Transcript How Science started

Welcome to Biol 201 Majors Biology I!
Lectures: MWF 1:00-1:50pm in ST-148
Labs: #4022: M&W 2:10-4:00pm; #4023 T&TH 2:10-4:00pm; labs are in
ST-243
Instructor: Dr. Vic Landrum (Ph.D. 1997, University of Texas at Austin)
Office Hrs.: T&TH 1:30-2:00pm, or before/after classes.
Email: [email protected]
Need to leave something for me? This can be done in the main office in
ST-103.
The Course:
An introduction to the biological sciences, emphasizing genetic and
cellular processes common to plants and animals. For majors
and non-majors; prepares students for advanced biology
courses and pre-professional programs.
PLEASE NOTE: This course is Canvas-enhanced, meaning we’ll
use the Canvas system to keep grades and occasionally submit
assignments (usually lecture assignments). If you’re note
familiar with Canvas, please attend one of the many introduction
sessions available on campus or online. I can help you a bit,
but a Canvas intro session is much more comprehensive.
Prerequisite: None, however, to satisfy the prerequisite for upper
division biology courses at some institutions, a year of general
chemistry must be completed.
Topics covered:
• The structure and function of major molecules that constitute
living organisms.
• The organization of cells and functions of their organelles.
• The principles of classical genetics for predicting inheritance.
• The molecular basis of genetics, including the structure and
replication of DNA, regulation of gene expression, and protein
synthesis.
• Various aspects of DNA biotechnology.
• The mechanisms of evolution and the origin of biological
diversity.
• The structure and evolution of the following basic groups of
living organisms: prokaryotes, protests, invertebrates, and
vertebrates.
• The flow of energy within cells, including cellular respiration.
• The mechanism and functions of cell division.
Evaluation Criteria &
Grading Standards
Your grade total is based on a total of 1000 points, and is
composed of the following parts:
• 3 lecture exams—each worth 150 points, for a total of 450
points;
• 8 lecture assignments—usually 20 points each, for a total of
160 points;
• 16 lab activity sheets—10 points each, for a total of 160 points
• 2 laboratory exams—each worth 100 points, for a total of 200
points.
• Lab attendance (2 pts per lab starting with Lab 2) = 30 points.
Powerpoint lectures:
• All notes online after class
• Write as little as possible during class
• Listening as important as writing!
How Science started
Until 1200AD--only 3 ways
to explain why/how things
happened in nature:
• religious
• metaphysical
• speculative
1. Religious method
• universe is assumed to either to be
created by gods or to contain them
• their actions cannot be studied or
predicted
2. Speculative method
• Greek philosophers-analyze by logic
• Ex.: Democritus,
and atomic theory;
Aristarchus & the
heliocentric model of
the solar system
3. Metaphysical method
• Universe governed by both natural
forces & supernatural, hidden forces
• Natural forcespredictable, can study
• Supernatural forcessee religious
method
• Ex.: bad omens, accurate horoscopes,
good/bad luck
4. Scientific Method
• Began in the early 1200s in Italy,
Germany
• has a rigid set of rules that govern it
The Scientific Method
• 1. information is derived only from
carefully documented and controlled
observations or experiments
The Scientific Method
• 2. All claims must be subjected to
verification and proof.
• Revolutionary!
The Scientific Method
• 3. Only phenomena and objects that
can be observed and studied are dealt
with, no supernatural forces accepted
The Scientific Method
• 4. All proposed explanations of natural
phenomena must be retested and
verified, otherwise they are rejected.
The Scientific Method
5. Present means to examine hypotheses
may not be adequate; may have to wait
until technology catches up
• ex. Wegner—in early 1900s, based on
aerial photography, he proposed that
South America and Africa were once
joined. He was roundly criticized, and it
wasn’t until 1960s that he was
vindicated.
The Scientific Method: Steps
• Observation
• Hypothesis
• Experimentation (& repeated
experimentation!)
• Theory
Four basic theories of Biology
1. Cell—all life composed of cells.
2. Gene—genes carry information to
reproduce the organism.
3. Biogenesis—only life can create life.
4. Evolution—organisms, by natural
selection and mutations, change over
time to fit their environments.
Science and Society
• "bad" science versus "good" science
Life is chemistry!
• Elements (atoms)  simple molecules
Carbon + 2 oxygens = Carbon dioxide (CO2)
• Simple molecules  complex molecules
Six CO2 + six waters (H2O) = sugar
• Complex molecules  life
• All organic molecules have carbon
• Oxygen, hydrogen, nitrogen also very
important
Periodic Table of Elements
Basic chemistry:
• Atoms composed of + (protons), neutral
(neutrons), & - (electrons) particles
Atoms/Molecules important to Biology are
based on how many electrons are involved
and what happens to them:
•2 electrons can ‘fit’ closest to the nucleus
•A little further out, 8 electrons can fit.
Hydrogen
Carbon
Neon
Periodic Table of Elements
Numbers=number of protons
Rows=# possible electron orbits
Columns=# electrons in outer
orbit
The number of electrons per orbit
determines how reactive an atom is:
• For example, Hydrogen has 1 electron (e-), but
needs 2 e- to be stable—it often gives up its
electron to stronger atoms, making it only positive
(H+)
• Carbon has 4 e- in its outer orbit, so it can give up
its 4 or take in 4 other e- from somwhere else,
making Carbon a reactive atom
• Neon has 8 in its outer orbit, so it is stable and
hardly ever reacts with other atoms—in chemistry,
Neon and atoms like Neon with their outer orbits full
are called “Noble gases”
Atoms
• Ions - Atoms in which number of electrons
does not equal number of protons.
Chemical bonds are created between atoms when
electrons get involved; 3 main types:
1.
Ionic—one atom gives up electron to
another atom, making the donor more
positive and the receiver more negative
2.
Covalent—usually involves Hydrogen;
hydrogen is weak; when attached to a
stronger atom, the stronger atom steals
the hydrogen’s electron most of the time
as it orbits.
3.
Hydrogen—form when the H has lost its
electron to a stronger atom like Oxygen,
and becomes more +; this attracts other
negative atoms (-). These bonds are the
weakest of the major bonds, but can be
powerful in huge numbers, as in DNA—
your DNA is held together by the hydrogen
bonds of the individual parts, so billions of
hydrogens make a strong force.
Making molecules: ex. salt
•Sodium (3 electrons) will lose 1 e- to chlorine; this makes
sodium more positive, and chlorine becomes more
negative. This +/- attractions forms an ionic bond.
•As a result, table salt or Sodium chloride (NaCl) is formed.
Making molecules
• Ex. Water (hydrogen bonding  e- lost most
of time but also covalent bond  e- of H are
shared with oxygen
Water
• Water (H2O) has several unusual properties:
–
–
–
–
Absorbs heat when it evaporates
Releases heat when it freezes
Loves to bond to itself (=cohesive)
Loves to bond to other things (=adhesive)
cohesion
Water
• Water also easily breaks down into H+
and OH• Pure water has an equal balance of H+
and OH• Thus water is considered neutral,
neither acidic or basic
Acids & Bases
• Acids: release H+ if dropped in water;
ex. pepsi
• Bases: release OH- if dropped in water;
ex.oven cleaner
• Amount of each released determines
pH!
Why pH is important:
• pH determines:
– If an enzyme (a chemical accelerator
molecule) works or not; ex. Amylase in
saliva (spit)
– If your blood chemistry is balanced
– Whether you digest properly
– Whether proteins are stable or break down
Remember: Electrons = energy in Biology
– In living organisms, chemical energy is stored by
using it to move electrons to more distant orbits.