Answer:
Metabolic pathways in monarch butterflies are as follows:
- Glycolysis
- Kreb's cycle
- Oxidative phosphorylation
Step-by-step explanation:
They convert sugar which they obtain from nectar into fats that they store as source of energy. Monarch have a little layer of fatty tissues which aid in conversion of Sugar in to fat.
They consume the stored fat during reproduction. A lot of fat is eventually converted to eggs and some of it is used to provide energy just to sustain the reproductive butterflies.
During winter season, when their metabolic is low they consume energy by converting stored fat into sugar called Trehalose. The conversion of fat also releases little water which help them to survive during winter.
1) Glycolysis:
- Glucose is phosphorylated by hexokinase enzyme to give glucose-6phosphate.
- This glucose-6-phosphate enters into glycolysis and is broken down into two molecules of pyruvate in a series of ten reactions. During glycolysis net two molecules of ATP are synthesised per glucose molecule. Moreover, two molecules of NADH+H+ are also synthesised.
- In aerobic organisms like monarch butterfly the pyruvate is again oxidised to give acetyl-CoA in the mitochondria. The enzyme responsible for this oxidation is Pyruvate Dehydrogenase Complex. This reaction occurs in the mitochondrial matrix. Here one CO2 molecule is removed from the pyruvate and one NADH is produced.
2. Kreb's Cycle:
The acetyl-CoA formed enters into the Kreb's cycle by condensing with oxaloacetate. In Kreb's cycle acetyl-CoA is completely oxidised to give carbon dioxide in eight enzymatic reactions. During Kreb's cycle NADH, FADH2 and one molecule of GTP is produced and oxaloacetate is regenerated to continue the cycle.
3. Oxidative Phosphorylation:
The NADH produced in the glycolysis and Krebs cycle and FADH2 produced during Krebs cycle are now oxidised to generate proton gradient across the inner mitochondrial membrane. This gradient is generated when the electrons from the reduced NADH and FADH2 are transported in the electron transport chain(ETC), and are finally accepted by the oxygen.
When the electrons are picked up by the complexes of the ETC they pick protons from the matrix. When the electrons are transferred to next complex the protons are transferred to the inter-membrane space. In this way a proton gradient is generated across the innner membrane of the mitochondria.
This proton gradient is used by the complex V of the ETC. This complex is the enzyme ATP Synthase. This enzyme complex is located in the inner mitochondrial membrane. When the protons flow back from the inter-membrane space into the matrix along the concentration gradient , they move through the channel in the ATP Synthase Complex. When these protons flow through this complex it catalyzes the phosphorylation of ADP to give ATP, the energy currency.
The fructose component of the sucrose is first converted into glycogen and then broken down to give glucose-1-phosphate, which enters into glycolysis.
Sucrose cannot enter the pathway of glycolysis as such. It is first hydrolysed to glucose and fructose as described above along with the path way.