are we alone?faculty.sxu.edu/dlc1/humanweb19/introduction.pdf · 1/16/2019 3 composed of cells...
TRANSCRIPT
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What is biology?
What characterizes life?
How do we classify life?
Where do humans fit into the big picture?
How do we study science?
Where is scientific information published and what should you be aware of?
Are We Alone?
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They both have water in large amounts
What are the basic characteristics that define life?
What evidence would you look for on one of these moons that would tell you that life may have existed on them in the past?
What does it tell us if we discover life on one of these moons and it has characteristics similar to those of life on Earth? What if it is very different?
Characteristics of Life
What characteristics are shared by living organisms?
Life is highly organized and made of cells
Reproduce and grow
Use materials and energy from the environment
Respond to internal and external stimuli
Maintain a relatively constant internal environment (homeostasis)
Evolve
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Composed of cells
• First organisms were single cells
• Basic unit of life
• Self-contained units
• Bacteria are single cells
• Multicellular organisms made of different specialized cells
Highly Organized
• Complex function
• Humans have tissues and organ systems
• Organization is required for function
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How are living things organized?
nervous system shoot system
leaf
photosynthetic tissue
plant cell
brain
nervous tissue
neuron
Biosphere
Regions of the Earth’s crust, waters, and atmosphere inhabited
by living things
Ecosystem
A community plus the physical environment
Community
Interacting populations in a particular area
Population
Organisms of the same species in a particular area
Organism
An individual; complex individuals contain organ systems
Organ System
Composed of several organs working together
Organ
Composed of tissues functioning together for a specific task
Tissue
A group of cells with a common structure and function
Cell
The structural and functional unit of all living things
Molecule
Union of two or more atoms of the same or different elements
Atom
Smallest unit of an element composed of electrons, protons, and neutrons
Figure 1.2 Levels of
biological organization.
Lower Level of Biological Hierarchy
• Atoms
• Molecules
– DNA and proteins
• Cells
– Many different types in higher organisms
• Tissues
– Made up of many cells
• Organs
– Heart and brains
Mid-level of Biological Hierarchy
• Organ systems
– Heart and blood vessels
– Work together to pump blood
• Individual organism
– Organ systems functioning together
– Each system supporting other systems
• Population
– Group of similar organisms
• All mice living in one field
Top Level of Biological Hierarchy
• Community
– Groups of different species or organisms
– Live and interact in a certain area
• Ecosystems
– Communities and their physical environment
• Biomes
– Large regions defined by distinctive characteristics
• Biosphere
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Importance of Biological Hierarchy
• Molecular level to biosphere level
– Intricate interactions that affect all living
things including us.
– Understanding the hierarchy helps us to understand the interactions.
What characteristics are shared by living organisms?
Life is highly organized and made of cells
Reproduce and grow
Use materials and energy from the environment
Respond to internal and external stimuli
Maintain a relatively constant internal environment (homeostasis)
Evolve
Reproduction via DNA
• Living organisms reproduce or replicate themselves
• Single-cell organisms – Produce two genetically identical
cells
• Multicellular organisms – Variety of ways
– Seeds, eggs and sperm, etc.
• Genetic material – Passed from parents to offspring
– DNA: deoxyribonucleic acid
Growth and Development
• DNA as a blueprint
– Organisms grow and propagate themselves
– Organisms develop and grow in complexity
What characteristics are shared by living organisms?
Life is highly organized and made of cells
Reproduce and grow
Use materials and energy from the environment
Respond to internal and external stimuli
Maintain a relatively constant internal environment (homeostasis)
Evolve
Capturing Energy
• Collect energy from their environment – Use energy to grow and develop
• Some use the energy of sunlight – Plants capture sun’s energy via
photosynthesis
– Convert solar energy to chemical energy in sugars
• Some use energy from other living organisms – Animals consume plants or animals
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The sun is the ultimate source of energy on Earth What characteristics are shared by living organisms?
Life is highly organized and made of cells
Reproduce and grow
Use materials and energy from the environment
Respond to internal and external stimuli
Maintain a relatively constant internal environment (homeostasis)
Evolve
Sense and Response
• Detect danger
• Many organisms have multiple senses – Smell, hear, taste, touch, and see
• Some senses different than human – Ultraviolet and infrared light
– Electrical and ultrasonic fields
– Some bacteria use magnetic particles to sense direction
What characteristics are shared by living organisms?
Life is highly organized and made of cells
Reproduce and grow
Use materials and energy from the environment
Respond to internal and external stimuli
Maintain a relatively constant internal environment (homeostasis)
Evolve
Homeostasis
• All organisms engage in maintaining homeostasis in some fashion.
What characteristics are shared by living organisms?
Life is highly organized and made of cells
Reproduce and grow
Use materials and energy from the environment
Respond to internal and external stimuli
Maintain a relatively constant internal environment (homeostasis)
Evolve
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All organisms Evolve!
What are the basic characteristics that define life?
