Chemistry of Life Lecture 18 (All matter in the universe is composed of…
Chemistry of Life Lecture 18
All matter in the universe is composed of atoms.
Atoms are composed of subatomic particles
Electrons are organised into orbitals
An orbital is a three dimensional space where an electron is found 90% of the time, each electron shell consists of a specific number of orbitals, Atoms with incomplete valence shells can share or transfer valence electrons with certain other atoms. These usually result in atoms staying close together held by attractions called chemical bonds
Matter is made up of elements, an element is a substance that cannot be broken down into other substances by chemical reactions. A compound is a substance consisting of two or elements in a fixed ratio. A compound has characteristics different from that of its elements, i.e. emergent properties.
Organisms are composed of matter. Matter is anything that takes up space and has mass. Atoms sometimes strip electrons from their bonding partners, an example is the transfer of an electron from sodium to chlorine. After the transfer of an electron both atoms have charges. A charged atom or molecule is called an ion
Most of the strongest bonds in organisms are covalent bonds that form a cell's molecules
A covalent bond is the sharing of a pair of valence electrons by two atoms
In a covalent bond the shared electrons count as part of each atoms valence shell
A molecule consists of two or more atoms held together by covalent bonds. A single covalent bond or single bond is the sharing of one pair of valence electrons
A double covalent bond or double bond is the sharing of two pairs of valence electrons
Non-polar and polar covalent bonds
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Relevant subatomic particles include Neutrons(no electric charge), Protons(positive charge) and electrons (negative charge), Neutrons and protons for the atomic nucleus, electrons form a cloud of negative charge around the nucleus. Neutron mass and proton mass are almost identical and are measured in Daltons
Weak chemical interactions, hydrogen bonds & van der waal interactions
Many large biological molecules are held in their functional form y weak chemical bonds
A hydrogen bond forms when a hydrogen atom covalently bonded to one electronegative atom is also attracted to another electronegative atom
In living cells, the elctronegative partners are usually oxygen or nitrogen atoms, if electrons are not evenly distributed they may accumulate by chance in one part of a molecule
If electrons are not evenly distributed they may accumulate by chance in one part of a molecule
Van der waal interactions, are attractions between molecules taht are close together as a result of these charges, Collectively such interactions can be strong as between a gecko's toe hairs and a wall surface. The reversibility of weak bonds can be an advantage
The elements of life
About 20-25% of the 92 natural elements are required for life (essential elements), Carbon hydrogen oxygen and nitrogen make up 96% of living matter. Most of the remaining 4% consists of Calcium, phosphorus, potassium and sulfur. Trace elements are required by an organism in only minute quantities.
Biological life can be studied at numerous levels.
Life can be studied at different levels. From molecules to entire living planet. This enormous range can be divided into different levels of biological organisation,
result from the arrangement and interaction of parts within a system
Chemical reactions and enzymatic reactions are similar
Molecular shape determines activity
Molecular shape determines how biological molecules recognize and respond to each other. Opiates such as morphine and naturally produced endorphins have similar effects because their shapes are similar and they bind the same receptors in the brain
Energy flow and chemical recycling
Plants take up chemicals from the soil and air
THE MOLECULES OF LIFE
All living things are made up of four classes of large biological molecules; carbohydrates, proteins, lipids ad nucleic acids
Macromolecules are large molecules and are complex
Large biomolecules have unique properties that arise from the orderly arrangement of their atoms. Enzymes are responsible for the assemble and disassembly of macromolecules and the processing of their intermediates
A polymer is a long molecule consisting of many similar building blocks.
A dehydration reaction occurs when two monomers bond together through the loss of a water molecule, polymers are disassembled to monomers by hydrolysis, a reaction that is essentially the reverse of a dehydration reaction
A cell has thousands of different macromolecules. Macromolecules vary between cells of an organism, vary more within a species and vary even more between a species. A huge variety of polymers can be built from a small set of monomers.
Orbitals and Bonding dictate a molecules shape and function
A molecule's size and shape are key to its function. A molecule's shape is determined by the positions of its atom's orbitals. In a covalent bond, the s and p orbitals may hybridize creating specific molecular shapes.