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AP Bio Review #4
Fossils, Cuvier, and
Catastrophism


The study of fossils

Helped to lay the groundwork for Darwin’s ideas
Fossils are remains or traces of organisms from the past

Usually found in sedimentary rock, which appears in layers or
strata
Figure 22.3
 Paleontology,

the study of fossils
Was largely developed by French scientist
Georges Cuvier
 Cuvier
opposed the idea of gradual
evolutionary change

And instead advocated catastrophism,
speculating that each boundary between
strata represents a catastrophe
Theories of Gradualism
 Gradualism

Is the idea that profound change can take
place through the cumulative effect of slow
but continuous processes
 Geologists


Hutton and Lyell
Perceived that changes in Earth’s surface
can result from slow continuous actions still
operating today
Exerted a strong influence on Darwin’s
thinking
Lamarck’s Theory of Evolution
 Lamarck


hypothesized that species evolve
Through use and disuse and the inheritance
of acquired traits
But the mechanisms he proposed are
unsupported by evidence
(a) Cactus eater. The long,
sharp beak of the cactus
ground finch (Geospiza
scandens) helps it tear
and eat cactus flowers
and pulp.
Figure 22.6a–c
(c) Seed eater. The large ground
finch (Geospiza magnirostris)
has a large beak adapted for
cracking seeds that fall from
plants to the ground.
(b) Insect eater. The green warbler
finch (Certhidea olivacea) uses its
narrow, pointed beak to grasp insects.
The Origin of Species
 Darwin


developed two main ideas
Evolution explains life’s unity and diversity
Natural selection is a cause of adaptive
evolution
Descent with Modification
 The

phrase descent with modification
States that all organisms are related through
descent from an ancestor that lived in the
remote past
Hyracoidea
(Hyraxes)
Sirenia
(Manatees
and relatives)
Elephas
maximus
(Asia)
Figure 22.7
Loxodonta
africana
(Africa)
Loxodonta
cyclotis
(Africa)
 Observation
#1: For any species,
population sizes would increase
exponentially
 Observation
#2: Nonetheless, populations
tend to be stable in size

Except for seasonal fluctuations
 Observation
#3: Resources are limited
 Inference #1: Production of more individuals
than the environment can support

Leads to a struggle for existence among
individuals of a population, with only a fraction
of their offspring surviving
Observation #4: Members of a population vary
extensively in their characteristics
No two individuals are exactly alike
Figure 22.9
 Observation
#5: Much of this variation is
heritable
 Inference #2: Survival depends in part on
inherited traits

Individuals whose inherited traits give them a
high probability of surviving and reproducing
are likely to leave more offspring than other
individuals
 Inference
#3: This unequal ability of
individuals to survive and reproduce

Will lead to a gradual change in a population,
with favorable characteristics accumulating
over generations
Artificial Selection
Terminal
bud
Lateral
buds
Brussels sprouts
Cabbage
Flower
cluster
Leaves
Cauliflower
Kale
Flower
and
stems
Broccoli
Stem
Wild mustard
Figure 22.10
Kohlrabi
Summary of Natural Selection
 Natural
selection is differential success in
reproduction

That results from the interaction between
individuals that vary in heritable traits and
their environment
(a) A flower mantid
in Malaysia
(b) A stick mantid
in Africa
Figure 22.11
 If

an environment changes over time
Natural selection may result in adaptation to
these new conditions
Homology, Biogeography, and
the Fossil Record
 Evolutionary

theory
Provides a cohesive explanation for many
kinds of observations
Homology
 Homology

Is similarity resulting from common ancestry
Anatomical Homologies
 Homologous
Human
Figure 22.14
structures
Cat
Whale
Bat
Comparative embryology

Reveals additional anatomical homologies
not visible in adult organisms
Pharyngeal
pouches
Post-anal
tail
Chick embryo
Figure 22.15
Human embryo
 Vestigial


organs
Are some of the most intriguing homologous
structures
Are remnants of structures that served
important functions in the organism’s
ancestors
Molecular Homologies
 Biologists
also observe homologies among
organisms at the molecular level

Such as genes that are shared among
organisms inherited from a common
ancestor
Anatomical resemblances
Species
Percent of Amino Acids That Are
Identical to the Amino Acids in a
Human Hemoglobin Polypeptide
100%
Human
Rhesus monkey
95%
Mouse
87%
Chicken
69%
Frog
Figure 22.16
Lamprey
54%
14%
Biogeography
 Darwin’s
observations of the geographic
distribution of species, biogeography

