BIOL 1201 Lecture Notes - Lecture 1: Chemical Polarity, Valence Electron, Ionic Bonding

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Biology Exam 1 Notes
What is science?
A body of knowledge
An approach to understanding nature
A process with an outcome of a body of knowledge
What do scientists do?
Make observations
Attempt to discern patterns from the observations
Assume that the future is like the past
o This assumption creates a problem not % sure can’t guarantee
o Science is not about the truth or being sure about things it’s about getting
to the best model or general understanding
Science is about creating really good models the best models that
are available at the moment
Scientific Method
The scientific method tells a lot about how we understand science
Steps of the Scientific Method:
o Observations
o Generalization or Model
o Predictions or Hypothesis
o Test
Tests generate new set of observations circular process
Science has a limit of observing phenomenon
o Science has limits Example: cannot observe ghost (outside the realm of
science)
What is the outcome of this process?
o Better model or generalization
New observations confirm that you are in agreement with model so
model is better
New observations disagree with model so you have to form new
model
**Model improves either way
o *Science is not about truth but about getting the best model*
Terminology
Hypothesis: an explanation for something that hasn’t been tested
o Carries with it no weight of validity
Theory: hypothesis that has been tested many times and has always been
supported
o With term comes some weight of evidence that says the theory is pretty
accurate
Has some weight of validity to it
o Very misused word in public speaking
Law: theory that has been tested even more and always supported
o Never violated
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What is biology?
Biology: the study of life
What is life?
Really hard to answer not a set definition
Defined as a set of characteristics
Characteristics of Living Systems
Organization*
o Living things are highly organized (molecular level to ecosystem level)
Energy Use*
o Life requires a huge amount of energy to keep you organized
Development
o Organisms change during lifetime
Reproduction*
o Living things can reproduce by themselves
Side note: viruses cannot reproduce by themselves must be put in a
living cell
Evolve
o Changes that occur between generations
Respond to the Environment* (* means covered in 1201)
o Reaction to surroundings
All living things respond to environment in one form or another
**Living things must do all of these things
o None of these characteristics by themselves define what it means to be alive
Cannot just have one or two of these characteristics and be alive
o Being alive means that you have to be able to do all of these things
simultaneously
o Virus not considered alive
Don’t use energy
Cannot reproduce on own can only reproduce if put in living cell
Viruses are halfway to alive can do all of the other characteristics
Scale of Nature
What scales are biologists interested in?
o Atomic Scale 10-8 meters (lowest level)
o Community/Ecosystem 106 meters
Scale has range of 14 orders of magnitude
Approaches to Biology
Two competing approaches
o Reductionist Approach
Take system apart and reduce it down to smallest parts then study
those parts (study the small pieces)
Once you understand the parts, you start putting the system back
together
o Wholist Approach
Study the whole thing intact
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Some say you can only understand when it is whole
To really understand biology, you must take both approaches
o Must study parts to understand whole, but also must study whole to
understand whole
o In this course, we will start will the reductionist approach and move to a
wholist approach
What determines solubility?
Whether a compound goes into a solution in water is really importantit
determines a lot of things
Compounds that are soluble in water behave differently than molecules that are not
soluble in water
o Which molecules can move through cell membrane and which can’t?
Determined by solubility
Simple version of solubility like dissolves like (different than opposites attract)
o Like is in terms of polarity
Polar molecules are soluble (dissolve) in polar solvents
Water is a polar solvent
Nonpolar molecules are soluble (dissolve) in nonpolar solvents
Cell membrane is nonpolar
o If you look at a molecule, how do you know if its polar or nonpolar?
If it is ionic, it is polar (One side has a + charge, one side has a
charge)
Compounds held together with a pure covalent bond have no
polarity (purely nonpolar molecules)
Carbon and Oxygen form a polar covalent bond not such a strong
bond but still has polarity
All carbons: nonpolar
Carbons and hydrogens: nonpolar (their electronegativities are
almost the same)
What determines polarity?
Cannot understand polarity without understanding valence
o Polarity is very important biologically so need to understand valence
Polarity of a molecule is determined by the types of bonds within that molecule
Atoms
Definition:
o Smallest unit of matter separable by normal chemical means
o Smallest unit of an element that retains all of the properties of that element
o Fundamental unit of an element
Why is the atomic structure biologically important?
o Atoms make up elements elements make up life
o Organisms are composed largely of 11 basic elements
o Value for an average human: $930
Can buy the elements that make up a human but the big difference is
how the chemicals are put together (atomic structure)
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