Cellular Energetics Flashcards
What is Cell Metabolism?
The sum of all chemical changes that take place in a cell through which energy and basic components are provided for essential processes, including the synthesis of new molecules and the breakdown and removal of others.
To be able to grow, divide and carry out day to day activities(assembling polymers, membrane transport, moving and reproducing), cells require a constant supply of what ?
Energy
How to cells obtain energy?
From food molecules
What are Autorophs?
Plants, Algae by photosynthesis
What are Heterotrophs?
Fungi, animals, humans by cellular respiration
What is the breakdown of food molecules? diagram
- During digestion, large food molecules are broken down (catabolism) into smaller molecules- monomers
ANABOLISM+CATABOLISM=METABOLISM
What is Cellular Respiration?
- step-wise process that breaks down (oxidation) sugars and other metabolites to CO2 and water
- Converts the energy released from food into the concomitant build-up of ATP molecules (the terminal phosphoanhydride bond)
- Cellular respiration is an aerobic process, it requires and consumes oxygen, except the glycolysis
- Oxidation-reduction enzymes include NAD+ and FAD as coenzymes
What is the Oxidation ?
What type of process is Cellular Respiration?
-An aerobic process, requires and consumes oxygen
What are the reduction enzymes involved in Cellular Respiration?
NAD+ and FAD as coenzymes
What is ATP used in the cell as? diagram
- Energy currency- used to drive a variety of chemical reactions in cells (also GTP)
- Hydrolysis of high-energy phosphate bonds (in particular between Y and B (beta) phosphates) release energy to fuel cellular processes/reactions
When is ADP recycled back into ATP?
-During cellular respiration, ADP is recycled back into ATP (requiring energy)
-ADP+phosphate+energy = ATP
What are organic fuel molecules?
What is the oxidation of organic fuel molecules?
-This is when during cellular respiration, glucose and other metabolites are oxidised and O2 is reduced in a series of steps
What are the steps of Oxidation during cellular respiration?
What is Oxidation?
-A molecule is oxidised, meaning it LOSES electrons
What is Reduction ?
-A molecule is reduced, meaning it GAINS electrons
What are the most common electron carriers?
-NAD+, nicotinamide adenine dinucleotide
-FAD, Flavin adenine dinucelotide
Electron Carrying molecules (NAD+ and FAD)add diagrams and more info
How many phases are in cellular respiration?
4
What are the 4 phases of cellular respiration?
-Glycolysis
-Pyruvate Oxidation to form acetyle-CoA
-Citric Acid Cycle
-Oxidative Phosphorylation
What is the process of Glycolysis during cellular respiration?
the breakdown of glucose into two molecules of pyruvate. Occurs in the cytoplasm. Does not utilise oxygen.
What is the process of Pyruvate oxidation to form acetyle-coA during Cellular Respiration?
Pyruvate is oxidised into acetyl-CoA. Occurs in the matrix of mitochondria. It requires oxygen.
What is the process of Citric acid cycle during Cellular Respiration?
oxidises acetyl group acetyl-CoA in CO2, with CoA release. Occurs in the matrix of mitochondria. It requires oxygen
What is the process of oxidative phosphorylation during Cellular Respiration?
(electron transport chain and chemiosmosis). Occurs in the matrix and inner membrane of mitochondria. It requires oxygen.
Add diagrams for the 4 phases of cellular respiration
Glycolysis -Key points
- Glycolysis (’splitting of sugar’) to break down glucose (6-C atoms) into 2 molecules of pyruvate (3-C atoms)
- It generates 2 ATP + 2 NADH (NET result)
- Glycolysis occurs in the cytoplasm
DOES NOT REQUIRE OXYGEN
-It is a source of energy for anaerobic microorganisms
-Consists of 10 different reactions (10 enzymes) in two major phases
- Energy investment phase
- Energy payoff phase
What happens to the NADH molecules during Glycolysis?
NADH molecules are transported into mitochondria, where they donate their electrons to an electron-transport chain that produces ATP by chemiomosis.
What is Fermentation?
- Occurring in the cytoplasm, in the absence of oxygen, to break down pyruvate
- No energy production, but it restores the NAD+ consumed in the gylcolysis
What is LACTIC FERMENTATION?
-Pyruvate is reduced to lactic acid
-Occurs in muscle cells, when the oxygen is not adequate
-Lactic acid can build up-cramps
What is ETHANOL FERMENTATION?
-Pyruvate is reduced to ethanol & CO2
-Occurs in bacteria and yeast cells, human cells can not ferment alcohol
-Used to produce alcoholic spirits, bread
What is the overall reactions of anaerobiotic metabolism for LACTIC FERMENTATION?
What is the overall reactions of anaerobiotic metabolism for ETHANOL FERMENTATION?
add diagrams of lactic and ethanol fermentation
What is Pyruvate Oxidation? add diagram
-In presence of O2, pyruvate enters the mitochondrion (in eukaryotic cells)
What is mitochondria ?-RECAP
- Double-layered structure with 4 distinct parts
- There is the intermembrane space between the outer and inner membranes and the matrix within the inner membrane.
