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Chapter 1: The Study of Life
Objectives
At the end of this lecture, students should be able to:
1. Discuss the scientific study of organisms
2. Describe the properties of life
3. Explain the assumptions, methods, and limitations of science
4. Explain the underlying themes of biology
5. Explain evolution as a unifying concept
1. The Science of Biology
A. The Process of Science
Much of modern biology investigate structures and functions of living organisms
B. Properties of Life
1.
2.
3.
4.
5.
6.
7.
C. Scientific Study
There are 2 primary ways to go about studying living organisms: describing and investigating.
Descriptive Biology
Investigative Biology
order
## evolutionary adaption
## regulation homeostasis
reproduction
response to envirement - > fly trap plant (triggers
growth + development
energy processing take energy from food , use it , and expend
> involves
observing , recording , describing aclassifying Phenomena
(scientific
> -
hypothesis - driven research
>
focused on testing hypothesis with expirement 2. The Scientific Method
A. Inductive and Deductive Reasoning
There are 2 types of reasoning: inductive and deductive reasoning
Inductive Reasoning
Deductive Reasoning
B. The Scientific Method
The scientific method is an idealized process of inquiry
It is an example of deductive reasoning
A hypothesis
1. Observation. My car wont start.
2. Question. Why wont my car start?
3. Think of hypothesis. Must be testable.
4. Make Prediction.
5. Do Experiment.
6. Analyze Results
assumption observations
the "Obvious" reaching
-conclusion makes sense be of facts given
counted information + data
proving conclusion right with obvious logic C. A Case Study: Investigating Coat Coloration in Mouse Populations
D. Theory vs. Hypothesis
Scientific Theory
Is part of inductive reasoning synthesizing a large amount of data
Hypothesis is part of deductive reasoning and the scientific method
In everyday language, people often use the word, theory to mean hypothesis (=opinion) .
Example of a scientific theory: The Cell Theory
>
different mice adapt to their habitat
Predicted mice who didn't match their habitat would get preyed on first
placed brown + white mice
Beach habitat Inland habitat
> -
light - 25 light - 75
dark - 75 dark - 25
non camo had higher predation rates
results supports hypothesis
broader in scope than hypothesis
Opinion
narrower in scope than a
## theory
big bang theory/gravity theory Three parts of the cell theory:
All living organisms made of at least 1 cell
The cell is the smallest unit of life
All cells come from other cells
3. Le vels of Biological Organization
From a single organelle to the entire biosphere, living organisms are parts of a highly structured
hierarchy
Atoms: Smallest unit of matter.
Molecules: Made of 2 or more atoms bonded together
Organelles: little organs; structures inside eukaryotic cells
Cells: Smallest unit of life.
Organisms: Individual living things made of at least 1 cell.
A. Biological Hierarchy
1.
E. coli colony, colorized
Anthonie van Leeuwenhoek
> D
Biosphere-sum of all Planet 2.
3.
4.
5.
6.
7.
8.
9.
10.
5. Connecting Themes
Themes help to organize biological information
A. New properties emerge at each level in the biological hierarchy
B. Five major themes in biology
1.
2.
3.
4.
5.
6. Biodiversity
A. Organizing Biodiversity
Ecosystem -
all organisms abiotic factors
communities - all organisms close enough to interact
populations -
group of individuals of same species tinterbreed/produce offspring
organisms -
individual consisting of 1-cell
## organs-specialized center of body function made of tissues
tissues -
group of cells that have common structure/function mitochondria J
cells - smallest unit of life , can perform all life activities nucleus
organelles (eukaryotic cells) -
Structures with specialized functions -
molecules -
2 + atams held together by matter
atams-smallest unit of matter , retains property of an element
> Atams-smallest unit of matter
> molecules -
> It atams
## organization sturture determines function organelles - little agans
> cells -smallest unit of life
information DNA +- tranfer genetic into
energy and matter producers and consumers
organisms -
living thing made of atleast cell
interaction feedback , negative/positive
evelation core them of biology .unit connection of organisms
1 . am species given name
## genus -> species belongs +
species -> name unique to them
## Taxonomy -branch that names + classifies species
into groups of increasing bread structure of atans - molecules
matter has mass-takes up space can't be broken to smaller parts
>
All matter is made of elements periodic table lists all elements
smallest unit is atas 25 elements important to living orga .
compounds are 1+ elements combined to a molecule < NaCl ,
I,
molecule is 1+ atans of same/ different element
> circle the nucleus
# only 25/92 elements are
## important to living organisms
mass : 31 15 Gi
Protons : 15 P C- mu
nuetron : 16 30 .
