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Title: Chapter 1 A View of Life


1
Chapter 1 A View of Life
2
A View of Life H1N1
3
H1N1
  • H1N1 influenza attracted global attention in
    April 2009, when more than 200 countries around
    the world reported confirmed cases within a few
    months
  • Pandemics such as H1N1 affect many aspects of
    life, including global economy, travel, tourism,
    and education

4
Biology
  • Biologists are making new discoveries that affect
    every aspect of our lives, including health,
    food, safety, relationships with humans and other
    organisms, and the environment of our planet
  • biology
  • The science of life

5
1.1 THREE BASIC THEMES
  • LEARNING OBJECTIVE
  • Describe three basic themes of biology

6
Three Basic Themes of Biology
  • Evolution
  • Evolution results in populations changing over
    time
  • Explains how the ancestry of organisms can be
    traced back to earlier forms of life
  • Information transfer
  • Information must be transmitted within cells,
    among cells, among organisms, and from one
    generation to the next
  • Energy transfer
  • Life requires continuous input of energy from the
    sun

7
KEY CONCEPTS 1.1
  • Basic themes of biology include evolution,
    information transfer, and energy transfer

8
1.2 CHARACTERISTICS OF LIFE
  • LEARNING OBJECTIVE
  • Distinguish between living and nonliving things
    by describing the features that characterize
    living organisms

9
Organisms are Composed of Cells
  • cell theory
  • A fundamental unifying concept of biology
  • Every living organism is composed of one or more
    cells
  • New cells are formed only by division of
    previously existing cells
  • Simple, unicellular life-forms consist of a
    single cell
  • Complex, multicellular organisms depend on
    coordinated functions of cells that are organized
    to form tissues, organs, and organ systems

10
Unicellular and Multicellular Life-Forms
  • Paramecium
  • African buffalo, plants

(a) Unicellular organisms consist of one
intricate cell that performs all the functions
essential to life. Ciliates, such as this
Paramecium , move about by beating their hairlike
cilia.
(b) Multicellular organisms, such as this African
buffalo (Syncerus caffer) and the plants on which
it grazes, may consist of billions of cells
specialized to perform specific functions.
11
Cell Structure
  • A plasma membrane protects the cell and regulates
    passage of materials between the cell and its
    environment
  • Specialized molecules usually deoxyribonucleic
    acid (DNA) contain genetic instructions and
    transmit genetic information
  • Internal structures (organelles) are specialized
    to perform specific functions

12
Two Types of Cells
  • prokaryotic cells
  • Exclusive to bacteria and archaea
  • Structurally simple they do not have a nucleus
    or other membrane-enclosed organelles
  • eukaryotic cells
  • Typically contain a variety of organelles
    enclosed by membranes, including a nucleus, which
    houses DNA

13
Organisms Grow and Develop
  • Biological growth involves an increase in size of
    individual cells of an organism, in number of
    cells, or in both
  • Some organisms (e.g. trees) grow throughout their
    lives
  • Many animals have a growth period that ends at
    adult size
  • Development includes all changes during an
    organisms life
  • Example A human develops from a fertilized egg
    into a multicellular organism with structures and
    body form adapted to specific functions

14
Organisms Regulate Their Metabolic Processes
  • Metabolism includes all chemical activities that
    take place in an organism, including chemical
    reactions essential to nutrition, growth and
    repair, and conversion of energy
  • Homeostatic mechanisms carefully regulate
    metabolic processes to maintain an appropriate,
    balanced internal environment (homeostasis)
  • Example Regulation of blood sugar (glucose)

15
Organisms Respond to Stimuli
  • Organisms respond to physical or chemical changes
    in their external or internal environment
    (stimuli)
  • Responses typically involve movement
  • Unicellular organisms may move by slow oozing of
    the cell (amoeboid movement), by beating tiny,
    hairlike extensions of the cell (cilia) or longer
    structures (flagella)

16
Flagella
  • Bacteria equipped with flagella for locomotion
  • Helicobacter pylori have been linked to stomach
    ulcers

17
Organisms Respond to Stimuli (cont.)
  • Most animals move by contracting muscles
  • Complex animals have highly specialized cells
    that respond to specific types of stimuli, such
    as light
  • Plants respond to light, gravity, water, touch,
    and other stimuli

18
Plants Respond to Stimuli
Fig. 1-3a, p. 4
19
Organisms Reproduce
  • asexual reproduction
  • Offspring have the same genes as the single
    parent
  • Variation occurs only by mutations
  • sexual reproduction
  • Offspring are produced by fusion of egg and sperm
  • Genes are typically contributed by two parents

