Transcript Biochemistry Powerpoint

Biochemistry
Key Concept: Polarity
• If a molecule is created (covalent bonds), the
electrons may or may not be evenly
distributed
– Evenly distributed: nonpolar molecule
– Unevenly distributed: polar molecule
• Brain check: what about ionic bonds?
Keyword: Macromolecule
• A macromolecule is a very large molecule
(hundreds or thousands of atoms)
– Molecule = held together with covalent bonds
• There are four groups of macromolecules
–
–
–
–
Carbohydrates
Lipids
Amino acids
Nucleic acids
• Vitamins and minerals are NOT macromolecules,
they are small (but still important!)
Keyword: Intermolecular Forces
• Break down the language!
– Inter=between two different things
– Molecular=molecule
– Force=a push or pull (in this case pull)
• The more intermolecular forces between
molecules, the more the molecules stick
together
– Do polar or nonpolar molecules have more
intermolecular forces?
Polar Molecules
• Polar molecules often
form hydrogen bonds,
a type of
intermolecular force
• Water is the king of
hydrogen bonds, since
it has two hydrogens
and one oxygen
– Makes it have a lot of
attractive forces
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
– Known as hydrophilic
– This is why honey is so sticky!
Starch
• Starches are made of many individual sugar rings
bonded together
– Some starches (white bread, white rice, human glycogen,
etc) are designed to break apart very quickly
– Others (brown rice, whole wheat bread etc) are designed to
break apart more slowly
• This is why brown carbs are better for you!
Carb Complexity
• Carbohydrates may be attached
in simpler or more complex
styles of arrangements
– Still the same covalent bonds,
but different arrangements of
the sugar rings
• Cellulose is plant fiber that is
made of sugar molecules
arranged into an indigestible
lattice
– This is why cows need 4
stomachs to eat grass
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
Common Lipids
• Triglycerides are how many
living things (including
humans) store energy
– Contains saturated fats
and/or unsaturated fats
• Cholesterol is an animal
lipid that is used for many
chemical processes but not
for energy
– Can build up and clog
arteries in excess
• Phospholipids are
triglycerides modified to
have a phosphate on one
end
Phospholipid Bilayer
• Phospholipids are special
because they are mostly
hydrophobic but the
phosphate head is hydrophilic
• This causes the molecules to
naturally line up and form a
thin layer of oil
• This forms the basis of the cell
membrane
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
Amino Acids
• Amino acids fit together
like beads on a chain
– Human bodies use 20
different kinds (there are
many more) and each
kind has a different
molecule on its side chain
• The order of the amino
acids cause the chain to
coil up and form a
protein
Some Protein Structures
Nucleic Acids
• How do our cells know what order to put the
amino acids into?
– Our DNA of course!
• DNA (Deoxyribose nucleic acid) is a
macromolecule that stores information
– The order of base pairs (A, T, G, C) codes for amino
acids in a sequence!
– This process will be covered in chapter 3
Nucleic Acids
Structure of a DNA Nucleotide
• A nucleotide is a single “letter”
of a DNA chain
– Contains a base (the “letter), a
sugar molecule, and one or more
phosphate molecules
– The energy is stored in the
phosphate molecules
• The cell often uses an
adenosine molecule with three
phosphates to provide energy
for chemical reactions
– The famous ATP
See you Friday!
• Also don’t forget the review quiz is online!