Download Water, Ph, and Macromolecules PPT

What to do about the world’s most deadly compound…
DIHYDROGEN MONOXIDE
(DHMO)
Unit 2 – Bio-molecules and Biochemistry
The Chemistry of Life
It all starts with Water
• Life depends on
water!
• Why do you think
water is so special?
• Water’s formula is
H2O, two hydrogens
covalently bonded
to one oxygen.
Water’s Shape
• Water is a polar
molecule
– Oxygen is slightly
negative
– The Hydrogens are
slightly positive
• Since positive and
negative charges
attract, this creates
a weak bond called
a hydrogen bond.
COHESION
• Due to the hydrogen
bonds…
– Water molecules
stick to other water
molecules. This is
called Cohesion. (Co
– think couple)
• Surface Tension –
enables organisms to
walk on the water
• Capillary action –
works with adhesion
to draw water up the
roots and stems of
plants
ADHESION
• Due to the hydrogen
bonds…
– Water molecules
stick to other
surfaces. This is
called Adhesion
(think adhesive, like
glue)
• Works with cohesion
to provide capillary
action in plants
High Specific Heat
• Water resists
changing temperature
– 3/4ths of Earth is
covered in water which
absorbs or releases
heat
– Creates very stable
marine and coastal
environments
– Prevents extreme
temperature
fluctuations like those
on other planets
Evaporative Cooling
• As water evaporates,
it removes heat from a
surface
– This is how sweating
keeps you cool!
Density of Water
• Water doesn’t follow the
normal rule of density.
MOST solids sink because
they are very dense, but
solid water (ice) floats
because it is less dense.
– Becomes more and more
dense until 4*C
– Expands after 4*C and
Freezes at the lowest
density at 0*C
– Floating ice prevents lakes
and streams from freezing
solid.
Density of Water (Gas)
Density of Water (Liquid)
Density of Water (ICE)
Water – the Universal Solvent
• Water will dissolve just about anything
which makes it important for chemistry
in living things
– Hydrophilic – water loving, substances
that dissolve easily in water (i.e. salt)
– Hydrophobic – water fearing, substances
that will not dissolve in water, these are
non-polar compounds (i.e. oil)
pH Scale – Acids and Bases
• The pH scale is used to determine if a
solution is an acid or a base.
– Acids are found below 7. They get stronger
as you approach zero.
– Neutral substances (like pure water) can
be found exactly at 7.
– Bases are found above 7. They get
stronger as you approach 14.
pH levels and Biology
• Strong acids and
strong bases cause
damage to cells
– Living things must
maintain a consistent
pH level (typically from
6-8) by using buffers,
which are substances
that can bring a pH level
back to normal.
– Where do you think
most of the buffers in
your body are found and
why?
• Acid Rain is a major
pollutant concern in
biology
– Rain or snow with a
pH lower than 5.6
can damage forests
and lakes or
streams.
– Caused by smoke
mixing with rain
water and lowering
the pH level.
Effects of Acid Rain
The pH Scale
1
2
Strong
Acid
3
4
Weak
Acid
5
6
7
8
Neutral
9
10 11 12 13 14
Weak
Base
Strong
Base
Macromolecules
• Living things are made of Carbon, Hydrogen,
Oxygen, Nitrogen, Phosporus, and Sulfur
(CHONPS) with a few other elements in small
amounts.
• These create carboyhdrates, lipids, nucleic
acids, and proteins, which are taken in
from/with food and used to build new
cells/tissues
• Most macromolecules are polymers (large
structures) made of monomers (repeating
smaller pieces)
Carbohydrates
• Monomer –
monosaccharide
carbon rings (1 or 2 =
sugar; 3 or more =
polysaccharide
starch)
• Look for –rings of
CHO with 1:2:1 ratio
(ex- C6H12O6)
• Uses – energy (food)
in all and
storage/building in
plants
• Test – Benedict’s
reagent turns orange
with sugar; Iodine
turns black with
starch
• Draw Them
Examples of Carbohydrates
Lipids (fats)
• Monomer – No
• Uses – store energy
monomer/polymer;
(fat), waterproof (oil),
found as fatty acids
insulation (blubber)
chains of C & H
• Test –Sudan Red
• Look for – Capital “E”
stains lipids dark red
shape OR a C-H
• Draw Them
chain OR a CHO
formula with very few
O (ex. C9H18O2)
Lipid Examples
Nucleic Acids (DNA or RNA)
• Monomer –
Nucleotides
(phosphate, sugar,
and nitrogen base);
DNA and RNA are
polymers
• Look for – P for
(phosphorus) OR a
spiral helix shape
• Uses – genetic info,
instructions for
proteins
• Test – No test
• Draw Them
Nucleic Acid Examples
Proteins
• Uses – Almost
• Monomer – amino
everything from
acids (20 types);
digesting food
polypeptide chains
(enzymes) to coloring
are the polymers that
your eyes. (structural)
eventually make the
(You are one big
protein
walking protein)
• Look for – the “amino
• Test – Biuret’s
head”
reagent turns dark
purple in the
presence of protein
• Draw Them
Protein Example