Transcript Molecules of Life

Molecules of Life
The stuff we’re made of
Water
• The human body is mostly water
– Lean muscle: 75% water
– Blood: 83% water
– Body fat: 25% water
– Bone: 22% water
• All living organisms require water to live
Properties of Water
• Water is a polar
molecule
– Each atom has a
partial charge
– Molecule has zero net
charge
• Polar molecules have
special properties
– Good solvents
– Bond with each other
(cohesion)
– Take longer to heat
and cool
δ-
O
H
δ+
H
δ+
Partial charges on atoms, no net charge overall!
Water Trivia
• What occupies more volume – 8 oz of water at
room temperature, or 8 oz of water at -10 F?
Ice
Liquid
Properties of Water
• Water molecules are
attracted to molecules
of solid surfaces
(adhesion)
• Adhesion allows
water to move
through very small
pores or tubes
against gravity
(capillary action)
Carbon
• A carbon atom has 4
outer (valence) electrons
– wants to make 4 bonds
to be stable
• Carbon can bond with
itself and many other
elements
• Because it’s so friendly,
carbon is present in all
life on earth
Organic Molecules
• Any molecule containing
carbon is called an
organic molecule
!! Except CO2 !!
• Most organic molecules
are arranged like chains
– Each link is a monomer
– A chain is a polymer
– A large molecule made of
a long chain or chains is a
macro molecule
Types of Organic Molecules
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•
•
•
Carbohydrates
Lipids
Nucleic acids
Proteins
Carbohydrates
• Molecules used for energy, made of C H O
– Monosaccharide: a simple sugar (glucose, fructose,
galactose)
– Disaccharide: two monosaccharides bound together
(sucrose aka table sugar)
– Polysaccharide: 3 or more monosaccharides (starch is
hundreds of glucose molecules bonded together)
Carbohydrates
Glycogen stored in liver cells (red)
Starch compartments in potato cells
Cellulose in plant cell walls (outer blue layer)
Lipids
• Fatty compounds made of C H O, don’t
interact with water (hydrophobic)
– Cell membranes are composed two lipid layers,
which keep water from crossing
• Lipids are polymers made up of fatty acid
monomers
– Fatty acids have oily “tails” and polar “heads”
Polar
(Yay water!)
Non polar
(Boo water!)
Lipid Layers
• Lipids in water will arrange
themselves to hide their
hydrophobic tails
• Cell membranes are
composed of a phospholipid
bi-layer
• What is a phospholipid?
Other Lipids
• Waxes
• Oils
• Steroids
Nucleic Acids
• The genetic material in any
cell
– Deoxyribonucleic acid (DNA)
and Ribonucleic acid (RNA)
– Polymer chains composed of a
combination of 5 different
monomers
Nucleic Acids
• The monomers are called
nucleotides
– Adenine, Cytosine, Guanine,
Thymine (DNA only), Uracil (RNA
only)
– Bond in specific pairs
– Adenine – Thymine (Uracil)
– Guanine – Cytosine
• Nucleic acid polymers are
millions of monomers long,
wound in a double helix
• Helix unwinds during
replication (copying)
DNA Trivia
• The DNA from a single human cell has a
length of ~ 5.9 feet.
• The biggest cells are less than 0.1 inches
across
• How can so much DNA fit in a cell?
Proteins
• Structural building blocks of cells in all tissues (not just
muscle!)
• Polymers composed of 300 – 100k+ monomers
• Monomers are called amino acid
• There are 20 amino acids, many of which must come
from your diet
Protein Structure
• Primary structure – the
order of amino acids making
up the polymer string
• Secondary structure –
helixes and sheets of the
polymer string folding on
itself
Protein Structure
• Tertiary structure – globs of
sheets and helixes folding around
each other
• Quaternary Structure – individual
proteins bound to each other to form a
multi-protein unit with is own unique
function
Hemoglobin carries oxygen in the blood
Actin fibers in skeletal muscle cells
Proteins make up the cell cytoskeleton
Enzymes to copy and repair DNA