Catabolism Flashcards
What is catabolism
The breakdown of complex materials within the organism
What is anabolism?
The constructive part of metabolism concerned with macromolecular synthesis.
What is the importance of catabolic reactions ?
Serve to capture chemical energy (in the form of ATP) from the degeneration of energy rich fuels molecules.
Provide the precursors needed for the synthesis of complex molecules.
Degeneration of complex molecules occur in three stages.
- Hydrolysis of complex molecules into component building blocks
- Conversion of building block to simple intermediates.
- oxidation of acetyl CoA
Describe stage 1 of Hydrolysis of complex molecules into component building blocks in the catabolism
The complex molecules are broken down into their simple building blocks. For e.g. Proteins into amino acids, polysaccharides into monosaccharides, triacylglyecerols to free fatty acids and glycerol
Stage two of catabolism: conversion of building blocks to simple intermediates
The diverse building blocks are further degraded to acetyl CoA and a few other simple molecules. Some energy is captured as ATP.
3rd stage of catabolism: oxidation of acetyl CoA
The citric acid cycle is the. Common pathway in the oxidation of fuel molecules. Acetyl Co A is oxidized to two CO2 and four pairs of electrons are transferred to the co enzyme NAD+ and Fad+ to produce NADH and FADH2. Large amounts of ATP are generated as electrons are from NADH and FADH2 flow to oxygen in oxidative phosphorylation .
What does anabolism entail?
Combine molecules such as amino acids to form complex molecules such as proteins. They need energy from break down of ATP to ADP and Pi. Anabolic reactions often involve chemical reductions in which the reducing power is provided by the electron donor.
Is catabolism a convergent process?
Yes! Convergent means a wide variety of molecules are transformed into a few common end products.
Divergent process in which a few biosynthesis precursor form a wide variety of polymeric or complex products.
list facts about intracellular receptors.
The receptors are located within the cytosol or nucleus.
The receptor agonist complex binds to specific regions of DNA such as enhancers regions thus increasing expression of specific genes. The agonist is high lipid based in order to gain access into to cytoplasm or nucleous through the membrane .
The effects of the agonist is not immediate because time is required for gene transcription and for subsequent translation of mRNA.
Describe the mechanism of intracellular receptors
Steroid for example have a high lipid affinity and can enter in to the membrane easily. The inactive receptor in located in the cytoplasm and the steroid binds to the intracellular receptor and become an activate receptor complex. The complex then enter the nucleus from the cytoplasm and binds to chromatin activation the transcription of specific genes. mRNA is then translated before a change in brought about.
Does cell surface receptors regulate gene expressions directly?
No
Four examples of intracellular receptors
Steroid receptors
Vitamin D and retinoic acid receptor
Thyroxine receptors
Fact about Neurotransmitter receptors linked to ion channels.
E.g. Ligand gate ion channels.
Composed of one complex called a single multiplex ulnar complex. For example the binding of a neurotransmitter causes a rapid opening of ion channels that are selectively permeable to either cation or anions.
What are the products of catabolism reactions ?
ATP
FADH2
NADH
NADPH
What does ATP mean?
Adenosine triphosphate
