BIOCHEMISTRY CHEMISTRY OF LIFE Elements simplest form of
BIOCHEMISTRY
CHEMISTRY OF LIFE • Elements: simplest form of a substance - cannot be broken down any further without changing what it is • Atom: the actual basic unit composed of protons, neutrons, and electrons
THE ATOM • Just like cells are the basic unit of life, the ATOM is the basic unit of matter. • They are very small. If placed side by side one million would stretch a distance. Particle of 1 cm. Charge PROTON • The atom is made up+ of 3 particles. NEUTRON NEUTRAL ELECTRON -
• Electrons are not present within the atom, instead THEY REVOLVE AROUND THE NUCELUS OF THE ATOM & FORM THE ELECTRON CLOUD • Draw a helium atom. Indicate where the protons, neutrons and electrons are. NEUTRONS PROTONS - ELECTRON S + + - ATOMIC # = 2 (PROTONS) ATOMIC MASS = 4 (PROTONS & NEUTRONS)
ISOTOPES • • • atoms of the same element that HAVE A DIFFERENT NUMBER OF NEUTRONS Some isotopes are radioactive. This means that their nuclei is unstable and will break down at a CONSTANT RATE over time. There are several practical uses for radioactive isotopes: 1. CARBON DATING 2. TRACERS
COMPOUNDS • a substance formed by the chemical combination of 2 or more elements in definite proportions – Ex: water, salt, glucose, carbon dioxide
• The cell is a COMPLEX CHEMICAL FACTORY containing some of the same elements found in the nonliving environment. • carbon (C), hydrogen (H), oxygen (O), and nitrogen (N) are present in the greatest percentages
TWO TYPES OF COMPOUNDS • Organic - Contain C, H, and O in some ratio (usually referred to as chemicals of life) – Carbohydrates, Proteins, Lipids, Nucleic Acids • Inorganic - usually "support" life no specific ratio of C, H, and O – Water (H 2 O), Carbon Dioxide (CO 2)
CHEMICAL BONDS • Chemical bonds hold the atoms in a molecule together. • There are 2 types of chemical bonds IONIC and COVALENT
IONIC BONDS • Occur when 1 or more electrons are TRANSFERRED from one atom to another. • When an atom loses an electron it is a POSITIVE charge. • When an atom gains an electron it is a NEGATIVE charge • These newly charged atoms are now called IONS – Example: Na. Cl (SALT)
COVALENT BONDS • Occur when electrons are SHARED by atoms. • These new structures that result from covalent bonds are called MOLECULES • ** In general, the more chemical bonds SHARING a molecule has the. ISmore energy it contains CARING!
MIXTURES • Water is not always pure. It is often found as part of a mixture. • A mixture is a material composed of TWO OR MORE ELEMENTS OR COMPOUNDS THAT ARE PHYSICALLY MIXED – Ex: salt & pepper mixed, sugar and sand – can be easily separated
SOLUTION Two parts: • SOLUTE – SUBSTANCE THAT IS BEING DISSOLVED (SUGAR / SALT) • SOLVENT - the substance in which the solute dissolves • Materials that do not dissolve are known as SUSPENSIONS. – Blood is the most common example of a suspension. – Cells & other particles remain in suspension.
FORMULA • The chemical symbols and numbers that compose a compound ("recipe") • Structural Formula – Line drawings of the compound that shows the elements in proportion and how they are bonded • Molecular Formula – the ACTUAL H 6 O formula for. C a 2 compound
ACIDS & BASES • Acids: always (almost) begin with "H" because of the excess of H+ ions (hydrogen) – Ex: lemon juice (6), stomach acid (1. 5), acid rain (4. 5), normal rain (6) Facts about Acids • Acids turn blue litmus paper RED and usually taste SOUR. • You eat acids daily (coffee, vinegar, soda, spicy foods, etc…)
ACIDS & BASES • Bases: always (almost) end with -OH because of the excess of hydroxide ions (Oxygen & Hydrogen) – EX: oven cleaner, bleach, ammonia, sea water, blood, pure water Facts about Bases • Bases turn red litmus paper BLUE. • Bases usually feel SLIPPERY to touch and taste BITTER.
