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Biology – Kevin Dees; online lecture
BIOL1406General Biology I
Chapter 1Biology = study of life
Biology – Kevin Dees; online lecture
Why study life???
• Think about some of the ways that biology can affect your daily life
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Biology – Kevin Dees; online lecture
Why study life???
• Medical technology and understanding our own bodies
Biology – Kevin Dees; online lecture
Why study life???
• Understanding our role as members of a living ecosystem and biosphere
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Biology – Kevin Dees; online lecture
Why study life???
• Understanding that decisions we make affect our Earth
Biology – Kevin Dees; online lecture
What defines a living thing??
7 properties of living things1. Order2. Evolutionary adaptation3. Response to the environment4. Regulation5. Energy Processing6. Reproduction7. Growth and Development
*As you study, be sure that you can think of an example of how each of these can help to define a living thing.
The next slide uses images to help illustrate these concepts.
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Biology – Kevin Dees; online lecture
Fig. 1-3
Order
Evolutionary adaptation
Responseto theenvironment
Reproduction
Growth anddevelopment
Energyprocessing
Regulation
Biology – Kevin Dees; online lecture
Themes connect biological concepts
• Understanding how these 7 properties of life are all intertwined is no small task.
• One of the most difficult obstacles for students who study biology (you!) is to prevent reducing the information to memorized facts; this can prevent full understanding.
• It is true that this semester you will need to commit some things to memory; you will learn lots of new vocabulary for example.
• To aid this understanding, consider the enormous realm of biology broken down into 7 themes.
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Biology – Kevin Dees; online lecture
Seven themes of biology
1. Evolution – the unifying theme in biology– Biology’s core theme
– It is the one idea that unifies all other concepts
– It can explain why organisms are similar and different at the same time
– More later……
Biology – Kevin Dees; online lecture
2. Biological hierarchy and emergent properties of life
• Life can be organized into a hierarchy from the submicroscopic level to a global scale which includes our entire Earth.
• To help make sense of this, we can explore this hierarchy be examining the next slide
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Biology – Kevin Dees; online lecture
Biology is also represented by a unique scale that is hierarchal in composition
Understanding this “scale” will help to keep things into perspective for you this semester. It will also help to reinforce that all of these levels are interconnected to one another.
Fig. 1-4
The biosphere
Communities
Populations
Organisms
Ecosystems
Organs and organ systems
Cells
Cell
Organelles
Atoms
MoleculesTissues
10 µm
1 µm
50 µm
Biology – Kevin Dees; online lecture
Emergent properties
• Emergent properties are properties that arise as we move “upwards” on this hierarchical scale
• Each level contains properties which are not found at the preceding level.
• It helps to explain life’s complexity:– As you move up the hierarchy, the complexity increases and the
number of possible interactions among components also increases. – The arrangement of these components also can produce the emergent
properties• It is important to note that emergent properties can help us to
understand life’s complexity but they are not limited to living things– Non-living things (abiotic) can also exhibit emergent properties – Can you think of an example?
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Biology – Kevin Dees; online lecture
• These emergent properties can make biology difficult to study.– A useful strategy for understanding complex things is
to reduce them to their simplest parts– This reductionism often does not allow for full study of
a living thing.• If you remove all of the parts of a frog – that frog ceases to
function properly
– You can see why studying the levels of organization in the biological hierarchy is important.
– One new aspect of study is an approach called systems biology where models of interactions among different systems or levels can help in the understanding of life
Biology – Kevin Dees; online lecture
3. Interactions of organisms with their environment
• Think about the interactions between a living thing an its surroundings.
• Life requires inputs and outputs• These inputs (such as food, nutrients, water, sunlight, etc…) come
from the environment. Outputs (such as wastes, sugars, food, heat, etc…) are given up to the environment.
• There are defined pathways in an ecosystem of these inputs and outputs between the various organisms and their abiotic surroundings
• All of these inputs and outputs require energy conversions and as we shall see, the same laws which govern how gas is converted into forward motion of your car, govern how life moves as well.
