Biochemistry B Flashcards
ATP Cycle
Hydrolysis: a water molecule gets added to a molecule of adenosine triphosphate. ATP gets split into ADP and Pi after releasing energy.
Dehydration Synthesis (Condensation): ADP and Pi release a water molecule through acquiring energy to become ATP.
What is ATP?
Light energy, comes from the sun. Fuels anything that requires energy: reactions, transport, etc.
Cellular respiration involves…
Numerous small exothermic reactions, with small activation energies. A controlled release of energy from organic compounds (glucose mainly, but lipids and proteins too), ro produce ATP
Why is cellular respiration not just a single large step?
Free energy would be released, the glucose would burn up in combustion. The free energy needs to be stored for later usage
Cellular respiration is a creation or transferral or energy?
Transferral, NOT creation
Aerobic Respiration Summary
Utilizing ozygen to completely break down glucose in the mitochondria for a larger ATP yield
Regulation of Cellular Respiration
End Product Inhibition, with ATP being the end product
Redox Reactions
Oxidation - reduction
The reducing agent vs the reduced
The reducing agent loses electrons, the reduced gains electrons
The oxidizing agent vs the oxidized
The oxidizing agent gains electrons, the oxidized loses electrons
Oxidation
Loss of electrons and hydrogen atoms, gain of oxygen atoms
Reduction
Gain of electrons and hydrogen atoms, loss of oxygen atoms
2 Reversible reactions in cellular respiration
NAD+ + 2 electrons and 2 hydrogen ions -> NADH + hydrogen ion
FAD + 2 electrons and 2 hydrogen ions -> FADH2
NADH
Nicotinamide adenine dinucleotide
FADH2
Flavin adenine dinucleotide
Electrons carriers and process of electron transfer
Transport electrons between different molecules.
- NAD+ within a cell along two hydrogen atoms
- NAD+ is reduced to NAD by accepting an electron from a hydrogen atom
- It picks up another hydrogen atom (an electron and a hydrogen ion) to become NADH
- NADH carries the electrons to a later stage of respiration and drops them off, becoming oxidized
NAD+ gets … by picking up 2 electrons and a hydrogen ion
NADH gets … by dropping off 2 electrons and a hydrogen ion
Reduced, oxidized
Glycolysis is the …
Splitting of sugar
3 Stages of Glycolysis
Activation, splitting and oxidation
Glycolysis Activation
2 molecules of ATP are hydrolysed into 2ADP + 2Pi. This is used to activate a molecule of glucose. Glucose forms fructose - 1, 6 - bisphosphate, or F1, 6 - BP, an unstable intermediate molecule.
Glycolysis Splitting
F1, 6 - BP is split into DHAP and molecule of G3P, both 3 carbon molecules. All the DHAP are eventually converted into G3P.
Glycolysis Oxidation
Restructuring to remove energy in a series of steps. Glucose is converted into two molecules of pyruvate and two molecules of water.
2 NAD+ picks up four hydrogen ions and four electrons to become 2 NADH + H+
4 ADP + 4 Pi becomes 4 ATP
Glycolysis ATP Net Gain
2 ATP
Pyruvate Oxidation
A molecule of pyruvate (C3H4O3) is decarboxylated to become acetate (C2H4O). Coenzyme A is added to acetate to help the enzyme stabilize the molecule and restructure it temporarily, and a NAD+ molecule is reduced. Acetyl - CoA is formed.
Pyruvate Oxidation Chemical Equation
2 pyruvate + 2 NAD+ -> 2 Acetyl Co - A + 2 NADH + 2 CO2
Substrate Level Phosphorylation
A metabolic reaction in which a phosphorylated compound transfers its phosphate group to ADP for ATP synthesis. Pi is an inorganic phosphate, not attached to anything, usually just floating in the cytoplasm. An enzyme catalyzes the phosphorylation, and it needs an input of energy.
3 Stages of Krebs Cycle
Restructuring, redox, substrate level phosphorylation (same as glycolysis)
Krebs Cycle Process (5 Steps)
- Acetyl - CoA loses CoA
- Oxaloacetate (C4H4O5) forms citrate (6 carbon) with acetic acid
- Citrate undergoes decarboxylation twice (to provide energy for step 4), fueled by the reduction of 2 NAD+, becoming a 4 carbon molecule
- Restructuring to provide energy for: one ADP -> ATP, one FAD -> FADH2, one NAD+ -> NADH.
- Oxaloacetate formed
Oxidative phosphorylation is named so because…
The energy to synthesize ATP is derived from the oxidation of NADH and FADH2
Purpose of the electron transport chain
Releases the energy stored within the reduced electron carriers in order to synthesize ATP by adding Pi to ADP.
Oxidative Phosphorylation Process (8 Steps)
- E carriers release electrons to the ETC
- As the e- move throguh the chain they lose energy, transferred to the hydrogen pumps within the chain
- The pumps use this energy to pump H+ from the matrix into the intermembrane space
- Accumulation of hydrogen ions creates and electrochemical gradient, or a proton motive force
- Chemiosmosis: H+ return to the matrix throguh the transmembrane enzyme ATP synthase
- H+ trigger a phosphorylation reaction, adding Pi to ADP as they pass through ATP synthase
- The de - energized electrons aer removed from the chain by oxygen, allowing new energy electrons to enter the chain
- Oxygen also binds matrix protons to form water, maintaining the hydrogen gradient
FADH2 is slightly more … than NADH
Electronegative
NADH is reduced at the xth hydrogen pump, FADH2 is reduced at the yth hydrogen pump
x: first
y: second
Phosphorylation is an catabolic vs anabolic, exothermic vs endothermic reaction
Anabolic, endothermic