Neutralization Reactions • When an acid reacts with a base to produce a salt and water.
p. H SCALE • measures degree of substance alkalinity or acidity • Ranges from 0 to 14 • • • 0 – 6 acidic 7 neutral 8 -14 basic
• The goal of the body is to maintain HOMEOSTASIS (neutrality) – to do this when p. H is concerned, we add weak acids & bases to prevent sharp changes in p. H. • These are called BUFFERS
And now for the Biochemistry portion of things….
CARBOHYDRATES • Living things use carbohydrates as a key source of ENERGY! • Plants use carbohydrates for structure (CELLULOSE) – include sugars and complex carbohydrates (starches) – contain the elements carbon, hydrogen, and oxygen (the hydrogen is in a 2: 1 ratio to oxygen)
Monosaccharides (simple sugars) • all have the formula C 6 H 12 O 6 • all have a single ring structure – (glucose is an example)
Lipids (Fats) • Fats, oils, waxes, steroids • Chiefly function in energy storage, protection, and insulation • Contain carbon, hydrogen, and oxygen but the H: O is not in a 2: 1 ratio • Tend to be large molecules -- an example of a neutral lipid is below
• Neutral lipids are formed from the union of one glycerol molecule and 3 fatty acids • 3 fatty acids + glycerol ----> neutral fat (lipid) • Fats -- found chiefly in animals • Oils and waxes -- found chiefly in plants • Oils are liquid at room temperature, waxes are solids • Lipids along with proteins are key components of cell membranes • Steroids are special lipids used to build
PROTEINS • contain the elements carbon, hydrogen, oxygen, and nitrogen • composed of MANY amino acid subunits • It is the arrangement of the amino acid that forms the primary structure of proteins. • The basic amino acid form has a carboxyl group on one end, a methyl group that only has one hydrogen in the middle, and a amino group on the
Major Protein Functions • Growth and repair • Energy • Buffer -- helps keep body p. H constant
Dipeptide • formed from two amino acid subunits • Formed by the process of Dehydration Synthesis • amino acid + amino acid ----- dipeptide + water
Polypeptide (protein) • composed of three or more amino acids linked by synthesis reactions • Examples of proteins include insulin, hemoglobin, and enzymes. • ** There an extremely large number of different proteins. • The bases for variability include differences in the number, kinds and sequences of amino acids in the proteins
NUCLEIC ACIDS • • in all cells composed of NUCLEOTIDES store & transmit heredity/genetic information Nucleotides consist of 3 parts: 1. 5 -Carbon Sugar 2. Phosphate Group 3. Nitrogenous Base
DNA (deoxyribonucleic acid) • contains the genetic code of instructions that direct a cell's behavior through the synthesis of proteins • found in the chromosomes of the nucleus (and a few other organelles)
RNA (ribonucleic acid) • directs cellular protein synthesis • found in ribosomes & nucleoli
CHEMICAL REACTIONS • a process that changes one set of chemicals into another set of chemicals • REACTANTS – elements or compounds that enter into a chemical reaction • PRODUCTS – elements or compounds that are produced in a chemical reaction • Chemical reactions always involve the breaking of bonds in reactants and the formation of new bonds in products.
• In a reaction, energy is either TAKEN IN (ENDOTHERMIC) or GIVEN OFF (EXOTHERMIC) • Can you think of an everyday example of each type of reaction?
Enzymes and Enzyme Action • catalyst: inorganic or organic substance which speeds up the rate of a chemical reaction without entering the reaction itself • enzymes: organic catalysts made of protein • most enzyme names end in -ase • enzymes lower the energy needed to start a chemical reaction. (activation energy) • begin to be destroyed above 45øC.
It is thought that, in order for an enzyme to affect the rate of a reaction, the following events must take place. 1. The enzyme must form a temporary association with the substance or substances whose reaction rate it affects. These substances are known as substrates. 2. The association between enzyme and substrate is thought to form a close physical association between the molecules and is called the enzymesubstrate complex. 3. While the enzyme-substrate complex is formed, enzyme action takes place. 4. Upon completion of the reaction, the enzyme and
How do enzymes work? • substrate: molecules upon which an enzyme acts • the enzyme is shaped so that it can only lock up with a specific substrate molecule enzyme substrate -------> product
"Lock and Key Theory" • each enzyme is specific for one and ONLY one substrate (one lock - one key) • this theory has many weaknesses, but it explains some basic things about enzyme function
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