20
Asexual and Sexual Reproduction
Fig. 1-4, p. 5
21
Populations Evolve and Become Adapted to the
Environment
  • As populations evolve, they become adapted to
    their environment
  • Adaptations may be structural, physiological,
    biochemical, behavioral, or a combination of all
    four
  • adaptations
  • Inherited characteristics that enhance an
    organisms ability to survive in a particular
    environment

22
Adaptations
  • Burchells zebras (1) are behaviorally adapted to
    watch for predators, (2) have stripes for visual
    protection against predators, (3) have stomachs
    adapted to coarse grass (enlarged cecum)

Fig. 1-5, p. 5
23
KEY CONCEPTS 1.2
  • Characteristics of life include
  • cellular structure
  • growth and development
  • self-regulated metabolism
  • response to stimuli
  • reproduction

24
1.3 LEVELS OF BIOLOGICAL ORGANIZATION
  • LEARNING OBJECTIVE
  • Construct a hierarchy of biological organization,
    including levels characteristic of individual
    organisms and levels characteristic of ecological
    systems

25
Organisms Have Several Levels of Organization
  • Atoms and molecules form cells
  • Cells associate to form tissues
  • Tissues organize into functional structures
    (organs)
  • In animals, major biological functions are
    performed by a coordinated group of tissues and
    organs (organ system)
  • Organ systems function together to make up a
    complex, multicellular organism

26
Several Levels of Ecological Organization Can Be
Identified
  • population
  • All members of one species living in the same
    geographic area at the same time
  • community
  • Populations of various types of organisms living
    and interacting with one another in a particular
    area
  • ecosystem
  • A community together with its nonliving
    environment

27
Levels of Organization (cont.)
  • All of Earths ecosystems together are known as
    the biosphere
  • The study of how organisms relate to one another
    and to their physical environment is called
    ecology

28
Hierarchy of Biological Organization
29
Stepped Art
Fig. 1-6, p. 7
30
KEY CONCEPTS 1.3
  • Biological organization includes chemical, cell,
    tissue, organ, organ system, and organism levels
  • Ecological organization includes population,
    community, ecosystem, and biosphere levels

31
1.4 INFORMATION TRANSFER
  • LEARNING OBJECTIVE
  • Summarize the importance of information transfer
    within and between living systems, giving
    specific examples

32
DNA Transmits Information from One Generation to
the Next
  • A DNA molecule consists of two chains of atoms
    twisted into a helix
  • Each chain is made up of a sequence of chemical
    subunits called nucleotides

33
DNA
  • DNA is the hereditary material that transmits
    information from one generation to the next
  • The sequence of nucleotides makes up the genetic
    code

Fig. 1-7, p. 8
34
Information is Transmitted by Chemical and
Electrical Signals
  • Genes control development and function of every
    organism
  • The DNA that makes up genes contains instructions
    for making all the proteins required by the
    organism
  • proteins
  • Large molecules important in determining the
    structure and function of cells and tissues

35
Communication Between Cells
  • Cells use proteins and other molecules to
    communicate with one another
  • Hormones and other chemical messengers signal
    cells in distant organs to secrete a required
    substance or change a metabolic activity
  • Animals nervous systems transmit information by
    electrical impulses and chemical compounds
    (neurotransmitters)

36
KEY CONCEPTS 1.4
  • Information transfer includes
  • DNA transfer of information from one generation
    to the next
  • Chemical and electrical signals within and among
    the cells of every organism
  • Chemicals, visual displays, and sounds that allow
    organisms to communicate with one another and to
    interact with their environment

37
1.5 THE ENERGY OF LIFE
  • LEARNING OBJECTIVE
  • Summarize the flow of energy through ecosystems
    and contrast the roles of producers, consumers,
    and decomposers

38
Energy and Metabolism
  • Life depends on continuous input of energy from
    the sun
  • Whenever energy is used to perform biological
    work, some is converted to heat and dispersed
    into the environment
  • All energy transformations and chemical processes
    within an organism are referred to as its
    metabolism

39
Cellular Respiration
  • All cells require nutrients that contain energy
  • During cellular respiration, cells capture energy
    released by nutrient molecules through a series
    of carefully regulated chemical reactions
  • Cells use this energy to do work, including
    synthesis of new cell components

40
Energy in Ecosystems
  • Ecosystems also depend on continuous energy input
  • Ecosystems include three types of organisms
    (producers, consumers, decomposers) and their
    physical environment
  • There is a one-way flow of energy through
    ecosystems
  • Organisms can neither create energy nor use it
    with complete efficiency
  • During every energy transaction, some energy
    disperses into the environment as heat