- Functions- Contain enzymes responsible for the ATP production (krebs cycle, oxidative phosphorylation)
What is the Inner mitochondrial membrane? RECAP
INNER MITOCHONDRIAL MEMBRANE - It is folded into cristae to increase surface area. Almost impermeable to ions and small molecules. It contains transporters, the electron transport chain.
What is the Matrix of mitochondria? RECAP
MATRIX- The gel-like material enclosed by the inner membrane. It contains a high concentration of enzymes.
Steps of Pyruvate oxidation/decarboxylation into Acetyl-CoA? diagram
- It links glycolysis to the citric acid cycle/Krebs cycle
-In the presence of 02, pyruvate produced by glycolysis is actively (with ATP) pumped into the mitochondrial matrix
-Pyruvate converted to a 2-carbon acetyl group, by the pyruvate dehydrogenase complex in the matrix
-Attached to Coenzyme A to form acetyl-CoA
-Electron picked up by NAD+ to form NADH
-CO2 released outside the mitochondria (waste)
What is the equation for the Pyruvate oxidation/decarboxylation into Acetyl-CoA?
Fats are broken down through what process?
Beta oxidation of fatty acids
What is Beta Oxidation of fatty acids?
-Break down of fats
-Fats are stores as triacylglycerol (in lipid droplets)
-3 fatty acid chains linked to glycerol by ester bonds
-When there is demand of energy, lipase hydrolyse these ester bonds to release fatty acids
-Glycerol can be converted and enter glycolysis
-Fatty acids are coupled to coenzyme A (activation), utilising ATP, to form fatty acyl CoA
-Fatty acyl CoA are transported into the mitochondrial matrix and subsequently oxidised in a cycle (beta oxidation) of 4 reactions
-Each turn of the cycle shortens the fatty acyl CoA by 2 carbons to form acetyl CoA (entering the citric acid cycle) and release FADH2, NADH
What is the Krebs’ Cycle?
The Citric Acid Cycle
What is the Citric Acid Cycle ?diagram
What are the NET RESULTS OF THE GLUCOSE CATABOLISM AFTER CITRIC ACID CYCLE?
- Glycolysis:
glucose converted into 2 molecules of pyruvate
producing 2 ATP, 2 NADH - Pyruvate oxidation ( 2 molecules/glucose breaking down)
pyruvate converted into acetyl CoA
producing 2 NADH - Citric Acid cycle (2 turns/glucose).
acetyl CoA converted to CO2
producing 2 ATP (from GTP), 6 NADH, 2 FADH2
What is the Total glucose catabolism after the citric acid cycle?
TOTAL/GLUCOSE = 4 ATP + 10 NADH + 2 FADH2
What is Oxidative phosphorylation ?
- Oxidative phosphorylation is composed of 2 stages:
-Electron Transport Chain
-Chemiosmosis
What is the Electron Transport Chain?
- NADH and FADH2 transfer their high-energy electrons to the electron transport chain**
- its composed of 4 protein complexes in the inner mitochondrial membrane, acting as electron carriers.
- Passage of electrons through the complex
- Electrons drop in free energy as they go through the chain and finally, are passed to O2 that combine with proteins, forming H2O.
What is Chemiosmosis ?
- The resulting proton gradient is used to drive the synthesis of ATP by the ATP synthase (a large, multisubunit complex in the inner mitochondrial membrane)
- The electron transport caused the pumping of protons from the matrix to the intermembrane space, generating a proton gradient across the inner membrane (chemiosmosis)
- ADP is pumped into the matrix and ATP is pumped out by an antiport process
Glucose Catabolism: Overall Energy Yield
The conversion of glucose to two molecules of pyruvate is the result of what process?
Glycolysis
What molecule enters Citric Acid Cycle?
Acetyl CoA
Food molecules are broken down in successive steps, in which…..
-Energy is captures in the form of activated carriers such as ATP, NADH and FADH2
What happens to the glucose during Glycolysis?
-The 6-carbon glucose is split to form two molecules of pyruvate
In the presence of oxygen, eukaryotic cells convert pyruvate into acetyl CoA plus CO2 in the mitochondrial matrix (otherwise it undergoes a fermentation). What happens next?
The citric acid cycle then converts the acetyl group in acetyl CoA to CO2 and H2O, regenerating oxaloacetate.
Fatty Acids can be converted to what and where? Through beta oxidation
Fatty acids can be converted to acetyl CoA in the mitochondria (beta oxidation)
What is generated in the first 3 steps of the cellular respiration?
-NADH and FADH2
What doe sNADH and FADH2 do during the first 3 steps of cellular respiration?
pass their high-energy electrons to an electron-transport chain in the inner mitochondrial membrane, which triggers the activation of the ATP synthase to obtain ATP.
What can Glucose Catabolism generate?
could generate around 30-32 ATP molecules (NET YIELD)