Formed an important part of his theory of
evolution
NORTH
AMERICA
Sugar
glider
AUSTRALIA
Flying
squirrel
Figure 22.17
 One
common misconception about
evolution is that individual organisms
evolve, in the Darwinian sense, during their
lifetimes
 Natural selection acts on individuals, but
populations evolve
The Modern Synthesis
 Population


genetics
Is the study of how populations change
genetically over time
Reconciled Darwin’s and Mendel’s ideas
 The


modern synthesis
Integrates Mendelian genetics with the
Darwinian theory of evolution by natural
selection
Focuses on populations as units of evolution
 The


gene pool
Is the total aggregate of genes in a
population at any one time
Consists of all gene loci in all individuals of
the population
The Hardy-Weinberg Theorem


Describes a population that is not evolving
States that the frequencies of alleles and
genotypes in a population’s gene pool remain
constant from generation to generation
provided that only Mendelian segregation and
recombination of alleles are at work
• Mendelian inheritance
– Preserves genetic variation in a population
Generation
1
CW CW
CRCR
genotype
genotype
Plants mate
Generation
2
All CRCW
(all pink flowers)
50% CR
gametes
50% CW
gametes
Come together at random
Generation
3
25% CRCR
50% CRCW
50% CR
gametes
25% CWCW
50% CW
gametes
Come together at random
Generation
4
25% CRCR 50% CRCW 25% CWCW
Figure 23.4
Alleles segregate, and subsequent
generations also have three types
of flowers in the same proportions
Preservation of Allele
Frequencies
 In
a given population where gametes
contribute to the next generation
randomly, allele frequencies will not
change
Hardy-Weinberg Equilibrium
 Hardy-Weinberg


equilibrium
Describes a population in which random
mating occurs
Describes a population where allele
frequencies do not change
 If
p and q represent the relative frequencies
of the only two possible alleles in a
population at a particular locus, then


p2 + 2pq + q2 = 1
And p2 and q2 represent the frequencies of the
homozygous genotypes and 2pq represents
the frequency of the heterozygous genotype
 The
five conditions for non-evolving
populations are rarely met in nature





Extremely large population size
No gene flow
No mutations
Random mating
No natural selection
 Mutation
and sexual recombination produce
the variation that makes evolution possible
 Two processes, mutation and sexual
recombination

Produce the variation in gene pools that
contributes to differences among individuals
Point Mutations
A



point mutation
Is a change in one base in a gene
Can have a significant impact on phenotype
Is usually harmless, but may have an
adaptive impact
Mutations That Alter Gene
Number or Sequence
 Chromosomal
mutations that affect many
loci


Are almost certain to be harmful
May be neutral and even beneficial
 Gene

duplication
Duplicates chromosome segments
Mutation Rates
 Mutation



rates
Tend to be low in animals and plants
Average about one mutation in every
100,000 genes per generation
Are more rapid in microorganisms
Sexual Recombination
 In
sexually reproducing populations,
sexual recombination

Is far more important than mutation in
producing the genetic differences that make
adaptation possible
 Three
major factors alter allele frequencies
and bring about most evolutionary change



Natural selection
Genetic drift
Gene flow
Natural Selection
 Differential

success in reproduction
Results in certain alleles being passed to the
next generation in greater proportions
Genetic Drift
 Statistically,

the smaller a sample
The greater the chance of deviation from a
predicted result
Genetic drift
CWCW
CRCR
CRCR
Only 5 of
10 plants
leave
offspring
CRCW
CWCW
CRCR
CRCR
CRCW
CWCW
CRCR
CRCW
CRCW
CRCR
CWCW
CRCW
CRCR
CRCR
CRCW
Generation 1
p (frequency of CR) = 0.7
q (frequency of CW) = 0.3
Only 2 of
10 plants
leave
offspring
CRCR
CRCR
CRCR
CRCR
CRCR
CRCR
CRCR
CRCR
CRCW
CRCW
Generation 2
p = 0.5
q = 0.5
Figure 23.7
CRCR
CRCR
Generation 3
p = 1.0
q = 0.0
The Bottleneck Effect
(a) Shaking just a few marbles through the
narrow neck of a bottle is analogous to a
drastic reduction in the size of a population
after some environmental disaster. By chance,
blue marbles are over-represented in the new
population and gold marbles are absent.
Figure 23.8 A
Original
population
Bottlenecking
event
Surviving
population
The Founder Effect
 The


founder effect
Occurs when a few individuals become
isolated from a larger population
Can affect allele frequencies in a population
Gene Flow



Causes a population to gain or lose alleles
Results from the movement of fertile
individuals or gametes
Tends to reduce differences between
populations over time
Genetic Variation


