Section
1: What is life?
- How do scientists ask and answer questions about
living organisms?
- How do scientists arrange that information into a
readable format?
- What is life?
What isn’t life?
- What is a biological hierarchy?
I.
How do
scientists ask and answer questions about living organisms?
v Science: method of inquiry that holds a central
place in modern society
o But, there is a widespread lack of understanding of how
science works, how it generates knowledge, and what its powers and limitations
are.
o This is unfortunate for several reasons:
v The study of the natural world involves a series of logical
steps known as the scientific method.
o Make an observation.
o Generate a hypothesis.
o Use the hypothesis to make predictions that can be tested.
o Test those predictions by conducting experiments or making
further observations.
o Determine whether the hypothesis has been supported (but NOT PROVEN TRUE) or rejected.
o Continue to test hypotheses and report findings.
1.
Remember, the
scientific method has limits.
2.
What’s a
theory?
3.
What’s a law?
II.
How do
scientists arrange the information they gather into a readable format?
v Three most common types of scientific papers
o Research Papers
o Abstracts
o Scientific Papers
1st
rule: ALWAYS use first person sparingly!!!
v Research Paper
o Introduction
§ Background on topic, why topic is interesting
o Body
§ Summarize findings of other scientists
§ Can make subheadings within the body
§ Avoid plagiarizing by paraphrasing with citations or
quotations with citations. ALWAYS cite unless it is common knowledge.
o Discussion
§ Summarize work done to date on the topic
§ Point out missing information
§ Suggest future work that could be done
o References
§ Use quality resources, usually from scholarly/peer-reviewed
journals
·
Scholarly
Journals
o Sober, serious look
o Articles always cite sources
o Articles written by scholar/researcher in the field
o EX: Journal of the American Medical Association; Current
Anthropology; Tropical Biology
o NOT: National Geographic; Sports Illustrated; The National
Enquirer!
·
Locating
scholarly journals
o Best way is to use your University Library
o Here, you can search for books and articles on your
relevant topic. The periodical holdings
list tells you which journals the library subscribes to. You can find
these in the library and make copies of the pages you need. If the library
doesn’t hold the journal you need, you can request the article be sent to you
through Interlibrary Loan. Click ILL
Request Form at the bottom of the page.
v Abstract
o 1 paragraph that summarizes the main points of an article.
No citations within the abstract.
§ At the top of your abstract, show the journal reference.
o Describe the problem
o Briefly summarize
o Tell what the results were
o Tell what these results suggest/imply
v Scientific Paper
o Abstract
o Introduction
§ Describe question/hypothesis
§ Explain why this is important
§ Describe approach
§ Briefly mention conclusion
o Materials and Methods
§ Describe techniques
o Results
§ Focus on what worked
§ Restate question/hypothesis
§ Use text and/or tables and figures
o Discussion
§ Restate and interpret results
o References
§ Format depends on journal you are submitting to, but must
always include a variety of articles published in scholarly journals.
III.
What is
life? What isn’t life?
v Early Views
o Animism: the belief that spirits can dwell in rivers,
trees, mountains, animals, or people
o Changed slightly to the idea that anything with “breath” is
alive
o Changed again to the idea that only humans have a soul
o Ideas have been rejected as scientific theories since the
Scientific Revolution (1550-1700 AD)
v The historical scientific debate lasted from the 16th
century to the beginning of the 20th century
o Three main groups of recent theorists:
§ Physicalists
§ Vitalists
§ Organicists
o The Physicalists
§ Living organisms and inanimate matter are exactly the same,
due to their inherent chemical and physical properties.
o The Vitalists
§ Argued against physicalist ideas
§ Claimed that living organisms were too complex to be
explained in such simple terms
§ Explanations for life seemed metaphysical in nature
§ Were unable to offer solid definitions for life
o The Organicists
§ Processes at the molecular level can be explained by
physical and chemical means
§ But, “a whole is more than the sum of its parts”--there is
a difference between living and inert matter
§ Organisms should be analyzed at different organizational
levels
v Biology = Study of Life
v Living organisms have 6 key characteristics
o Are made of cells
o Are highly organized
o Acquire materials and energy from their environment
o Respond to stimuli
o Develop and reproduce, utilizing hereditary material
(DNA/RNA)
o Have adaptations
v Living versus nonliving
o What about viruses?
o What about nanobes?
v The Origins of Virology (study of viruses)
o Evidence of smallpox exists from 3700 BC.
o Smallpox was endemic to China by 1000 BC.