41
The Producers
  • Plants, algae, and some bacteria are producers
    (autotrophs) that produce their own food from
    simple raw materials
  • Most producers use sunlight as energy for
    photosynthesis, which transforms light energy
    into chemical energy stored in chemical bonds of
    food molecules
  • Photosynthesis synthesizes food molecules such as
    glucose (sugar) from carbon dioxide and water,
    and releases oxygen
  • carbon dioxide water light ? glucose oxygen

42
The Consumers
  • Animals are consumers (heterotrophs) that obtain
    energy by breaking down food molecules produced
    in photosynthesis
  • Primary consumers eat producers secondary
    consumers eat primary consumers
  • Chemical bonds are broken in the process of
    cellular respiration, and stored energy is made
    available
  • glucose oxygen ? carbon dioxide water energy

43
The Decomposers
  • Most bacteria and fungi are decomposers,
    heterotrophs that obtain nutrients by breaking
    down nonliving organic material such as wastes,
    dead leaves and branches, and bodies of dead
    organisms
  • In the process of obtaining energy, decomposers
    make the components of these materials available
    for reuse

44
Energy Flow Within and Among Organisms
45
Light energy
Photosynthesis captures light energy
Oxygen
Energy stored in glucose and other nutrients
Carbon dioxide and water
Oxygen
Energy
Cellular respiration releases energy stored in
glucose molecules
Synthesis of needed molecules and structures
Other Life Activities Homeostasis Growth
and development Reproduction Movement of
materials in and out of cells Movement of body
Fig. 1-8, p. 9
46
Energy Flow Through the Biosphere
  • During every energy transaction, some energy is
    lost to biological systems, dispersing into the
    environment as heat

47
Light energy
Heat
Heat
Food
Heat
Primary consumer (caterpillar)
Secondary consumer (robin)
Heat
Producer (plant)
Dead bodies
Plant litter, wastes
Decomposers (bacteria, fungi)
Soil
Fig. 1-9, p. 10
48
1.6 THE BASIC CONCEPTS OF BIOLOGY
  • LEARNING OBJECTIVES
  • Demonstrate the binomial system of nomenclature
    using specific examples, and classify an organism
    in its domain, kingdom, phylum, class, order,
    family, genus, and species
  • Identify the three domains and the kingdoms of
    living organisms, and give examples of organisms
    in each group
  • Give a brief overview of the scientific theory of
    evolution and explain why it is the principal
    unifying concept in biology
  • Apply the theory of natural selection to any
    given adaptation and suggest a logical
    explanation of how it may have evolved

49
Evolution
  • evolution
  • Process by which populations of organisms change
    over time
  • Involves passing genes for new traits from one
    generation to another, leading to differences in
    populations

50
Biologists Use a Binomial System for Naming
Organisms
  • Systematics is the field of biology that studies
    the diversity of organisms and their
    relationships
  • Taxonomy, is the science of naming and
    classifying organisms

51
Binomial System
  • The binomial system of nomenclature is used to
    name each species, it is called such because each
    species has a two-part name
  • The first part of the name is the genus
  • The second part, the specific epithet, designates
    a particular species in that genus
  • Example The domestic dog, Canis familiaris (or
    C. familiaris), and timber wolf, Canis lupus (C.
    lupus), are in the same genus

52
Species and Genus
  • A species is a group of organisms with similar
    structure, function, and behavior
  • Closely related species are grouped into a genus
    (genera)

53
Taxonomic Classification is Hierarchical
  • Related genera are grouped in a family
  • Families are grouped into orders, orders into
    classes, and classes into phyla (phylum)
  • Phyla are assigned to kingdoms, and kingdoms are
    grouped in domains
  • Each level is a taxon (taxa)

54
Classification of the Cat, Human, and White Oak
Tree
Table 1-1, p. 11
55
DOMAIN
Eukarya
KINGDOM
Animalia
PHYLUM
Chordata
CLASS
Mammalia
ORDER
Primates
FAMILY
Pongidae
GENUS
Pan
SPECIES
Pan troglodytes
Fig. 1-10, p. 12
56
Three Domains
  • Most biologists assign organisms to three domains
    and several kingdoms
  • There are two domains of organisms with
    prokaryotic cells (prokaryotes) Bacteria and
    Archaea
  • Kingdom Archaea corresponds to domain Archaea
  • Kingdom Bacteria corresponds to domain Bacteria
  • All other organisms belong to the domain Eukarya

