Molecular Biology Flashcards
Vitalism
Doctrine stating organic molecules/ living organisms can only be synthesizes/ produced by living organisms due to a vital force
In 1828, Frederick Wohler disproved this theory by artificially synthesizing Urea. He heated Ammonium chloride and silver isocyanate and produced Urea. Now used as a nitrogen-releasing fertilizer & in automobile industry for medical use
Metabolism
A web of all chemical processes9 enzyme-catalyzed reaction) within the cells of organisms.
Metabolic pathways- Consists of chains or cycles, can be anabolic or catabolic
Molecular biology explains these biological processes in terms of the chemical molecules involved
Anabolism
- Synthesis of complex molecules from simpler ones.
- Formation of macromolecules from monomers by condensation reactions. Amino acids –> polypeptide + water
- Associated with condensation reactions, removal of a water molecule when a monomer is added to a polymer chain or another monomer
Catabolism
- Breakdown of complex molecules into simpler molecules includes hydrolysis of macromolecules into monomers
- Hydrolysis reactions water molecules are split/ water added to break down a polymer
dipeptide + water–> 2 amino acids
Carbon
- Molecules used by living organisms are based on carbon
- Carbon atoms form 4 covalent bonds, leading to great diversity of compounds to exist
- Carbohydrates, lipids, proteins and nucleic acids are the main types fo molecules used by living organisms.
Bonds
- Covalent bonds are strong, so molecules are stable structures
- Intermolecular forces- Weaker bonds formed better molecules
- Covalent bonding consists of sharing electrons between atoms.
Biomacromolecules
The following are made of recurring monomers
Carbohydrate - Monosaccharide - polysaccharide
Protein - Amino acid - polypeptide
Nucleic acid - Nucleotide - DNA/RNA
Lipids are not, but contain smaller subunits
Triglyceride - Glycerol + Fatty Acids x3
Polar and Non-polar molecules
Polar molecules - Have an uneven distribution of charges across the molecule. i.e it is more negative at one end and more positive at another.
Non-polar molecules- Have an even distribution of charges
across the molecule, so no positive or negative poles are formed
Water
Due to covalent bonding, water is polar, water has a slightly +ve charged pole, and hydrogen atoms are a slightly -ve charged pole.
Water has 2 poles, dipoes= Dipolarity
Polarity of water, -ve charged O2 atoms attract slightly +ve charged H atoms from other molecules. Form hydrogen bonds between molecules.
When water evaporates, H bonds between other water molecules and the molecule itself are broken, heat energy is used, Why sweat is a coolant, evaporation of water removes heat from body
Explains waters thermal, cohesive, adhesive and solvent properties
Thermal Properties Water & Methane
- High specific heat capacity - A lot of energy is required to raise waters temperature, H bonds are the strongest of the weakest bonds so they restrict movements.
Water- 4.2 J per g per Celsius. Methane- 2.2 J per g per Celsius - High Latent heat of vaporization- H bonds in water molecules in liquid form make it hard for single molecule to escape as vapor. When vaporized, energy is released causing cooling effect
Water- 2257 J/g
Methane- 760 J/g - High latent heat fusion- At 0 degrees celsius water must lose a lot of energy before forming ice, water expands as it freezes.
Melting point
Methane- -182 degrees celsius
Water- 0 degrees celsius
Boiling point
Methane- -160 degrees celsius
Water- 100 degrees celsius
Cohesive Properties of water
- Water molecules cohere(stick to each other) due to hydrogen bonds between them
- Explains the formation of water droplets, why some organisms can “walk on water” & why columns of water can be sucked up in xylem vessels along tall trees, without breaking despite suction forces.
Adhesive properties of water
- Dipolarity of water molecules allows them to adhere to surfaces that are polar through H bonds, hydrophilic
- Adhesion between water and cellulose in cell walls, leaf cause water to be drawn out of the xylem vessel, keeping cell walls moist and act as a gas exchange surface
Solvent properties of water
- Water is a solvent, due to its polarity
- Water can form bonds around other polar compounds such as NaCl separating them, & form hydrogen bonds around molecules whose elements are tightly bonded, as a transport medium for polar molecules.
- Glucose and amino acids are polar, so they can be freely transported and dissolved in the blood
Transport in Blood
Blood transports a variety, via blood plasma, the mode of transport depends on solubility in water
- NaCl is soluble in water, dissolved in the plasma transported as Na+ and Cl- ions
- Oxygen is non-polar, the amount dissolved is insufficient, red blood cells with hemoglobin is needed, oxygen binds
- Cholesterol and fats are non-polar, insoluble in water, transported in droplets, lipoproteins. They are cotted with phospholipids and proteins.
Hydrophilic
Water-loving
- Molecules that can readily dissolve in water and can freely form intramolecular bonds.
- Include polar molecules and ionic compounds
- Hydrophilic compounds can readily dissolve in water
