Download natural selection - faculty.fairfield.edu

The first semester of
General Biology: The cell,
genetics and development
(BI170)
Instructors:
Dr. Geoffrey Church
Dr. Anita Fernandez
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Announcements
Pre-Health student meeting tomorrow night @ 7:30 pm, here.
EMT course still open, starts tomorrow evening (Registrar)
No Gen Bio class on Friday. Go to convocation
The Syllabus
Your contract for the course (everything you can expect to have to
do, and expect from the professors)
You can find it at
http://www.faculty.fairfield.edu/biology/gen_bio/lecture_170.html
Print out a copy and keep it with your class materials!
-let’s take a look
General Biology website
(BI170, 171, & 172)
http://www.faculty.fairfield.edu/gen_bio
BI170 Course Website
Course ID: BI170FALL09
http://www.masteringbio.com
iClicker Registration
http://www.iclicker.com/registration
The Text Book
Biological Science 3rd ed. By Scott Freeman
Study aids are found online at MasteringBio.com
Managing Gen Bio with other
courses/obligations
•Time management!
•Bio, chem, calc, English, core
•3 hours for every 1 hour in class for the
sciences (2:1 for others)
What is covered? What isn’t?
Skipping chapter 2 (chemistry of water and basic bonding etc.)
-you’ll need to refresh on your own
Chapter 1
Cell Theory, Natural Selection, Tree of Life, experimental design
and hypothesis testing, “Doing Biology”
Chapters 3, 4, 6, 7 (Skipping 5)
First Exam is Sept. 22nd (that’s only three weeks!)
Biology and the Tree of Life
Chapter 1
1.1 The Cell Theory
1.2 The Theory of Evolution by Natural Selection
1.3 The Tree of Life
1.4 Doing Biology
What is a theory?


Are there different meanings for the term
theory?
How is it understood in science?
How does the word theory in
science differ from its use in
everyday English?
A.
B.
C.
D.
There is no difference—the usages are
interchangeable.
A scientific theory is always right and never
changes.
Scientific theories are testable
explanations, not speculative guesses.
A scientific theory can be confirmed by a
single experiment designed to prove its
accuracy.
1.1 The Cell Theory
In
the late 1660s, Robert Hooke
and Anton van Leeuwenhoek
were the first to observe cells
(Figure 1.1).
…using only a crude
microscope (mag of
only 30X).
…using a more
advanced microscope
(mag of 300X).
Are All Organisms Made of Cells?
By 1800’s, enough data was collected to support
this theory. YES!
(with even better scopes today this is still the case)
So where do cells come from?
Louis Pasteur demonstrated that
cells arise from cells and NOT by
spontaneous generation (Figure 1.2).
Example of the scientific method.

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The Cell Theory
(Virchow, 1858)
1.
2.
All organisms are made of cells.
All cells come from pre-existing cells.
This is one of the two fundamental theories in biology.
*What is the other one?
1.2 The Theory of Evolution
by Natural Selection
 In 1858, MOST scientists believed that species are
independent and unrelated entities, which do NOT change
over time.
Charles
Darwin and Alfred Wallace INSTEAD made two
claims:
All species are related through a common ancestor
Characteristics of species DO change over time
The Theory of Evolution
Evolution is the process by which
species change over time while also
being related to one another.
This is usually referred to as
“Descent with modification”
The
UNIQUE contributions of Darwin and
Wallace came from their explanation of HOW
evolution occurs. They called this process
“descent with modification” - later known as
natural selection.
Theory
of Natural Selection: Individuals in
a population that possess more favorable,
heritable traits produce more offspring than
do individuals without those traits.
Two conditions must be met for natural
selection to occur in a population:
(1) individuals in a population must differ from
one another for some heritable trait(s);
and
(2) individuals with certain heritable traits
must survive and/or reproduce better than
individuals with other traits (“fitness”).
…so,
In natural selection, the population’s
characteristics will change over time as the
individuals with the favorable traits produce
more offspring, and increase in frequency.
We can control evolution! - Artificial Selection
Evolution by Natural Selection
Adapted from the University of California, Los Angeles Life Sciences 1 Demonstration Manual
Copyright 2008 by Jennifer Doherty and Dr. Ingrid Waldron, Department of Biology, University of Pennsylvania
Describe what is happening in figures 1-3. Is the population
of mice different in figure 3 than in figure 1? Explain why.
What characteristic could lion XXXXX have passed on to his
offspring to increase their survival?
1.3 The Tree of Life
The cell theory and the theory
of evolution by natural selection
imply that all species are
descended from a single common
ancestor at the root of a family
tree of all organisms—the tree of
life.

Linnaean Taxonomy (1735)
 Linnaeus
proposed a
hierarchical system
for classifying
organisms. This was
based on obvious
features such as
ability to move,
ability to make own
food, etc.
2-kingdoms at first
5-kingdoms (1960s)
Using Molecules to Understand the Tree of
Life!
 Carl Woese
and colleagues
began comparing
organisms at the
level of
ribosomal RNA
(rRNA), a
molecule found in
all organisms.
They used this to
understand the
evolutionary
relationships
among
organisms.
•
The rRNA tree of life reflects PHYLOGENY. It
suggests three major groups of organisms, termed
“domains”.
Doing Biology
Why are chilies hot (capsaicin)?
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Predictions?
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What to do BEFORE next
week’s class
•Register for Mastering biology at www.masteringbio.com
using your access code from your book and the course ID
•Our class ID is BI170FA09
•Complete assignments on MasteringBio
•Register your “clicker” at www.iclicker.com
•PLGs do not begin until next week (Tues, Wed, Thurs)
Read Chapter 3 up to page 58.