01 Intro to the science of life(1)

© 2013 Pearson Education, Inc.Lectures by Edward J. Zalisko

PowerPoint® Lectures forCampbell Essential Biology, Fifth Edition, andCampbell Essential Biology with Physiology, Fourth Edition – Eric J. Simon, Jean L. Dickey, and Jane B. Reece

Chapter 1Chapter 1Introduction: Biology Today

• Biology is the scientific study of life

• The study of biology encompasses a wide scale of size and a huge variety of life, both past and present

THE SCOPE OF LIFE The Properties of Life

© 2013 Pearson Education, Inc.

• Biologists explore life at levels ranging from the biosphere to the molecules that make up cells

Life at Its Many Levels


Figure 1.1a

(a) Order (b) Regulation

(d) Energy processing(c) Growth and development

Figure 1.1b

(f) Reproduction

(g) Evolution(e) Response to the environment

Figure 1.2-3

Organisms5

12

3

4

7

6

8

109

BiosphereEcosystems

Populations

Communities

Organ Systemsand Organs

Tissues

Cells

OrganellesMolecules and Atoms

NucleusAtom

Ecosystems

• Each organism interacts continuously with its environment

– Organisms interact continuously with the living and nonliving factors in the environment

– All the living organisms in a specific area, along with all of the nonliving factors with which they interact, form an ecosystem


Ecosystems

• The dynamics of any ecosystem depend on two main processes:

– Recycling of chemical nutrients

– Flow of energy

• Within ecosystems

– Nutrients are recycled but energy flows through


Figure 1.3

ECOSYSTEMInflowof lightenergy

Outflowof heatenergy

Producers(plants and otherphotosyntheticorganisms)

Chemicalenergy(food)

Cyclingof

nutrients

Consumers(animals)

Decomposers(in soil)

Cell Theory

• The cell is the level at which the properties of life emerge

• All organisms are composed of cells

• Cells are the lowest level of structure that can perform all activities required for life

– In other words, the smallest living organism is composed of at least one cell

• Cells are the subunits that make up multicellular organisms such as humans and trees


• Cells share many characteristics

– All cells are enclosed by a membrane that regulates the passage of materials between the cell and its surroundings

– All cells have ribosomes where proteins are made

– Every cell uses DNA as its genetic information

Cells


• We can distinguish two major types of cells:

1. The prokaryotic cell is

– Simpler and usually smaller because it lacks a nucleus and organelles

– Characteristic of bacteria and archaea

2. The eukaryotic cell is

– Subdivided by internal membranes into different functional compartments called organelles, the largest of which is the nucleus

– Found in protists, fungi, plants, and animals

Prokaryotes versus Eukaryotes


Figure 1.4

Nucleoidregion Nucleus

Organelles

Prokaryotic cell (bacterium)

Smaller

Simpler structure

DNA concentrated innucleoid region, which isnot enclosed by membrane

Lacks most organelles

•••

•

••

•

•

Larger

More complexstructure

Nucleus enclosedby membrane

Contains many types of organelles

Eukaryotic cell

Co

lori

zed

TE

M

• All cells use DNA as the chemical material of genes, the units of inheritance that transmit information from parents to offspring

• The chemical language of DNA

– Is common to all organisms

– Consists of just four molecular building blocks with names that are abbreviated as A, G, C, T

– A is for adenine, G for guanine, C for cytosine, and T for thymine

Cells and Their DNA


Figure 1.5

A DNA molecule

The fourchemicalbuildingblocks of DNA

• The entire “book” of genetic instructions that an organism inherits is called its genome

• The nucleus of each human cell packs two genomes, one from mom and one from dad, that are about 3 billion base pairs long

Cells and Their DNA


Life in Its Diverse Forms

• Diversity is a hallmark of life

– The diversity of known life includes about 1.8 million species that biologists have identified and named

– Estimates of the total number of species range from 10 million to over 100 million


Figure 1.7

Grouping Species: The Basic Concept

• Biodiversity can be beautiful but overwhelming

• Categorizing life into groups helps us deal with this complexity

• Taxonomy is the branch of biology that names and classifies species

– It formalizes the hierarchical ordering of organisms into broader and broader groups


The Three Domains of Life

• The three domains of life are

– Bacteria

– Archaea

– Eukarya

• Bacteria and Archaea have prokaryotic cells

• Eukarya have eukaryotic cells


• Eukarya include

– Kingdom Plantae

– Kingdom Fungi

– Kingdom Animalia

– Protists (multiple kingdoms)