• The next slide illustrates some of the processes found in an ecosystem– Nutrient cycling through conversion of light energy into sugars usable by
living things– Energy conversions needed to perform the activities of life
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Biology – Kevin Dees; online lecture
Fig. 1-5
Sunlight
Ecosystem
Heat
Heat
Cyclingof
chemicalnutrients
Producers(plants and other photosynthetic
organisms)
Chemical energy
Consumers(such as animals)
Biology – Kevin Dees; online lecture
4. Form=function
• Form fits function• There is a reason why a hammer is shaped
differently than a screwdriver• There is a reason why the leaf of a maple tree is
green, broad, thin and transparent• There is a reason the wing of a chicken is
shaped differently than the wind of s gull• Understanding how something works can reveal
understanding of its structure• Conversely, understanding the structure of
something can reveal its many functions
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Biology – Kevin Dees; online lecture
5. Cells – the basic unit of life• The cell is considered to be the basic unit of life• Cells retain all of the required properties of life• Cells also contain information in the form of genes (units of
inheritance)– Genes are organized on chromosomes which are composed of
deoxyribonucleic acid (DNA)• Cells are prokaryotic (without a true nucleus) or eukaryotic (with a
true nucleus)
Biology – Kevin Dees; online lecture
6. The continuity of life depends on heritable information - DNA
• Deoxyribonucleic Acid• DNA is organized into heritable units called
genes• The entire assemblage of genes in an organism
is known as the genome• We shall learn more about the structure and
function of DNA this semester; for now understand that DNA is a complex molecule which controls the development of an organism as illustrated on the following slide
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Biology – Kevin Dees; online lecture
Fig. 1-9
NucleicontainingDNA
Sperm cell
Egg cell
Fertilized eggwith DNA fromboth parents
Embryo’s cells withcopies of inherited DNA
Offspring with traitsinherited fromboth parents
Biology – Kevin Dees; online lecture
7. Feedback mechanisms regulate biological systems
• There are two basic types of feedback mechanisms– Negative feedback
• most common• accumulation of an end product slows the process
– Positive feedback• Less common• End product speeds up a process
• So if platelets aggregate at the site of a damaged blood vessel to aid in formation of a blood clot, and in the process attract more platelets, is this positive or negative feedback?
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Biology – Kevin Dees; online lecture
So, there is an order to living systems exemplified by these themes
• Order related to ‘scale’ – from molecules to the biosphere
• Energy is required at each step of the way– But there is also a second dimension to life on
earth; biodiversity.• >1.8 million species of life (actual number could be
as high as 200 million!)
• Understanding this tremendous diversity of life requires a system of organization
Biology – Kevin Dees; online lecture
Classification and Taxonomy
• Classification – the grouping of organisms into taxa (categories) based on similarities to other organisms
• Taxonomy – the science of naming and classifying organisms
• Taxa (sing. taxon) – hierarchal groups
DomainKingdomPhylumClassOrderFamilyGenusSpecies
• Binomial nomenclature – species given two part scientific name– Homo sapiens Colinus virginianus
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Biology – Kevin Dees; online lecture
There are three domains
• Bacteria
• Archaea
• Eukarya – composed of organisms with eukaryotic cell structure
Both are composed of organisms with prokaryotic cell structure
Biology – Kevin Dees; online lecture
Fig. 1-14
Species Genus Family Order Class Phylum Kingdom Domain
Ursus americanus(American black bear)
Ursus
Ursidae
Carnivora
Mammalia
Chordata
Animalia
Eukarya
taxa
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Biology – Kevin Dees; online lecture
Biodiversity reflects the unity of life through evolution
• Evolution - descent with modification
• Darwinism – Charles Darwin – Author of On the Origin of Species by
Natural Selection, 1859
• Two main concepts:– Organisms arose from a
succession of ancestors
– Natural selection is the process which drives evolution
Biology – Kevin Dees; online lecture
Natural Selection as a process
Population of organisms
Hereditary variation Overpopulation/competition for resources
Evolution of adaptations in population (traits which enhance survival)
Differences in reproductive success
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Biology – Kevin Dees; online lecture
Biology is also unified as a science
• At the heart of any science is inquiry – the search for information and explanation
• Modern biology relies heavily on the other science disciplines to help make sense of this tremendous complexity
Biology
Chemistry
Mathematics
Geology
Physics
Computer Science
Biology – Kevin Dees; online lecture
Hypotheses and inquiry
• Science is based on fact finding logic
• Tests or experiments are developed to evaluate a hypothesis– A tentative answer to a well-framed question
– Consider it an educated guess based on previously discovered facts
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Biology – Kevin Dees; online lecture
Fig. 1-24
Observations
Question
Hypothesis #1:Dead batteries
Hypothesis #2:Burnt-out bulb
Prediction:Replacing batterieswill fix problem
Prediction:Replacing bulbwill fix problem
Test prediction Test prediction
Test falsifies hypothesis Test does not falsify hypothesis