BIOS 208/210: Fundamentals of Cell Biology
Chapter 1: Introduction: Themes in the Study of Life
Key Concepts
1.1)
The themes of this book make connections across
different areas of biology.
·
Theme: New properties emerge at each level in the
biological hierarchy.
o
The hierarchy of
life unfolds as follows:
§ Biosphere
§ Ecosystem
§ Community
§ Population
§ Organism
§ Organ System
§ Organ
§ Tissue
§ Cell
§ Organelle
§ Molecule
§ Atom
o
With each step
upward from atoms, new properties emerge as a result of interactions among
components at the lower levels. In an approach called reductionism, complex
systems are broken down to simpler components that are more manageable to
study.
o
In systems
biology, scientists attempt to model the dynamic behavior of whole biological
systems based on a study of the interactions among the system’s parts.
·
Theme: Organisms interact with other organisms and the
physical environment.
o
Plants take up
nutrients from the soil and chemicals from the air and use energy from the sun.
Interactions between plants and other organisms result in cycling of chemical
nutrients within an ecosystem. One harmful outcome of human interactions with
the environment has been global climate change, caused by burning of fossil
fuels and increasing atmospheric CO2.
·
Theme: Life requires energy transfer and
transformation
o
Energy flow through
an ecosystem. All organisms must perform work, which requires energy. Energy
from sunlight is converted to chemical energy by producers, which is then
passed on to consumers.
·
Theme: Structure and function are correlated at all
levels of biological organization.
o
The form of
biological structure suits its function and vice versa.
·
Theme: The cell is an organism’s basic unit of
structure and function.
o
The cell is the
lowest level of organization that can perform all activities required for life.
o
Cells are either
prokaryotic or eukaryotic. Eukaryotic cells contain membrane-enclosed
organelles, including a DNA-containing nucleus. Prokaryotic cells lack such
organelles.
·
Theme: The continuity of life is based on heritable
information in the form of DNA.
o
Genetic
information is encoded in the nucleotide sequences of DNA. It is DNA that
transmits heritable information from parents to offspring.
o
DNA sequences
program a cell’s protein production by being transcribed into RNA and then
translated into specific proteins, a process called gene expression. Gene
expression also results in RNAs that are not translated into protein but serve
other important functions.
o
Genomics is the large-scale
analysis of the DNA sequences within a species as well as the comparison of
sequences between species.
·
Theme: Feedback mechanisms regulate biological
systems.
o
In negative
feedback, accumulation of an end product slows the process that makes the
product.
o
In positive
feedback, the end product stimulates the production of more product.
o
Feedback is a
type of regulation common to life at all levels, from molecules to ecosystems.
·
Theme: Evolution, the Overreaching Theme of Biology
o
Evolution
accounts for the unity and diversity of life and also for the match of
organisms to their environments.
1.2)
The Core Theme: Evolution accounts for the unity and
diversity of life.
·
Biologists
classify species according to a system of broader and broader groups. Domain
Bacteria and Doman Archaea consist of prokaryotes. Domain Eurkarya, the
eukaryotes, include various groups of protists and the kingdoms Plantae, Fungi,
and Animalia. As diverse as life is, there is also evidence of remarkable
unity, which is revealed in the similarities between different kinds of
organisms.
·
Darwin proposed
natural selection as the mechanism for evolutionary adaptation of populations
to their environments.
·
Each species is
one twig of a branching tree of life extending back in time through ancestral
species more and more remote. All of life is connected through its long
evolutionary history.
1.3)
In studying nature, scientists make observations and
then form and test hypotheses.
·
In scientific
inquiry, scientists make observations (collect data) and use inductive
reasoning to draw a general conclusion, which can be developed into a testable
hypothesis. Deductive reasoning makes predictions that can be used to test
hypotheses: If a hypothesis is correct, and we test it, then we can expect the
prediction to come true. Hypotheses must be testable and falsifiable; science
can address neither the possibility of supernatural phenomena nor the validity
of religious beliefs.
·
Controlled experiments,
such as the study investigating mimicry in snake populations, are designed to
demonstrate the effect of one variable by testing control groups and
experimental groups that differ in only one variable.
·
A scientific
theory is broad in scope, generates new hypotheses, and is supported by a large
body of evidence.
1.4)
Science benefits from a cooperative approach and
diverse viewpoints.
·
Science is a
social activity. The work of each scientist builds on the wok of others that
have come before. Scientists must be able to repeat each other’s results, so
integrity is key. Biologists approach questions at different levels; their
approaches complement each other.
·
Technology is a
method or device that applies scientific knowledge for some specific purpose
that affects society. The ultimate impact of basic research is not always
immediately obvious.
·
Diversity among
scientists promote progress in science.
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