97 carbon :
#
# group 4 - valence carbon
electrons
groups : vertical , similar proper 12
period : horizontal , - Period 2e z electron
Shells
All elements in group are
atomic weight noble ,
> want shell to be
full electrons = Protons
electrons have most
# energy in outside shell
electrons orbit nucleus
in energy shells
each orbit must be filled
Shell : 1-2 electrons before moving to the next
2 Shell : 18 elections
3 Shell : Selections I
lewis method P= 11
## only countvalence electrons &bour diagram -
> =12
#
> *
because those are the ches *
>
that form bands
# Cl : p
> oD
only count valence elections (outer shell) valence shell
isotopes : elements with # of pt but different # of no
different isotopes have same atomic but different atomic mass. . Protes can't vary so # of neutrons does
When the % of each isotope of an element is added , we get the atanic mass
> #
of neutrons = atomic mass -
atomic number
## unstable-radioactive
radioactive isotopes can be used to check to kin cancerous cells akill microbes
its also used to determine the age of something by using the decay
# using isotopes gives an ESTIMATE Chemical bands and interactions
Types of Bands
2 or more atoms form bonds to make molecules ionic
chemical bands are formed by interaction of valence electrons covalent
Ionic bands hydrogen
> -
are formed when Iatam gives electron(s) to another atom
> -
atoms most likely to give up electron are ones with Ivalence electron
cation positively charged ion , with more protons than electrons
Anich negatively charged ion , with fewer protons than electrons
lonic bands ar formed when anions + cations attract
covalent bonds 3
> -
occurs when valence electrons are shared between atoms
> -
by sharing ,
each atom acts like their shells are full electron model
> &
single :
Sharing of 2e : 1from each atom >
Structural formula H-I
double :
Sharing 4 electrons , I from each atam Molecular formula He
triple : Sharing Gelectrons ,
3 fram each atom
> -
stronger than imic
can most
## always
## a
> -
most found in molecules of living organisms M
polar refers to having different ends ex . north south Poles of Earth atoms with F ,
> O,CI ,
N have
> most
electronegativity
Polar band when Iatan of band is Partly positive + other atan partly neg
. So different ends
Non Polar band when there is charge difference from one end of the molecule to the other This sets Up
different ends of polar
Electronegativity & Polar covalent bonds #
> coud lent band
> -
the more electronegative atems attract electrons toward themselves -
Causes aton to have partly negative charge
> -
the other atem becomes partly positive because electrons spend more time With electronegative atom
Nanpolar covalent bands covalent bands formed by C , H , O , N :
> -
do not show electronegativity
I farms I band , single band
> O
foms 2 bands , 2 single or 1 double -
Maecules made of same atoms made of low electronegative atans N forms 3 bands , a single - double/triple
> (
forms 4 bands , cambo of single , double , + triple
Hydrogen bands
form in special case of a polar covalent band where Partly negative atant partly
Positive atom is a hydrogen - -
is attracted to a + hydrogen of a nearby molecule 20
%. x
>
since they're only polar attraction of different molecules , they're the weakest of all bands
>
can form between same or different molecules but must have electronegative atah attached to hydrogen
# east strongest band Acids , bases , Ph
## Hydrogen atom VS
## hydrogen ion
> -
has 1 protons1 election -
lost its electron , orily has y protons + charged
the l names : Hydrogen ion/Itplus/Proton -
Hydrogen atom only has 1 proton when electron lost
When a polar covalent band of Ho pulls electron so far toward O that -o molecule dissociates equation a
It is quickly picked up by passing It .O to become Hz0 +:
hydronium in I, O -* OH + 14 +
Acids are substances that can donate It -
