chapter 1 exploring life copyright © 2005 pearson education, inc. publishing as benjamin cummings

Chapter 1Chapter 1

Exploring Life

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

Biology - the scientific study of life

The phenomenon we call life

– We recognize life by what living things do


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HIGHLY ORDERED


EVOLUTIONARY ADAPTATION

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RESPOND TO ENVIRONMENT


REGULATIONLiving things adjust and control cell processesto maintain conditionssuitable for life

HOMEOSTASIS


ENERGY PROCESSING


GROWTH & DEVELOPMENT

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REPRODUCTION

Ecosystems

Communities

Organisms

Populations

Biosphere

A Hierarchy of Biological Organization

8 Cells

6 Organs and organ systems

7 Tissues

10 Molecules

9 Organelles

50 µm

10 µm

1 µm

Atoms

New properties emerge with each step up in hierarchy of biological

orderStructural arrangement and interaction

of parts is important to function!

http://www.animationlibrary.com/sc/101/Bicycling/?page=1http://www.cartoonstock.com/lowres/jmc0030l.jpg

EMERGENT PROPERTIES~ the sum is greater than the parts

http://www.rpi.edu/dept/bcbp/molbiochem/MBWeb/mb1/part2/images/dipeptide.gifhttp://www.biologie.uni-hamburg.de/b-online/library/cat-removed/enzyme_.gif

Individual amino acids don’t catalyze chemical reactions… but proteins do!

11 MAJOR THEMES

that unify

biology

Connect concepts and provide aframework forunderstanding

Unifying Themes in Biologyconnect concepts & provide framework for understanding

•Evolution ~ biology’s core theme; differential reproductive success

•Emergent Properties ~ the sum is greater than the parts

•The Cell ~ basic structure of all organisms

•Heritable Information ~ DNA

•Structure & Function ~ form follows function

•Environmental Interaction ~ organisms are open systems

•Energy and life ~ work requires energy that flows from sunlight to producers to consumers

•Regulation ~ feedback mechanisms

•Unity & Diversity ~ universal genetic code

•Scientific Inquiry ~ observation; testing; repeatability

•Science, Technology & Society ~ functions of our world

Evolution – Evolution, biology’s core theme, explains both the unity and diversity of life. The Darwinian theory of natural selection accounts for adaptation of populations to their environment through the differential reproductive success of varying individuals.

11 MAJOR THEMES that unify biology

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EVOLUTION is the CORE THEME

SLIDE FROM BIOLOGY ZONE by Kim B. Foglia


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Energy and Life – All organisms must perform work, which requires energy. Energy flows from sunlight to producers to consumers.

Producers

(plants and other

photosyntheticorganisms)

Consumers(including animals)

Sunlight

Chemical

energy

Heat

Heat

Ecosystem



Continuity and Change (Unity & Diversity) – All species tend to maintain themselves from generation to generation using the same genetic code. However, there are genetic mechanisms that lead to change over time, or evolution.

•Diversity is a hallmark of life BUT . . .


. . . as diverse as life is, there is also evidence of remarkable unity

Cilia of Paramecium.The cilia of Parameciumpropel the cell throughpond water.

Cross section of cilium, as viewedwith an electron microscope

15 µm

1.0 µm

5 µm

Cilia of windpipe cells. The cells that line the human windpipe are equipped with cilia that help keep the lungs clean by moving a film of debris-trapping mucus upward.


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Structure and Function – Form and function are correlated at all levels of biological organization


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Regulation - Everything from cells to organisms to ecosystems is in a state of dynamic balance that must be controlled by positive or negative feedback mechanisms.

http://www.me-go.net/rtw/images/biggulp.jpg

In feedback regulation

– The output, or product, of a process regulates that very process

http://www.wildtech.org/images/feedback.gif

• In negative feedback

– An accumulation of an end product slows the process that produces that product

B

A

C

D

Enzyme 1

Enzyme 1

Enzyme 2

Enzyme 3

DD D D

D

D

DD

DD

C

B

A Negative feedback

Example: sugar breakdown generates ATP; excess ATP inhibits an enzyme near the beginning of the pathway

• In positive feedback (less common)

– The end product speeds up production WW

X

Y

Z

ZZ

ZZ

Z

Z Z Z

Z Z Z Z

Z

ZZ Z

ZZ

Y

X

Enzyme 4

Enzyme 5

Enzyme 6

Enzyme 4

Enzyme 5

Enzyme 6

Positivefeedback

EXAMPLE: Chemicals released by platelets that accumulate at injury site, attract MORE platelets to the site.


Image from BIOLOGY ZONE by Kim B. Foglia

Interdependence in Nature – No organism

“is an island”.

Organisms are open systems that exchange materials and energy with their surroundings.



Science as a Process - Science is a way of knowing. It can involve a discovery process using inductive reasoning, or it can be a process of hypothesis testing.



Science, Technology, and Society – Scientific research often leads to technological advances that can have a positive and/or negative impacts on society as a whole.



Cells are every organism’s basic units of structure and function.

The TWO main types of cells are: PROKARYOTES (bacteria & archaea) EUKARYOTES

(protists, fungi, plants & animals)


HERITABLE INFORMATION-The continuity of life depends on the inheritance of biological information in the form of DNA molecules. This genetic information in encoded in the nucleotide sequences of the DNA

http://www.biosciences.bham.ac.uk/labs/minchin/tutorials/mddna.gif



EMERGENT PROPERTIES-The living world has a hierarchical organization, extending from molecules to the biosphere. With each step upward in level, system properties emerge as a result of interactions among components at the lower levels.

