The Chemistry of Life

Matter Life depends on chemistry Eat food, Breathe in oxygen – chemical reactions allow your body to use these substances

Matter Just as an architect needs to understand the materials used to build a skyscraper …biologists need to understand the chemical building blocks of life.

Matter Matter – anything that takes up space and has mass Mass – the amount of matter a substance contains This is NOT the same as weight!

Mass The international unit of measure for mass is the kilogram 1kg is equal to the mass of a single cylinder of platinum kept by the international committee of weights and measure

Democritus A Greek philosopher If you break and object in half, are both halves still the same thing? If you break a piece of chalk, are the two pieces still chalk?

The Atom Atom – the basic unit of matter Everything is made of atoms An atom cannot be broken and still be the same thing

Subatomic Particles Atoms are made up of even smaller parts Protons, Neutrons, Electrons Protons are positively charged particles Neutrons have no charge Electrons are negatively charged particles

Element Element – a pure chemical substance that consists entirely of one type of atom We know of over 100 different elements Only about 2 dozen are commonly found in living things

http://youtu.be/HvVUtpdK7xw

Element Elements are represented by letter symbols H = hydrogen C = carbon O = oxygen Na = sodium He = helium

Element Elements are determined by the combination of protons, neutrons, and electrons in their atoms Ex. Hydrogen is the first element on the periodic table H has 1 proton and 1 electron

Isotope Isotope – atoms of an element that have a different number of neutrons A change in the number of neutrons alters the atomic mass Isotopes are important to many chemical processes in life We’ve already learned they are useful when using radioactive dating

Radiocarbon Dating Carbon dating is one of the most accurate ways to determine the age of organic material C has an atomic mass of 12 C14 has an atomic mass of 14 - it is an isotope

Chemical Compounds Elements are usually found combined with other elements Chemical Compound – substance formed by the combination of chemical elements in defined proportions H2O, NaCl, C6H12O6

Chemical Compounds Physical and chemical properties of compounds are usually very different from the individual elements Take Sodium (Na) and Chlorine (Cl) for example…

Chemical Compounds Compounds are formed when elements are chemically bonded The sole of your shoe is bonded to the upper A book cover is bonded to the pages A reaction has occurred and the two types of atoms are now chemically linked together http://youtu.be/afRlDab1_e8

Chemical Bonds Ionic bond – one or more electrons are transferred from one atom to another Covalent Bond - electrons are shared between atoms

Chemical Bonds http://youtu.be/QqjcCvzWwww http://www.youtube.com/watch?v=_M9khs87 xQ8

Van der Waals Van der Waals forces – weak attraction between oppositely charged atoms Electrons are not shared or transferred Kind of like magnets!

Water! H2O 2 hydrogen and 1 oxygen

Water is Polar Polarity – having poles or a positive and negative side Water is polar because there is an uneven distribution of electrons between the oxygen and hydrogen atoms

Hydrogen bonds Polar molecules can attract each other Hydrogen bond – the attraction between water molecules

Adhesion and Cohesion Cohesion – attraction between molecules of the same substance Water is the best example! It sticks together! Adhesion – attraction between molecules of different substances

Why can this spider walk on top of the water?!

Solutions and Suspensions You can mix things without chemically bonding them! Mixture – material made of two or more elements physically mixed together NOT chemically combined!

Solutions Solution – a mixture of two or more substances that are evenly distributed Ex. Salt dissolved in water! 2 components of a solution The Solute The Solvent

Solute Solute – what is being dissolved Solvent – what is doing the dissolving (most of the time this is water)

Ions When NaCl dissolves the Na and the Cl atoms are pulled apart by the water molecules forming ions Ion - an atom or molecule with a net electric charge due to the loss or gain of electrons http://youtu.be/EBfGcTAJF4o

Suspension When a substances does not dissolve in water Instead it separates into pieces so small they do not settle Suspension – mixture of water and materials that do not dissolve Ex. Dirt/sand in water

Acids vs. Bases

Carbon Compounds We already know carbon is an important element Carbon is found in each and every living thing There is an entire branch of chemistry for just Carbon called Organic Chemistry

Carbon Compounds Carbon can bond to other carbon atoms Carbon can link into long chains …or form rings! Carbon can form millions of different complex structures

Organic vs. Inorganic Organic compound must have BOTH carbon and hydrogen Ex. CH4; C6H12O6

Macromolecules Many molecules in living things are so large we call them macromolecules Macro = large Monomers – small unit that can join together with other units Polymer – large compound formed from many smaller monomers

Macromolecules Carbohydrates Lipids Nucleic Acids Proteins We can group organic compounds found in living things into 4 categories Carbohydrates Lipids Nucleic Acids Proteins

Carbohydrates Carbohydrate – compound made of C, H, and O atoms; major source of energy for living things Carbohydrates are polymers The monomers that make up carbohydrate molecules are sugars

Carbohydrates Carbohydrates are broken down into glucose molecules in living things Glucose is the source of energy for all your body cells

Lipids Lipid – macromolecule made of mainly C and H Fats, oils, and waxes Lipids are used to store energy Important parts of membranes and waterproof coverings

Lipids Lipids are long carbon hydrogen chains Saturated and unsaturated fats You may have seen these terms on food labels

Saturated vs. Unsaturated

Nucleic Acids Nucleic Acid – macromolecule containing C, H, O, N, and P Store and transmit genetic info Two kinds: DNA RNA

Nucleic Acids Nucleic acids are polymers of nucleotides Nucleic Acid – a sugar, a phosphate, nitrogenous base

Proteins Proteins – macromolecule made of C, H, O, and N Needed for growth and repair Made of amino acids

Proteins Proteins can have up to 4 levels of organization Primary Secondary Tertiary Quaternary

Primary Level Primary protein organization = the initial chain of amino acids Peptide bond – the bond between amino acids to form the long chain we call a protein

Secondary Level Secondary structure consists of two shapes Alpha helix Beta sheets Caused by hydrogen bonding

Tertiary Level Three dimensional structure of a single protein molecule Caused by hydrophobic interactions

Quaternary Structure 3D structure with multiple protein subunits Held together by disulfide bonds

Proteins Some proteins help to control reactions and cell processes Enzyme – protein that can speed up reactions Other proteins build bone and muscle Some help with transport

Chemical Bonds There are two main types of chemical bonds Ionic Bonds Covalent Bonds Ionic bonds transfer electrons Covalent bonds share electrons

Ions When a molecule with an ionic bond dissolves in water… The molecule breaks into a positive and negative ion NaCl  Na+ and Cl-

Chemical Reactions Living things are all made of chemical compounds Chemistry is also how life works and what it does! Growth, reproduction, movement

Chemical Reaction Chemical Reaction – process that changes, or transforms one set of chemicals into another Chemical reactions drive life processes! Some reactions are slow Some reactions are fast

*chemical reactions always involve changes in the chemical bonds Reactants – the chemicals that enter into a chemical reaction Products – the chemicals that are produced by the chemical reaction Reactants  Products *chemical reactions always involve changes in the chemical bonds

Chemical Reaction H2O + CO2 + sunlight  C6H12O6 + O2 K2CO3 + 2HCl --> 2KCl + H2O + CO2

Energy in Reactions Energy can be either released or absorbed whenever chemical bonds form or are broken Living things carry out chemical reactions that require energy Organisms need a source of energy Plants have the sun Animals eat food

Energy in Reactions Activation energy – the energy needed to start a chemical reaction

Energy in Reactions Remember! Some reactions give off energy…and some absorb energy!