HCL/hydrochloric acid) HCL + H = 0 -Cl + Hz 0 +
strong acids strongly dissociate in 10 by donating a H2-H , SO sulfuric acid) HeSOn + 10 - ItSOn + He Ot
> -
HNOz (nitric acid) HNOz + H , O -> NOs + Hy Ot
weak acids only partly dissociate in He HzCO3 /Carbonic acid) He CO3 + He 0 -HCO3 +
Ho ot
H30 + CH-COOH(acetic acid) CHzCOOH + H20 -> CHz COO -
> +
130 +
Bases are atoms/molecules that can accept H + -
> >
decrease It" concentration in a solution
Bases decrease It directly by picking up H +: weak base like NHs/ammonial in water NIts + H+
Eg NH
weak bases like NHs pick up hydrogen ions directly , weak bases DONT dissociate completely
Bases decrease It by indirectly picking up H: same increase the hydroxide ions (H) NaOH Na" + OH
net effect : reduce concentration of It in solution done indirectly Cause Nad does NOT Pick up It +
strong bases make outials that pick up hydrogen icns indirectly NaOH CalON KOH
strong bases dissociate 100 % into cations ot- (hydroxide ion) sodium hydroxide , calcium ,
Potassium
NH3 KCO3 NazCO3
weak bases do not dissociate completely in HO ammonia , potassium carbonate , sodium carbonate
PIt is a measure of acidity in a solution -concentration of H+ acidic --> basic
properties of acids and bases
change of 1 whole # on logathmic scale represents loxchange in #of H +
Ions acids Bases
0 . 001MH" = [H +
]= 10 -
3 M -
taste sour -
bitter taste
pHt is exponent for +4 - PH < 7 -
pH > 7
> -
if plt around protein changes too much , protein will denature -
caustic -
slippery feel
> -
harmful for organisms to change put much - H +
in HO - OH- in HeO
> -
accepts +
Buffer is a substance that has ability to resist sudden changes to original put - donate H+
> -
turns red
-turns blue
acids - bases can neutralize eachother combo of weak acid aweak bases litmus red litmus bluf
H +
of an acid will canbine with OH-to make H2O neutral properties are
Salts are substances when added to Ito dissociation into cations panions neither acidic nor basic
Acids bases react to form water and a salt both neutral 114
selectrolytes are salts that are dissolved in water C+
]< [OH] basic
Functions : < conduct electricity PH
>
maintain salt/water balance
# [H =
[OH] neutral
>
maintain acid/base balance
>
involved with nerve function parts of bale and teeth
eX : Nat ,
Cli ,
K + Ca2 , Mgz + [H +]) [OH] acidic
vo water is foundati Of life
Water is a polar molecule - O is partly neg It is partly positive water can be :
gas
> -
in living organisms most hydrogen bands invave molecules with CH or NI
> molecules keep it
-liquid It bands between Ito
> -
Water can dissolve MOST material liquid within 0-1000
solid
it forms a hydration shell around molecules like Nat and C-
Hydrophobic molecules are "water hating"
Hydrophilic molecules are "water loving"
evaporation = liquid to gas molecules must more fast enough to break hydrogen bands
>
boiling is similar to evaporation
Heat vaporization is amount of heat needed to get 1 gram of a substance fram liquid-gas
>
water has a high heat of vaporization
specific heat amount of heat needed to raise 19 of water 10
good for living organisms , can tolerate wide I
range of temps without dying
Cohesion -
when water sticks to itself : this happens because of hydrogen bands between water molecules
surface tension-water molecules at surface form stronger hydrogen bands with Homolecules on the sides
Adhesion-water sticks to different molecules :
hydrogen bands form between 12o molecules & other polar molecules
cohesion I cohesion Surface Tension &
water molecules stick to
echoner before spilling water molecules stick to hydrogen bands form between
other polar molecules bug and water
water is a good lubricant /joints of knee , around heart)
water is a good Cushion /amniotic fluid , brain , Spinal cord)
The hydrogen bands in ice create a crystal with molecules in It -0 further apart than in liquid water
*
# Which is why ife floats