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Biology – Kevin Dees; online lecture
BIOL1406 General Biology I
Chapter 1 Biology = study of life
Biology – Kevin Dees; online lecture
Why study life???
• Think about some of the ways that biology can affect your daily life
Biology – Kevin Dees; online lecture
Why study life???
• Understanding our role as members of a living ecosystem and biosphere
Biology – Kevin Dees; online lecture
Why study life???
• Medical technology and understanding our own bodies
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 things
1. Order 2. Evolutionary adaptation 3. Response to the environment 4. Regulation 5. Energy Processing 6. Reproduction 7. 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.
Biology – Kevin Dees; online lecture
Fig. 1-3
Order
Evolutionary adaptation
Response to the environment
Reproduction Growth and development
Energy processing
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.
– Use flashcards!!
• To aid this understanding, consider the
enormous realm of biology broken down into 7 themes.
1. Evolution – the unifying theme in biology 2. Biological hierarchy and emergent properties of
life 3. Interactions of organisms with their environment 4. Form=function 5. Cells – the basic unit of life 6. DNA - The continuity of life depends on heritable
information 7. Feedback mechanisms regulate biological
systems
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……
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
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
Molecules Tissues
10 µm
1 µm
50 µm
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?
• 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.
– Systems biology approach
3. Interactions of organisms with their environment
• 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
• 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
Fig. 1-5
Sunlight
Ecosystem
Heat
Heat
Cycling of
chemical nutrients
Producers (plants and other photosynthetic
organisms)
Chemical energy
Consumers (such as animals)
4. Form=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
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)
6. DNA - The continuity of life depends on heritable information
• Deoxyribonucleic Acid (DNA) • 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
Fig. 1-9
Nuclei containing DNA
Sperm cell
Egg cell
Fertilized egg with DNA from both parents
Embryo’s cells with copies of inherited DNA
Offspring with traits inherited from both parents
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?
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
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
There are three domains
• Bacteria • Archaea
• Eukarya – composed of organisms with
eukaryotic cell structure
Both are composed of organisms with prokaryotic cell structure
Fig. 1-14
Species Genus Family Order Class Phylum Kingdom Domain
Ursus americanus (American black bear)
Ursus
Ursidae
Carnivora
Mammalia
Chordata
Animalia
Eukarya
taxa
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
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
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
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
Fig. 1-24
Observations
Question
Hypothesis #1: Dead batteries
Hypothesis #2: Burnt-out bulb
Prediction: Replacing batteries will fix problem
Prediction: Replacing bulb will fix problem
Test prediction Test prediction
Test falsifies hypothesis Test does not falsify hypothesis