57
Domain Eukarya
  • Organisms with eukaryotic cells (eukaryotes) are
    classified in domain Eukarya
  • Protists (including five supergroups) are
    unicellular, colonial, or simple multicellular
    eukaryotic organisms
  • Kingdom Plantae (plants) are complex
    multicellular organisms adapted for
    photosynthesis
  • Kingdom Fungi (yeasts, mildews, molds, and
    mushrooms) do not photosynthesize they obtain
    nutrients by secreting digestive enzymes into
    food and absorbing it
  • Kingdom Animalia includes complex multicellular
    organisms that obtain nutrition by eating other
    organisms

58
Three Domains of Life
59
Stepped Art
Fig. 1-11, p. 13
60
Species Adapt in Response to Changes in Their
Environment
  • Every organism is the product of numerous
    interactions between environmental conditions and
    genes inherited from its ancestors
  • If all individuals of a species were exactly
    alike, any change in the environment might be
    disastrous to all, and the species would become
    extinct
  • Adaptations to changes in the environment occur
    as a result of evolutionary processes that take
    place over time and involve many generations

61
Natural Selection An Important Evolutionary
Mechanism
  • Charles Darwin and Alfred Wallace proposed a
    theory of evolution and suggested a mechanism
    natural selection
  • Darwins book, On the Origin of Species by
    Natural Selection (1859), supported his
    hypothesis that present forms of life descended,
    with modifications, from previously existing forms

62
Darwins Four Observations
  • Darwin based his theory on four observations
  • Individual members of a species vary from one
    another
  • Organisms produce many more offspring than will
    survive to reproduce
  • More individuals are produced than the
    environment can support, so organisms must
    compete for necessary, but limited, resources
    also, some are killed by predators, disease
    organisms, or unfavorable natural conditions
  • Individuals with characteristics that enable them
    to withstand prevailing environmental conditions
    and challenges are more likely to survive and
    reproduce

63
Adaptation
  • Survivors that reproduce pass their adaptations
    for survival on to their offspring
  • The best-adapted individuals leave, on average,
    more offspring than other individuals
    (differential reproduction)
  • The environment selects the best-adapted
    organisms of a population for survival
  • Adaptation involves changes in populations, not
    individuals

64
Mutation and Variation
  • Most variations among individuals result from
    different varieties of genes that code for each
    characteristic
  • The ultimate source of these variations is random
    mutations (chemical or physical changes in DNA
    that can be inherited)
  • Mutations modify genes and provide the raw
    material for evolution

65
Populations Evolve Due to Selective Pressures
from Environmental Changes
  • All genes in a population make up its gene pool
    (a reservoir of genetic variation)
  • Natural selection acts on individuals within a
    population
  • Selection favors individuals with genes for
    traits that allow them to respond effectively to
    environmental pressure these individuals are
    most likely to survive and produce offspring
  • Over time, members of a population become better
    adapted to their environment and less like their
    ancestors new species may evolve

66
1.7 THE PROCESS OF SCIENCE
  • LEARNING OBJECTIVES
  • Design a study to test a given hypothesis, using
    the procedure and terminology of the scientific
    method
  • Compare the reductionist and systems approaches
    to biological research

67
Process of Science
  • Science is a way of thinking, and a method of
    investigating, the natural world in a systematic
    manner
  • The process of science is investigative, dynamic,
    and often controversial observations,
    questions, and experimental design depend on the
    creativity of the individual scientist
  • Science is influenced by cultural, social,
    historical, and technological contexts, so the
    process changes over time

68
Scientific Method
  • The scientific method involves a series of
    ordered steps
  • Make careful observations
  • Ask critical questions and develop hypotheses
  • Make predictions that can be tested by making
    further observations or by performing experiments
  • Gather information (data) that can be analyzed
  • Interpret the results of experiments and draw
    conclusions

69
Careful Observations and Chance
  • 1928 Alexander Fleming did not set out to
    discover penicillin
  • When a blue mold invaded one of his bacterial
    cultures, he noticed that the contaminated area
    was surrounded by a zone where bacterial colonies
    did not grow
  • Fleming benefited from chance, but his mind was
    prepared to make observations and formulate
    critical questions

70
A Hypothesis is a Testable Statement
  • A hypothesis is a tentative explanation for
    observations or phenomena
  • A good hypothesis has three characteristics
  • It is reasonably consistent with well-established
    facts
  • It is capable of being tested and test results
    should be repeatable by independent observers
  • It is falsifiable (can be proven false)