Occurs in individuals in populations of all
species
Is not always heritable
(a) Map butterflies that
emerge in spring:
orange and brown
(b) Map butterflies that
emerge in late summer:
black and white
Figure 23.9 A, B
Variation Within a Population
 Both

discrete and quantitative characters
Contribute to variation within a population
 Discrete

characters
Can be classified on an either-or basis
 Quantitative

characters
Vary along a continuum within a population
 Polymorphism
 Phenotypic

Describes a population in which two or more
distinct morphs for a character are each
represented in high enough frequencies to be
readily noticeable
 Genetic

polymorphism
polymorphisms
Are the heritable components of characters
that occur along a continuum in a population
• Some examples of geographic variation
occur as a cline, which is a graded change
in a trait along a geographic axis
Heights of yarrow plants grown in common garden
EXPERIMENT
Researchers observed that the average size
Mean height (cm)
of yarrow plants (Achillea) growing on the slopes of the Sierra
Nevada mountains gradually decreases with increasing
elevation. To eliminate the effect of environmental differences
at different elevations, researchers collected seeds
from various altitudes and planted them in a common
garden. They then measured the heights of the
resulting plants.
Atitude (m)
RESULTS The average plant sizes in the common
garden were inversely correlated with the altitudes at
which the seeds were collected, although the height
differences were less than in the plants’ natural
environments.
CONCLUSION The lesser but still measurable clinal variation
in yarrow plants grown at a common elevation demonstrates the
role of genetic as well as environmental differences.
Figure 23.11
Sierra Nevada
Range
Great Basin
Plateau
Seed collection sites
Directional, Disruptive, and
Stabilizing Selection
 Selection

Favors certain genotypes by acting on the
phenotypes of certain organisms
 Three



modes of selection are
Directional
Disruptive
Stabilizing
 Directional

Favors individuals at one end of the
phenotypic range
 Disruptive

selection
Favors individuals at both extremes of the
phenotypic range
 Stabilizing

selection
selection
Favors intermediate variants and acts against
extreme phenotypes
Original population
Original
population
Evolved
population
(a) Directional selection shifts the overall
makeup of the population by favoring
variants at one extreme of the
distribution. In this case, darker mice are
favored because they live among dark
rocks and a darker fur color conceals them
from predators.
Fig 23.12 A–C
Phenotypes (fur color)
(b) Disruptive selection favors variants
at both ends of the distribution. These
mice have colonized a patchy habitat
made up of light and dark rocks, with the
result that mice of an intermediate color are
at a disadvantage.
(c) Stabilizing selection removes
extreme variants from the population
and preserves intermediate types. If
the environment consists of rocks of
an intermediate color, both light and
dark mice will be selected against.
Diploidy
 Diploidy

Maintains genetic variation in the form of
hidden recessive alleles
Heterozygote Advantage
 Some
individuals who are heterozygous at a
particular locus

Have greater fitness than homozygotes
 Natural

selection
Will tend to maintain two or more alleles at that
locus
 Frequency-Dependent
Selection
 In frequency-dependent selection

The fitness of any morph declines if it
becomes too common in the population
Industrial Melanism
Neutral Variation
 Neutral

variation
Is genetic variation that appears to confer no
selective advantage
Sexual Selection
 Sexual


selection
Is natural selection for mating success
Can result in sexual dimorphism, marked
differences between the sexes in secondary
sexual characteristics
 Intrasexual

selection
Is a direct competition among individuals of
one sex for mates of the opposite sex
 Intersexual

selection
Occurs when individuals of one sex (usually
females) are choosy in selecting their mates
from individuals of the other sex
Figure 23.15
Why Natural Selection Cannot
Fashion Perfect Organisms
 Evolution
is limited by historical constraints
 Adaptations are often compromises
The Biological Species Concept
Defines a species as a population or group of
populations whose members have the
potential to interbreed in nature and produce
viable, fertile offspring but are unable to
produce viable fertile offspring with members
of other populations
Reproductive Isolation
 Reproductive


isolation
Is the existence of biological factors that
impede members of two species from
producing viable, fertile hybrids
Is a combination of various reproductive
barriers
 Prezygotic

barriers
Impede mating between species or hinder the
fertilization of ova if members of different
species attempt to mate
 Postzygotic

barriers
Often prevent the hybrid zygote from
developing into a viable, fertile adult
Prezygotic barriers impede mating or hinder fertilization if mating does occur
• Prezygotic and postzygotic barriers
Habitat
isolation
Behavioral
isolation
Temporal
isolation
Individuals
of different
species
Mechanical
isolation
Mating
attempt
HABITAT ISOLATION
TEMPORAL ISOLATION
BEHAVIORAL ISOLATION
(b)
MECHANICAL ISOLATION
(g)
(d)
(e)
(f)
(a)
(c)
Figure 24.4
Gametic
isolation
Reduce
hybrid
fertility
Reduce
hybrid
viability
Hybrid
breakdown
Viable
fertile
offspring
Fertilization
REDUCED HYBRID
VIABILITY
GAMETIC ISOLATION
REDUCED HYBRID FERTILITY HYBRID BREAKDOWN
(k)
(j)
(m)
(l)
(h)
(i)
• Concept 24.2: Speciation can take place
with or without geographic separation
• Speciation can occur in two ways
– Allopatric speciation
– Sympatric speciation
Figure 24.5 A, B
(a) Allopatric speciation. A (b) Sympatric speciation. A small
population becomes a new species
population forms a new
species while geographically without geographic separation.
isolated from its parent
population.
Polyploidy
 Polyploidy


