. Data loggers can automatically record the data measured by the oxygen sensor. This reduces the chance of human area. The results can also be put into data analysis software which can help to draw conclusions from the data set . |
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