Post on 20-Jan-2016
Topic 1Introduction to the Study of Life
1.1 The Unifying Characteristics of Life
Biology 1001September 9, 2005
Why Study Biology?
• Rooted in the human spirit
Curiosity, recreation, enjoyment of nature
Our connectedness to living things
Conservation of biodiversity important
E. O. Wilson’s biophilia
Why is Biology Important?
• Woven into the fabric of society
- Health and disease
- Nutrition
- Agriculture
- Management of natural resources
• Applicable in diverse disciplines
- Psychology, sociology, criminal science
- Even architecture!
Life Is A Myriad of Diverse Forms
So How Do We Recognize Life?Unifying Properties & Processes Characterize Living Things
• Order• Evolutionary adaptations
Cells as the basic unit of structure
DNA as the hereditary material
The study of life has both horizontal and vertical dimensions!
• Response to environment• Reproduction• Energy processing• Growth and development• Regulation and homeostasis
Figure 1.2 Some properties of life
(c) Response to the environment
(a) Order
(d) Regulation
(g) Reproduction (f) Growth and development
(b) Evolutionary adaptation
(e) Energy processing
Examples – Order & Energy Utilization
Examples – Reproduction, Growth & Development
A Hierarchy of Biological Organization
• The study of life– Extends from the microscope scale of molecules and
cells to the global scale of the entire living planet
• The hierarchy of life– Extends through many levels of biological
organization
• The challenge is integration across dimensions!
Figure 1.3 Exploring Levels of Biological Organization1 The biosphere
2 Ecosystems
3 Communities
4 Populations
5 Organisms
8 Cells
6 Organs and organ systems
7 Tissues
10 Molecules
9 Organelles
50 µm
10 µm
1 µmCell
Atoms
Cells
• A diversity of cell form!
• The cell– Is the lowest level of organization that can perform all activities
required for life
• All cells share certain characteristics– They are all enclosed by a membrane– They all use DNA as genetic information– They all contain a cellular fluid and ribosomes
• There are two main forms of cells– Eukaryotic– Prokaryotic
Cells
• Pro=first, eu=true, karyon=nucleus
• Eukaryotic cells– Are subdivided by internal membranes into various membrane-enclosed organelles– Nucleus, mitochondria, chloroplasts– All other organisms
• Prokaryotic cells– Lack the kinds of membrane-enclosed organelles found in eukaryotic cells– Are smaller than eukaryotic cells– Prokaryotes
Prokaryotic Vs. Eukaryotic Cells
EUKARYOTIC CELL
Membrane
Cytoplasm
Organelles
Nucleus (contains DNA) 1 µm
PROKARYOTIC CELL
DNA
(no nucleus)Membrane
Figure 1.8
DNA - The Cell’s Heritable Information
• Cells contain chromosomes made partly of DNA, the substance of genes– Which program the cells’ production of proteins and transmit
information from parents to offspring
Egg cell
Sperm cell
NucleicontainingDNA
Fertilized eggwith DNA fromboth parents
Embyro’s cells with copies of inherited DNA Offspring with traits
inherited fromboth parents
The molecular structure of DNAaccounts for its information-rich nature
DNA
Cell
Nucleotide
ACTA
T
A
CC
G
G
TA
TA
(b) Single strand of DNA. These geometric shapes and letters are simple symbols for the nucleotides in a small section of one chain of a DNA molecule. Genetic information is encoded in specific sequences
of the four types of nucleotides (their names are abbreviated here as A, T, C, and G).
(a) DNA double helix. This model shows
each atom in a segment of DNA.Made up of two long chains of building blocks called nucleotides, a DNA molecule takes the three-dimensional form of a double helix.
Nucleus
Feedback Regulation in Biological Systems
• A “supply-and-demand” feature regulates some of the dynamics of living systems
• The output, or product, of a process regulates that very process
Feedback can be Negative or Positive
In negative feedbackAn accumulation of an end product slows the process that
produces that product
In positive feedbackThe end product speeds up production
The Emergent Properties of Biological Systems
A system is a combination of components that form a more complex organization
Biological systems are much more than “the sum of their parts”
New properties emerge with each step upward in the hierarchy of biological organization
Examples of Emergent Properties
Non-Living Examples
• Graphite vs. diamond • NaCl
• A hammer
Biological Examples
• Ecosystems
• Feedback regulation
• Consciousness
• Photosynthesis
• Enzymes & other proteins
Systems Biology Systems biology seeks to create models of the dynamic
behavior of whole biological systems
With such models scientists will be able to predict how a change in one part of a system will affect the rest of the system
Is now taking hold in the study of life at the cellular and molecular levels
Includes three key research developments: high-throughput technology, bioinformatics, and interdisciplinary research teams
Examples of Systems BiologyCELL
Nucleus
Cytoplasm
Outer membraneand cell surface
Figure 1.10
CELL
Nucleus
Cytoplasm
Outer membraneand cell surfaceCELL
Nucleus
Cytoplasm
Outer membraneand cell surfaceCELL
Nucleus
Cytoplasm
Outer membraneand cell surface
Figure 1.10
2. A systems map of interactions between proteins
in a cell
1. The “greenhouse effect”
3. The Human Genome Project
Correlation Between Structure and Function at All Levels of Biological Organization