§ Variolation was developed in response.
·
Inhalation of
dried crusts from smallpox lesions
·
Inoculation of
pus from a lesion into a scratch
v Edward Jenner vaccinated James Phipps in 1796.
o Initially controversial, but the vaccination against
smallpox was adopted worldwide in the 19th century
v Structure of Viruses
o All viruses have:
§ An inner core of nucleic
acid (DNA/RNA)
§ A capsid (outer covering) made of protein that acts as a “shell” to
protect the virus from damage
·
Some capsids
are “naked”
o Naked capsids are found in viruses that infect cells that
are nearing the end of their reproductive cycle.
o Viral reproduction in viruses with naked capsids
§ Either via the Lytic Cycle
·
Attachment
·
Penetration
·
Biosynthesis
·
Maturation
·
Release
§ Or, via the Lysogenic Cycle:
·
Attachment
·
Penetration
·
Integration
·
Biosynthesis
·
Maturation
·
Release
§ This virus strategy has drawbacks, including the potential
for causing cells to die prematurely. (Remember that viruses need the cells to
reproduce)
·
An alternative
is to try and leave the cell intact (via “enveloped” capsids).
o Cells are coated by a lipid membrane that must remain
undamaged, or the cell will die.
o Viruses must enter and leave the cell without damaging the
lipid layer.
o Viral reproduction: Enveloped viruses
§ Attachment
§ Penetration by Fusion
§ Biosynthesis
§ Maturation
§ Release by Budding
v Why are viruses so annoying?
o They prevent the body’s cells from functioning properly.
o They generally cannot be treated with medicine.
v If that weren’t enough, there are also virus-like
structures that can also cause disease
o Viroids
§ No capsid or envelope
§ Associated with certain plant diseases
o Virusoids
§ Viroid-like, but larger
§ Travel inside of virus capsids
o Prions
§ One single protein molecule, no nucleic acid component
§ Can be found in normal, unaffected cells
§ Ex: mad cow disease, scrapes, CJD
v How can we be saved???
o Cell envelope
§ Receptors on our cells are very specific.
·
Receptors
differ in plants, animals, fungi, and bacteria.
·
Receptors on
different types of cells within the host differ.
o Restriction endonucleases
§ Little structures that cut out foreign DNA from the genetic
code during cell replication
o Interferons
§ Bind to the virus particles to keep the viral DNA from
multiplying
o Antibodies
§ Proteins that bind to virus particles and prevent them from
attaching to new cells
§ Useful against slow viral diseases
o Vaccines against viruses
§ Vaccines stimulate the body to produce antibodies.
§ Killed/inactivated vaccines: chemically kill or inactivate
bacteria or viruses, rendering them harmless
§ Live vaccines: produced from weakened strains that are
strong enough to stimulate a protective immune response.
v So, back to the main question….Are viruses living or not?
o Living characteristics:
o What do they lack?
o What have you decided?
v What about nanobes?
o What have you decided?
v Do the biological definitions of life have any bearing on
your opinions of issues such as abortion, one’s decision to remove a loved one
from life support, the choice to eat meat?
Should there be scientific classifications regarding whether an organism
is sentient or not? Could scientists
determine whether a living organism is sentient? Does science play a role in
delineating acceptable behavior in decisions regarding human life and
death? Who is ultimately responsible for
that determination?
IV.
Back to Living Things:
What is a biological hierarchy?
v A method of organizing living organisms
o Includes organizing the components that make up an
individual organism as well as elements in the individual’s environment
o Many levels of organization ranging from molecules at the
lowest level (one-millionth of a meter) up to the entire biosphere at the
highest level (12 million meters), with the highest level being the most
inclusive
§ Molecules
§ Cells
§ Tissues
§ Organs
§ Organ systems
§ Individual Organism
§ Population
§ Community
§ Ecosystems
§ Biomes
§ Biosphere
