Download File chemical comp. in cells notes 8a

Chemical Compounds in Cells
You are surrounded by particles that you can’t see! Air is made up of
millions of tiny particle. They bump into your skin, hide in the folds of
your clothes, and whoosh into your nose every time you take a breath!
You and the world around you, including the cells in your body, are
composed of tiny particles. Some of these particles are elements are other
are compounds.
Elements – is any substance that cannot be broken down into simple
substances – the smallest unit of an element is called an atom and an
element is made up of only ONE kind of element!
Ex: the air around you is a mixture of gases! The gases in the air are
oxygen, nitrogen, carbon dioxide (compound)
Compounds – when two or more elements combine chemically, they
form a compound – most elements in living things are in compound form
and the smallest unit of a compound is call a molecule!
Ex: carbon dioxide is a compound made up of the elements carbon
and oxygen (written as CO2)
Like CO2, water is a compound, too! Each water (H2O) molecule is made
up of 2 hydrogen atoms and 1 oxygen atom!
Water makes up about 2/3 of your body, and most chemical reactions
within cells could not take place without water!
Many compounds in living things contain the element carbon. Most
compounds that contain carbon are called organic compounds and
compounds that don’t contain carbon are called inorganic compounds!
Ex: H2O (water) and NaCl (sodium chloride) and table salt are all
inorganic!
Carbohydrates, lipids, proteins and nucleic acids are important
groups of organic compounds in living things!
Carbohydrates – is an energy-rich organic compound made of elements
C (carbon), H (hydrogen) and O (oxygen) – sugar and starches are
carbohydrates
Carbohydrates are important components of some cell parts – the cellulose
found in the cell walls of plants is a type of carbohydrate
Lipids – are energy-rich organic compounds made of C, H and O – fats,
oils and waxes are all lipids
Lipids contain even more energy than carbohydrates! Cells store energy
in lipids for late use
What do a bird’s feathers, a spider’s web and your fingernails have in
common? All of these substances are made mainly of proteins!!
Proteins – are large organic molecules made of C, H, N (nitrogen) and in
some cases, S (sulfur) – meat, eggs, nuts and beans are all high in protein
Protein molecules are made up of smaller molecules called Amino Acids.
Although there are only 20 amino acids, cells can combine them in
different ways to form thousands of different proteins!
The kind of amino acids and the order in which they link together
determine the type of protein that forms
Think of the 20 amino acids as being the 26 letters of the alphabet – the
letters can form thousands of words, and the letters you use and their order
determine the words you form – a change in one letter, for example, from
rice to mice creates a new word, and if you change the order or type of
amino acid may result in a different protein!
Proteins known as enzymes perform important function in the chemical
reactions that take place in cells
Enzyme – type of protein that speeds up a chemical reaction in a living
thing and without enzymes, many chemical reactions that are necessary
for life would either take too long or not occur at all
Ex: enzymes in saliva speed up the digestion of food by breaking down
starches into sugars in your mouth
Nucleic Acids – are very long organic molecules made of C, O, N and P
(phosphorus) and the contain instructions that cells need to carry out all
the functions of life
2 Kinds of Nucleic Acids:
 Deoxyribonucleic Acids (DNA) – the genetic material that carries
info about an organism and is passed from parent to offspring – most
DNA found in a cell is in the chromatin, in the nucleus
 Ribonucleic Acid (RNA) – plays an important role in the production
of proteins and is found in the cytoplasm as well as the nucleus