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Figure 3.1 The seven traits that Mendel studied. Note that each trait appears in one of two distinct


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Title: Figure 3.1 The seven traits that Mendel studied. Note that each trait appears in one of two distinct

Figure 3.1 The seven traits that Mendel studied.
Note that each trait appears in one of two
distinct forms.
Figure 3.2 (a) Flower of a pea plant, cut to
show male and female flower parts. (b) Using
artificial cross-fertilization, Mendel controlled
matings between plants.
Figure 3.3 One of Mendel's crosses between
smooth round-seeded and wrinkled-seeded plants.
Figure 3.6 Punnet square illustrating possible
genotypes of the offspring of a father suffering
from sickle cell anemia and a normal mother. All
children born to this couple are sickle cell
Figure 3.7 Punnett squares illustrating
inheritance of the Hb gene. (a) The offspring of
a normal mother and a father who is a carrier for
sickle cell anemia have a 50 percent chance of
being carriers themselves. (b) When both parents
are sickle cell carriers, the offspring have a 25
percent chance of inheriting no alleles for the
disease (HbA/HbA), a 25 percent chance of
inheriting the disease (HbS/HbS), and a 50
percent chance of being sickle cell carriers.
Figure 3.9 Wild type and mutant fruit flies. A
wild type fly has at least one V allele for wing
shape and at least one E allele for body color.
An ebony fly must have two e alleles for body
color. Likewise, a fly with vestigial wings must
have two v alleles for wing shape.
Figure 3.10 Genotypes of the F2 generation of a
dihybrid cross. Each parent fly is heterozygous
for two traits, wing shape and body color. This
kind of cross creates nine distinct genotypes.
Figure 3.11 Phenotypes of the F2 generation in a
dihybrid cross. Four phenotypes result from this
cross between files heterozygous for both wing
shape and body color. The ration of phenotypes in
nine wild type flies (broad wings, striped body),
to three flies with vestigial wings and striped
bodies, to three flies with broad winds and ebony
bodies, to one fly with vestigial wings and an
ebony body.
Figure 3.14 Punnett square illustrating possible
offspring of a cross between a red-flowered and a
white-flowered four-o'clock plant. The ratio of
phenotypes is the same as the ration of
genotypes, namely 121 white/pink/red.
Figure 3.16 Inheritance of coat color in mice.
The phenotypic ration in the offspring of a cross
between heterozygous yellow mice is closer to 21
than to the 31 ratio predicted by Mendelian
genetics. The difference between the observed
ratio and the predicted ratio is due to the
recessive lethality of having two yellow Y
Figure 12.21 Structures of the male reproductive
system. Sperm produced in the testes move into
the epididymis where they mature. Sperm are
stored in the vasa deferentia. During sexual
arousal, sperm move into the urethra where they
are combined with secretions from accessory
glands to make semen. Semen is ejected from the
penis during ejaculation.
Figure 12.22 Structures of the female
reproductive system. Eggs are produced in the
ovaries and released, usually one every 28 days,
into the fallopian tubes. If an egg encounters
sperm in the oviduct, it may be fertilized
resulting in a zygote. The zygote begins to
divide in the oviduct, becoming an embryo that
may implant in the thickened endometrium of the
uterus. If it is not fertilized, the egg passes
through the uterus and is expelled from the
Figure 12.23 The female menstrual cycle in the
absence of fertilization. During the first half
of the cycle, called the follicular phase, FSH
stimulates several ovarian follicles to mature,
and LH stimulates estrogen secretion from the
ovaries. High estrogen levels cause midcycle
surges in LH and FSH, which, in turn, cause
ovulation. During the second half of the cycle,
called the luteal phase, the follicle develops
into a corpus luteum and begins to secrete
progesterone. Progesterone maintains the
endometrium, but the corpus luteum degenerates
toward the end of the cycle, and progesterone
levels fall. As the cycle begins again at day 1,
the endometrium is sloughed off during
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Figure 12.24 Pollen grains form in anthers, part
of the male reproductive structures called
stamens. Mother cells in the anthers divide by
meiosis, giving rise to four haploid cells called
microspores. The microspores become enclosed in a
tough outer coat and divide by mitosis. The
result is pollen grains, each containing a sperm
nucleus and a tube cell. The sperm nucleus
divides again by mitosis, yielding two sperm
nuclei (not shown).
Figure 12.26 The female flower parts house the
gametes and female gametophyte. A diploid
megaspore mother cell in the ovule divides by
meiosis, giving rise to the one megaspore mother
cell and three cells that degenerate. The
