Molecules of Life: Water, Carbon, Organic Molecules

Contributed by:
Sharp Tutor
We will the molecules we're made of, and some complex molecules that are a part of the composition of a cell. The four molecules of life are proteins, carbohydrates, lipids, and nucleic acids. Each of the four groups is vital for every single organism on Earth. Without any of these four molecules, a cell and organism would not be able to live.
1. Molecules of Life
The stuff we’re made of
2. 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
3. Properties of Water
• Water is a polar
– Each atom has a
partial charge
– Molecule has zero net δ+ δ+
charge δ-
O -
• Polar molecules have δ
special properties O
– Good solvents δ+ δ+
– Bond with each other δ
– Take longer to heat
and cool
4. Partial charges on atoms, no net charge overall!
5. Water Trivia
• What occupies more volume – 8 oz of water at
room temperature, or 8 oz of water at -10 F?
Ice Liquid
6. Properties of Water
• Water molecules are
attracted to molecules
of solid surfaces
• Adhesion allows
water to move
through very small
pores or tubes
against gravity
(capillary action)
7. 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
• Because it’s so friendly,
carbon is present in all
life on earth
8. 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
9. Types of Organic Molecules
• Carbohydrates
• Lipids
• Nucleic acids
• Proteins
10. Carbohydrates
• Molecules used for energy, made of C H O
– Monosaccharide: a simple sugar (glucose, fructose,
– Disaccharide: two monosaccharides bound together
(sucrose aka table sugar)
– Polysaccharide: 3 or more monosaccharides (starch is
hundreds of glucose molecules bonded together)
11. Carbohydrates
Glycogen stored in liver cells (red)
Starch compartments in potato cells
Cellulose in plant cell walls (outer blue layer)
12. 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
– Fatty acids have oily “tails” and polar “heads”
Polar Non polar
(Yay water!) (Boo water!)
13. Lipid Layers
• Lipids in water will arrange
themselves to hide their
hydrophobic tails
• Cell membranes are
composed of a phospholipid
• What is a phospholipid?
14. Other Lipids
• Waxes
• Oils
• Steroids
15. Nucleic Acids
• The genetic material in any
– Deoxyribonucleic acid (DNA)
and Ribonucleic acid (RNA)
– Polymer chains composed of a
combination of 5 different
16. Nucleic Acids
• The monomers are called
– Adenine, Cytosine, Guanine,
Thymine (DNA only), Uracil (RNA
– 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)
17. 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
• How can so much DNA fit in a cell?
18. Proteins
• Structural building blocks of cells in all tissues (not just
• Polymers composed of 300 – 100k+ monomers
• Monomers are called amino acid
• There are 20 amino acids, many of which must come
from your diet
19. 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
20. Protein Structure
• Tertiary structure – globs of • Quaternary Structure – individual
sheets and helixes folding around proteins bound to each other to form a
each other multi-protein unit with is own unique
21. Hemoglobin carries oxygen in the blood
22. Actin fibers in skeletal muscle cells
23. Proteins make up the cell cytoskeleton
24. Enzymes to copy and repair DNA