What evidence would you look for on one of these moons that would tell you that life may have existed on them in the past?
What does it tell us if we discover life on one of these moons and it has characteristics similar to those of life on Earth? What if it is very different?
Fossilized Bacteria from Mars rock? NO!
What are the basic characteristics that define life?
What evidence would you look for on one of these moons that would tell you that life may have existed on them in the past?
What does it tell us if we discover life on one of these moons and it has characteristics similar to those of life on Earth? What if it is very different?
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Adaptation to Environmental
Conditions
Human
Evolutionary
History
Three Domains of Life
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Classification of Life How do we classify humans?
Human House cat
• Domain Eukarya Eukarya
• Kingdom Animalia Animalia
• Phylum Chordata Chordata
• Class Mammalia Mammalia
• Order Primates Carnivora
• Family Hominidae Felidae
• Genus Homo Felis
• Species sapiens domesticus
What distinguishes humans from other animals?
Cultural heritage or patterns of our behavior passed from one generation to the next – also seen in monkeys and some birds
Highly developed brains
Completely upright stance
Creative language skills
Varied tool use – many animals use tools including monkeys and birds among others!
Modification of our environment for our own purpose which may threaten the biosphere – other animals can engineer their habitat ex. beaver
Humans Negatively Impact Natural Systems
Way of knowing
Natural World
Objective Statistics
Conclusions Change
Process Scientific Method
Laws, Theories
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Scientific theories in biology
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Germ Theory of Disease: Koch’s Postulates
• The suspected pathogen (virus or bacterium) must be present in every case of the disease;
• The pathogen must be isolated from the host and grown in a lab dish;
• The disease must be reproduced when a pure culture of the pathogen is inoculated into a
healthy susceptible host; and
• The same pathogen must be recovered again from the experimentally infected host.
Scientific Method
Scientific Method Example Dr. Barry Marshall discovers the cause of
stomach ulcers
H. Pylori and ulcers
• Experimented on animals – Conclusion not accepted
• 1985, Marshall decided to perform the experiment on himself!
– He and another volunteer swallowed solution of H. pylori.
• Within the week, they felt sick and were vomiting up their stomach contents.
• Examination by endoscopy showed that their stomachs were now inflamed, and biopsies of the stomach lining contained the suspected bacterium.
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A controlled study
• Variables
• Experimental variable is the variable that is purposely changed or manipulated.
• All other variables need to remain constant.
• Groups
• Test group is a group of subjects that are exposed to the experimental variable.
• Control group is a group for comparison that is not exposed to the experimental variable.
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• Observations: Many patients had a particular
bacterium near their ulcers.
• Hypothesis: Helicobacter pylori is the cause of
gastritis and ulcers.
How the cause of ulcers was discovered:
The scientific method in action
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• Experiment/observations:
1st – H. pylori was isolated and grown from ulcer
patients.
2nd – Humans swallowing a H. pylori solution
developed inflammation in their stomachs.
• Conclusion: H. pylori was the cause of most
ulcers and can be cured by antibiotics.
How the cause of ulcers was discovered:
The scientific method in action (Koch’s Postulates) A controlled study in action
Figure 1.9 A controlled
laboratory experiment to
test the effectiveness of a
medication in humans.
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Reading about scientific information
• Scientific journals are considered the best source of information but can be difficult for the lay person to understand.
• Often the lay person reads secondary sources and must be wary of information taken out of context.
• Be careful of information on the Internet by using reliable sources such as URLs with .edu, .gov and .org.
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What should you look for when
you read about science?
• Beware of anecdotal data.
• Understand methodology and results.
• Does the data justify the conclusions inferred by
the scientists?
• Be able to read a graph.
• Have some understanding of statistics.
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Reading a graph What information does this line graph convey?
Figure 1.10 The presentation of scientific data. 62
Statistical Significance
• When scientists conduct an experiment, there is always
the possibility that the results are due to chance or to
some factor other than the experimental variable.
• Investigators take into account several factors when they
calculate the probability value (p) that their results were
due to chance alone.
• If the probability value is low, researchers describe the
results as statistically significant.
• A probability value of less than 5% (usually written as p
< 0.05) is acceptable, but p values of <0.001 are
common in many studies.
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Does science have social
responsibilities?
• Science is a way of acquiring knowledge about
the natural world.
– It is a slightly different endeavor than technology.
– Collection of data is non-judgemental
– Bioethicists argue about the social issues
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Does science have social
responsibilities?
• Technology is the application of scientific
knowledge to human interests.
• Bioethics is the branch of ethics concerned
with the development and consequences of
biological technology.
- Genetic engineering (genetically modified crops)
- Threat to biodiversity
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Human Influence on
Ecosystems
• Humans tend to modify ecosystems for their own
purposes.
• Changes in human behavior and use of new
technology can result in new diseases (emerging
diseases).
• Human activities may attribute to climate change
(global warming).
Biologists work in many environments