Transcript Chemistry & Biology

Atoms, Molecules
and Macromolecules
Building Complex Molecules
That Comprise Living Things
Prof. Mary Colavito
& Dr. John Shepanski
Comparison of Terms
Element
Atom
Molecule
Substance that cannot be broken down
to another substance with different
properties
Smallest unit that has characteristic
properties of the element
Two or more atoms joined by chemical
bonds
Macromolecule Large polymer made of monomer units
Composition
of an Atom
• Nucleus
Proton = positively charged particle (+)
Neutron = uncharged particle (n or +)
Number of protons + Number of neutrons = Atomic mass
Number of protons = Atomic number
•Electrons = negatively charged particles
Number of electrons = Number of protons
Each electron circles the nucleus in an orbit
representing a specific energy level.
12
6
C
Atomic Models
Electron
Shell
Nucleus
Hydrogen (H)
Helium (He)
Different Kinds of Atoms
Innermost
electron shell
8e- +
8n 8p
Oxygen
Max 2e2e- +
2n 2p
+2p+
+2n±
+2e+7p+
+8n±
+7e-
Max 8e-
+4p+
Helium
+4n±
+4e-
15e- +
16n 15p
+5p+
+4n±
+5e
Phosphorus
6e- +
6n 6p
Carbon
20e- +
20n 20p
Calcium
http://www.sciencegeek.net/tables/lbltable.pdf
Electron Energy Levels
Energy
Level
Capacity for
Electrons
1
2
3
2
8
18 (8*)
*In forming molecules, atoms combine to fill their outer
(valence) energy levels. When 8 valence orbitals are
filled, remaining, unused slots available in inner levels
are filled before a new valence shell is added.
Chemical Bonds
Bond
Ionic
Characteristics
One atom loses an electron,
another gains an electron
Covalent Atoms share electrons
Electrons are shared
Polar
unequally
Covalent
Hydrogen Covalently-bound hydrogen is
attracted to another atom
Positive
charge
Ionic Bonding in NaCl
–
–
–
–
–
–
+±+
+
++±±
±
±
+
±
+
±±±
+
–
–
–
–
–
–
–
Sodium
–
–
– –
–
–
–
–
–
–
–
– –
–
–
–
–
+±+
+
++±±
±
±
+
±
+
±±±
+
–
–
Electron
Completely
Transferred
–
–
–
#electrons=10
–
–
+±+
+
++±±
±
±
+
±
+±±
±
+
–
Sodium ion
#electrons=11
–
–
–
–
Chlorine
#electrons=17
–
–
–
–
–
–
+±+
+
++±±
±
±
+
±
+
±±±
+
–
–
–
–
–
–
–
–
Negative
charge
–
Chlorine
#electrons=18
Ionic Bonding in NaCl
• Ion: charged atom
with unequal
numbers of protons
and electrons.
• Ions of opposite
charges attract.
• Sodium ions nestle
between chlorine
ions.
• Perfectly cubical
crystals form.
Cl- +Cl- +Cl- +Cl-
Na Na Na Na+
Cl- +Cl- +Cl- +Cl- +
- ClNa Na
- Na
- Na
Cl
Cl
Cl
Na-+ Cl
Na+ Na+ Na+
Cl- + Cl- +Cl
+ - Na+ Na Na
Na
ClCl
Cl
Cl
Na-+ Cl
Na-+ Na+ Na+
Cl- +Cl- +Cl
+ - Na+ Na Na
Na
Cl Cl Cl ClNa+ Na+ Na+ Na+
- Cl- Cl-
Cl +Cl
Na
Na+
Na+
Na+
Covalent Bonding
Oxygen Atom
Oxygen Atom
Oxygen Molecule (O2)
In Water, Polar Covalent Bonds
Join Oxygen and Hydrogen
Hydrogen Bonds Join Water Molecules
Water molecules
are dipoles—the
hydrogen side is
more positive;
the oxygen side
is more negative
Hydrogen bonds
form between O
of one water
molecule and H
of another
H
H
+
–
O
+
H
+
O
–
+
H
+
Hydrogen
Bonds
Due to hydrogen bonding, ionic and
polar substances dissolve in water
Organic Molecules
Contain Carbon
Each carbon atom can make four
covalent bonds with other types of
atoms or additional carbons.