• Most plants, fungi, and animals are multicellular

• Protists are generally single-celled, but large multicellular seaweeds and kelps (aka algae) are also placed in this group



• Bacteria and Archaea are all single-cell prokaryotic organisms

• The Eukarya are distinguished by how they obtain food

– Plants produce their own sugars and other foods by photosynthesis

– Fungi are mostly decomposers, digesting dead organisms

– Animals obtain food by ingesting (eating) and digesting other organisms

– The protists don’t fit neatly into this scheme because seaweeds and protozoans are very different



Figure 1.8

Protists (multiple kingdoms)

Kingdom Animalia

Kingdom Fungi

Kingdom Plantae

DO

MA

IN E

UK

AR

YA

DO

MA

IN

AR

CH

AE

A D

OM

AIN

B

AC

TE

RIA

EVOLUTION: BIOLOGY’S UNIFYING THEME

• The history of life is a saga of a constantly changing Earth billions of years old

– Fossils and other evidence document this history


Figure 1.9

• Life evolves

– Each species can be seen as one twig of a branching tree of life extending back in time through ancestral species more and more remote

– Species that are very similar, such as the brown bear and polar bear, share a more recent common ancestor

EVOLUTION: BIOLOGY’S UNIFYING THEME


Figure 1.10

Millions of years ago

Giant panda

Common ancestor ofpolar bear and brown bear

2025 101530 5

Common ancestor of all modern bears

Ancestral bear

Spectacled bear

Sloth bear

Sun bear

American black bear

Asiatic black bear

Polar bear

Brown bear

The Darwinian View of Life

• The evolutionary view of life came into focus in 1859 when Charles Darwin published On the Origin of Species by Means of Natural Selection


• Darwin’s book developed two main points:

1. Species living today descended from a succession of ancestral species in what Darwin called “descent with modification,” capturing the duality of life’s

– unity (descent) and

– diversity (modification)

2. Natural selection is the mechanism for descent with modification (evolution)

The Darwinian View of Life


Figure 1.11

Observing Artificial Selection

• Artificial selection is the selective breeding of domesticated plants and animals by humans

• In artificial selection, humans do the selecting instead of the environment


Figure 1.13a

(a) Vegetables descendedfrom wild mustard

Wild mustard

Cabbagefrom end buds

Cauliflowerfrom flowerclusters

Broccoli fromflowers and stems

Kale from leaves

Kohlrabifrom stems

Brusselssprouts from side buds

Figure 1.13b

(b) Domesticated dogsdescended from wolves

Domesticated dogsGray wolves

THE PROCESS OF SCIENCE

• There are two main scientific approaches:

– Discovery science is mostly about describing nature through verifiable observations and measurements

– What we see through discovery science causes us to ask questions and seek explanations

– This results in hypothesis-driven science where we try to explain why something is the way it is

– We make an educated guess called a hypothesis and then set out to test it through experimentation


Figure 1.14a

Figure 1.14b

• Once a hypothesis is formed, an investigator can use logic to test it

– A hypothesis is tested by performing an experiment to see whether results are as predicted

– This deductive reasoning takes the form of “If…then” logic

Hypothesis-Driven Science


Figure 1.15-3

Experimentdoes notsupport

hypothesis.

Experimentsupports

hypothesis;make morepredictions

and test.

ObservationThe remote

doesn’twork.

HypothesisThe

batteriesare dead.

QuestionWhat’swrong?

ExperimentReplace

batteries.

PredictionWith new

batteries, itwill work.

Revise.

Theories in Science

• What is a scientific theory, and how is it different from a hypothesis?

– A scientific theory is much broader in scope than a hypothesis

– Theories only become widely accepted in science if they are supported by an accumulation of extensive and varied evidence


The Culture of Science

• Scientists build on what has been learned from earlier research

– They pay close attention to contemporary scientists working on the same problem

• Cooperation and competition characterize the scientific culture

– Scientists check the conclusions of others by attempting to repeat experiments

– Scientists are generally skeptics


• Science has three key features that distinguish it from other forms of inquiry

– Science depends on observations and measurements that others can verify

– It requires that ideas (hypotheses) are testable by experiments that others can repeat

– It also requires that hypotheses be falsifiable, i.e., there must be some circumstance that you could think of where the hypothesis could be proven false

The Culture of Science


– Technology has improved our standard of living in many ways, but it is a double-edged sword

– Technology that keeps people healthier has enabled the human population to double to 7 billion in just the past 40 years

– The environmental consequences of this population growth may be devastating

Science, Technology, and Society


01 Intro to the science of life(1)

Documents

Transcript of 01 Intro to the science of life(1)