Biology Chapter 6: The Chemistry of Life Name:
All matter is made up of atoms

______________________ are the building blocks of matter

All atoms have the same basic structure o They contain a ______________________
 Protons (___) and neutrons (___) o ____________________ surround the nucleus
 Electrons (___) o In a neutral atom, the number of protons and electrons are ___________
 Protons and electrons each have a charge of about 1.6x10
-19 coulombs

The positive charge of the proton and the negative charge of the electron cancel out
 Neutrons have no charge
Elements
 ___________________ refer to atoms with a particular number of ________________. o Every atom in the universe that has 6 protons is Carbon o The number of protons an element has is called its ___________________

Elements cannot be broken down into simpler forms by chemical means o In chemical reactions, a molecule is broken down into elements
 Water can be broken down into 2 Hydrogen atoms and 1 Oxygen atom

Elements can gain or lose electrons or neutrons and remain the same element o However, if the number of protons changes, the element changes

Elements in Human Body o Life is primarily made up of _____ elements
 Oxygen (______)-65%
 Carbon (______)-18.5%
 Hydrogen (_____)-9.5%
 Nitrogen (_____)-3.3%
 Carbon (_____)-1.5%
 Phosphorus (________)-1 % o Mnemonic: __ur __ooks ___ave __o ___kes or __ies o Other atoms make up less than 1% of the elements in the human body
 However, all play important roles
 Called _____________________________________

Electrons

Electrons are what determine the ______________________ of substances o Electrons are located outside of the nucleus in electron clouds

The electron clouds have different ________________________ o Only certain numbers of electrons can fit in the difference energy levels
 The first energy level can only ever hold ___ electrons
 The second can only hold ___ electrons each o If an energy level is not full, the atom is _______________
 ___________________ (Ne, Ar, Kr, Xe, Rn) are ___________________ (nonreactive) because they have full energy levels

Li, Na, K, F, Cl, Br, and I are very reactive because they do not. o They each have 1 electron in their outer cloud, and really want to give it up
 Ions o Sodium, for example, has _______________, so it will have ___________________ when it is neutral
 The ___________________ is full (___), The ____________________ is full (____)
 Leaving ___ electron in the _________________________, which needs 8 to become stable
 It is much easier to lose the 1 than gain 17… o Sodium really wants to get rid of that 1, so will readily give up its electron o In giving up its electron, sodium has _______________________________________): 11+(-10)=+1

It has a __________________________, and has become a charged atom o This is called an________________ o Ionic Bonds-Attraction between ions
 Chlorine (atomic number 17)

___ electrons in the first level, ___ electrons in the second level, ___ electrons in the third level o ___________ of being stable
 Chlorine will gladly take the electron from sodium

Chlorine will then have more electrons than protons (18 electrons, 17 protons), so becomes an ________: (-18)+17= _____
 Because chlorine then has a negative charge and sodium has a positive charge, ____________ one another (like magnets)
 The __________ is rather ____________. Put into water, they will split easily.
 Everyone wins. Sodium has its levels full, chlorine has its levels full. And we get NaCl (a.k.a. table salt)

Covalent Bonds-sharing electrons

Oxygen (atomic number 8) has a similar problem o 1 st energy level (___), 2 nd energy level (___)
 ___________________ of stability

Hydrogen (atomic number 1) also has a problem o 1 st energy level (___)
 _______________ of stability
 Each need electrons, so decide to _______________________ o 2 hydrogens work together with oxygen to share electrons
 This fills all energy levels
 This forms a water molecule o The bonds are _______________________
 Unequal Sharing-Polar Covalent Bonds o In a covalent bond, one atom generally controls the shared electrons a little bit more than the other atoms
 This creates _____________________ at the ends (__________________) of the molecule

These molecules have small attractive forces and can _________________________ o ____________________
Chemical Equations

____________________  _______________________

Reactants are what react to produce the product

Na + Cl  NaCl o Must be __________________ (same number of each element on each side of the equation.)

Hydrogen and oxygen each exist as molecules in nature: H
2
and O
2
respectively o Water formation:
 2H
2
+ O
2
 2 H
2 o
 4H, 2O  4H 2O
Properties and Importance of Water
 Water is the only raw material _____________________________ on earth.
 Water is needed for ___________________________ in the body to occur o The water dissolves the chemicals, and transports them
 Water’s ____________ allows it to _________________, and to ___________________________ o This leads to __________________________ and ____________________________ o Also allows it to easily __________________________________________________


Water has a ___________________________ o Specific heat is the amount of ____________ needed to ____________________________ of a substance
 It takes a lot of energy of raise or lower the temperature of water
 This helps keep cells (which are mostly water) in homeostasis, as water acts a little as an insulator pH Scale