megaspore mother cell divides by mitosis three
times, yielding eight nuclei, only one of which
is the egg. Cells of the ovule form a protective
coat around the female gametophyte.
Figure 12.27 Fertilization in flowering plants.
Figure 5.13 Griffith's experiments proving that
a nonvirulent form of bacteria (the R form) can
be converted to a virulent form (the S form) by a
transforming agent. That agent was later
identified as DNA, the genetic material.
Figure 5.15 The bacteriophages that Hershey and
Chase used in their experiments contained either
protein with radioactive sulfur and unlabeled
DNA, or DNA with radioactive phosphorus and
unlabeled protein.
Figure 5.16 The Hershey-Chase experiment that
showed that DNA and not protein enters the host
cell when bacteriophage infect bacteria.
Figure 6.1 The chemical structure of the
nucleotides. (a) A DNA nucleotide with thymine as
the nitrogenous base. (b) An RNA nucleotide,
shown with uracil as the nitrogenous base. (c)
The four nitrogenous bases that occur in DNA.
Except for thymine, they also occur in RNA.
Figure 6.3 The double helix of DNA. The rails of
the twisted ladder are held together by covalent
bonds between sugars and phosphates. The rungs
connecting the two rails are held together by
weaker hydrogen bonds between adenine and
thymine, or cytosine and guanine. The sequence of
nitrogenous bases encodes the genetic information.
Figure 6.4a DNA replication. (a) A short segment
of a DNA molecule is untwisted to show how new
nucleotides form new pairs with the exposed
nitrogenous bases on the parental strands. The
two parental strands separate when the weak bonds
holding them together are broken.
Figure 6.4b DNA replication. (b) The same
process is illustrated on a larger DNA molecule
in its characteristic helical shape.
Figure 6.6 Messenger RNA carries the genetic
information from the DNA in the nucleus to the
cytoplasm, where it is translated into a sequence
of amino acids.
Figure 6.7 Transfer RNA interprets the
nucleotide language of mRNA into the amino acid
language of protein. Its characteristic t-shaped
structure includes both an anticodon region and
an amino acid binding region.
Figure 6.8 (a) Ribosomal RNA has a complex
folded structure that aids in its many roles as
part of the structure of the ribosome. (b)
Several rRNAs and many proteins join to make the
subunits of the ribosome, shown here in a
diagrammatic representation. The subunits of the
ribosome join when it is participating in
Figure 6.9 In transcription, the sequence of
nucleotides in DNA is used to construct a
molecule of RNA.
Figure 6.10 Translation converts the mRNA
nucleotide sequence into an amino acid sequence.
The linear mRNA is held in place on the ribosomal
subunits, while complementary tRNAs are brought
in. There are two tRNA binding sites on the
ribosome. When both are occupied, the rRNA
catalyzes the formation of a peptide bond between
the amino acids on the tRNAs. The process
continues until a stop codon is reached on mRNA,
at which point the complex comes apart.
Figure 6.12 The genetic code. To use this chart
to translate the codon UGC, for example, find the
first letter (U) in the column on the far left.
Follow the U row toward the right until you reach
the column headed by the second letter (G) at the
top. The find the amino acid that matches the
third letter (C) in the column on the far right.
UGC specifies cysteine. The genetic code is
usually written in the language of mRNA and not
DNA or tRNA. The triplets correspond to codons
that are found on mRNA. Some examples of
complementary tRNAs are shown at the far right.
Figure 6.13 Regulation of gene expression by
means of operons. Jacob and Monod found that
genes for proteins that digest lactose are only
expressed when lactose is the only sugar present
in the growth medium. Without lactose, the genes
cannot be transcribed because a repressor protein
blocks the RNA polymerase. With lactose, the
repressor binds to a lactose molecule and cannot
bind to DNA. The RNA polymerase can then
transcribe the genes.
Figure 6.15 The point mutation in sickle cell
anemia. A mutation involving a single nucleotide
base at a critical position in DNA results in the
substitution of an A for a T. When this DNA is
transcribed and translated, the final protein,
the beta chain of hemoglobin, has a valine where
a glutamic acid occurs in the normal beta chain
of hemoglobin.
Chapter 7- Biotechnology
  • We can isolate and copy (clone) any gene we want
    from any organism
  • Restriction enzymes and cloning vectors
  • The polymerase chain reaction (PCR)
  • Agarose gel electrophoresis used to see DNA
  • DNA sequencing several genomes are sequenced
    (human, fruit fly, a nematode worm, Arabidopsis,
    yeast, many bacteria)
  • DNA fingerprinting using PCR genetic testing
  • Genetic engineering (Bt toxin and insulin)
  • Gene therapy (ADA gene SCID)
  • Stem cells (embryonic and adult stem cells)
  • Mammalian cloning (Dolly the sheep, cats, dogs,

