2.1 Metabolic molecules Flashcards
Living organisms control their composition by a complex web of chemical reactions.
What is molecular biology?
Field of study that focuses on investigating biological activity at a molecular level.
- Elucidating the structure and function of chemical substances.
- Determining their interactions as parts of living processes.
How are biological processes regulated?
Biological processes are tightly regulated by enzymes, whose expression is controlled by gene activation (DNA).
Changes in activity are typically determined by signaling molecules (either endogenous or exogenous in origin).
What are organic compounds? example + exceptions
Organic compounds contain carbon and are found in living organisms.
EXAMPLE: carbohydrates, fats (lipids), proteins, and nucleic acids.
EXCEPTIONS: carbides (CaC2), carbonates, oxides of carbon (CO, CO2) and cyanides (CN-).
What are the classes of carbon compounds?
Carbohydrates
Lipids
Nucleic Acids
Proteins
What are carbohydrates?
composition + function + example
Composed primarily of C, H, O atoms - common ratio = (CH2O)n
Principally function as energy source & short-term storage, recognition molecule + structural component.
E.G. Monosaccharide (sub-unit), Starch (polymer), granules in chloroplast (cellular structure).
What are lipids?
composition + function + example
Non-polar, hydrophobic molecules - simple, complex, derived
Major component of cell membranes, long term energy storage & signaling molecule
E.G. Fatty acid (subunit), triglyceride (polymer), adipose cells (cellular structure).
What are nucleic acids?
composition + function + example
Genetic material that determines inherited features of an organism.
DNA functions as a master code for protein assembly. RNA active role in manufacturing proteins
E.G. Nucleotide (subunit), DNA (polymer), chromosome (cellular structure).
What are proteins?
composition + function + example
C, H, O, N (sometimes S) atoms
A regulatory molecule in catalysis (enzymes = proteins), structural molecule & role in cellular signaling (transduction pathways).
E.G. Amino acid (subunit), polypeptide (polymer), intermediate filaments (cellular structure).
macromolecules
Commonly composed of monomers (recurring subunits).
carbohydrates, nucleic acids & proteins = joined monomeric subunits, larger polymer.
lipids ≠ recurring monomers, however certain types are composed of distinct subunits. e.g. triglycerides.
Carbohydrates
Composed of monosaccharides (‘single sugar unit’) monomers. AKA, composition of monomeric subunits to form a complex carbohydrate structure.
Builds disaccharides (2) & polysaccharides (many).
forms ring structures and exists in different 3D configurations (stereoisomers).
Glucose monomers combine to form various polymers:
glycogen
cellulose
starch
Composition of nucleic monomers:
join to form polynucleotide chains.
Composition of bases and sugar type differs between RNA and DNA.
Describe DNA composition
Nucleotide bonds form polynucleotide chains.
In DNA, 2 complimentary chains pair by H-bonds between nitrogenous bases, to form a double-stranded molecule to form a double-helical arrangement
Describe a nucleic acid
Phosphate group + pentose sugar + nitrogenous base
Describe a protein
Composed of amino acid monomers joining to form polypeptide chains.
amine group (2H + N) + H + C + (R) variable group + carboxyl group (O ++ C + OH)
The variable group determines properties of the amino acid
Dipeptide + H20 results from
fusion of 2 amino acids
Polypeptide chain results from
fusion of 2+ amino acids
Different classes of lipids
- simple (neutral) lipids
- compound lipids
- derived lipids
simple (neutral) lipids
esters of fatty acids and alcohol
triglycerides, waxes
compound lipids
esters of fatty acids + alcohol + additional groups
phospholipids, glycolipids
derived lipids
derived from simple/compound lipids
steroids, carotenoids
What is vitalism?
dictates that organic molecules could only be synthesised by living organisms. It was believed that organisms possessed a certain “vital force” / non-physical element lacking from inorganic molecules.
Disproving vitalism
Disproven with the discovery of artificially synthesizing organic molecules (1828, Frederick Woehler) - heated inorganic salt (ammonium cyanate), producing urea.
What is urea? (and why is it so important?)
waste of nitrogen metabolism, eliminated by kidneys in mammals.
artificial synthesis of urea – demonstrates that organic molecules are not fundamentally different to inorganic molecules.
define metabolism
Total chemical processes (web of all enzymes-catalysed reaction) that occur within a living organism in order to maintain life.
E.g. The Urea cycle, citric acid cycle, beta-oxidation, and the electron transport chain.
Why is metabolism important?
- provides a source of energy for all cellular processes
2. enables the synthesis and assimilation of new materials for use
Define anabolism
Synthesises complex molecules from simpler ones, occurs via condensation reactions (monomers are covalently joined + H2O by-product).
Uses energy to construct new bonds (endergonic) < typically involves reduction reactions.
example of an anabolic reaction
Gluconeogenesis.
The process of making glucose from the breakdown products of lipids or proteins. Gluconeogenesis occurs mainly in cells of the liver or kidney
Define catabolism
Breaks down complex molecules into simpler ones via hydrolysis reaction (consumption of H2O to break bonds).
Releases energy when bonds are broken (exergonic) < typically involves oxidation reactions.
example of a catabolic reaction
Glycolysis.
The process in which glucose is broken down to produce energy. It produces two molecules of pyruvate, ATP, NADH and water. The process takes place in the cytosol of the cell cytoplasm, in the presence or absence of oxygen. Glycolysis is the primary step of cellular respiration.