71
A Falsifiable Hypothesis Can Be Tested
  • A well-stated hypothesis can be tested
  • If no evidence is found to support it, the
    hypothesis is rejected
  • The hypothesis can be shown to be false
  • A hypothesis can be supported by data, but it
    cant really be proven true

72
Models Are Important in Developing and Testing
Hypotheses
  • Hypotheses may be derived from models that
    scientists develop to provide a comprehensive
    explanation for a large number of observations
  • Examples Model of the structure of DNA model of
    the structure of the plasma membrane
  • The best design for an experiment can sometimes
    be established by performing computer simulations

73
Many Predictions can be Tested by Experiment
  • Scientists make predictions (deductive, logical
    consequences of a hypothesis) that can be tested
    by experiments
  • Some predictions can be tested by controlled
    experiments in which an experimental group
    differs from a control group only with respect to
    the variable being studied

74
Key Experiment
  • Scientists observed that the nucleus was the most
    prominent part of the cell, and predicted that
    cells would be adversely affected if they lost
    their nuclei
  • Experiment
  • Experimental group Nucleus was removed
  • Control group A microloop was inserted into the
    cell to simulate removal, but the nucleus was
    left inside
  • Result The control group lived the experimental
    group died

75
Key Experiment (cont.)
76
Amoeba dies
(a) Experimental group. When its nucleus is
surgically removed with a microloop, the amoeba
dies.
Fig. 1-17a, p. 18
77
Amoeba lives
(b) Control group. A control amoeba subjected to
similar surgical procedures (including insertion
of a microloop), but without actual removal of
the nucleus, does not die.
Fig. 1-17b, p. 18
78
Researchers Must Avoid Bias
  • In scientific studies, researchers must try to
    avoid bias or preconceived ideas of what should
    happen
  • In a double-blind study neither patient nor
    physician knows who gets an experimental drug and
    who gets a placebo
  • Not all experiments can be so neatly designed
    it is often difficult to establish appropriate
    controls

79
Scientists Interpret Results and Make Conclusions
  • Scientists gather data in an experiment,
    interpret results, and draw conclusions from them
  • In the amoeba experiment, investigators concluded
    that data supported the hypothesis that the
    nucleus is essential for the survival of the cell
  • Results that falsify a hypothesis also may be
    valuable and may lead to new hypotheses

80
Sampling Error and Repeatability
  • One reason for inaccurate conclusions is sampling
    error
  • Not all cases can be observed or tested
  • If the sample is too small, it may not be
    representative because of random factors
  • Scientists try to state that any specific
    conclusion has a certain statistical probability
    of being correct
  • Experiments must be repeatable by other scientists

81
Statistical Probability
Fig. 1-19, p. 21
82
Curtain
Single selection
Marbles
produces
Assumption
100 blue
Actual ratio 20 blue 80 white
(a) Taking a single selection can result in
sampling error. If the only marble selected is
blue, we might assume all the marbles are blue.
Fig. 1-19a, p. 21
83
Curtain
Multiple selections
Marbles
produce
Assumption
30 blue 70 white
Actual ratio 20 blue 80 white
(b) The greater the number of selections we take
of an unknown, the more likely we can make valid
assumptions about it.
Fig. 1-19b, p. 21
84
A Theory is Supported by Tested Hypotheses
  • A scientific theory is an integrated explanation
    of some aspect of the natural world, based on a
    number of hypotheses, each supported by
    consistent results from many observations or
    experiments
  • By showing relationships among classes of facts,
    a scientific theory clarifies our understanding
    of the natural world

85
Paradigm Shifts Allow New Discoveries
  • A paradigm is a set of assumptions or concepts
    that constitute a way of thinking about reality
  • As new facts are discovered, biologists have to
    make paradigm shifts they change their view of
    reality to accommodate new knowledge
  • Systems biology is a field of biology that builds
    on information provided and integrates the
    different levels of information

86
Science Has Ethical Dimensions
  • Honesty is particularly important in science
    science tends to correct itself through
    consistent use of the scientific process
  • Scientists face many societal and political
    issues surrounding areas such as genetic
    research, stem cell research, cloning, and human
    and animal experimentation
  • Human genome research raises ethical concerns
    about the privacy of genetic information and the
    ethical, legal, and social implications of its
    findings

87
KEY CONCEPTS 1.7
  • Biologists ask questions, develop hypotheses,
    make predictions, and collect data by careful
    observation and experiment
  • Based on their results, they come to conclusions
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