EXPLORING LIFEChapter 1

WHAT IS THE SCIENCE OF BIOLOGY?

Biology is the study of life Scientific inquiry is key

Asking questions about living organisms and deriving scientifically supported answers

What makes a living organism?Seven characteristics are used by scientists

to define lifeNeither inclusive or exclusiveLIMITATIONS EXIST

LIFE’S COMMON FEATURES

LIMITATIONS EXIST

HIERARCHICAL CLASSIFICATION OF LIFE Biosphere – all regions of Earth the support life Ecosystems – all living and non-living organisms in an area Communities – all species living in one area Populations – individuals of a species in a specific area Multi-celled organisms – each living individual in an area Organ systems – 2+ organs interacting to enhance survival Organs – body part with 2+ tissues performing common tasks Tissues – cells working together for a specialized activity Cells – smallest unit able to demonstrate characteristics of life Organelles – internal compartments of cells for specialized

reactions Molecules – 2 or more atoms bonded together

THE WHOLE IS MORE THAN THE SUM OF ITS PARTS

Emergent properties Novel properties emerge

with each step up the hierarchy (most exclusive to most inclusive)

Reductionism Reducing complex

systems into simpler parts make them more manageable

Limited because life’s properties emerge with increasing complexity

LIVING THINGS MUST ACQUIRE ENERGY AND UNDERGO METABOLISM

Organisms interact with living and non-living components

2 major processes Recycling chemical

elements Flow of energy

Some energy is converted to heat Chemical within

Light to chemical to KE to thermal energy

Energy through Light in & heat out

THE CELL: FORM FITS FUNCTION

Prokaryotic Cell Eukaryotic Cell

Single cells No nucleus or organelles Smaller, less complex

Single- or multi-celled Nucleus and other organelles Larger, more complex

CELLULAR INSTRUCTIONS

All cells have DNA (deoxyribonucleic acid) Direct the development of organisms through protein

production Inherited by offspring from parents through reproduction All of the genetic information inherited constitutes an

organism’s genome Chemical arrangement of determines function

Similar to arrangement of the alphabet into words Contributes to the diversity of life

All life forms basically use the same code Can artificially create instructions when necessary

FEEDBACK MECHANISMS

Most commonExcess end product halts processSugar breakdown to ATP; sufficient levels = stop sugar breakdown

End product speeds up processBlood vessel damage causes platelets to aggregate = signal more platelets

ORGANIZING AND CLASSIFYING LIFE

DifferentKillerPenguinsCrawlOverFrozenGlacialShores

Subheadings exist for all taxons

DOMAINS Bacteria

Prokaryotes Most diverse and wide

spread Most are singled-celled

Archaea Prokaryotes Live in extreme

environments (extremophiles)

Eukarya Eukaryotes Have a nucleus and

organelles

INTRODUCTION TO EVOLUTION

November 1859 Charles Darwin published On the Origin of the Species by Means of Natural Selection

Main points Evidence for evolution

Descent with modification All living organisms evolved from common ancestry

Natural Selection was the mechanism for evolution Pieced together existing information

Individual variation and overproduction of offspring Unequal reproductive success and accumulation of favorable

traits

THE PEPPERED

MO

TH STO

RY

Prior to England’s Industrial Revolution, vast numbers of these moths existed. Light in color to blend with lichen on trees

Afterwards the lichen began to die and the trees became covered in soot.

Light colored individuals began to die off.

Increase in numbers of darker colored moths appeared.

Lighter versions returning with improved environmental standards

http://www.expelledexposed.com/images/kettlewell.jpg

Biston betularia betularia morpha typica Biston betularia betularia morpha carbonaria,

http://en.wikipedia.org/wiki/Peppered_moth

ANTIBIOTIC RESISTANCE

Antibiotics are used to kill bacteria Mutations for antibiotic resistance exist or arise Antibiotic-resistant bacteria survive and reproduce

better than nonresistant Over time, proportion of antibiotic-resistant bacteria

increases

THE SCIENCE OF BIOLOGY

Science stems from natural curiosity about the world around us

Limited by what we can observe and measure Blends two forms of inquiry

Discovery science Verifiable observations and measurements General principles from a large number of specific observations

Hypothesis based science Seeking natural causes and explanations for discovery

observations Proposing and testing a hypothesis

SCIENTIFIC METHOD

LIMITS TO THE SCIENTIFIC METHOD

Can never concretely prove something (No absolute truths)Hypothesis Theory Law

Can’t address supernatural phenomenas Limited by our current knowledge and

understanding Can’t answer moral or ethical questions Limited by our fallibility