Figure 6.17 The polymerase chain reaction, also
called PCR, is a procedure in which tiny amounts
of DNA are duplicated many times over to yield
quantities large enough to be analyzed. Each
strand of DNA that is produced is exactly like
the original strand.
Chapter 8-Population Genetics
  • Species-a group of organisms of the same kind
    that have the ability to interbreed to produce
    fertile offspring
  • Population-a group of organisms of the same
    species located in the same place and time
  • A population can be defined by its gene pool
    (i.e., every allele of every gene of every
    organism in the population)
  • Alleles occur at certain frequencies (e.g., for a
    gene with 2 alleles, p and q, p q 1.0)
  • Variation exists in populations (e.g., height,
    weight, eye color, etc., and this variation is
    governed by particular alleles-genetic variation)

The Hardy-Weinberg principle relates genotypes
and allelic frequencies
  • For 2 alleles, p and q, p q 1 and
  • following mating, p2 2pq q2 1.0
  • Populations in which allele frequencies do not
    change are in genetic equilibrium (zero
  • Assumes 5 conditions
  • 1. Population is large
  • 2. Mating is random
  • 3. No immigration or emigration
  • 4. Natural selection is not occurring
  • 5. No mutations

Microevolution-changes in allele frequency over
time caused by
  • Populations can be small and experience genetic
    drift (chance events)/founder effect/population
  • Non-random mating
  • Gene flow (individuals do leave or enter
  • Natural selection-nature selects individuals in a
    population that have favorable alleles which
    allow for survival in a given environment (e.g.,
    Peppered moth and DDT stories)
  • Mutations do occur

Figure 8.9 The Hardy-Weinberg proportions of
genotypes in a population can be illustrated
using a square. The lengths across the top of the
square are divided into proportions p and q,
representing the frequencies of alleles M and m
in populations of peppered moth. The areas
represent the proportions of the different
genotypes in the population. In (a), the
proportions represent the situation before
industrial melanism. In (b), the proportions
represent the situation after natural selection
has increased the frequency of the M allele. Note
that the areas of both the p2 and p x q boxes are
larger in (b), and the area of the q2 box is
Figure 8.17 The frequency of the DDT-resistance
allele in malaria-carrying mosquitoes increased
dramatically as a result of selection. Mosquitoes
carrying the DDT-resistant allele infiltrated
mosquito populations worldwide.
Figure 2.3b Many of Charles Darwin's ideas began
to develop on his five-year voyage around the
world sailing on the HMS Beagle. At every
opportunity, Darwin went ashore to take notes and
gather specimens. (b) Map showing the voyage of
the Beagle.
Figure 2.5c The major points of Darwin's
theories of evolution and natural selection can
be summarized into four observations and three
Theory of Darwinian Evolution
  • Organisms beget like organisms
  • In a given population, variation exists (these
    are not acquired characteristics) and such
    variation can be inherited
  • The number of individuals that survive and
    reproduce is small compared with the number
  • The individuals which survive and reproduce are
    determined by their interaction with their
    environment. i.e. natural selection of favorable
    variations or "survival of the fittest"

