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Chapter 1

WHAT IS LIFE?

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Life is an emergent

property of the

organization ofmatter!

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Emergence is what happens when the whole issmarter than the sum of its parts

- Steven Johnson

An emergent property is something that cannotbe explained simply by the sum of its parts.

Other Examples:Consciousnessis an emergent property of theorganization of neurons in the rainMemoriesare an emergent property of theorganization of trillions of synaptic connections

For Example:From Tiles to Tubes"lattene#$ tile shape# en#othelial cellsecome organize# into tues--theo#ies capillaries that play a vital role in#elivering %& to every cell in the o#yan# removing C%& waste

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'atter

C

omple(ity$

%rganization$

)otent

ial

Energy

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Cell Sie 'ost cells are 1-1**

m in #iameter

! meter "m# $re%x

!cm & !'()m centi!mm & !'(*m milli!m & !'(+m micro!nm & !'(,m nano! - & !'(!'m angstrom

Units of measurement:

1 meter (m) = 39.37 inches

1 centimeter (cm) = 0.01 m

1 millimeter (mm) = 0.001 m1 micrometer (m) = 0.000001 m

1 nanometer (nm) = 0.000000001 m

frog embryo

most eukaryotic cells

mitochondrion

most prokaryotic cells

virus

proteins

diameter of !"

double heli#

chicken egg

adult human

tallest trees

atoms

$i%e

100 m

10 m

1 m

10 cm

1 cm

visible&ithunaided

humaneye

visible&ith

lightmicroscope

1 mm

100 m

10 m

1 m

100 nm

10 nm

1 nm

0.1 nm

visible&ithco

nventional

electronmic

roscope

visible&ithspecial

electronmicroscope

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The Cell is the smallest unit of Life-

the simplest level of organization of

matter (molecules) that expresses all ofthe characteristics of Life

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Life cannot e #e+ne# y a single characteristicut y many characteristics in comination,

!. Cellular Organiation(Every organism iscompose# of one or more cells

). Metabolism- aility to acuire an# use energy*. Self(egulation/0omeostasis.aility to

maintain a constant internal environment vis avis e(ternal worl#/

1. eproduction2 3ro4th 5 6e7elopment8. esponsi7ity( aility of in#ivi#uals to respon#

to the environment

+.

E7olutionary Adaptation- aility ofpopulations .through generations/ to respon# to

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Energy 0se 'etaolism

'etaolism2 the sum total of iochemical

reactions that acuire use energyinan organism in or#er to maintain thecon#itions of life.

Why do organisms need energy? to comat entropy .the ten#ency towar#s #isor#er/ to uil# new structures to rea3 #own an# repair ol# structures to repro#uce

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How do organisms obtain energy? 4y e(tracting energy from the environment

Producers (Autotrophs) get energ! from non-living sources (ex"plants# algae# photos!nthetic microorganisms)

Consumers ($eterotrophs)get nutrients from other organisms %ecomposersget nutrients from dead organisms-(ex" &ungi# certain

'acteria)

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5he "low of Energy an# the 6ecyclingof 7utrients

&ig" -

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Life on earth is #iverse$ yet similar as aresult of our common ancient

ancestry8

*volution(genetic change +ithin a population)

is the process '! +hich all modern organisms

descended# &ith modification# from pre-existing

life forms"

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:omains

5here are four Eu3aryotic;ing#oms, Animals2 Fungi2

$lants2 5 $rotists

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Three natural processesunderlie e7olution:

3enetic 7ariationamong memers of a

population #ue to #i

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,enetic variation provides the ra+ material for

natural selection-a process that results

in evolutionar! adaptation"'enetic variation arises from alterations in an organisms

genetic code (%.A)# that are transmitted to the next

generation"

Changes in %.A se/uence are called mutations"

0utations arise from a num'er of sources including ultra-

violet (12) radiation# viruses# transposons# and occasionall!#

cop!ing mista3es during cell reproduction"4exual 5eproduction (genetic recom'ination 'et+een t+o

parental genomes) and mutations suppl! the ra+ material

for volutionary "daptation"

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7atural Selection- the meansy whichpopulations ecome genetically a#apte# totheir environment=

5he enhance# survival reproductive successof in#ivi#uals whose inherited traitsettera#apt them to a particular environment

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9#aptation- an inherite# ehavior orphysical characteristic that enales anorganism to survive repro#uce in aparticular environment

%ver time$ a#aptations can mol# the characteristics of

population as the genetic composition of the population

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9ll living things share acommon ancestry -we allevolve# from the same

primor#ial cells!

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E7olution is an ongoingprocess;

The emergence of drugresistant strains ofbacteria is a current

example of e7olutionaryadaptation.

Antibiotic(esistant Mycobacteriumtuberculosis"T

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7atural Selection gives riseto uniue a#aptations to the

environment which eventuallyaccounts for the wi#e variety oflife forms on this planet

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4io#iversity results from the manya#aptive strategies organisms use toacuire energy .foo#/ an# maintain

homeostasis

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9ature is a problem sol7er.

3enetic 7ariationan# 9aturalselectionare the means an# themetho# y which nature solves theprolem of life>s perpetuation in#i

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5he roa#est$ most inclusive group .ta(on/ is

the :omain 9ll life elong to one of three:omains,

arya

5he narrowest an# most speci+c category isspecies

5he Genusan# speciesname constitutes thebinomialor scienti+c name .E(Homo

sapiens; Felis#omesticus=Escherichia coli /

5a(onomy is the #iscipline ofclassifying organisms an# placing them

into groups that reDect theirevolutionary relationships

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umans are omini#s

:omain Eu3arya

;ing#om 9nimalia)hylum Chor#ata

Class 'ammalia

%r#er )rimates

"amily omini#ae

Fenus species Homo sapiens

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