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Biology – Kevin Dees; online lecture

Biology Chapter 1

Biology = study of life


Why study life???

• Think about some of the ways that biology can affect your daily life


Why study life???

• Medical technology and understanding our own bodies


Why study life???

• Understanding our role as members of a living ecosystem and biosphere


Why study life???

• Understanding that decisions we make affect our Earth


What defines a living thing??7 properties of living things

1. 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.


Fig. 1-3

Order

Evolutionary adaptation

Responseto theenvironment

ReproductionGrowth anddevelopment

Energyprocessing

Regulation


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.


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

MoleculesTissues

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. – 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


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


Fig. 1-5

Sunlight

Ecosystem

Heat

Heat

Cyclingof

chemicalnutrients

Producers(plants and other photosynthetic

organisms)

Chemical energy

Consumers(such as animals)


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


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. 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


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


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 groupsDomain Kingdom Phylum Class Order Family Genus Species

• 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

BiologyBiology

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 batterieswill fix problem

Prediction:Replacing bulbwill fix problem

Test prediction Test prediction

Test falsifies hypothesis Test does not falsify hypothesis

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