Chemistry of Living Things
Chemistry
 Chemistry- the study of the structure of matter and
composition of substances, their properties, and their
chemical reactions
 Many chemical reactions occur in the human body
 Reactions can range from digestion of meat in the
stomach and formation of urine in the kidneys
 The study of the chemical reactions of living things is
called biochemistry
Matter and Energy
 Matter- anything that has weight and takes up space
 Matter exists in the forms of solid, liquid, and gas
 Example in our bodies
 Solid: bone
 Liquid: blood
 Gas: oxygen
 Physical changes occur when we chew a piece of food and break
it into smaller pieces
 Chemical changes occur when food is acted upon by chemicals
in the body that change its composition
 Energy- the ability to do work or put matter into motion
 Potential energy- energy stored in cells waiting to be released (lying
in bed)
 Kinetic energy- work resulting in motion (getting out of bed)
Atoms
 Atom- smallest piece of an element
 Invisible to the human eye but are part of our human structure
 Atoms are made up of protons, neutrons, and electrons
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Protons- positive
Electrons- negative
Neutrons- neutral
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Number of protons=number of electrons
 Isotopes- atoms of a specific element that have the same number
of protons but a different number of neutrons
 Radioactive isotopes- unstable and may decay
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As they decay they may give off radiation
Used to study structure and function of particular tissue
Strong radiation is useful in the treatment of cancer and other diseases
Chemical terms
 Ion: A positively or negatively charged particle
 Organic compounds: compounds found in living
things that contain carbon
 Element: combined atoms that are alike
 Compound: various elements that combine in a
definite proportion
Types of compounds
 Inorganic compounds
 Made of molecules that do not contain carbon
 Water is an inorganic compound
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Makes up between 55 to 65% of human body weight
Most important inorganic compound to living organisms
Small
 Organic compounds
 Always contain carbon
 More than a million known organic compounds
 Large and complex
 4 main organic compounds
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Carbohydrates
Lipids
Proteins
Nucleic acids
Carbohydrates
 Compounds that contain carbon, hydrogen, and
oxygen
 Divided into 3 groups
 Monosaccharides
 Disaccharides
 Polysaccharides
Monosaccharides
 Means one sugar and cannot be broken down any
farther
 Known as single or simple sugars
 Types
 Glucose- main source of energy in cells
 Fructose- sweetest monosaccharide found in fruit and
honey
 Galactose
 Ribose- found in RNA
 Deoxyribose – found in DNA
Disaccharides
 Known as a double sugar
 Formed from two monosaccharides
 Types
 Sucrose- table sugar
 Maltose- found in grains
 Lactose- found in milk
 Must be broken down by digestion to be absorbed and
used by the body
Polysaccharides
 Large complex molecules of hundreds to thousands of
glucose molecules bonded together in a long chain
 Types
 Starch- found in grain products and potatoes
 Cellulose- main structural component in plant tissue
 Glycogen- stored in the liver
Lipids
 Molecules containing carbon, hydrogen, and oxygen
 Fats- consist of glycerol and fatty acids
 Also known as triglycerides
 Most abundant in the body
 Phospholipids- contain carbon, hydrogen, oxygen, and
phosphorous
 Found in cell membranes, the brain, and nervous tissue
 Steroids- lipids that contain cholesterol
 Cholesterol is needed to make cortisol
Proteins
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Contain C, H, O, N, phosphorous and sulfur
Found in every part of the living cell
Also found in the outer protein coat of a virus
Serve as binding and structural components of all living things
 Example: large amounts of protein are found in fingernails, hair, cartilage, tendons,
ligaments, and muscle
 Building blocks of proteins are amino acids
 22 different amino acids that can combine to form different proteins
 Essential amino acids must be ingested because the body does not naturally make them
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Histidine
Isoleucine
Leucine
Lysine
Methionine
Phenylalanine
Threonine
Tryptophan
Valine
Enzymes
 Special proteins found in all cells
 Help control chemical reactions
 Help provide energy for the cell
 Assist in making new cell parts
 Control almost every process in the cell
 Known as organic catalysts
Nucleic Acids
 Contains carbon, hydrogen, nitrogen, and phosphorus
 2 major nucleic acids
 DNA (deoxyribonucleic acid)
 RNA (ribonucleic acid)
 Largest known organic molecule
 Made of repeating subunits called nucleotides
DNA structure and function
 Involved in the process of heredity
 DNA molecule passes on genetic information from one
generation to the next
 Double stranded referred to as a double helix
 Sides of ladder are made of sugars and phosphates
 Rungs of the ladder are nitrogenous bases
 A with T
 G with C
 DNA is unique for every person and is used as a means of
identification
 Because all cells contain DNA a very small amount can
identify anyone
RNA structure and function
 A with U
 G with C
 Single stranded
 3 types of RNA
 Messenger RNA- carries instructions for protein
synthesis
 Transfer RNA- picks up amino acids and transfers them
to the ribosome to form proteins
 Ribosomal RNA- helps in the attachment of mRNA to
the ribosome