How can we understand biological systems?

DILEMMA:

Because of EMERGENT PROPERTIESwe can’t fully explain a higher level of order by breaking it into parts, but . . . organisms are too complex to analyze without taking them apart!

TWO STRATEGIES :

REDUCTIONISM SYSTEMS BIOLOGY

REDUCTIONISM

Reducing complex systems to simpler components that are more manageable to study

http://www.hallucinogens.com/lsd/francis-crick.htmlhttp://faculty.uca.edu/~johnc/mbi1440.htm

EXAMPLE:By studying the molecular structure of DNA, James Watson & Francis Crick were able to infer how this

molecule could serve as thechemical basis of inheritance

http://www.hallucinogens.com/lsd/index.html

The study of DNA structure has led tofurther study of heredity, such as the Human Genome Project


https://www.genome-sci.jp/english/images/zu2.gif

SYSTEMS BIOLOGY tries to understand how all parts are functionally integrated

Systems biology

• Seeks to create models

– Diagrams

– Graphs

– 3-D objects

– Computer programs

– Mathematical equations

• models of ideas, structures, and processes help us understand scientific phenomena and make predictions

To lungs To body

Rightartium

Rightartium

Rightventricle

Right ventricle

Fromlungs

Frombody


Concept 1.5: Biologists use various forms of inquiry to explore life

• At the heart of science is inquiry

– A search for information and explanation, often focusing on specific questions

• Biology blends two main processes of scientific inquiry

– Discovery science

– Hypothesis-based science

Discovery science

– Describes natural structures and processes as accurately as possible through careful observation and analysis of data


Types of Data

• DATA are recorded observations

Can be:

– Quantitative involves analysis of numerical data(measure, count, etc)

– Qualitative involves analysis of data such as words (e.g., from interviews), pictures (e.g., video), or objects (e.g., an artifact).

http://www.3g.co.uk/PR/August2006/Casio.jpghttp://www.bio-world.com/images/042135.jpghttp://plus.maths.org/latestnews/may-aug05/millionaire/measure.jpg


Induction in Discovery Science• In inductive reasoning

– Scientists derive generalizations based on a large number of specific observations

EX: “The sun always rises in the East.”

“All living things are made of cells.”

http://virtualbible.net/literature/firstprinciples/Inductive.jpg

Hypothesis-Based Science (Deductive reasoning)

• Inquiry that asks specific questions

– Usually involves the proposing and testing of hypothetical explanations, or hypotheses

• Hypothesis

– Is a tentative answer to a well-framed question, an explanation on trial

– Makes predictions that can be tested

– Usually expressed as an:

If…., then …. statement

Deduction: The “If…then” Logic of Hypothesis-Based Science

• In deductive reasoning

– The logic flows from the general to the specific

• If a hypothesis is correct

– Then we can expect a particular outcome

• We all use hypotheses in solving everyday problems

Observations

Questions

Hypothesis # 1:Dead batteries

Hypothesis # 2:Burnt-out bulb

Prediction:Replacing batterieswill fix problem

Prediction:Replacing bulbwill fix problem

Test prediction

Test does not falsify hypothesis

Test prediction

Test falsifies hypothesis


A Closer Look at Hypotheses in Scientific Inquiry

• A scientific hypothesis must have two important qualities

– It must be testable

– It must be falsifiable

An hypothesis can only be proven to be FALSE, never proven to be TRUE!

The Myth of the Scientific Method• The scientific method

– is an idealized process of inquiry

• There is not “ONE” methodMay design experiment, then backtrack when realize need more observations

May redirect research if realize been“barking up wrong tree”

Hind sight is 20/20

EXPERIMENTAL DESIGN• A CONTROLLED experiment must see the

effect of ONE VARIABLE at a time

• Hard to do in field/lab

• Don’t eliminate unwanted variables…. cancel their effects by using a CONTROL GROUP

• Must be repeated (at least 3 X)

• Can’t ignore or rule out data which do not support the hypothesis

VARIABLESA variable is any factor, trait, or condition that

can exist in differing amounts or types.

– independent variable is the one that is changed by the scientist.

– dependent variable is observed to see how it responds to the change made to the independent variable. The new value of the dependent variable is caused by and depends on the value of the independent variable.

– controlled variables. are quantities that a scientist wants to remain constant, and must be observed as carefully as the dependent variables.

HYPOTHESIS

Independent variable(What I change)

Dependent variable(What I observe)

Controlled variables(What I keep the same)

If fertilizer is added, then a plant will grow bigger.

Measure amount of fertilizer (grams)

•Growth of the plant measured by its height

•Growth of the plant measured by the number of leaves

•There are other ways to measure growth

•Same size pot

•Same type of plant

•Same type and amount of soil

•Same amount of water and light

•Make measurements of growth for each plant at the same time

The many variables above can each change how fast a plant grows, so to insure a fair test of the fertilizer, each of them must be kept the same for every pot.

“IT’S JUST A THEORY”In every day conversation, a theory often implies an untested guess.

In science, the word “theory” means something different than in common usage.

• Broader than a hypothesis• General enough to spin off more hypotheses• Supported by a massive body of evidence

“IT’S JUST A THEORY”

A theory is a well supported, testable explanation of natural phenomena.

EX: Cell Theory, Gravitational theory, or Atomic theory

http://www.avgoe.de/StarChild/DOCS/STARCH00/questions/apple_falling.gif http://sixthsense.osfc.ac.uk/chemistry/atomic_structure2/atom.gif

TECHNOLOGY applies scientific knowledge for a specific purpose


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