Is the presence of extra sets of
chromosomes in cells due to accidents
during cell division
Has caused the evolution of some plant
species
autopolyploid
Failure of cell division
in a cell of a growing
diploid plant after
chromosome duplication
gives rise to a tetraploid
branch or other tissue.
Gametes produced
by flowers on this
branch will be diploid.
Offspring with tetraploid
karyotypes may be viable
and fertile—a new
biological species.
2n
2n = 6
4n = 12
Figure 24.8
4n
• An allopolyploid
– Is a species with multiple sets of
Unreduced gamete derived from different
Unreduced gamete species
chromosomes
with 4 chromosomes
with 7 chromosomes
Viable fertile hybrid
(allopolyploid)
Hybrid with
7 chromosomes
Species A
2n = 4
Meiotic error;
chromosome
number not
reduced from
2n to n
2n = 10
Normal gamete
n=3
Species B
2n = 6
Figure 24.9
Normal gamete
n=3
Adaptive Radiation
Figure 24.11
adaptive radiation
Dubautia laxa
1.3 million years
MOLOKA'I
KAUA'I
MAUI
5.1
million
years O'AHU LANAI
3.7
million
years
Argyroxiphium sandwicense
HAWAI'I
0.4
million
years
Dubautia waialealae
Figure 24.12
Dubautia scabra
Dubautia linearis
punctuated equilibrium
Figure 24.13
Time
(a) Gradualism model. Species (b) Punctuated equilibrium
descended from a common
model. A new species
ancestor gradually diverge
changes most as it buds
more and more in their
from a parent species and
morphology as they acquire
then changes little for the
unique adaptations.
rest of its existence.
 Macroevolutionary
changes can
accumulate through many speciation
events
 Macroevolutionary change

Is the cumulative change during thousands
of small speciation episodes
 Homeotic

genes
Determine such basic features as where a
pair of wings and a pair of legs will develop
on a bird or how a flower’s parts are
arranged
Hox genes
Chicken leg bud
Zebrafish fin bud
Figure 24.18
Region of
Hox gene
expression
Phylogenies are based on common
ancestries inferred from fossil,
morphological, and molecular evidence
The Fossil Record
1 Rivers carry sediment to the
ocean. Sedimentary rock layers
containing fossils form on the
ocean floor.
2 Over time, new strata are
deposited, containing fossils
from each time period.
3 As sea levels change and the seafloor
is pushed upward, sedimentary rocks are
exposed. Erosion reveals strata and fossils.
Younger stratum
with more recent
fossils
Figure 25.3
Older stratum
with older fossils
 The

fossil record
Is based on the sequence in which fossils have
accumulated in such strata
 Fossils

reveal
Ancestral characteristics that may have been
lost over time
Convergent evolution
Figure 25.5
Evaluating Molecular
Homologies
1
Ancestral homologous
DNA segments are
identical as species 1
and species 2 begin to
diverge from their
common ancestor.
1 C C A T C A G A G T C C
2 C C A T C A G A G T C C
A C G G A T A G T C C A C T A G G C A C T A
T C A C C G A C A G G T C T T T G A C T A G
Deletion
2
3
4
Figure 25.6
Deletion and insertion
mutations shift what
had been matching
sequences in the two
species.
Homologous regions
(yellow) do not all align
because of these mutations.
Homologous regions
realign after a computer
program adds gaps in
sequence 1.
1
C C A T C A G A G T C C
2
C C A T C A G A G T C C
G T A
Insertion
1
C C A T
C A
2
C C A T
G T A
1
2
A G T C C
C C A T
C C A T
G T A
C A G
A G T C C
C A
A G T C C
C A G
A G T C C
Figure 25.7
Binomial Nomenclature
 Binomial


nomenclature
Is the two-part format of the scientific name
of an organism
Was developed by Carolus Linnaeus
Hierarchical Classification
Panthera
Species pardus
Panthera
Genus
Felidae
Family
Carnivora
Order
Class
Phylum
Kingdom
Figure 25.8
Domain
Mammalia
Chordata
Animalia
Eukarya
Species
Panthera
Order
Family
Panthera
Mephitis
Canis
Canis
Lutra lutra
pardus
mephitis
familiaris
lupus
(European
(leopard) (striped skunk)
(domestic dog) (wolf)
otter)
Genus
Linking Classification and
Phylogeny
Figure 25.9
Felidae
Mephitis
Lutra
Mustelidae
Carnivora
Canis
Canidae
• Each branch point
– Represents the divergence of two species
Leopard
Domestic cat
Common ancestor
“Deeper” branch points
Wolf
Leopard
Common ancestor
Domestic cat

A cladogram


A clade within a cladogram


Is a depiction of patterns of shared characteristics
among taxa
Is defined as a group of species that includes an
ancestral species and all its descendants
Cladistics

