Biology 1201 Wischusen

Introduction Notes
What is Science?
Study of/tool to understand/body of knowledge/process to understand the natural world
What do Scientists do?
Make observations
Attempt to discern patters
Assume the future is like the past
What is Biology?
The study of life
What is Life?
Not ever clearly defined
Characteristics of living systems:
Highly organized
Huge energy users
90% of food we eat is used to keep us going
Development
Development from a single cell to billons of cells
Reproduction
Evolving
Individuals do not evolve, populations do
Response to the environment
These things along do not define life—something must contain all of these qualities simultaneously

Scientific Method
What is Science?

What do Scientists do? make observations attempt to discern patterns assume that the future is like the past
Scientific Method
What are the basic steps of the method?
Observation
Must be observable
Generalization or model
We are always looking more better models are are more accurate
Prediction or Hypothesis
Testing
Someone else must be able to do your experiment or test
What is the outcome of this process?
A continuation of the Scientific Method
New discoveries and advances

Terminology
Hypothesis-an educated answer to a well framed question; “an explanation on trial”; an untested theory of a phenomena
Theory-supported and proven/tested hypothesis
Law-widely accepted theory proved many times over

We are going to begin by using the reductionist approach
Reducing down to its fundamental parts
Start small and put the pieces together
Wholist approach (opposite):looking at something as a whole first
Scales of Nature
Atomic: smallest (10^-8 meters)
Community/Ecosystem: largest (10^6 meters)
Atoms: smallest unit of matter separated by normal chemical means; smallest unit of an element that retains all of the elements properties; an atom is composed of many smaller particles.
Proton
Positively charged
Located in the nucleus
Weighs 1 Dalton
Neutron
No charge
Located in the nucleus
Weighs 1 Dalton
Electron
Negatively charged
Located in the electron cloud
Weighs less than 1 Dalton
Element
Substance that cannot be broken down into other substances by chemical reactions
Organisms are composed of roughly 11 elements
92 elements are natural
20-25% of elements are essential (an organism needs them to live)
Trace elements are required only in minute quantities
Bohr Model
This model has electrons moving in orbitals or shells around the nucleus
Electrons try to always be in the lowest orbital or energy shell (closest to the nucleus)
Lowest level: K
Next level: L
The outer most shell is called the valence shell
Valence and valence electrons are different
Valence electrons: electrons on the outermost shell
Valence: number of electrons needed to be gained or lost in order to fill the outer shell
What determines solubility?
“Like dissolves like”
“Like” in terms of polarity
Polar dissolves polar and vice versa
What determines polarity?
How many bonds are made determines polarity
The type of bond determines polarity
Isotope
Different atomic forms of the same element
They can be light or heavy
Same number of protons but different number of neutron
Energy
The capacity to do work
Chemical Bonds: form when atoms gain or lose electrons/share electrons and are a result of an electrical attraction
Strong
Ionic Bonds
Form when atoms completely gain or lose electrons
Strongest bonds when dry
Usually a metal and a non-metal
A non-sharing of electrons
Covalent Bonds
A sharing of electrons
Strongest bonds in water
Equally shared=pure and non-polar
Not equally shared=polar (one atom is pulling the electrons more than the other one)
Weak
Not involved in making a substance
Hold atoms together
Cause interactions between molecules
A bond which the result of very weak electrical attractions between atoms bearing partial electrical charges are HYDROGEN BONDS
Weak attractions between atoms on different molecular or different parts of a large molecule
Hydrogen is partially positive
Oxygen is partially negative
Water is polar covalent
One atom involved must be hydrogen
Very, very weak
Occur between molecules that are polar covalent to ionic
Partial bonds
Water
The only common substance to exist in the natural environment in all 3 physical stages
Cells are 70-90% water
Water is bonded together by HYDROGEN BONDING
Properties:
1.Cohesive/Adhesive:
Adhesion: the clinging of one substance to another
Cohesion: water is more constructed than most liquids due to HYDROGEN BONDING linking many molecules at once
How trees get water to leaves (the water molecules stick to the tubes in the plant and also pull each other up).
2.High specific heat: specific heat: the amount of heat that must be absorbed or lost for 1 gram of that substance to change its temp by 1 degree Celsius water will change its temperature less when absorbing or losing heat (1cal/gramxCelsius)
3. High heat of vaporization:
The quantity of heat a liquid must absorb for 1 gram to go from liquid to gas
This is why you sweat
Lower density as a solid compared to a liquid:
Water expands when it turns solid making it less dense
Solvent for polar molecules:
Many molecules come apart or dissociate when placed into water
Molecules and Compounds
Compound: a substance consisting of two or more different atoms in specific proportions, bonded together in a specific pattern
Molecule: the smallest unit of a compound that retains all the properties of that compound
Molecular formulas: describes the compound
A shorthand way to represent the types and numbers of different atoms present in a molecule
H2O, CO2, C6H12O6
Isomers
Molecules with the same molecular formula with a different arrangement of atoms (Glucose, Galactose, and Fructose all have the same molecular formula as sucrose).
The pattern of the structure determines the quality more than the molecular formula
3 types
Structural
Variations in how the carbon skeletons are set up
Variations in where single and double bonds are located
Cis-trans
Variations in the flexibility of atoms due to single (flexible) or double (non-flexible) bonding
Enantiomers
Isomers that are mirror images of each other and differ in shape due to the presence of an asymmetric carbon
Molecular weight
The sum of the atomic masses of all the atoms in a molecule
Water: H2O=(1x2)+16=18 Daltons
Carbon Dioxide: CO2=12+(2x16)=44 Daltons
Sucrose: C6H12O6
Gram Molecular Weight
The mass of a substance equal to its molecular weight in grams
Contains a constant number of molecules (found by calculating Avogadro’s Number).
Concentrations or Numbers of Molecules
The amount of a compound equal to its molecular weight in grams always containing the same number of molecules (6.02x10^23). This is known as Avogadro’s Number
1 Mole=the mass of a substance equal to its gram molecular weight
18 grams of water (H2O) contains the same number of molecules as:
44 grams of carbon dioxide
______ grams of sucrose
1 Molar solution
In a solution the concentration of a compound is measured by the number of moles/liter of a solution (Molarity)
Dissociation
Many molecules come apart when placed in water (“Like Dissolves Like”)
The molecule is said to “break-up” into its constituent ions
For example:
NaCl breaking apart to Na+ and Cl- when placed in water (salt)
NaOH breaking apart to Na+ and OH- (base)
HCl breaking apart to H+ and Cl- (acid)
Acids
A molecules that dissociates and RELEASES H+ ions
Bases
A molecule that releases OH- molecules OR accepts H+ molecules pH Scale
A measure of the hydrogen ion concentration
Acidity of a solution is measured by the pH scale which is calculated pH=-log[H+]
A solution with a pH of 1 has 10-1 moles of H+ per liter pH is measured on a log scale; a small change is large bc it is a multiple of 10
Relationship between OH- and H+
[H+][OH-]=10^-14
Buffers
What do they do?
Minimize changes in the concentrations of H+ and OH-
Substances that maintain a constant pH
How do they work?
By accepting H+ bonds when they are in excess and donating H+ ions when they have been depleted
Electronegativity
1.7>ionic
.5