Please enable JavaScript.
Coggle requires JavaScript to display documents.
Biological processes, Biological processes., Electron transport., Kerb…
Biological processes
Metabolism
- Series of all life-sustaining chemical reactions within the cells of living organisms
involving two main processes
- Catabolic reactions that break down large, complex molecules to provide energy and smaller molecules
- Anabolic reactions that use ATP energy to build larger molecules (biosynthetic pathways)
Metabolism takes place spontaneously in the cytoplasm and the mitochondria.
- enzymes catalyse these reactions.
-
Oxidation
- loss of electrons
- loss of hydrogen
- gain of oxygen
- increase of number of bonds to oxygen
Reduction
- Gain of electrons
- Gain of hydrogen
- loss of oxygen
Decrease of number of bonds to oxygen.
Metabolism
- obtains energy for the cell.
- Converts nutrients into macromolecules.
- Assembles macromolecules into cellular structures.
- Degrades macromolecules for biological functions.
Stages of cellular respiration
- Stage 1: digesting and hydrolysis.
- stage 2: Degradation and some oxidation to smaller molecules
- Stage 3 oxidation to carbon dioxide, water and energy for ATP synthesis.
how is energy generated
- Glycolysis
- Critic acid cycle
- Oxidative phosphorylation. (Electron transport chain)
Carbohydrates metabolism.
Glycolysis
- Metabolic pathway that's uses glucose.
A digestion product.
- Degrades 6 carbon glucose molecules to three pyruvate molecules
Anaerobic (no oxygen required)
Glycolysis energy investment (1-5)
- Energy is required to add phosphate group to glucose.
- Glucose is converted to two three- carbon molecules.
In reactions 6–10
- sugar phosphates are cleaved to triose phosphates
- 4 ATP molecules are produced.
Glycolysis: Overall Reaction
- 2 ATP add phosphate to glucose and fructose-6- phosphate.
- 4 ATP are formed in energy generation by direct transfers of phosphate groups to four ADP
Biological processes.
- Other monosaccharides, such as fructose and galactose, can enter glycolysis
- They must first be converted to intermediates that can enter the pathway
- in muscles and kidneys, fructose is phosphorylated to fructose-6-phosphate, which enters glycolysis in reaction 3
Galactose reacts with ATP to yield galactose-1-phosphate, which is converted to glucose-6-phosphate, which then enters glycolysis at reaction 2
Glycolysis is regulated by three enzymes
- Reaction 1, hexokinase is inhibited by high levels of glucose-6-phosphate, which prevents the phosphorylation of glucose.
Reaction 3, phosphofructokinase, an allosteric enzyme,
is inhibited by high levels of ATP and activated by high levels of ADP and AMPReaction 10, pyruvate kinase, another allosteric enzyme is inhibited by high levels of ATP or acetyl CoA
Aerobic Conditions (oxygen present) - three-carbon pyruvate is decarboxylated and
- two-carbon acetyl CoA and CO2 are produced
anaerobic conditions (without oxygen)
- pyruvate is reduced to lactate and
- NADH oxidizes to NAD+ allowing glycolysis to
continue
Citric Acid Cycle (stage 3)
- operates under aerobic conditions only
- oxidizes the 2-carbon acetyl group in acetyl-CoA to produce CO2
- produces reduced coenzymes NADH
- and FADH2 and one ATP directly
- acetyl (2C) bonds to oxaloacetate (4C) to form citrate (6C)
- oxidation and decarboxylation reactions convert
citrate to oxaloacetate
- oxaloacetate bonds
with another acetyl to repeat the cycle
- Citrate (citrate)
- is (Isocitrate)
- Kerb's (a Ketoglutarate)
- Starting (Succinyl-CoA)
- Substrate (Succinate)
- For (Fumerate)
- Making (Malate)
- Oxaloacetate (Oxaloacetate)
Reaction 1:
Formation of Citrate Oxaloacetate (4C)
- combines with the **two-carbon acetyl-Cao (2C)
- to form citrate (6C)
Reaction 2:
- Citrate isomerizes to isocitrate
- has a tertiary —OH group converted to a secondary —OH in isocitrate that can be oxidized
- Initially dehydrates then undergoes a hydration reaction
Reaction 3
- Isocitrate undergoes decarboxylation (carbon removed as CO2)
- oxidizes the —OH to a ketone, releasing H+ and 2 e–
- provides H to reduce coenzyme NAD+ to NADH
Reaction 4:
- a Ketoglutarate undergoes decarboxylation to form succinyl-CoA.
- produces a four-carbon compound that bonds to CoA
- provides H+ and 2 e– to reduce NAD+ to NADH
Electron transport.
uses electron carriers
- transfers hydrogen ions and electrons from NADH
- and FADH2 until they combine with oxygen
- Forms H2O
- Produces ATP.
- The electron carriers are attached to the **inner
membrane of the mitochondrion**
four protein complexes
- Complex I NADH dehydrogenase
- Complex II Succinate dehydrogenase
- Complex III CoQ-Cytochrome c reductase
- Complex IV Cytochrome c oxidase
at complex 1, NADH dehydrogenase
-
Complex III
- Two electrons transferred from CoQH2
enter a series of iron-containing proteins called cytochromes
- and eventually cytochrome c
iron ion within the cytochromes is
oxidized (Fe3+) and reduced (Fe2+) as Electrons are lost and gained.
- Hydrogen ions released from CoQH2
to yield CoQ diffuse into the intermembrane space producing a proton gradient
Complex IV: Cytochrome c Oxidase - At Complex IV, electrons are transferred from four
cytochrome c, combine with hydrogen ions and O2 to make two molecules of water
overall, reduced coenzymes NADH and FADH2 from the citric acid cycle enter electron transport
reduced coenzyme provide hydrogen ions and electrons that react with oxygen, producing water, NAD+ and FAD
- When NADH enters electron transport at complex I, the energy released from oxidation synthesizes 3 ATP molecules. FADH2 enters electron transport at complex II (which is at a lower energy level) provides the energy for the synthesis of 2ATP molecules.
Regulation of Electron Transport
- low levels of ADP, Pi oxygen, and NADH that decrease electron transport activity.
-
The complete oxidation
of glucose yields
Kerb cycle.
Reaction 5
- Succinyl CoA undergoes hydrolysis of the thioester bond.
- provides energy to add phosphate to GDP and form GTP a high energy compound.
GTP eventually undergoes hydrolysis with the release of energy that is used to add a phosphate group to ADP to ATP.
- Citric Acid Cycle’s only direct transfer of a phosphate group to make ATP
Regulation of Citric Acid Cycle
- increases when low levels of ATP or NAD+ activate
isocitrate dehydrogenase
-