Evidence for evolution is based on
  • The fossil record
  • Comparative morphology (embryology, homologous
  • Analogous structures
  • Comparative biochemistry (protein and DNA
    sequence similarities)
  • Evolutionary patterns (branchings, adaptive
    radiations, extinctions)
  • Reflected in artificial selection by humans
    (i.e., domestic breeding of plants and animals)

Figure 2.11 In The Origin of Species, Darwin
stressed the importance of selective breeding in
developing domesticated animals and plants. The
Auroch, now-extinct ancestor of modern cattle,
once roamed Europe and may have been one of the
first cattle breeds to be domesticated.
Selectively breeding cattle who produced the most
meat resulted in modern beef cattle. Similarly,
selectively breeding cattle who produced the most
milk resulted in modern dairy cattle.
Figure 2.12 Evolution of the modern horse
involved a 60-million-year odyssey. Limbs
experienced a reduction in the number of toes on
each foot and a modification of the remaining toe
shape and size of the head, and changes to the
teeth. Basically, evolution of the modern horse
involved the transition of a rather small, not
particularly fast forest browser into a
relatively large, fast-running,
grassland-dwelling grazer. (Adapted from W.K.
Gregory, Emerging Evolution. New York Macmillan,
1951. Courtesy of the American Museum of Natural
Figure 2.13 Although forelimbs of vertebrates
vary widely in form and function, they have
similar skeletal elements. The upper portion of
the forelimb consists of a single, large, long
bone, which meets two smaller long bones in the
lower portion of the forelimb. These in turn
connect to varying numbers of smaller,
irregularly shaped bones. Because of their
similar structure, vertebrate forelimbs are
homologous. All vertebrates derived from an
ancestral fish. All mammals evolved from a common
reptilian ancestor.
Figure 2.14 Sharks and dolphins are examples of
convergent evolution. They belong to widely
different vertebrate groups--sharks are fish,
whereas dolphins are mammals--yet they live in
similar environments and have evolved similar
characteristics. Note their similar overall shape
and coloration, location and shape of dorsal
(back) fins, and shape (but not orientation) of
tail flukes.
Figure 2.17 The ancestors of all terrestrial
plants growing in the Hawaiian Islands had to
come from somewhere else. The islands started as
volcanoes on the ocean floor. Over millions of
years, the volcanoes grew, reached the surface,
and became islands. They were never connected to
any mainland. Most pioneer seeds came from
sources lying south and west of the islands. Only
about 20 percent came from the east.
Figure 2.20 Darwin came to realize that the
several species of finch on the Galapagos Islands
had a common ancestor, even though some had large
bills and ate seeds while others had smaller
bills and ate insects. Today, scientists
recognize 14 species of Darwin's finches (one
lives on Cocos Island, north of the Galapagos).
All descended from a single ancestral species.
Figure 2.22 Similar to Darwin's finches on the
Galapagos Island, other birds on other islands
have also experienced adaptive radiations. The
honeycreepers of the Hawaiian Islands provide a
fascinating example. Their common ancestor is
also thought to have been a finch. How are these
birds similar to Darwin's finches? (Hint Look at
the bills.) How do the two groups differ? How do
you explain the similarities and differences?
(Adapted from G.C. Monroe, Birds of Hawaii.
Vermont and Tokyo Charles E. Tuttle, 1960. Used
by permission.)
Figure 2.24 Convergent evolution is not limited
to animals. These plants belong to four different
families cacti, spurge, aster, and milkweed. All
live in deserts, where water is scarce and
temperatures are often high and fluctuate widely.
All have evolved similar adaptations to cope with
these conditions. All lack leaves and have thorns
and fleshy, green stems.
Figure 2.25 Gradualism and punctuated
equilibrium can be depicted as evolutionary tree
diagrams. (a) In gradualism, branching is gently
angled, indicating slow, steady accumulations of
changes over time. Speciation occurs at each
branching point. (b) In punctuated equilibrium,
branching is more abrupt, indicating that
speciation has occurred through more sudden
accumulation of changes, followed by long periods
of time in which few, if any, changes occur.
Common evolutionary patterns
  • Convergent evolution-Organisms raised in similar
    environments can evolve similarly
  • Example desert plants can look like same species
    although they are different species or dolphins
    and sharks look similar because both are in an
    aquatic environment
  • Divergent evolution- Closely related species
    living in different environments and facing
    different environmental challenges sometimes
    evolve dissimilar characteristics
  • Example small Hyracotherium evolved through
    several intermediate species and into today's
    horses, zebras, onagers
  • Adaptive radiation-A number of species evolve
    from a single ancestral species
  • Example Hawaiian bird group (honey creepers)
  • Extinction-A species dies out because it lacks
    genetic variations which allow for survival in a
    particular environment
  • Example dinosaurs
  • Coevolution-Parallel evolutionary changes
    occurring simultaneously between interacting
    species or evolution of one species affects the
    evolution of another species
  • Example As predators evolve, prey evolves. As
    prey evolves, predators evolve. Cheetahs feed on
    Thompsons gazelles

