A1.1 Water Flashcards
What is the medium of life
Water
Where does the first cell originate
Water
When does water first existed on Earth
around 4.5 billion ago
When did first life emerged on Earth
at least 3.8 billion years ago
What must happen for life to form and maintain itself
the molecular ingredients of life needed to react with each other
What are the functions of water
-solvent
-metabolite
-temperature buffer
-maintain biological structures
Define metabolite
chemical substance needed(necessary)/produced in metabolism
how is water a solvent
-universal solvent, dissolve variety of molecules
-helps multicellular organisms transport material
-acts as a medium in which chemical reactions occur
how is water a metabolite
Water is a metabolite in many reactions, either as a reactant or as a product of reaction.
Condensation, hydrolysis
how is water a temperature buffer
-high specific heat capactiy
-buffer temperature changes in cells
-this allows the temperature-sensitive enzymes to work in metabolic reactions effectively
what is the structure of water Molecules
what does it exhibit
Water is a polar molecule: it has different charges at each end and so exhibits dipolarity.
What is the consequence of the polar covalent bonds within water molecules
Hydrogen bond
how does water maintain biological structures
3 points
-Water contributes to the formation of cell membranes.
Phospholipids form bilayers with the hydrophilic heads facing outwards towards the surrounding water and the hydrophobic tails facing inward.
-Water drives the folding of amino acid chains as different types of amino acids seek and avoid interacting with water.
-Water surrounds DNA to support the double helix shape.
define chemical bond
A chemical bond is an attraction between atoms, ions or molecules that enables the formation of chemical compounds.
define covalent bond
A covalent bond holds together two atoms that share one or more pair of electrons between atoms.
