Transcript 1. Cells are the structural and functional units of life

UNIFYING THEMES OF BIOLOGY
Copyright © 2009 Pearson Education, Inc.
1. Cells are the structural and functional units of
life
 Two distinct groups of cells exist
– Prokaryotic cells
– Simple and small
– Bacteria are prokaryotic
– Eukaryotic cells
– Possess organelles separated by membranes
– Plants, animals, and fungi are eukaryotic
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Prokaryotic cell
DNA
(no nucleus)
Membrane
Nucleus
(contains DNA)
Organelles
Eukaryotic cell
1. Cells are the structural and functional units of
life (continued)
 Unicellular organisms
 Multicellular organisms
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1. Cells are the structural and functional units of
life (continued)
 Form generally fits function
– By studying a biological structure, you can determine
what it does and how it works (from molecules to
organisms!)
– Life emerges from interactions of structures
– Combinations of structures (components) provide
organization called a system
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Form and
Function
2. In life’s hierarchy of organization, new
properties emerge at each level
 Life’s levels of organization define the scope of
biology
 Life emerges through organization of various levels
 With addition of each new level, novel properties
emerge—called emergent properties
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Biosphere
Ecosystem
Florida coast
Community
All organisms on
the Florida coast
Population
Group of brown
pelicans
Organism
Brown pelican
Spinal cord
Nerve
Organ system
Nervous system
Brain
Organ
Brain
Tissue
Nervous tissue
Cell
Nerve cell
Atom
Nucleus
Organelle
Nucleus
Molecule
DNA
Biosphere
Ecosystem
Florida coast
Community
All organisms on
the Florida coast
Population
Group of brown
pelicans
Organism
Brown pelican
Organism
Brown pelican
Spinal cord
Nerve
Organ system
Nervous system
Brain
Organ
Brain
Tissue
Nervous tissue
Atom
Cell
Nerve cell
Nucleus
Organelle
Nucleus
Molecule
DNA
3. Stability and Homeostasis
 Organisms must regulate their internal
environment to survive in diverse ecosystems.
 Behaviors and adaptations can help maintain
homeostasis
What are some examples?
 Regulation occurs at every level of organization
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Application:
How does your body regulate temperature?
4. Reproduction and Inheritance
 Organisms pass their traits from one generation to
the next generation via reproduction.
 DNA is the molecular basis of life (ALL life on Earth)
DNARNAProtein
 The inheritance of genetic material through
reproduction explains the continuity of life
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4. Reproduction and Inheritance (continued)
 Continuity of life is based on heritable
information in the form of DNA
 DNA–the genetic
material–carries
biological information
from one generation
to the next
5. Metabolism
 Organisms have methods of capturing matter and
energy (photosynthesis in plants) and using
matter and energy (respiration in ALL organisms)
 The process of regulating biochemical reactions is
called metabolism.
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5. Metabolism (continued)
 Life is an open system that depends on
energy transfer
 Organisms continuously interact
with the environment
 Stuff comes in
stuff goes out
 Energy is used
What happens to the
consumers when they
die?
6. Living organisms interact with their
environments, exchanging matter and energy
 Species rely on one another and their environment
 Life requires interactions between living (biotic)
and nonliving (abiotic) components
– Photosynthetic organisms provide food and are called
producers
– Organisms that eat plants or other organisms are called
consumers
 The nonliving components are chemical nutrients
required for life
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(PRODUCERS)
7. EVOLUTION--THE CORE
THEME OF BIOLOGY
“Nothing in biology makes sense except in the light of
evolution.”
--Theodosius Dobzhansky
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7. Evolution
 Evolution explains the unity and diversity of life.
 Unity
 What do organisms have in common?
 Why do similarities exist?
 Diversity
 Are there differences between organisms of the same
species?
 Unity
 Shared genetic code
 Evolutionary relationships
 Connected through a common ancestor
 Diversity
 Differences in DNA structure among organisms
 Natural selection: selection of some DNA
structures over others
 Adaptations: naturally selected traits
 Natural selection was inferred by connecting two
observations
 Individuals within a population inherit different
characteristics and vary from other individuals
 A particular population of individuals produces more
offspring than will survive to produce offspring of their
own
(Lamarckian evolution and giraffes)
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In this example:
• Dark-colored
beetles are
selected for
• Light-colored
beetles are
selected against
• Predation is the
selective agent
• Dark coloration
becomes an
adaptation for this
population of
beetles
1 Population with varied inherited traits
2 Elimination of individuals with certain traits
3 Reproduction of survivors
 Natural selection is an editing mechanism
– It results from exposure of heritable variations to
environmental factors that favor some individuals over
others
– Over time this results in evolution of new species adapted to
particular conditions/environments
– Evolution is biology’s core theme and explains unity and
diversity of life
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The Three-Domain System
Protists
Plants
Fungi
Animals
Domain Eukarya
Domain Bacteria
Bacteria (multiple kingdoms)
Protists (multiple kingdoms)
Kingdom Plantae
Kingdom Fungi
Kingdom Animalia
Domain Archaea
Archaea (multiple kingdoms)
YOU ARE
HERE
Dr. R.M. Moody
Characteristics of Life
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1.4 The unity of life: All forms of life have
common features
 All living things share common properties
– Cellular Organization—All organisms composed of
one or more cells; cells are organized to play certain
roles in organisms.
– Response to stimuli—Ability of organisms to respond
to their environment.
– Homeostatis—an ability to maintain an internal
environment consistent with life
– Metabolism—acquiring energy and transforming it to a
form useful for the organism
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1.4 The unity of life: All forms of life have
common features
 Common properties continued
– Growth and development—consistent growth and
development controlled by DNA
– Reproduction—the ability to perpetuate the species
– Evolutionary adaptation—acquisition of traits that
best suit the organism to its environment
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(1) Cellular Organization
(2) Regulation
(5) Response to the environment
(3) Growth and development (4) Energy processing
(6) Reproduction
(7) Evolutionary adaptation