Download 13) PHENOTYPE: the set of observable characteristics of an

12) GENOTYPE: the genetic makeup of an organism with reference to a single
trait, set of traits, or the entire complex of traits.
13) PHENOTYPE: the set of observable characteristics of an
individual resulting from the interaction of its genotype with the
environment.
Is this the correct phenotype for the genotype shown?
12) GENOTYPE: the genetic makeup of an organism with
reference to a single trait, set of traits, or the entire complex of
traits. (It’s the recipe – the directions)
11a) DOMINANT ALLELE: its trait will “win” when at least one of the paired
alleles is dominant.
11b) RECESSIVE ALLELE: its trait will “win” only when both paired alleles
are recessive
10) ALLELES: variations of genes that determine traits; the
two alleles on paired chromosomes constitute a gene.
The walkingsticks had only one feature
we investigated – color. We started with
a population of 48 walkingsticks. The
population was composed of equal
numbers of thee different traits – brown,
green-brown, and geen. In addition to
the walkingsticks there were birds that
preyed on the insects for food.
•  In what way did the population
change?
•  What factors in the environment
affected the change in the
walkingstick population?
•  How did variation help the
walkingstick population survive?
•  Was there more or less variation in
the walkingstick population after 5
generations?
•  Is there variation in the yammer of larkeys?
•  How might a predator have an impact on the
population of larkeys?
•  What trait might disappear from the population
after five generations?
Inside the nucleus is
the inheritance
messenger, DNA.
(Deoxyribonucleic
acid). DNA molecules
are “huge” containing
millions of atoms.
In order to fit inside the
nucleus, they are coiled
and coiled again into
structures called
CHROMOSOMES - the
______________
structures that carry the
message of inheritance.
This drawing shows the
nucleus of a cell from
our animal, the larkey.
Notice that there are
eight chromosomes,
looking a little bit like
bent hot dogs of
different lengths.
If you look closely, you
will see that these two
chromosomes are the
same, these two are
the same, and so on.
Chromosomes always
come in pairs. So our
larkey actually has four
pairs of chromosomes
rather than eight
different ones.
Now look at the dark
areas. Both
chromosomes in a pair
have dark areas exactly
the same location. The
dark areas are called
alleles.
Note: Alleles are not really dark. The dark color is used to represent
the location of the alleles on the chromosomes
The two alleles on the paired
chromosomes work together.
Together they constitute a gene.
Summary
•  Nuclei contain chromosomes.
•  Chromosomes come in
almost identical pairs.
•  Chromosomes have specific
active locations called alleles.
•  The two alleles in identical
locations on paired
chromosomes constitute a
gene
A gene (two alleles working
together) controls a trait.
This gene could be the one that
determines the larkey’s eye
color, or perhaps the pattern of
its fur. Let’s say it determines
eye color.
The larkey has four features of
interest to us. Each feature is
controlled by one gene. Each of
the four genes is on a different
chromosome (although they could have
all been on the same chromosome).
The gene location for
appendages (legs) is these
two alleles on this pair of
chromosomes. The alleles
are labeled with the letter A
for appendages.
Find the gene locations
for eye color (letter E),
fur pattern (letter F), and
tail shape (T).
Notice that some of the
alleles are labeled with
uppercase letter and
some are lowercase
letters. Both upper and
lowercase letter Es are
alleles for eye color.
Alleles don’t all have
equal influence in
determining traits. Moreinfluential alleles are
dominant alleles, and
they are represented by
an uppercase letter.
Less-influential alleles
are called recessive
alleles, and they are
represented by a
lowercase letter.
The alleles are the code
that determines the traits
of the larkeys. The chart
at the bottom is the
genetic code for one of
the 32 larkeys we
viewed previously.
The alleles for legs is aa,
eye color = Ee, fur
pattern = FF, and tail
shape = tt;
The alleles for legs is aa,
eye color = Ee, fur
pattern = FF, and tail
shape = tt;
The combination of
alleles in an organism's
chromosomes is the
organism’s genotype.
The genotype lists the
paired alleles that are
particular to that
organism.
Let’s look at the
genotype of our larkey to
see what is dominant
and what is recessive.
•  Two recessive alleles
for leg length (aa)
•  One dominant and one
recessive allele for eye
color (Ee)
•  Two dominant alleles
for fur pattern (FF)
•  Two recessive alleles
for tail shape (tt).
The parents of a Larkey both have red eyes. Is it possible for
them to produce an offspring with grey eyes? In your
notebook use a Punnet Square to prove or disprove this grey
eye question. (The alleles for eyes are E or e.)
Mendel studied pea plant traits
such as: flower color, seed color,
and tall versus short
F1 generation were ALL TALL
but not all F2’s were tall!
Tt
Tt
Tt
Tt
Draw this Punnett
square
This generation
produces plants at a
rate of 3 tall for every 1
short.
2
3
1
1) By conducting careful
__ over many years,
Mendel made landmark
discoveries in__ and
established a new
science: __.
2) List three significant
variations observed by
Mendel regarding the
common garden pea
Pisum sativum.
3) How did Mendel obtain
pure breeding strains of
plants for a trait such as
plant height?
1) Experiments heredity,
genetics.
2) Color of seeds, color of
flowers, height of plants.
3) Mendel obtained pure
breeding strains for traits
such as plant height by
using self pollination over
several generations.
The parents of a Larkey both have red eyes. Is it possible for
them to produce an offspring with grey eyes? In your
notebook use a Punnet Square to prove or disprove this grey
eye question. (The alleles for eyes are E or e.)
The parents of a Larkey both have red eyes. Is it possible for
them to produce an offspring with grey eyes? In your
notebook use a Punnet Square to prove or disprove this grey
eye question. (The alleles for eyes are E or e.)
Female Ee
E
Male Ee
e
E
E E
E
e
E e
e e
e
WORD BANK (top)
chromosomes (2x)
dominant, DNA, genes,
genotype, nucleus, paired
alleles, phenotype,
recessive;
WORD BANK (bottom)
allele, chromosome,
gene, nucleus.
Top (in order)
nucleus, DNA,
chromosomes,
chromosomes, genes,
paired alleles, genotype,
phenotype, dominant,
recessive.
Bottom (in order)
chromosome, gene,
nucleus, allele
AA
Aa
Aa
aa
F1
F1
Aa
F1
Aa
F2
F2
aa
F3
AA
Aa
F2
aa
F3
AA
F3
AA
Aa
Aa
aa
F1
F1
Aa
F1
Aa
F2
F2
aa
F3
AA
Aa
F2
aa
F3
AA
F3
AA
Aa
Aa
aa
F1
F1
Aa
F1
Aa
F2
F2
aa
F3
AA
Aa
F2
aa
F3
AA
F3
AA
Aa
Aa
aa
F1
F1
Aa
F1
Aa
F2
F2
aa
F3
AA
Aa
F2
aa
F3
AA
F3
http://www.pbs.org/wgbh/evolution/library/03/4/l_034_04.html