Transcript A View of Life

A View of Life
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Defining Life (1)
How do you know if something is alive?
What are properties of living things that nonlivings things do no possess?
What is the smallest living thing you can think
of?
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So what is required of life?
Living “things” are:
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Defining Life (1)
Living things vs. nonliving objects:
Comprised of the same chemical elements
Obey the same physical and chemical laws
The cell is the smallest, most basic unit of all
life
Familiar organisms are multicellular
Some cells independent – single-celled
organisms
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Defining Life
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Levels of Biological Organization
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Living Things:
Acquire & Process Food
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Energy - the capacity to do work
The sun:
- Ultimate source of energy for nearly all life on
Earth
- Drives photosynthesis
Metabolism - all the chemical reactions in a
cell
- Homeostasis - Maintenance of internal
conditions within certain boundaries
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Acquiring Nutrients
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Living Things:
Respond to Stimuli
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Living things detect changes in environment
Response often involves movement
Vulture can detect and find carrion a mile
away
Monarch butterfly senses fall and migrates
south
Microroganisms follow light or chemicals
Even leaves of plants follow sun
Responses collectively constitute behavior
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Living Things:
Reproduce and Develop
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Organisms live and die
Must reproduce to maintain population
Multicellular organisms:
Begins with union of sperm and egg
Developmental instructions encoded in genes
- Composed of DNA
- Long spiral molecule in chromosomes
Rockhopper Penguins & Offspring
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Living Things:
Adapt to Change
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Adaptation
Any modification that makes an organism
more suited to its way of life
Organisms, become modified over time
However, organisms very similar at basic level
- Suggests living things descended from same
ancestor
- Descent with modification - Evolution
- Caused by natural selection
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So what is required of life?
Living “things”
eat
give off wastes
reproduce
breathe
die
respond to their environment
adapt
contain heritable material
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Organization of the Biosphere
Population - Members of a species within an
area
Community - A local collection of interacting
populations
Ecosystem - The communities in an area
considered with their physical environment
- How chemicals are cycled and re-used by
organisms
- How energy flows, from photosynthetic plants
to top predators
Terrestrial Ecosystems:
A Grassland
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Marine Ecosystems:
A Coral Reef
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Classification
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Classification
Taxonomy:
The rules for identifying and classifying
organisms
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 usually includes more species than the
level below it, and fewer species than the one
above it
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Levels of Classification
Taxon
Human
Corn
Domain
Eukarya
Eukarya
Kingdom
Animalia
Plantae
Phylum
Chordata
Anthophyta
Class
Mammalia
Liliopsida
Order
Primates
Commelinales
Family
Hominidae
Poacae
Genus
Homo
Zea
H. sapiens
Z. mays
Species
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Domains
Bacteria
Microscopic unicellular prokaryotes
Archaea
Bacteria-like unicellular prokaryotes
Extreme aquatic environments
Eukarya
Eukaryotes – Familiar organisms
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Domains:
The Archaea
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Domains:
The Bacteria
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Kingdoms
Archaea – Kingdoms still being worked out
Bacteria - Kingdoms still being worked out
Eukarya
Kingdom Protista
Kingdom Fungi
Kingdom Plantae
Kingdom Animalia
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Domains:
The Eukaryote Kindoms
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Scientific Names
Binomial nomenclature (two-word names)
Universal
Latin-based
First word represents genus of organism
Second word is specific epithet of a species
within the genus
Always Italicized asa Genus species (Homo
sapiens)
Genus may occur alone (Homo), but not
specific epithet
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