Transcript Introduction: Ten Themes in the Study of Life

Introduction: Ten
Themes in the Study
of Life
Chapter 1
Theme #1: Emergent Properties

The living world has a hierarchal
organization, extending from molecules to
the biosphere.
 With
each step upward in organizational level,
novel properties emerge as a result of
interactions among components at the lower
levels.
Theme #2: The Cell

Cells are every organism’s basic units of
structure and function. The two main
types of cells are:
1.
PROKARYOTIC in bacteria & archaea

2.
no nucleus, no membrane bound organelles
EUKARYOTIC in protists, fungi, plants, and
animals

Larger & more complex w/ nucleus & membrane
bound organelles
Prokaryotes v/s Eukaryotes
Theme #3: Heritable Information

The continuity of life depends on the
inheritance of biological information in the
form of DNA molecules. The genetic
information is encoded in the nucleotide
sequences of the DNA.
DNA DOUBLE HELIX
Structure & Function

Form and function are correlated at all levels of
biological organization.
 Bird’s
build makes flight possible
 Honeycombed construction of bones provides
lightweight skeleton of great strength
 Form of a cell fits its specialized function – nerve cells
have long extensions that transmit nerve impulses
 Mitochondria has inner membrane that is extensively
folded – able to pack large amount of membrane into
very small container
Form Fits Function
Theme 5 – Interaction with the
Environment
Organisms are open systems that
exchange materials and energy with their
surroundings.
 An organism’s environment includes other
organisms (biotic) as well as nonliving
(abiotic) factors.

Energy Flow & Transformation in
an Ecosystem
Regulation
Feedback mechanisms regulate biological
systems.
 In some cases, the regulation maintains
homeostasis, a relatively steady state for
internal factors such as body temperature.

Positive & Negative Feedback
http://bcs.whfreeman.com/thelifewire/content/chp41/41020.html
Feedback Inhibition – mechanism of
homeostasis whereby a change in a
physiological variable (D) that is being
monitored triggers a response that
counteracts the initial fluctuation (A). Final
product (D) inhibits first enzyme in
sequence (A) and shuts reaction down.
Positive Feedback – a physiological
control mechanism in which a change in
some variable (Z) triggers mechanisms that
amplify the change. In this example, the
product of the reaction (Z) enhances the
reaction of one of the enzymes (black
arrow), increasing the rate of production of
the product.
Theme 7 - Unity and Diversity
The diversity of life is grouped into 3
domains: Bacteria, Archaea, and Eukarya.
 Life is diverse, but we can find unity in the
genetic code – the more closely related
two species are, the more characteristics
they share.

Classifying Life
Theme 8 - Evolution
Evolution is biology’s core theme. It
explains both the unity and diversity of life.
 The theory of natural selection accounts
for adaptation of populations to their
environment through the differential
reproductive success of varying
individuals.

Natural Selection
Theme 9 – Scientific Inquiry
The process of science includes
observation-based discovery and the
testing of explanations through the
hypothetic-deductive method.
 Scientific credibility depends on the
repeatability of observations and
experiments.

Idealized Version of Scientific
Method
Theme 10 – Science, Technology,
and Society
Many technologies are goal-oriented
applications of science.
 The relationships of science and
technology to society are now more crucial
to understand than ever before.
