Transcript Biochemistry Powerpoint

Biochemistry
Macromolecules
• To discuss
macromolecules, we will
have to explore some
chemistry
• Everything you’ll need to
know about chemistry
will fit on these few
slides
– I promise!
The Basics
• All matter is made of atoms
• Every atom has a nucleus with at least one
proton and usually some neutrons
– Protons exert a + charge around them
– Neutrons have no charge
• These + charges attract electrons which each
have a – charge
– Electrons are way smaller so they zoom around
really fast and can’t hold still
Chemistry is Electron Behavior
• The number of protons determines what element it is
– Where it goes on the periodic table of the elements
• The reason this matters is because there are fixed
slots the electrons fit into, and electrons “want” to fill
the slots if possible
• Atoms will sometimes donate or receive electrons
– Ionic bonds
• Other atoms will share electrons to fill the slots
– Covalent bonds
Ionic Bonds
• An ionic bond is weak; it dissolves in an
environment with many charges
– Salt dissolves in water
• Sodium, potassium and calcium are three
common metals that form ionic bonds
– They donate their electrons to halogens like
chlorine and become cations (positive charges)
– They are required in our bodies in specific
amounts, dissolved in our blood and cells
Covalent Bonds
• Covalent bonds are formed as a sharing of
electrons between nonmetals
– Metals do NOT typically form covalent bonds
• The goal is to have four pairs of electrons for
most nonmetals
– Carbon has four unpaired electrons so it can make
four covalent bonds
– Oxygen has six electrons so only makes two bonds
Covalent Bond Behavior
• Sometimes covalent bonds are uneven
– Electron spends more time on one end than the
other
– Anyone who’s shared custody of children knows
sharing is often uneven!
• This means the atom with more than 50%
time is slightly negative and the atom with less
than 50% is slightly positive
– This is a polar bond and may make the molecule a
polar molecule
Example of Polar Molecule:
• Water!
• Water dissolves salt (ionic
bonds) because the positive
and negative atoms mix with
the positive and negative
charges in the water
• This means water (and other
polar chemicals) are slightly
“sticky”
Three questions:
• Why is water “sticky”
when you can slip on
it?
• What is a very sticky
liquid?
• What is a very notsticky liquid?
Best Answers:
1) All liquids are slippery to some degree
– Also note: ice is only slippery if it has a layer of
water on the outside
2) Honey, syrup, molasses: all have sugar in
them!
3) Oil, grease: all have lipids which are
nonpolar!
Sugar (Carbohydrates)
• Sugars are carbon molecules
with lots of oxygen and
hydrogen, so they are also
polar molecules
• They mix well with water
and form many more + attachments
– This is why honey is so sticky!
Starch
• Starches are made of many individual sugar rings
bonded together
• Some starches (white bread, white rice, etc) can be
digested quickly
• Others (brown rice, whole wheat bread etc) are
digested more slowly
– This is why brown carbs are better for you!
Lipids (Fats & Oils)
• Lipids are made with
carbon and hydrogen
– Carbon and hydrogen form
a nonpolar bond
• Since electron sharing is
even, no + and – charges
form
• This means they do not
mix with water
– Hydrophobic
Consider the Following:
• Since oils are not sticky (no
polar bonds) they don’t stick to
glass like water does
• Since oil and water don’t mix,
how do you get oil off your
hands?
– Soap! Soaps are chemicals with
hydrophobic and hydrophilic parts
so they can make oil and water
mix (detergent)
– The term for this is to emulsify
Nucleic Acids and Amino Acids
• DNA and RNA
• Stores/handles
information
• Usually made of a
nitrogenous base
attached to a sugar with 1
or more phosphate
groups
• Strung together to make
proteins
• Proteins perform almost
all jobs in human body
– The phosphate groups
store energy
• Made using information
in DNA
–
–
–
–
Messengers
Structural fibers
Enzymes
Transportation
See you next week!
• DNA and Protein structures will not be
discussed until week 6
– Their functions will be lightly covered next week