Download Biological Chemistry Chemical Elements Examples of Atoms

Biological Chemistry
• Life is made up of matter
matter: anything that occupies space & has
mass (e.g., air, rock, wood, salamander)
mass: quantity of matter
weight: gravitational “pull”
• Matter consists of chemical elements
Chemical Elements
• 92 naturally occurring
• 25 essential to life
• 4 elements make up most of living matter
Oxygen (O)
Carbon ( C )
Hydrogen (H)
Nitrogen (N)
compounds: substance comprised of >2
elements (e.g., salt = sodium & chloride)
• Elements consist of atoms
atom: smallest unit of matter that still has
properties of an element
• Atoms are made of subatomic particles:
1) protons: positive charge
2) electrons: negative charge
3) neutrons: no charge (neutral)
Examples of Atoms
nucleus: core of an atom;
protons & neutrons
• Electrons orbit nucleus due to attraction
of electrical charges (+ & -)
electron
proton
neutron
Hydrogen
1p+, 1e_
Helium
2p+, 2e_
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• All atoms of a given element have same
number of protons = atomic number
Helium = 2 protons = atomic number =2
Carbon = 6 protons = atomic number = 6
• Same # protons & electrons, electrical
charge = 0, what is charge of He?
atomic mass: protons + neutrons
C = 6 protons + 6 neutrons = 12
isotope: variety of an element, different
number of neutrons & different mass
Importance of Electrons
• Determine how atoms interact
• Energy level differences, higher energy
farther from nucleus
electron shell: energy levels around nucleus
in which electrons are found
1) Each shell holds certain # electrons
2) Inner shell hold 2 electrons (e-)
3) Outermost shell hold max. 8 e-
Carbon
6p+, 6e_
Oxygen
8p+, 8e_
Sodium
11p+, 11e_
Chlorine
17p+, 17e_
2
How does a Reaction Occur?
• 2 atoms with incomplete e- shells,
give/take of e-, such that both atoms
gain full shells
Chemical bond: 2+ atoms attracted to one
another by a reaction
molecule: 2+ atoms held together by
chemical bond, e.g., water H2O
Types of Chemical Bonds
1) Ionic Bonds (e.g., NaCl = salt)
1 atom loses e- & 1 atom gains eResult = form ions or charged atoms
ionic bond: 2 ions with opposite charges
are attracted to each other
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electron transfer
SODIUM
ATOM
11 p+
11 e-
SODIUM
ION
11 p+
10 e-
CHLORINE
ATOM
17 p+
17 e-
Stepp
CHLORINE
ed Art
ION
17 p
18 e
Figur
e
2.3a(1
+
-
Types of Chemical Bonds
2) Covalent Bonds (e.g., H2O)
2 atoms share outer shell e- The number of single covalent bonds is
dependent on the # of e- needed to fill
the outer shell
H =1; O = 2; N = 3; C = ?
Water: The Basis of All Life
polar covalent bonds: 2 atoms with very
different electronegativities (attraction
for shared e- in covalent bond) – results
in charged molecule (+ & - ends)
hydrogen bonds: H(+) attracted to O(-)\
- multiple natural states!
- Cohesion, Temperature Regulation
organic compounds: any compound with
carbon (4 e- in outer shell)
hydrocarbons: carbon & hydrogen only
CH4 = methane
C2H6 = ethane
C6H6 = benzene
Functional group: portion of organic
compound giving it unique properties;
usually involved in reactions
Four Functional Groups
1) hydroxyl group (-OH)
- oxygen bonded to carbon chain
C-O-H
- alcohols (e.g., ethanol)
2) carbonyl group (C=O, carbon double
bonded to oxygen)
- Carbonyl group at end of carbon
chain = aldehyde (formaldehyde)
- Carbonyl group within carbon chain
= ketone (acetone)
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Four Functional Groups
Four Macromolecules of Life
3) carboxyl group (COOH)
- 1 O double bonded C, 1 OH bonded
to C
- carboxylic acids (acetic acid)
1) Carbohydrates (sugars = alcohol &
aldehyde or ketone)
2) Lipids (fats = alcohol & carboxylic acid)
3) Proteins (made of amino acids)
4) Nucleic Acids
4) amino group (NH2)
- bases = amines (methylamine)
How are Polymers Made?
How are Polymers Broken Down?
Dehydration Synthesis
- “free” monomers have H & OH groups
- Add “free” monomers to polymer chain
= 1 H2O released
- Form new covalent bond between
monomers
* Make polymers (macromolecules) for
storage/transport, but cells must break
them down to monomers in order to use
them
Sucrose Formation
Glucose
(monosaccharide)
- Cells make macromolecules by
combining monomers (simple
molecules) into polymers(large
molecules)
Hydrolysis (hydro = water; lysis = to break
- Reverse of dehydration synthesis
- Break covalent bond by adding water
- OH group to 1 monomer & H to
adjacent monomer
Major Polysaccharides
Fructose
(monosaccharide)
+ H2O
cellulose
glycogen
Sucrose (disaccharide)
amylose (a starch)
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DNA
• Double-stranded
• Sugar-phosphate
backbone
• Covalent bonds in
backbone
• H bonds between
bases
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