Is the study of resemblances among clades
Lamprey
Tuna
Turtle
Leopard
Salamander
Lancelet
(outgroup)
CHARACTERS
TAXA
Hair
0
0
0
0
0
1
Amniotic (shelled) egg
0
0
0
0
1
1
Four walking legs
0
0
0
1
1
1
Hinged jaws
0
0
1
1
1
1
Vertebral column (backbone)
0
1
1
1
1
1
Turtle
(a) Character table. A 0 indicates that a character is absent; a 1
indicates that a character is present.
Leopard
Hair
Salamander
Amniotic egg
Tuna
Four walking legs
Lamprey
Hinged jaws
Lancelet (outgroup)
Vertebral column
Figure 25.11a, b
(b) Cladogram. Analyzing the distribution of these
derived characters can provide insight into vertebrate
phylogeny.
• Applying parsimony to a problem in
molecular systematics
Human
Human
Mushroom
0
Mushroom
Tulip
30%
0
Tulip
Figure 25.14
(a) Percentage differences between sequences
40%
40%
0
• Applying parsimony to a problem in
molecular systematics
25%
15%
15%
15%
20%
10%
5%
5%
Tree 1: More likely
Figure 25.14
(b) Comparison of possible trees
Tree 2: Less likely
The Tree of Life
An Introduction to Biological
Diversity
 Geological

events that alter environments
Change the course of biological evolution
 Conversely,
inhabits
Figure 26.1
life changes the planet that it
 Geologic
history and biological history
have been episodic

Marked by what were in essence revolutions
that opened many new ways of life
Synthesis of Organic
Compounds on Early Earth
 Earth

formed about 4.6 billion years ago
Along with the rest of the solar system
 Earth’s

early atmosphere
Contained water vapor and many chemicals
released by volcanic eruptions
EXPERIMENT
Miller and Urey set up a closed system in their
laboratory to simulate conditions thought to have existed on early
Earth. A warmed flask of water simulated the primeval sea. The
strongly reducing “atmosphere” in the system consisted of H2,
methane (CH4), ammonia (NH3), and water vapor. Sparks were
discharged in the synthetic atmosphere to mimic lightning. A
condenser cooled the atmosphere, raining water and any dissolved
compounds into the miniature sea.
Water vapor
Cold
water
As material circulated through the apparatus,
Miller and Urey periodically collected samples for analysis. They
identified a variety of organic molecules, including amino acids such
as alanine and glutamic acid that are common in the proteins of
organisms. They also found many other amino acids and complex,
oily hydrocarbons.
Organic molecules, a first step in the origin of
life, can form in a strongly reducing atmosphere.
Figure 26.2
Electrode
Condenser
RESULTS
CONCLUSION
CH4
H2O
Cooled water
containing
organic
molecules
Sample for
chemical analysis
Abiotic Synthesis of Polymers
 Small

organic molecules
Polymerize when they are concentrated on
hot sand, clay, or rock
Protobionts
 Protobionts

Are aggregates of abiotically produced
molecules surrounded by a membrane or
membrane-like structure
 For
example, small membrane-bounded
droplets called liposomes

Can form when lipids or other organic
molecules are added to water
Glucose-phosphate
20 m
Glucose-phosphate
Phosphorylase
Starch
Amylase
Phosphate
Maltose
Maltose
Figure 26.4a, b
(a) Simple reproduction. This liposome is “giving birth” to smaller
liposomes (LM).
(b) Simple metabolism. If enzymes—in this case,
phosphorylase and amylase—are included in the
solution from which the droplets self-assemble,
some liposomes can carry out simple metabolic
reactions and export the products.
• RNA molecules called ribozymes have been
found to catalyze many different reactions,
including
– Self-splicing
– Making complementary copies of short
stretches of their own sequence or other short
pieces of RNA
Ribozyme
(RNA molecule)
3
Template
Nucleotides
Figure 26.5
Complementary RNA copy
5
5
Table 26.1
Mass Extinctions
Millions of years ago
600
400
500
300
200
100
0
2,500
100
Number of
taxonomic
Permian mass families
extinction
80
2,000
Extinction rate (
60
1,500
40
1,000
Cretaceous
mass extinction
Number of families (
)
Extinction rate
)
500
20
Paleozoic
Mesozoic
Paleogene
Cretaceous
Jurassic
Triassic
Permian
Carboniferous
Devonian
Ordovician
Silurian
Cambrian
Proterozoic eon
Figure 26.8
Cenozoic
Neogene
0
0
NORTH
AMERICA
Yucatán
Peninsula
Figure 26.9
Chicxulub
crater
The First Prokaryotes
 Prokaryotes

were Earth’s sole inhabitants
From 3.5 to about 2 billion years ago
Photosynthesis and the Oxygen
Revolution
 The

earliest types of photosynthesis
Did not produce oxygen
 When
oxygen began to accumulate in the
atmosphere about 2.7 billion years ago



