Transcript Day 2: Orientation Powerpoint

Orientation to Bio & Chem
By the end of this class you should understand:
• The organization of the fields of science
• Characteristics common to all living things
• The organization of living things, and humans
in particular
• The nature of atoms, bonds, and polarity
• The four major macromolecules found in living
things including humans
Biology is an Integrated Science
• To understand
biology well, one
must also
understand:
– Chemistry
– Physics
– Math
– Statistics
Science!
Source: xkcd.com
Organization of Living Things
• All living things are highly organized into
levels of organization
• More complex organisms are organized into
more levels
– Some living things are only one cell
– Some living things do not have organs
Smallest “unit” of life?
• A cell is the smallest
thing that is alive
– It is made of things
that are not alive
– It meets all the
criteria of being alive
• Huge variety of cells
Consider a car
• A car is made of many parts
• Each part is made of
materials
• Only the complete car will
drive around
• Cells are alive but made of
nonliving things just as cars
can drive but are made of
parts that cannot
Characteristics of Life
•
•
•
•
•
•
Maintain homeostasis (WTF is that?)
Acquire energy and raw materials
Excrete waste products
Respond to environment
Grow and reproduce
Made of macromolecules (WTF are those?)
WTF are these?
• Homeostasis: the process of maintaining a
constant internal temperature despite
changes in external environment
– Example: body temperature
• Macromolecules: large molecules made
mostly with carbon. Refers to nucleic acids,
proteins, sugars, and fats.
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
Why Does This Matter??
• 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
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 Proteins will be discussed in week 3