Transcript Organism

Chapter 1
Invitation to Biology
Hsueh-Fen Juan
阮雪芬
Sep. 11, 2012
1.1 Life’s Levels of Organization
 We understand life by thinking about nature at
different levels of organization
 Nature’s organization begins at the level of
atoms, and extends through the biosphere
 The quality of life emerges at the level of the cell
Making Sense of the World
 Nature is everything in the universe except what
humans have manufactured
A Pattern in Life’s Organization
 Atoms
• Fundamental building blocks of all substances
 Molecules
• Consisting of two or more atoms
 Cell
• The smallest unit of life
 Organism
• An individual consisting of one or more cells
A Pattern in Life’s Organization
 Population
• Individuals of the same species in the same area
 Community
• Populations of all species in the same area
 Ecosystem
• A community and its environment
 Biosphere
• All regions of the Earth where organisms live
Levels of Organization in Nature
Levels of Organization in Nature
Emergent Properties
 Each level of organization in nature has
emergent properties – a characteristic of a
system that does not appear in any of its
component parts
1.1 Key Concepts:
Levels of Organization
 We study the world of life at different levels of
organization, which extend from atoms and
molecules to the biosphere
 The quality of “life” emerges at the level of cells
1.2 Overview of Life’s Unity
 All living things have similar characteristics
• Continual inputs of energy and the cycling of
materials maintain life’s complex organization
• Organisms sense and respond to change
• DNA inherited from parents is the basis of growth
and reproduction in all organisms
Energy and Life’s Organization
 Energy
• The capacity to do work
 Nutrients
• Atoms or molecules essential in growth and
survival that an organism cannot make for itself
Producers and Consumers
 Producers
• Acquire energy and raw materials from the
environment
• Make their own food (photosynthesis)
 Consumers
• Cannot make their own food
• Get energy by eating producers and other
organisms
Organisms Sense and
Respond to Change
 Organisms sense and respond to change both
inside and outside the body by way of receptors
 Receptor
• A molecule or cellular structure that responds to a
specific form of stimulation
Homeostasis
 Homeostasis
• Organisms use receptors to help keep conditions
in their internal environment within ranges that
their cells can tolerate
Organisms Grow and Reproduce
 Organisms grow, develop, and reproduce
using information in their DNA, a nucleic acid
inherited from parents
 Information encoded in DNA is the source of an
individual’s distinct features (traits)
Same Materials, Many Products
 20 amino acids are the building blocks used to
build a great variety of proteins
1.2 Key Concepts:
Life’s Underlying Unity
 All organisms consist of one or more cells, which
stay alive through ongoing inputs of energy and
raw materials
 All sense and respond to change; all inherited
DNA, a type of molecule that encodes
information necessary for growth, development,
and reproduction
1.3 Overview of Life’s Diversity
 Of an estimated 100 billion kinds of organisms
that have ever lived on Earth, as many as 100
million are with us today
Scientific Naming
 Each type of organism is given a two-part name
that includes genus and species names
 Genus
• A group of species that share unique features
 Species
• Individuals that share one or more heritable traits
and can interbreed (if sexually reproducing)
Classification Systems
 Classification systems group species by their
shared, heritable traits
 All organisms are classified into three domains
• Bacteria, archaea, and eukaryotes
• Eukaryotes include plants, animals, protists
and fungi
Comparison of Life’s Three Domains
1.3 Key Concepts:
Life’s Diversity
 Many millions of kinds of organisms, or species,
have appeared and disappeared over time
 Each kind is unique in some aspects of its body
form or behavior
One-Way Flow of Energy and Cycling of
Materials through an Ecosystem
1.4 An Evolutionary View of Diversity
 A theory of evolution by natural selection is an
explanation of life’s diversity
Variation and Mutation
 Information encoded in DNA is the basis of traits
an organism shares with others of its species
 Mutations are the original source of variation in
traits
Adaptation
 Some forms of traits are more adaptive than
others, so their bearers are more likely to survive
and reproduce
 Over generations, adaptive traits tend to
become more common in a population; less
adaptive forms of traits become less common or
are lost
Evolution and Natural Selection
 Evolution is change in a line of descent
• Traits that characterize a species can change
over generations in evolving populations
 Natural selection is an evolutionary process
• Differential survival and reproduction among
individuals that vary in the details of their shared,
heritable traits
1.4 Key Concepts:
Explaining Unity in Diversity
 Theories of evolution, especially a theory of
evolution by natural selection, help explain why
life shows both unity and diversity
 Evolutionary theories guide research in all fields
of biology
1.5 Critical Thinking and Science
 Critical thinking is judging the quality of
information
 Science is limited to that which is observed
• Helps minimize bias in judgments by focusing on
testable ideas about observable aspects of nature
A Guide to Critical Thinking
1.6 How Science Works
 Scientists make and test potentially falsifiable
predictions about how the natural world works
Observations, Hypotheses, and Tests
 Researchers make observations, form
hypotheses (testable assumptions), and make
predictions about what might occur if the
hypothesis is correct
A Scientific Approach
Research in Laboratory and Field
Systems Biology
牛頓2003年11月2003年11月
Prof. Kitano