Many chemical reactions in the body can occur only under specific conditions o One of these conditions is that the ____ of a substance must be in a certain range
 pH is the measure of how _________________________ a solution is
 pH of _____________________ (pure water)
 pH ___________________________ o Blood, with a pH of 7.3-7.4, is slightly basic. o Mucus lining the stomach is basic to prevent damage by stomach acid
 pH ________________________________ o Stomach acid is very acidic (1.5-3.5)
 Upset stomachs can be calmed with antacid (base with pH around 10)

Bases o Bases are substances that form __________________________ in water
 Ammonia (NH
3
)

Ammonia strips water molecules of a hydrogen ion, forming hydroxide ions o NH
3
+ H
2
O  NH
4
+ + OH¯
 Sodium Hydroxide (NaOH)-component in drain cleaners

Water breaks the weak ionic bond o NaOH  Na + + OH -

Acids o Acids are substances that form ________________________________ in water
 Hydrochloric acid (component of stomach acid) is a strong base

HCl  H + + Cl -

Life Substances

Life is based on _________________ (atomic number 6) o 1 st energy level (___) o 2 nd energy level (___) o ___________________ to become stable
 Carbon can bond with other carbon atoms, or other atoms

Often forms ____________________ of atoms
 4 main categories of biological _____________________________ (large molecules) o Carbohydrates, Lipids, Proteins. Nucleic Acids
 Structure of Biological Macromolecules o All biological molecules are chains of molecules
 Small molecules are bonded together to form one large molecule
 Think cars on a train o The ____________________ (the cars) are called _______________ (mono=1) o The _____________________ (the train) is a collection of molecules called a
_____________________ (poly=many)

The monomers are bonded together by ________________________-

Carbohydrates (a.k.a. Carbs and sugars) o Carbohydrates are made up of carbon, hydrogen, and oxygen
 They are often in a ratio around _______________

Example: C
6
H
12
O
6
, C
12
H
22
O
11 o They are used by cells to __________________________ o Sugars can be ________saccharides (monomer), ____saccharides (polymer), or ________saccharides
(polymer)
 Monosaccharides include:

Glucose (C
6
H
12
O
6
)

Fructose (C
6
H
12
O
6
) o These are _____________, or molecules that have the _____________, and the same number of each atom, but in __________________________
 When glucose and fructose are linked together, they form a polymer called a disaccharide
 Sucrose: table sugar (C
12
H
22
O
11
)
 Polysaccharides are the largest carbohydrates
 _______________ o Still a similar ratio, but can have several different numbers of atoms


Lipids o Large molecules made from carbon, hydrogen, and small amounts of oxygen o _________, oils, waxes, _______________ o Used for _______________________ o Fatty acids and glycerol (___________________-) form lipid chains (________________) o Saturated fats are lipids where each carbon is bonded to another carbon by a _______________
 Saturated fats are _________ at room temperature (butter, lard) o Unsaturated fats have at least one carbon __________________________ to another carbon
 Unsaturated fats are _______________ at room temperature (oils)
 Proteins o Large complex polymers composed of carbon, hydrogen, oxygen, nitrogen, and occasionally sulfur o Extremely important to life
 ________________ up biological structures
 Play a role in _______________________
 Assist with _________________________
 ___________________ are proteins that help chemical reactions occur o Monomers are ___________________. They join by special covalent bonds called peptide bonds o Each protein has a _________________________ that determines its job
 Nucleic Acids (DNA and RNA) o Consist of Carbon, Hydrogen, Nitrogen, Oxygen, and Phosphorus atoms
 Arranged in 3 groups

A ____________________________

A ____________________________

A ____________________________ (ribose or deoxyribose) o Most important molecule in an organism
 Contains ________________________________________

Therefore, determines how an organism looks, acts, etc. o ___________________________________
 This is what is passed from parents to offspring o Monomers are _______________________

Neon-2 full energy levels (stable) Argon-3 full energy levels (stable) How an atom becomes an
(the atom goes from unstable
to stable)
Why sodium and chlorine form a ionic bond Formation of a covalent bond between carbon and 2 oxygen molecules, forming carbon dioxide
Water as a polar molecule-Because the Oxygen atom has a higher positive charge (because it has 8 protons and hydrogen only has 1) the electrons are attracted to the oxygen atom more, and will spend more time around the oxygen nucleus (unequal sharing) pH scale: higher=basic
lower=acidic

Monomers form covalent bonds, making a polymer
Glucose and fructose are monosaccharides (monomers) and bond together to form sucrose, a disaccharide (polymer)
Saturated lipids-carbons are only single bonded
Unsaturated lipids-Some carbons are double bonded to each other
Proteins are polymers of amino acids. The sequence of amino acids determine the 3-D structure, which is critical Nucleic acids are polymers formed from nucleotides. for the protein to do its job. Nucleotides are formed from a sugar, a phosphate
group, and a nitrogenous base.