It posed a challenge for life
It provided an opportunity to gain abundant
energy from light
It provided organisms an opportunity to exploit
new ecosystems
 Concept
26.4: Eukaryotic cells arose from
symbioses and genetic exchanges between
prokaryotes
 Among the most fundamental questions in
biology

Is how complex eukaryotic cells evolved from
much simpler prokaryotic cells
Endosymbiotic Origin of
Mitochondria and Plastids
 The

theory of endosymbiosis
Proposes that mitochondria and plastids
were formerly small prokaryotes living within
larger host cells
Cytoplasm
DNA
Plasma
membrane
Ancestral
prokaryote
Infolding of
plasma membrane
Nucleus
Endoplasmic
reticulum
Nuclear envelope
Engulfing
of aerobic
heterotrophic
prokaryote
Cell with nucleus
and endomembrane
system
Mitochondrion
Mitochondrion
Engulfing of
photosynthetic
prokaryote in
some cells
Ancestral
heterotrophic
eukaryote
Figure 26.13
Plastid
Ancestral
Photosynthetic
eukaryote
 The
evidence supporting an
endosymbiotic origin of mitochondria and
plastids includes


Similarities in inner membrane structures
and functions
Both have their own circular DNA
The “Cambrian Explosion”
 Most

of the major phyla of animals
Appear suddenly in the fossil record that was
laid down during the first 20 million years of
the Cambrian period
five kingdoms
Monera, Protista, Plantae, Fungi, and
Animalia
Plantae
Fungi
Protista
Figure 26.21
Monera
Animalia
Reconstructing the Tree of Life:
A Work in Progress
A


three domain system
Has replaced the five kingdom system
Includes the domains Archaea, Bacteria, and
Eukarya
 Each

domain
Has been split by taxonomists into many
kingdoms
Chapter 27
Prokaryotes
 Prokaryotic

cells have a variety of shapes
The three most common of which are
spheres (cocci), rods (bacilli), and spirals
1 m
Figure 27.2a–c (a) Spherical (cocci)
2 m
(b) Rod-shaped (bacilli)
5 m
(c) Spiral
Gram stain
Lipopolysaccharide
Cell wall
Peptidoglycan
layer
Cell wall
Outer
membrane
Peptidoglycan
layer
Plasma membrane
Plasma membrane
Protein
Protein
Grampositive
bacteria
Gramnegative
bacteria
20 m
(a) Gram-positive. Gram-positive bacteria have
a cell wall with a large amount of peptidoglycan
that traps the violet dye in the cytoplasm. The
alcohol rinse does not remove the violet dye,
which masks the added red dye.
Figure 27.3a, b
(b) Gram-negative. Gram-negative bacteria have less
peptidoglycan, and it is located in a layer between the
plasma membrane and an outer membrane. The
violet dye is easily rinsed from the cytoplasm, and the
cell appears pink or red after the red dye is added.
Motility - flagella
Flagellum
Filament
50 nm
Cell wall
Hook
Basal apparatus
Figure 27.6
Plasma
membrane
endospores
Endospore
0.3 m
Figure 27.9
 Examples
of all four models of nutrition
are found among prokaryotes




Photoautotrophy
Chemoautotrophy
Photoheterotrophy
Chemoheterotrophy
Major nutritional modes in prokaryotes
Table 27.1
 Obligate

aerobes
Require oxygen
 Facultative

Can survive with or without oxygen
 Obligate

anaerobes
anaerobes
Are poisoned by oxygen
 Some

archaea
Live in extreme environments
 Extreme

thermophiles
Thrive in very hot environments
halophiles
Figure 27.14
 Methanogens


Live in swamps and marshes
Produce methane as a waste product
Chemical Recycling
 Prokaryotes

play a major role
In the continual recycling of chemical
elements between the living and nonliving
components of the environment in
ecosystems
 Chemoheterotrophic
prokaryotes function as
decomposers

Breaking down corpses, dead vegetation, and
waste products
 Nitrogen-fixing

prokaryotes
Add usable nitrogen to the environment
Symbiotic Relationships
Figure 27.15
Pathogenic Prokaryotes
Figure 27.16
5 µm
 Pathogenic
prokaryotes typically cause
disease

By releasing exotoxins or endotoxins
 Many

pathogenic bacteria
Are potential weapons of bioterrorism
bioremediation
Figure 27.17
 Prokaryotes



are also major tools in
Mining
The synthesis of vitamins
Production of antibiotics, hormones, and
other products
Chapter 28
Protists
Photoautotrophs, which contain chloroplasts
Heterotrophs, which absorb organic molecules
or ingest larger food particles
Mixotrophs, which combine photosynthesis
and heterotrophic nutrition
Diplomonads
Figure 28.5a
(a) Giardia intestinalis, a diplomonad (colorized SEM)
5 µm
 Kinetoplastids

