Metabolism Flashcards
Catabolism
Reactions for using energy.
The breaking of large molecules and fuels (food), together with O2 and H2O to produce CO2 and intermediates. Intermediates can then convert ADP and NAD into ATP and NADH.
Anabolism
Reactions for storing energy.
Small molecules and toxins are ‘burned’ with energy from ATP, and with NADH, to create macromolecules and eliminate toxins. This also creates ADP and NAD.
Why is the Liver important in metabolism
Key organ for synthesising molecules for all tissues in the body, and storing key compounds such as glycogen. Self sacrificing.
Role of Adipose Tissue
Fat Cells - storing lipids, and mobilising fatty acids when energy is required.
Role of Kidneys
Can metabolise several toxins into inert substances that can be eliminated.
Role of Muscles
The movers. Can store glycogen, and use whatever fuel is available (fat, ketones, protein, or glucose)
Role of cytoplasm/cytosol in Metabolism
Soup of the cell, conducts non-oxidative catabolism, synthesis of molecules, and stores fuels (glycogen and TAGs)
Role of Endoplasmic Reticulum and Golgi Apparatus
Synthesise and process proteins and complex lipids, modifying their structure to ensure they fulfil their function in the right place.
Role of Lysosomes
Garbage dump of the cell, pH of 5.5 enables the hydrolysis (destruction) of external compounds
Role of Peroxisomes
Conduct initial breakdown (oxidation) of very long-chain fatty acids (24-26 carbons) before they enter the mitochondria.
Role of Mitochondria
Responsible for many metabolic reactions, including 90% of ATP synthesis, providing lots of energy.
How are hydrophobic molecules transported between organs
Either on albumin protein (can carry 7 FA’s at one time), or inside lipoproteins.
How is Glucose absorbed in the cell
Primarily through the GLUT family, a widespread group of passive transporters that allow hydrophilic glucose to cross the cell membrane.
How are Amino Acids absorbed into the cell
Most commonly linked with sodium, but through a number of different paths, including Excitatory Amino Acid Transporters.
Why are compartments important in cells
Allow molecules and/or enzymes for a particular reaction to be grouped together and controlled by a transporter.
What are Enzymes
Specialised proteins that serve as a catalyst for reactions. They do not change equilibrium, but can lower the rate of reaction or the activation energy.
How do enzymes play their role
Acid-Base provision (supplying or removing proton to increase the electrophilic or nucleophilic character of the groups).
Promote Transition State Formation - change shape of molecule or distribution of charge to allow extra proton or electron in.
Proximity - holding reactants together at an appropriate orientation.
Manipulating protein structure - to increase the likelihood of a reaction.
What is the enzyme’s Active Site
A small site that is very attractive to the substate, and instantly commits the substrate to the reaction.
How does short-term metabolic regulation occur
Almost instantaneously within a cell or group of cells, using specialised hormones that can affect a cell’s redox state (ADP/ATP supply or necessary cofactors).
How does longer-term metabolic regulation occur
Hormones are released by organs or glands that monitor the system. These hormones use signal transduction pathways to change the behaviour of an enzyme. Much more complex than short-term ATP/ADP binding.
What is Phosphorylation
The addition of a Phosphate group to a protein, changing its electrochemical profile (phosphate is very negative). This changes the shape and behaviour of the protein. It is conducted by Kinases.
What is dephosphorylation
The removal of a phosphate group from a protein, changing its electrochemical profile, and thus its shape and behaviour. It is conducted by phosphatases.
Why is phosphorylation important
Phosphate has a very negative charge, so can easily change the shape and behaviour of a protein - it is thus a key regulation, acting as a trigger to about 30% of our protein. Around 2% of our genome is devoted to phosphorylation and dephosphorylation.
