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CHAPTER 3
CELL PROCESSES
SECTION 1 - CHEMISTRY OF LIFE
 All things are made up of matter and energy
 Matter is anything that takes up space and has mass
 Energy is anything that brings about a change
 Energy can hold matter together or break it up
ATOMS
 Matter is made of atoms
 At center of atom is the nucleus which contains protons (+ charge) and neutrons
(no charge
 Outside nucleus are electrons that are negative
ELEMENTS
 Something made up of only one kind of atom is an element
 An atom can not be broken down into simpler forms
 Everything is made up of elements
 Most things are made of a combination of elements
COMPOUNDS AND MOLECULES
 Compounds are made up of two or more elements in exact proportions
 Example – pure water is always 2 atoms of hydrogen and one oxygen
 Compounds have properties different than the elements they are made of
MOLECULAR COMPUNDS
 A molecule is a group of atoms held together
 When chem. Reactions occur, new molecules are produced that are different from
original
IONS
 Atoms are usually neutral, but sometimes gain or lose an electron, making them +
or –
 Electrically charged atoms are called ions
Mixtures
 Can be solids, liquids or gases
 When substances combine,the individual substances retain their own properties
 In a solution, two or more substances are mixed evenly
 Suspensions – formed when a liquid or gas has another substance evenly spread
throughout it.
 Substances in a suspension eventually sink to the bottom
Organic compounds
 All living things are made up of organic compounds
 They always contain carbon and hydrogen
 Associated with living things
Organic compounds in all living things
 Carbohydrates, lipids, proteins, and nucleic acids
Carbohydrates
 Supply energy for cell processes
 Ex. Sugar and starches
 Cellulose carbohydrate is important in plant cells
Lipids
 Do not mix with water
 Fats and oils – release larger amounts of energy than carbs.
Proteins
 Made up of amino acids
 Building blocks of many structures inside organism
 Enzyme proteins regulate nearly all chemical reactions in cells
Nucleic acids
 Store important coded information – dna
 Carries info. That directs cells activities
Inorganic compounds
 Made from elements other than carbon
 Source of elements needed by living things
 Many foods we eat contain inorganic compounds
 Water is one of the most important inorganic compounds
Importance of water
 Living things are composed of more than 50% water
 Can live for only days without water
 Seeds, spores, fungi, bacteria need water to grow and reproduce
 All chemical reactions in living things need water
 Organisms need water to transport materials through their body
 Blood is mostly water
 Plants use water to move materials thru the plant
Characteristics of water
 2/3 of your body’s water is contained in cells
 Water helps maintain cell shape and size
 1/3 of body’s water is found outside of the cell