Have a single, large mitochondrion that
contains an organized mass of DNA called a
kinetoplast
Figure 28.7
9 m
Euglenids
 Euglenids

Have one or two flagella that emerge from a
pocket at one end of the cell
Store the glucose polymer paramylon
Long flagellum

Eyespot: pigmented
organelle that functions
as a light shield, allowing
light from only a certain
direction to strike the
light detector
Light detector: swelling near the
base of the long flagellum; detects
light that is not blocked by the
eyespot; as a result, Euglena moves
toward light of appropriate
intensity, an important adaptation
that enhances photosynthesis
Short flagellum
Euglena (LM)
Nucleus
Contractile vacuole
5 µm
Plasma membrane
Figure 28.8
Pellicle: protein bands beneath
the plasma membrane that
provide strength and flexibility
(Euglena lacks a cell wall)
Chloroplast
Paramylon granule
Dinoflagellates
 Dinoflagellates


Are a diverse group of aquatic
photoautotrophs and heterotrophs
Are abundant components of both marine
and freshwater phytoplankton
 Rapid

growth of some dinoflagellates
Is responsible for causing “red tides,” which
can be toxic to humans
Apicomplexans
 Apicomplexans



Are parasites of animals and some cause
serious human diseases
Are so named because one end, the apex,
contains a complex of organelles specialized
for penetrating host cells and tissues
Have a nonphotosynthetic plastid, the
apicoplast
2 The sporozoites enter the person’s
liver cells. After several days, the sporozoites
undergo multiple divisions and become
merozoites, which use their apical complex
to penetrate red blood cells (see TEM below).
1 An infected Anopheles
mosquito bites a person,
injecting Plasmodium
sporozoites in its saliva.
Inside mosquito
Inside human
Sporozoites
(n)
7 An oocyst develops
from the zygote in the wall
of the mosquito’s gut. The
oocyst releases thousands
of sporozoites, which
migrate to the mosquito’s
salivary gland.
Merozoite
Liver
Liver cell
Apex
Oocyst
MEIOSIS
Zygote
(2n)
Red blood
cell
Merozoite
(n)
Red blood
cells
FERTILIZATION
Gametes
Key
3 The merozoites divide asexually inside the
red blood cells. At intervals of 48 or 72 hours
(depending on the species), large numbers of
merozoites break out of the blood cells, causing
periodic chills and fever. Some of the merozoites
infect new red blood cells.
Gametocytes
(n)
Haploid (n)
Diploid (2n)
Figure 28.11
0.5 µm
4 Some merozoites
form gametocytes.
6 Gametes form from gametocytes.
Fertilization occurs in the mosquito’s
digestive tract, and a zygote forms.
The zygote is the only diploid stage
in the life cycle.
5 Another Anopheles mosquito
bites the infected person and picks
up Plasmodium gametocytes along
with blood.
Ciliates
 Ciliates,


a large varied group of protists
Are named for their use of cilia to move and
feed
Have large macronuclei and small
micronuclei
 The

micronuclei
Function during conjugation, a sexual
process that produces genetic variation
 Conjugation

is separate from reproduction
Which generally occurs by binary fission
FEEDING, WASTE REMOVAL, AND WATER BALANCE
Paramecium, like other freshwater
protists, constantly takes in water
by osmosis from the hypotonic environment.
Bladderlike contractile vacuoles accumulate
excess water from radial canals and periodically
expel it through the plasma membrane.
Contractile Vacuole
Paramecium feeds mainly on bacteria.
Rows of cilia along a funnel-shaped oral
groove move food into the cell mouth,
where the food is engulfed into food
vacuoles by phagocytosis.
Oral groove
Cell mouth
50 µm
Thousands of cilia cover
the surface of Paramecium.
Micronucleus
Food vacuoles combine with
lysosomes. As the food is digested,
the vacuoles follow a looping path
through the cell.
Macronucleus
Figure 28.12
The undigested contents of food
vacuoles are released when the
vacuoles fuse with a specialized
region of the plasma membrane
that functions as an anal pore.
Oomycetes (Water Molds and
Their Relatives)
 Oomycetes


Include water molds, white rusts, and downy
mildews
Were once considered fungi based on
morphological studies
Diatoms
 Diatoms

are unicellular algae
With a unique two-part, glass-like wall of
hydrated silica
Diatoms are a major component
of phytoplankton
Figure 28.16
50 µm
 Accumulations

of fossilized diatom walls
Compose much of the sediments known as
diatomaceous earth
 Golden

Are named for their color, which results from
their yellow and brown carotenoids
 The

