2.1 Molecules to Metabolism Flashcards
Organic Compounds
A compound that contains carbon and is found in living things.
Carbon
Carbon forms the basis of organic life due to its ability to form large and complex molecules via covalent bonding.
Carbon atoms can form four covalent bonds (with bonds between carbon atoms being particularly stable (catenation)).
These properties allows carbon to form a wide variety of organic compounds that are chemically stable: rings, chains & chains of rings
All life is based of carbon compounds such as proteins, carbohydrates, lipids and nucleic acids
Carbohydrates
Most abundant compound found in nature, composed primarily of C,H, and O atoms in a common ratio- (CH2O)n
Lipids
Non polar, hydrophilic molecules which may come in a variety of forms (simple, complex, derived).
Lipids serve as a major component of cell membranes.
They may be utilized as long term energy storage (fats and oils)
Also may function as signaling molecules (steroids)
Nucleic Acids
Genetic material of all cells and determines the inherited features of an organism.
Dna functions as a master code for protein assembly, while RNA plays an active role in the manufacturing of proteins.
Proteins
Make over 50% of the dry weight of cells.
They are composed of of C,H,O and N atoms (some may include S).
Major regulatory molecules involved in catalysis (all enzymes are proteins).
May also function as structural molecules or play a role in cellular signalling (transduction pathways)
Main Classes of Organic Compounds in Cells
Carbohydrates, Proteins, Lipids, and Nucleic Acids
Ribose
carbon
hydrogen
oxygen
Glucose
carbon
hydrogen
oxygen
Fatty Acid
carbon
hyrdrogen
oxygen
Monosaccharides
Carbohydrates are composed of monomers called monosaccharides (‘single sugar unit’)
Monosaccharides are the building blocks of disaccharides (two sugar units) and polysaccharides (many sugar units)
Most monosaccharides form ring structures and can exist in different 3D configurations (stereoisomers)
Glucose, Galactose, Fructose
examples of mono saccharides
ribose
glubose
galactose
fructose
3 TYPES OF LIPIDS
- Triglyceride
glycerol + 3 fatty acids - Phospholipid
phosphate + glycerol + 2 fatty acids - Steroid
4 fused hydroarbon rings
Falsifying Vitalism
Vitalism was a doctrine that dictated that organic molecules could only be synthesised by living systems
It was believed that living things possessed a certain “vital force” needed to make organic molecules
Hence organic compounds were thought to possess a non-physical element lacking from inorganic molecules
Vitalism as a theory has since been disproven with the discovery that organic molecules can be artificially synthesised
In 1828, Frederick Woehler heated an inorganic salt (ammonium cyanate) and produced urea
Urea is a waste product of nitrogen metabolism and is eliminated by the kidneys in mammals
The artificial synthesis of urea demonstrates that organic molecules are not fundamentally different to inorganic molecules
Phosphorus
Building block of nucleotides
Phospholipids essential
component of cell membranes
Iron
Important role in mitochondrial
cellular respiration
Cofactor for enzymes
important in processes such
as cell protection and cell
division
Sodium
In animal cells -Essential role in active transport across membranes - Conducting nerve impulses and muscle contractions
In Plants
- is not essential, but may substitute for potassium in maintaining water homeostatis
Sulphur
essential to make two of the twenty amino acids protein contain
Metabolism
Metabolism is the web of all enzyme catalysed
reactions in a cell or organism
Most of these reactions occur in the cytoplasm of
the cell but some can occur outside of the cell for
example digestion.
*Therefore metabolism is the sum of all the
chemical reactions that occur in an organism
Metabolism consists of pathways whereby one
molecule is transformed into another
These pathways are mostly chains or reactions but
can be cycles as well.
Metabolic reactions serve two key functions:
They provide a source of energy for cellular processes (growth, reproduction, etc.)
They enable the synthesis and assimilation of new materials for use within the cell
Anabolism
Anabolism is the synthesis of complex molecules
from simpler molecules including the condensation
of macromolecules from monomers by condensation
reactions
Examples of anabolism include-
Protein synthesis (using ribosomes)
DNA synthesis during replication
Photosynthesis - production of glucose from carbon
dioxide and water
Synthesis of complex carbohydrates such as starch,
cellulose and glycogen
Purpose: synthesizing complex molecules from simpler ones
Energetics: uses energy to construct new bonds (endergonic)
Mechanism: Typically involves reduction reactions
Examples: glucogenesis
Condensation Reaction
Monosaccharides are joined via glycosidic linkages to form disaccharides and polysaccharides
Amino acids are joined via peptide bonds to make polypeptide chains
Glycerol and fatty acids are joined via an ester linkage to create triglycerides
Nucleotides are joined by phosphodiester bonds to form polynucleotide chains
Joining of molecules releases water molecule
Catabolism
Catabolism is the breakdown of complex
molecules into simpler molecules including
the hydrolysis of macromolecules into
monomers.
Examples include-
Digestion of food
Cell respiration
Decomposition of organic material
Purpose:
Breaking down complex molecules into simpler ones
Energetics:
Releases energy when bonds are broken (exergonic)
Mechanism:
Typically involves oxidation reactions
Examples;
glycolysis