Results of evolution
  • Everywhere we look on the Earth, you can find
  • Scientists have described 1.5 millions species
  • Still many species yet to be described.
  • Predictions indicate there may be 10-100 times as
    many species as those already described.

Darwins Theory Debated
  • Three main criticisms
  • Darwin lacked direct evidence for natural
  • Indirect evidence was unconvincing
  • Darwin could not explain the source of variation
    in a population and inheritance of variation.
  • Answered by an understanding of genetics
  • What is the rate at which organisms evolve?
  • Slow and continuous or jerky and discontinuous?

Figure 9.1 Darwin imagined that life might have
originated in some small, warm pond (1). Other
biologists have proposed (2) hydrothermal vents
at the bottom of the ocean, (3) heat-stressed
ponds near ancient volcanoes, (4) clay beds in
estuaries or bays, (5) tidal pools, (6) within
bubbles of foam formed by ocean waves, and (7)
even asteroids.
Figure 9.2 The apparatus used by Miller and Urey.
Conditions inside the apparatus duplicated
conditions of Earth's early atmosphere. Gases
contained no free oxygen, but were rich in
methane, ammonia, and hydrogen. Water was heated
in the flask at the lower left. Water vapor
flowed through the tubes and past the sparking
electrode, representative of lightning, which
supplied an energy source for the reacting
chemicals. The water condenser turned water vapor
into droplets that flowed into the trap and
eventually back into the flask. In a surprisingly
short period of time, organic compounds,
including amino acids, gathered in the trap.
Figure 9.3 Key events in the chemical evolution
of life.
The oldest fossil evidence for life on Earth has
been dated to be approximately 3.5 billion years
old this fossil clearly reflects a prokaryotic
life form. How could the primitive conditions on
Earth some 3.5 to 4.6 billion years ago given
rise to such a life form?
  • Inorganic Chemicals Organic Chemicals
    Precells First Cells (Prokaryotic)

There are two kinds of cells that make up all
life forms, prokaryotic and eukaryotic cells.
Fossil evidence indicates that prokaryotic life
arose first. How can we account for the origin
of eukaryotic cells 1.5-2 billion years ago?
  • Remember, Prokaryotes-no membrane bound
    organelles including no nucleus naked DNA
    Eukaryotes-have membrane-bound organelles
    including a nucleus DNA complexed with protein
  • Membrane Invagination Theory in-pocketing and
    pinching off of the plasma membrane results in a
    number of membrane-bound organelles including
    nuclei, vacuoles, Golgi complexes and ER (i.e.,
    primitive eukaryotes)
  • Endosymbiont Theory precursor mitochondria were
    originally prokaryotes which were endocytosed by
    primitive eukaryotes similarly precursor
    chloroplasts were originally photosynthetic
    prokaryotes which were endocytosed by primitive
    eukaryotes to become plant cells

Earth came into existence approximately 4.6
billion years ago. Life appeared less than 1
billion years later. Those vast spans of time are
divided into four great eras based on the
structure of rocks and the fossils found within