Question

CELLULAR RESPIRATION

1- Steps of Cellular Respiration: Anaerobic vs. Aerobic

a. Glycolysis

b. Citric acid cycle

c. Electron transport chain (ETC)

2- Carbohydrate storage.

Answer 1

CELLULAR RESPIRATION: It is a set of metabolic reations and processes that take place in the cells of organisms to convert biochemical energy from nutrients into Adenosine Triphosphate and release waste products

STEPS:

AEROBIC RESPIRATION Glycolysis Citric Acid Cycle(Krebs Cycle) Electron Transport Chain (ETC)

ANAEROBIC RESPIRATION Glycolysis Fermentation

GLYCOLYSIS:

STEP 1 Glucose is converted into Glucose-6-phosphate by adding phosphate from Adenosine Triphosphate(ATP) on action of enzyme Hexokinase

STEP 2 Glucose-6- phosphate is converted into Fructose-6-phosphate by enzyme by action of enzyme Phosphoglucoseisomerase

STEP 3 Fructose-6-phosphate is converted into Fructose1,6-biphosphate by adding phosphate from ATP on action of enzyme Phosphofructosekinase

STEP 4 Fructose 1,6 - biphosphate splits into 1 molecule of DIHYDROXYACETONE PHOSPHATE(DHAP) and Glyceraldehyde-3-phosphate.

STEP 5 Glyceraldehyde-3-phosphate and DHAP are isomers and DHAP is coverted into glyceraldehyde-3-phophate by action of enzyme Triosephosphate Isomerase.

STEP 6 Glyceraldehyde-3-phophateis oxidised and NAD⁺ is reduced to NADH and H⁺ and converted to 1,3 biphosphoglycerate by action of enzyme Glyceraldehyde-3-phophate dehydrogenase

STEP 7 1,3 biphosphoglycerate donates one of its phosphate groups to ADP making a molecule of ATP and converts into 3-phosphoglycerate by action of enyzme Phosphoglycerate kinase

STEP 8 3-Phosphoglycerate is converted into its isomer 2-phosphoglycerate by action of enzyme phosphoglycerate mutase

STEP 9 2-Phosphoglycerate loses a molecule of water becoming Phosphoenolpyruvate (PEP) by action of enzyme Enolase

STEP 10 PEP readily converts into pyruvate by donating its phosphate to ADP and making second molecule of ATP by action of enzyme Pyruvate Kinase.

KREB'S CYCLE:

STEP 1 Acetyl CoA joins with oxaloacetate releasing CoA forming citrate by action of citrate synthase

STEP 2 Citrate is converted into Isocitrate by action of enzyme aconitase

STEP 3 Isocitrate is oxidised and converts into Ketoglutarate and NAD⁺ is reduced to NADH by action of enzyme isocitrate dehydrogenase

STEP 4 Ketoglutarate is coverted into alpha-ketoglutarate by oxidizing and reducing of NAD⁺ to NADH by action of enzyme alpha-ketoglutarate dehydrogenase

STEP 5 Co A of Succinyl Co A is replaced by a Phophate group which is transferred to ADP to make ATP and coverts into suucinate by action of enzyme Succynl CoA synthetase

STEP 6  Succinate is oxidised and forms fumarate where 2 hydrogen atoms transferrd to Flavin Adenine Dinucleotide(FAD) to FADH₂ by action of enzyme succinate dehydrogenase

STEP 7 water is added to fumerate converting it to malate by action of enzyme fumerase

STEP 8 Malate is converted to Oxaloacetate by action of enzymeMalate dehydrogenase

ELECTRON TRANSPORT CHAIN

1. NADH , H⁺ and FADH₂ become oxidized donating electrons to the Protein Complex I and II
2. NADH act as 1st electron donor and gets oxidized to NAD⁺ in Complex I
3. The electron is transported to Complex II which converts succinate to fumerate
4. Oxygen acts as a electron acceptor in Complex IV and gets converted into water molecule
5. Each enzyme complex carries out transport of electrons accompanied by release of protons in the intermembrane space
6. The accumulation of protons outside the membrane gives rise to proton gradient and the higher concentration of protons initiates chemiosmosis ad activates ATP Synthase which utilises this potential and acts as proton pump and leads to phosphorylation of ADP to ATP

FERMENTATION(ANAEROBIC RESPIRATION)

• It starts with Pyruvate, the end product of Glycolysis and depending on the organismn, pyruvate will fermented into ethanol and lactic acid

CARBOHYDRATE STORAGE:

The storage form of Carbohydrates is GLYCOGEN and is primarily found in liver and muscle.

If glycogen stores are full, the body convert excess carbohydrates into triglyceride molecules and stored them as fats.