Download Core Concepts Observe this image How do scientist study Biology?

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Life: Chemical, Cellular, and Evolutionary Foundations
Chapter 1
Core Concepts
1.The scientific method is a deliberate way of asking and answering questions about the natural world.
2.Life works according to fundamental principles of chemistry and physics.
3.The fundamental unit of life is the cell.
4.Evolution explains the features that organisms share and those that set them apart.
5.Organisms interact with one another and with their physical environment, shaping ecological systems that sustain life.
6.In the 21st century, humans have become major agents in ecology and evolution.
Observe this image
Biology: The Science of How Life Works
• Molecular mechanisms of cells
• Integrated actions of many cells within an
organ or body
• Interaction among different organisms in
nature
Concept 1.1: Scientific Method
• Observation allows us
to draw tentative
explanations called
hypothesis.
• Hypothesis makes
predictions that can
be tested by
experiments
• A hypothesis
supported by many
experiments and
observations can
become a theory.
How do scientist study Biology?
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Observation
Asking questions
Hypothesis
Design an experiment
Collect data
Conclusion
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Concept 1.2 Life works according to fundamental principles of chemistry and physics
What is common between living and COMPOSITION OF EARTH AND HUMAN BODY
nonliving things?
• What’s the difference between the living and nonliving environment?
• Earth’s crust:
- Mainly Oxygen and
Silicon
• Living organisms:
- Oxygen, Carbon,
Hydrogen and nitrogen.
What are the characteristics of life?
1. Complex
2. Able to change in response to environment
3. Able to reproduce
4. Have the capacity to evolve
5. Process energy
ODYNAMICS
How do organisms obtain energy? • From sunlight or
food.
• First Law of
thermodynamics
states that energy
can neither be
created nor
destroyed
Organisms come from other living organisms. Life does not spontaneously arise from nonliving matter
FRANCESCO REDI EXPERIMENTATION
Science as a Process
Louis Pasteur Experimentation
Broth remains clear and sterile—no microbes appear.
Straight‐
neck flask
Broth
Swan‐
neck flask
Boiling kills all the microbes, thereby sterilizing the broth.
Dust particles carrying microbes enter the straight‐neck
flask, but not the swan‐neck flask.
Broth becomes cloudy because of growth of microbes.
Figure 1.9 Can microscopic life arise from nonliving matter?
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Concept 1.3: Cells Cell: the simplest self-replicating entity that
can exist as an independent unit of life
ESSENTIAL FEATURES OF A CELL
What is a Cell?
Cell is a basic unit of life. It varies in shape and size
• It can store and transmit information.
• It has a plasma membrane.
• It can harness energy from the environment.
STORE AND TRANSMIT INFORMATION
Nucleic Acids Store and Transmit Information • Information is stored in DNA. It’s a double helix with each strand made of four different molecules (A,C,G &T)
• DNA has instructions to make proteins, the molecule that does the work of the cell. THE CENTRAL DOGMA
Flow of Information in all Living Organisms
• Central Dogma:
DNA→RNA → Protein
• Gene – a segment of DNA that has instructions to make a specific protein
• Genes are made of DNA
• Genes control protein production indirectly
• DNA is transcribed into RNA then translated into a protein
• Gene expression is the process of converting information from gene to cellular product (protein)
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PLASMA MEMBRANE
Plasma membrane
Two Main Forms of Cells
Outside of cell
• Separates the cell from its environment
• Controls exchange of material between cell and the environment
Cytoplasm
All cells
• are all enclosed by a membrane
• Use DNA as the genetic material
• Two main forms of cells
– Eukaryotic‐ nucleus & organelles present
– Prokaryotic‐nucleus and organelles absent
Transmission electron micrograph of a cell
TREE OF LIFE: Three Domains of Life
Most of life’s diversity, and
so most of its deep
evolutionary history, is
microbial.
ARCHAEA
BACTERIA
EUKARYOTES
Plants
Proposed
position of
root
Time runs from the
root to the branches.
All land
plants lie on
this branch.
Animals
Animal diversity lies
on this branch of the
tree.
Domain Eukarya
• The domain Eukarya includes all eukaryotic organisms.
• Eukarya includes three multicellular kingdoms
– Plantae: Autotrophs
– Fungi: heterotrophs, absorb nutrients
– Animalia: heterotrophs, ingest nutrients
• Other eukaryotic organisms were formerly grouped into the Protist kingdom (unicellular/multicellular, autotroph/heterotroph) though these are now often grouped into many separate kingdoms
Domain Bacteria and Archaea
• Domain Bacteria: Unicellular diverse prokaryotes
• Domain Archaea: Prokaryotes that live in earth’s extreme environments such as salty lakes, boiling hot springs
• Most prokaryotes are single‐celled and microscopic
Aren’t viruses smaller than cells?
What are Viruses?
Shouldn’t they be considered the smallest living organisms?
A. A virus can store and transmit information.
B. A virus has a plasma membrane (protein coat).
C. A virus can harness energy from the environment.
D. They can reproduce on their own
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Aren’t viruses smaller than cells?
What are Viruses?
Shouldn’t they be considered the smallest living organisms?
A. A virus can store and transmit information.
B. A virus has a plasma membrane (protein coat).
C. A virus can harness energy from the environment.
D. They can reproduce on their own
Concept 1.4: Evolution ‐ Change over time
• Fossils and other evidence document the evolution of life on Earth over billions of years
Variation
Environmental
Genetic
PHYLOGENETIC TREE IN PRIMATES
• Evolution explains patterns of unity and diversity in living organisms
• Similar traits among organisms are explained by descent from common ancestors
• Differences among organisms are explained by the accumulation of heritable changes
• Charles Darwin published On the Origin of Species by Means of Natural Selection in 1859
• Darwin made two main points: – Species showed evidence of “descent with modification” from common ancestors
– Natural selection is the mechanism behind “descent with modification”
• Darwin’s theory explained the duality of unity and diversity
• Darwin observed that:
– Individuals in a population have traits that vary
– Many of these traits are heritable (passed from parents to offspring)
– More offspring are produced than survive
– Competition is inevitable
– Species generally suit their environment
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Concept 1.5: Ecology
The study of how organisms interact with one another and with their environment
Concept 1.6: Human Footprint
What is our role in evolution? Some species have benefited
Some species have not benefited from human activity
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