Golden
Algae
algae,
or chrysophytes
cells of golden algae
Are typically biflagellated, with both flagella
attached near one end of the cell
Brown Algae
 Brown


algae, or phaeophytes
Are the largest and most complex algae
Are all multicellular, and most are marine
 Brown

algae
Include many of the species commonly called
seaweeds
 Seaweeds
Blade
Stipe
Figure 28.18
Holdfast
Figure 28.19
Human Uses of Seaweeds
 Many


seaweeds
Are important commodities for humans
Are harvested for food
(a) The seaweed is
grown on nets in
shallow coastal
waters.
(b) A worker spreads
the harvested seaweed on bamboo
screens to dry.
Figure 28.20a–c
(c) Paper-thin, glossy sheets
of nori make a mineral-rich wrap
for rice, seafood, and vegetables
in sushi.
Alternation of Generations
A

variety of life cycles
Have evolved among the multicellular algae
 The
most complex life cycles include an
alternation of generations

The alternation of multicellular haploid and
diploid forms
Foraminiferans (Forams)
20 µm
Figure 28.22
Amoebozoans have lobe-shaped
pseudopodia
 Amoebozoans


Are amoeba that have lobe-shaped, rather
than threadlike, pseudopodia
Include gymnamoebas, entamoebas, and
slime molds
Plasmodial Slime Molds
4 cm
Figure 28.25
Red Algae
 Red

algae are reddish in color
Due to an accessory pigment call
phycoerythrin, which masks the green of
chlorophyll
(b) Dulse (Palmaria palmata). This edible
species has a “leafy” form.
(c) A coralline alga. The cell walls of
coralline algae are hardened by calcium
carbonate. Some coralline algae are
members of the biological communities
around coral reefs.
Figure 28.28a–c
(a) Bonnemaisonia hamifera. This red alga
has a filamentous form.
Green Algae
 Green



algae
Are named for their grass-green chloroplasts
Are divided into two main groups:
chlorophytes and charophyceans
Are closely related to land plants
Chapter 31
Fungi
Nutrition and Fungal Lifestyles
 Fungi

are heterotrophs
But do not ingest their food
 Fungi
secrete into their surroundings
exoenzymes that break down complex
molecules

And then absorb the remaining smaller
compounds
 Fungi



exhibit diverse lifestyles
Decomposers
Parasites
Mutualistic symbionts
Body Structure
Reproductive structure.
The mushroom produces
tiny cells called spores.
Hyphae. The mushroom and its
subterranean mycelium are a
continuous network of hyphae.
Spore-producing
structures
20 m
Figure 31.2
Mycelium
 Fungi

Mycelia, networks of branched hyphae
adapted for absorption
 Most

consist of
fungi
Have cell walls made of chitin
 Mycorrhizae

Are mutually beneficial relationships between
fungi and plant roots
 Concept
31.2: Fungi produce spores
through sexual or asexual life cycles
 Fungi propagate themselves

By producing vast numbers of spores, either
sexually or asexually
• The generalized life cycle of fungi
Key
Heterokaryotic
stage
Haploid (n)
Heterokaryotic
(unfused nuclei from
different parents)
PLASMOGAMY
(fusion of cytoplasm)
Diploid (2n)
KARYOGAMY
(fusion of nuclei)
Spore-producing
structures
Spores
SEXUAL
REPRODUCTION
ASEXUAL
REPRODUCTION
Zygote
Mycelium
MEIOSIS
GERMINATION
GERMINATION
Spore-producing
structures
Spores
Figure 31.5
Decomposers
 Fungi
are well adapted as decomposers of
organic material

Performing essential recycling of chemical
elements between the living and nonliving
world
Symbionts
 Fungi

form symbiotic relationships with
Plants, algae, and animals
Mycorrhizae
EXPERIMENT Researchers grew soybean plants in soil treated with fungicide (poison that kills fungi) to
prevent the formation of mycorrhizae in the experimental group. A control group was exposed to fungi that formed
mycorrhizae in the soybean plants’ roots.
RESULTS
The soybean plant on the left is typical of the experimental group. Its
RESULTS
stunted growth is probably due to a phosphorus deficiency. The taller, healthier plant on
the right is typical of the control group and has mycorrhizae.
Figure 31.21
CONCLUSION
These results indicate that the presence of mycorrhizae benefits a soybean
plant and support the hypothesis that mycorrhizae enhance the plant’s ability to take up
phosphate and other needed minerals.
Fungus-Animal Symbiosis
 Some
fungi share their digestive services
with animals

Helping break down plant material in the guts
of cows and other grazing mammals
 Many

Figure 31.22
species of ants and termites
Take advantage of the digestive power of
fungi by raising them in “farms”
Lichens
(a) A fruticose (shrub-like) lichen
Figure 31.23a–c
(b) A foliose (leaf-like) lichen
(c) Crustose (crust-like) lichens
Pathogens
 About

30% of known fungal species
Are parasites, mostly on or in plants
Figure 31.25a–c
(a) Corn smut on corn
(b) Tar spot fungus on maple leaves
(c) Ergots on rye