Transcript You Light Up My Life

Life’s Underlying Unity
• Life’s organization extends from the
molecular level to the biosphere
• Shared features at the molecular level
are the basis of life’s unity
Levels of Organization
Cell
Multicelled organism
Population
Community
Ecosystem
Biosphere
atom
Smallest unit of an element that still retains the
element’s properties. Electrons, protons, and
neutrons are its building blocks. This hydrogen
atom’s electron zips around a proton in a
spherical volume of space
Fig. 1-1a, p.2
molecule
Two or more joined atoms of the
same or different elements. The
“molecules of life” are complex
carbohydrates, lipids, proteins,
DNA, and RNA. In today’s world only
living cells make them
Fig. 1-1b, p.2
cell
Smallest unit that can live
and reproduce on its own
or as part of a multicellular
organism. It has an outer
membrane, DNA, and
other components
Fig. 1-1c, p.2
tissue
Organized cells and
substances that interact
in a specialized activity.
Many cells (white) made
this bone tissue from
their own secretions
Fig. 1-1d, p.2
organ
Two or more tissues interacting in some task. A parrotfish eye, for
example, is a sensory organ used in vision
Fig. 1-1e, p.2
organ system
Organs interacting physically, chemically, or both in some task
Parrotfish skin is an organ system with tissue layers, organs such
as glands, and other parts
Fig. 1-1f, p.2
multicelled organism
Individual made of different types of cells
Cells of most organisms, including this Red Sea parrotfish, are
organized as tissues, organs, and organ systems
Fig. 1-1g, p.3
population
Group of single-celled or multicelled individuals of the same
species occupying a specified area
This is a fish population in the Red Sea
Fig. 1-1h, p.3
community
All populations of all species
occupying a specified area
This is part of a coral reef
in the Gulf of Aqaba at the
northern end of the Red Sea
Fig. 1-1i, p.3
ecosystem
A community that is
interacting with its physical
environment
It has inputs and outputs of
energy and materials
Reef ecosystems flourish in
warm, clear seawater
throughout the Middle East
Fig. 1-1j, p.3
the biosphere
All regions of the Earth’s waters, crust, and atmosphere that hold
organisms
Earth is a rare planet; without its abundance of free-flowing water,
there would be no life
Fig. 1-1k, p.3
Nothing Lives without Energy
Energy = capacity to do work
Metabolism = processes by which
cells acquire and use energy for
maintenance,
growth, and reproduction
Interdependencies among Organisms
Producers
Make their own food
Consumers
Obtain energy by eating other
organisms
Decomposers
Break down remains and wastes
Energy
input,
from
sun
Producers
plants, and other
self-feeding organisms
Nutrient
Cycling
Consumers
animals, most fungi,
many protists, many bacteria
Energy output (mainly metabolic heat)
Fig. 1-3, p.5
Homeostasis
• Organisms maintain certain conditions
in their internal environment
• A defining feature of life
Mutation: Source of Variation
• Mutation = change in structure of DNA
• Basis for variation in heritable traits
• May be harmful, neutral, or beneficial
Evolution
• Heritable change in a line of descent
over time
• Changes in populations result in
diversity
Classification Systems
• Organisms are grouped into three
domains:
Eubacteria
(Bacteria)
Archaebacteria
(Archaea)
Eukaryotes
(Eukarya)
Major Groups
Protistans
Plants
Fungi
Animals
Eukaryotes
Archaebacteria
Eubacteria
Origin of life
Unity of Life
All organisms
– Consist of one or more cells
– Have the capacity to reproduce based
on instructions in DNA
– Engage in metabolism
– Sense and respond to the environment