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

The Chemistry of Life

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!

Matter

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

Mass

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?

Democritus

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

same thing

The Atom

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

Subatomic Particles

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

Element

http://youtu.be/HvVUtpdK7xw

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

Element

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

Isotope

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

Radiocarbon Dating

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 Compounds

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=_M9khs87xQ8

Chemical Bonds

Van der Waals forces – weak attraction between oppositely charged atoms

Electrons are not shared or transferred Kind of like magnets!

Van der Waals

H2O 2 hydrogen and 1 oxygen

Water!

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

Water is Polar

Polar molecules can attract each other

Hydrogen bond – the attraction between water molecules

Hydrogen bonds

Cohesion – attraction between molecules of the same substance◦ Water is the best example! It sticks together!

Adhesion – attraction between molecules of different substances

Adhesion and Cohesion

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

You can mix things without chemically bonding them!

Mixture – material made of two or more elements physically mixed together

NOT chemically combined!

Solutions and Suspensions

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

Solutions

Solute – what is being dissolved

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

Solute

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

Ions

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

Suspension

Acids vs. Bases

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

Carbon Compounds

Organic compound must have BOTH carbon and hydrogen

Ex. ◦ CH4; C6H12O6

Organic vs. Inorganic

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

We can group organic compounds found in living things into 4 categories

◦Carbohydrates◦Lipids◦Nucleic Acids◦Proteins

Macromolecules

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

Carbohydrates

Lipid – macromolecule made of mainly C and H

Fats, oils, and waxes

Lipids are used to store energyImportant 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

Lipids

Saturated vs. Unsaturated

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

Nucleic Acids

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

Proteins

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

Primary Level

Secondary structure consists of two shapes◦Alpha helix◦Beta sheets

Caused by hydrogen bonding

Secondary Level

Three dimensional structure of a single protein molecule

Caused by hydrophobic interactions

Tertiary Level

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

Quaternary Structure

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

Proteins

There are two main types of chemical bonds◦ Ionic Bonds◦ Covalent Bonds

Ionic bonds transfer electrons

Covalent bonds share electrons

Chemical Bonds

When a molecule with an ionic bond dissolves in water…

The molecule breaks into a positive and negative ion

NaCl Na+ and Cl-

Ions

Living things are all made of chemical compounds

Chemistry is also how life works and what it does!

◦ Growth, reproduction, movement

Chemical Reactions

Chemical Reaction – process that changes, or transforms one set of chemicals into another

Chemical reactions drive life processes!

Chemical Reaction

Some reactions are slow

Some reactions are fast

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 Reactions

H2O + CO2 + sunlight C6H12O6 + O2

K2CO3 + 2HCl --> 2KCl + H2O + CO2

Chemical Reaction

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!

Energy in Reactions