Hydrophobic Not attracted to water
& non-polar substances
Hydrophilic
Attracted to water,
polar and ionic substances
Macromolecules: Polymers
Made of Repeating Monomers
Macromolecule
Monomer Unit
Carbohydrates
Sugars
Lipids
Proteins
Fatty acids
Amino acids
Nucleic Acids
Nucleotides
Synthesis and Breakdown of
Macromolecules
Condensation
Synthesis
Hydrolysis
Removal of water to add
monomer units
Addition of OH and H
groups of water to break
a bond between
monomers
Dehydration Synthesis / Hydrolysis
Dehydration Synthesis
Hydrolysis
Carbohydrates: Structure
• Simple
– Monosaccharides= one sugar unit
Glucose = blood sugar
All cells use glucose for energy
Carbohydrates: Structure
• Simple
– Disaccharides = two sugar units
– Examples: sucrose, lactose, maltose
CH2OH
HOCH2 O H
O
H
H
+
H
H HO
OH H
CH2OH
HO
OH HO
HO
H
H HO
Glucose + Fructose
CH2OH
H
HOCH2
O
O
H
H
H HO
H
OH H
O
HO
CH2OH
H
H HO HOH HO
Sucrose & Water
Carbohydrates: Structure
• Complex
– Polysaccharides= many sugar units
• Starch -- storage in plants
• Glycogen -- storage in animals
• Cellulose -- plant cell walls, indigestible
Carbohydrates: Structure
• Complex
– Polysaccharides= many sugar units
found in plant cell walls
energy storage
in plants
energy storage
in animals
Carbohydrates: Functions
• Energy source
• Structural component
• Cell-cell communication
Lipids: Structure
• Phospholipid—component of cell membranes
Polar
Head
Glycerol
Hydrophilic
Fatty Acid Tails
Hydrophobic
Lipids: Structure
• Types of Fatty Acids
– Saturated – 2H per internal carbon
– Unsaturated -- <2H per internal carbon
one or more double bonds
• Monounsaturated – one double bond
• Polyunsaturated – more than one double bond
Which Is a Source of Unsaturated Fatty Acids?
Linseed Oil
Beef Fat
Lipids: Functions
• Concentrated energy source
• Structural components of cell membranes
– Phospholipids
– Cholesterol
• Communication
– Steroid Hormones
• Metabolism
– Fat-soluble vitamins
• Insulation
Cholesterol
• Protection from water
Phospholipids
– Waxes
Per 23
chromosomes
Now estimated
at 30,000
genes
Information Flow From DNA
replication
(before cell
duplicates)
Gene: sequence
of DNA that codes
for a protein
DNA
transcription
(ongoing parts of
cell metabolism)
RNA
translation
Protein
DNA and RNA Structure
Primary
Structure
Secondary
Structure
DNA
RNA
Chain of
nucleotides
Double
helix
Chain of
nucleotides
Single
folded chain
Nucleotide =
phosphate + sugar + nitrogen-containing base
DNA Replication
•DNA chains separate
•Each chain is used
as a pattern to
produce a new chain
•Each new DNA helix
contains one “old”
and one “new” chain
Transcription = Production of RNA Using
DNA as a Template
•DNA chains separate
•ONE DNA chain is used
as a pattern to produce
an RNA chain
•RNA chain is released
and the DNA chains
reform the double-helix
In DNA In RNA
A
U
T
A
G
C
C
G
Transcription  Protein Synthesis
• Messenger RNA
Contains the code words for
the sequence of amino acids
in a specific protein
CODON = group of three
nucleotides acting as a code
word for a protein amino acid
• At sub-cellular structures
called ribosomes, RNA code
is used to guide the assembly
of proteins
Four Levels of Protein Structure
Tertiary
Primary
(Sequence)
(Folding by
R-group
interactions)
Quaternary
(Two or more chains
associating)
Secondary
(Coiling by
Hydrogen Bonding)
Proteins: Structure
• Primary structure = chain of amino acids
– Amino acids have common features
Carboxylic Acid
Group
Amino
Group
R
Central
Carbon
The “R” Group
Differs for Each Amino Acid
Proteins: Structure
Forming the Protein Chain
Phenylalanine
Leucine
Dehydration Synthesis
between COOH & NH2
Secondary structure
governed by hydrogen bonds
Tertiary structure governed by
attraction/repulsion of R-groups
Four Levels of Protein Structure
• Quaternary Structure:
Association of two or more protein
chains
eg. Hemoglobin is composed
of 4 protein chains
2 are called alpha
hemoglobin
2 are called beta
hemoglobin
Cell
Membrane
The Cell
Tissues & Organs
Lung Tissue
Neurons
The Brain
The Most
Complex
Assembly
Of Matter
Of Which
We Know