Respiration Flashcards
Outline the processes involved in ATP generation through chemiosmosis.
- electron transport chain
- channels associated with ATP synthase
1. NADH + FADH2 reoxidised - H atoms split into H+ and e-
2. e- move into e- carrier protein
3. e- move into e- transport chain in cristae, releasing energy to pump H+ into intermembrane space
4. creates H+ concentration gradient + proton motive force
5. H+ flows down gradient through hydrophilic trasnsmembrane channel
6. conformational change in ATP synthase
Why do organisms respire?
- release energy - reactions in cells
- make ATP
- exocytosis, endocytosis
- movement along cytoskeleton
What are components of mitochondria?
Matrix, granule, loop of DNA, cristae, ribosomes, outer membrane, inner membrane, inter membrane space.
Where does glycolysis take place?
Cytoplasm, because the mitochondrial membrane is impermeable to glucose.
What happens during glycolysis?
Glucose -> glucose phosphate -> hexose bisphosphate -> 2 triose phosphate -> 2 pyruvate.
Phosphorylation, splitting, oxidation.
What are the products of glycolysis?
2 NADH, 2 pyruvate, 2 ATP.
What is the process of anaerobic respiration in animals?
Lactate fermentation: in cytoplasm.
2 pyruvate -> 2 lactate. NADH is oxidised to NAD.
Why is lactate buildup dangerous?
It is lactic acid, so decreases pH, inhibiting enzymes. At the liver, is converted to pyruvate or recycled to glucose.
Why is anaerobic respiration efficient?
For the short term - glycolysis is repeated very fast.
What is the process of anaerobic respiration in yeast?
Ethanol fermentation in cytoplasm.
Pyruvate -> ethanal -> ethanol.
Pyruvate decarboxylase, then ethanol dehydrogenase.
Where does the link reaction take place?
Pyruvate is transported into the matrix by a symport protein - 1 pyruvate, 1 H+.
What is a symport protein?
A type of cotransporter protein - same direction at same time, 2 different molecules.
What happens in the link reaction?
Pyruvate -> acetate -> 2 acetyl CoA
What are the products of the link reaction?
2 NADH, 2 acetyl CoA, 2 CO2.
What is substrate level phosphorylation?
Phosphate group transfers from 1 molecule to another.
What is chemiosmosis?
Flow of protons down a concentration gradient, across membrane through channel associated with ATP synthase.
What is phosphorylation?
Addition of phosphate group - increases reactivity.
What are the products of the Krebs cycle?
2 ATP, 6 NADH, 2 FADH2, 4 CO2, 2 CoA, 2 oxaloacetate.
What is oxidative phosphorylation?
Formation of ATP from ADP + Pi using energy released in e- transport chain in presence of O2.
What are features of oxidative phosphorylation?
e- carrier proteins in inner mitochondrial membrane.
Folded membrane increases SA for carrier proteins.
Phospholipids = barrier for H+ creating a concentration gradient.
What are the steps for oxidative phosphorylation?
- NADH + FADH2 re-oxidised as release H - split into H+ and e-
- e- move along e- transport chain in series of redox reactions
- energy released from e- used to pump H+ from matrix to inter membrane space - creating chemiosmotic potential (energy source)
- H+ down concentration gradient through hydrophilic transmembrane channels with ATP synthase
- drives ADP + Pi to ATP
- O2 is the final e- acceptor. Accepts 4 e- and 4 protons to make 2 H2O.
What is the net ATP gain for each stage of respiration?
Glycolysis - 2
Link reaction - 0
Krebs cycle - 2
Oxidative phosphorylation - 28
TOTAL: 32
Why is the theoretical yield rare?
H+ leak through the inner mitochondrial membrane, not ATP synthase.
ATP used to move pyruvate from the cytoplasm to the matrix.
H from NADH made in glycolysis needs to be moved to the matrix.
What is a respiratory substrate?
Any organic substance that can be oxidised by respiration, releasing energy and making ATP.
What are features of carbs?
Glucose is the most important,
Some cells can only respire glucose. Excess is stored as glycogen/starch. Disaccharides are broken down by hydrolysis - break glycosidic bonds. Sometimes need isomerase enzymes.
What are the RQ values you need to know?
Carbs: 1
Lipids: 0.7
Proteins: 0.9
What are features of lipids?
Glycerol can be converted to triose phosphate.
Fatty acids can be joined to CoA and broken down by acetyl CoA in beta oxidation.
What are features in proteins?
Excess amino acids are broken down by hydrolysis.
How is RQ calculated?
CO2 produced / O2 consumed.
If RQ > 1, some anaerobic respiration. The lower the RQ, the more ATP produced per molecule.
What are ways of investigating respiration?
Gas syringe, respirometer, haemocytometer.
How is a gas syringe used to measure respiration?
vol of CO2 / time.
Investigate temp with water bath (also control variable)
Algae, bacteria, YEAST
Oil layer above glucose/yeast for anaerobic respiration.
How is a respirometer used to measure respiration?
Rate of O2 consumption in aerobic respiration.
Changes in reading measured + syringe barrel depressed to measure vol of O2 absorbed.
Find vol of O2 absorbed /m/g with vol of cylinder equation.
How is a haemocytometer used to measure respiration?
Counting cells - rough estimate for respiration rate.
Specialised microscope slide with 2 grooves, count no of cells see in each area, use vol of sample to find no of cells /mm2.
Many samples to be representative. Over longer time.
What are potential issues with measuring respiration rate?
Data logger - CO2/O2 probes, pH probes. More readings for continual data, no human error.
Ethics - no killing. Temp range suitable for organism (or use fungi).
Photosynthetic? Tube in black paper.
