Transcript Life Science I 83.101.102 Dr. Ekaterina (Kate) Vorotnikova Office

Life Science I
83.101.102
Dr. Ekaterina (Kate) Vorotnikova
Office: 413b
E-mail: [email protected]
Lecture 2
Evolution, biosphere, and science
(pages 9-16)
Mader, Essentials of Biology 2E with CONNECT Plus Access Card
Essentials of Biology Second Edition
Sylvia S. Mader with McGraw-Hill
Connect Biology
Student registration info
Course:
Life Science 83.101.102
Instructor: Ekaterina Vorotnikova
Section: Spring 2010 mwf 9 am
online registration instructions
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Assignments for a 1/25 week:
1. Lec 1 Assignment
2. Quiz 1
3. Work on LearnSmart study
modulus to study chapter 1 until
Feb.2
Due on Monday Feb. 1 at 11:00 p.m.
Final grade
Grade for exams – 50%;
Grade for assignments – 30% (20% for
assignments + 10% LearnSmart
activity);
Grade for quizzes – 20%
(100 points max + 5 points for
attendance.)
Total number of points -105.
Evolution, the Unifying Concept of
Biology
• Despite diversity, organisms share the same basic
characteristics
– Composed of cells organized in a similar manner
– Their genes are composed of DNA
– Carry out the same metabolic reactions to acquire
energy
• This suggests that they are descended from a
common ancestor
Classification
Taxonomy:
Discipline of identifying and classifying
organisms according to certain rules
Hierarchical levels (taxa) based on
hypothesized evolutionary relationships
Levels are, from least inclusive to most
inclusive:
Species, genus, family, order, class, phylum,
kingdom, and domain
A level (e.g. phylum) includes more species than the level below
it (e.g. class), and fewer species than the one above it (e.g.
kingdom)
Scientific Names
• Binomial nomenclature (two-word names)used to assign each organism with two part name
e.g. Homo Sapience
• Universal
• Latin-based
– First word represents genus of organism e.g. Homo
– Second word is specific epithet of a species within
the genus e.g. Sapience
– Always italicized as a Genus species (Homo sapiens)
– Genus may be abbreviated e.g. Escherichia coli as
E. coli
Taxonomy
Leopard: Panthera pardus
Jaguar: Panthera onca
Tiger: Panthera tigris
Lion: Panthera leo
Domain: Eukarya
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Carnivora
Family: Felidae
Genus: Panthera
Species: P. pardus; P. onca; P. tigris; P. leo
Crossota millsae, a brilliant red and
purple jellyfish found at a depth of 2000m
in the Arctic Ocean
Miniature Muntjac, Muntiacus putaoensis
The small blue jelly, a type of
Narcomedusae, is new to science.
Rhacophorus suffry
Domains
Common
ancestor
• Bacteria : Microscopic unicellular prokaryotes
• Archaea: Bacteria-like unicellular prokaryotes;
Extreme aquatic environments
• Eukarya: Eukaryotes – Familiar organisms
EUKARYOTES
PROKARYOTES
Prokaryotic cell
Eukaryotic cell
DNA
(no nucleus)
Membrane
1-10 µm
Nucleus
(contains DNA)
Organelles
10-100 µm
Evolution, the Unifying Concept
of Biology
In 1859, Charles Darwin (12
February 1809 – 19 April 1882)
published On the Origin of
Species by Means of Natural
Selection, presenting a strong,
logical explanation of descent
with modification, evolution by
the mechanism of natural
selection.
Evolution is descent of species from common ancestors, with
genetic modifications that make each species more suited to its
environment.
Randal Keynes, 62, is the great-great-grandson of Charles Darwin. He is also the
author of the book Darwin, His Daughter, and Human Evolution, inspiration for
the new film Creation, starring Paul Bettany and Jennifer Connelly. The film
opened last Friday and gets a wider release Jan. 29.
Natural Selection
A process in which steps 1-3
result in population adapted to
the environment (4)
1. The members of a population
have heritable variations:
differences in their DNA that
can be passed from one
generation to the next.
2. The population produces
more offspring than the
resources of an environment
can support.
3. The more adapted
individuals survive and
reproduce to a greater extent
than those that lack the
adaptations.
4. Across generations, a larger
proportion of the population
becomes adapted to the
environment.
Descent with Modification.
The various species of
Hawaiian honeycreepers
all evolved from one
species of finch which
originated in North America
and arrived in the Hawaiian
Islands millions of years
ago. They have different
bill shapes adapted to
different kinds of food:
flower nectar, seeds, fruits,
insects..
All honeycreepers
still share certain
characteristics from
common finch
ancestor – body
shape, nesting
behavior, etc.
Organization of the Biosphere
• Population - Members of a species within
an area
• Community - A local collection of
interacting populations
• Ecosystem – A community plus its
physical environment
• How chemicals are cycled and re-used by
organisms
• How energy flows, from photosynthetic plants to top
predators
23
A grassland,
terrestrial
ecosystem
1. Chemicals cycle
through an
ecosystem.
2. Energy flows
through ecosystem
and dissipates as
heat.
What are two most
biologically diverse
ecosystems?
Science: A Way of Knowing
• Biology is the
scientific study of life.
Biologists
• Scientific method
begins with
observations.
– May take advantage of
knowledge and
experiences of other
scientists
• Scientist uses inductive
reasoning – uses
creative thinking to
combine isolated facts
into a cohesive whole.
– Hypothesis – possible
explanation for an event
• Consider only those that
can be tested.
Flow diagram for the
scientific method
• Experiments further
observations and test
hypothesis.
– Good experimental
design, all conditions
constant except
experimental variable
• Test group versus control
group
– Data may suggest
correlation.
• Does not necessarily
mean causation
• Scientists are skeptics
• Conclusion – is the
hypothesis supported
or not?
– Experiments and
observations must be
repeatable.
• Scientific theory
– Ultimate goal of
science is to
understand the
natural world in
accepted
explanations for how
the world works.
– Cell theory, gene
theory
– Theory of evolution is
considered a unifying
concept in biology.
– Some biologists refer to the principle or law of
evolution due to over 100 years of support by so
many observations and experiments.
Controlled laboratory
experiment to test the
effectiveness of a
medication in humans
Controlled study
• Hypothesis :
Antibiotic B is better
than Antibiotic A in
current use for the
treatment of ulcers.
3 experimental groups
Reduce possible variances by randomly dividing large group.
Control group receives placebo.
The Scientific Method
– Begins with observation
– Hypothesis
– Experimentation (Purpose is to challenge the
hypothesis)
– Often divides subjects into a control group and an
experimental group
– Predicts how groups should differ if hypothesis is
valid
– Results or Data (Observable, objective results from
an experiment)
– The results are analyzed and interpreted
– Conclusions are what the scientist thinks caused
the results
Scientific Theory
• Scientific Theory:
– Joins together two or more related hypotheses
– Supported by broad range of observations,
experiments, and data
• Scientific Principle / Law:
– Widely accepted set of theories
– No serious challenges to validity
Biodiversity
• Biodiversity is variation in life on Earth, in a zone of
air, land, and water where organisms exist (the
number of different species)
– Abundance of species estimated about 15 million.
– Fewer than 2 mln. have been identified, named and
classified
– The variability of their genes, and
– The ecosystems in which they live
• Extinction is:
– The death of the last member of a species
– Estimates of 400 species/day lost worldwide