Download Science Notebook Chapter 10

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Date
Mendel and Meiosis
Section 10.1 Mendel’s Laws of Heredity
Main Idea
Details
Skim Section 1 of your book, write three questions that come to mind
from reading the headings and illustration captions.
1. Accept all reasonable responses.
2.
3.
allele
Use terms in the left margin to complete the paragraph below.
Genetics is the branch of biology that studies heredity , which is
fertilization
the passing on of characteristics, known as traits , from parents to
gamete
offspring. Male and female sex cells, called gametes , unite during
genetics
heredity
hybrid
law of independent
assortment
law of segregation
pollination
trait
zygote
fertilization (which is called pollination in plants) to form a fertil-
ized cell, called a zygote . Hybrid offspring result from parents that
have different forms of alleles for certain traits. Mendel’s law of
segregation states that every individual has two alleles of each
gene and when gametes are produced, each gamete receives one of
these alleles. Mendel’s law of independent assortment states that
genes for different traits are inherited independently of each other.
Compare and contrast each pair of terms by defining them
and/or noting their differences.
Accept all reasonable responses.
dominant
dominant trait
recessive trait
genotype
an observed trait that masks
the recessive form of a trait
trait that can be observed if the
dominant trait is not present
genotype
phenotype
the allele combination an
organism behaves, contains
the way an organism looks
and regardless of its genes
heterozygous
homozygous
phenotype
recessive
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homozygous
heterozygous
an organism’s two alleles
for a trait are the same
an organism’s two alleles
for a trait are different
Mendel’s Laws of Heredity
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
New
Vocabulary
Name
Date
Section 10.1 Mendel’s Laws of Heredity
Main Idea
Why Mendel
Succeeded
I found this information
on page
.
SE, pp. 253–254
RE, p. 100
(continued)
Details
Describe how a plant self-pollinates.
A plant self-pollinates when its male and female gametes come from the
same plant. Its own male sex cells pollinate its own female sex cells.
Describe how Mendel cross-pollinated pea plants. Why did
Mendel use this technique to study inheritance?
Mendel opened the petals of a flower and removed the male reproductive
organs. He then dusted the female reproductive organ with pollen from the
plant he wished to cross it with. The seeds that develop from crosspollination have traits of both plants. He did this so he could be sure of
the parents in his cross.
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
Mendel’s
Monohybrid
Crosses
I found this information
on page
.
SE, pp. 255–257
RE, pp. 101-102
Summarize Mendel’s first experiment.
Mendel crossed: two true-breeding plants.
He controlled variables by: studying just one trait at a time.
The first trait he studied: height.
Results: When a six-ft-tall plant was crossed with a less than
two-ft-tall plant, all offspring were 6 ft tall.
When the offspring were allowed to self-pollinate:
Three-fourths
of the plants were tall, and one-fourth of the plants were short.
The dominant allele was: tall.
The recessive allele was: short.
The number of monohybrid crosses he eventually tried:
7
His conclusion: Each organism has two alleles for each trait.
Phenotypes and
Genotypes
I found this information
on page
.
SE, p. 258
RE, p. 103
Compare genotypes and phenotypes for pea plants.
genotype
phenotype
TT
homozygous or
heterozygous
homozygous
Tt
heterozygous
tall plant
tt
homozygous
short plant
tall plant
Mendel and Meiosis
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Name
Date
Section 10.1 Mendel’s Laws of Heredity
Main Idea
Mendel’s Dihybrid
Crosses
I found this information
on page
.
SE, pp. 259–260
RE, p. 103
(continued)
Details
Demonstrate the law of independent assortment by listing the four
alleles that are produced when a pea plant with the genotype RrYy
produces gametes.
1.
R
2.
Y
3.
r
4.
y
List two things that can be predicted by a Punnett square.
possible genotypes of offspring
probable proportions of each genotype
Punnett Squares,
Probability
I found this information
on page
.
SE, pp. 260–262
RE, p. 105
Complete the Punnett squares for height in the F1 and F2 generations. Write the expected genotypes and the probability for each.
F1
F2
T T
T
t
Tt 100%
TT 25%
t Tt Tt
T TT Tt
t Tt Tt
t Tt tt
Tt 50%
Identify the locations, within the Punnet square showing Mendel’s
F2 dihybrid results, of genotypes that satisfy each description.
RY ry Ry rY
RY
A
B
C
D
ry
E
F
G
H
Ry
I
J
K
L
rY
M
N
O
P
1. peas with only dominant alleles A
2. green peas F, G, J, K
3. wrinkled yellow peas H, N, P
4. round green peas G, J, K
5. peas with only recessive alleles F
6. round peas A, B, C, D, E, G, I, J, K, L, M, O
7. homozygous for color A, D, F, G, J, K, M, P
8. heterozygous for roundness B, D, E, G, J, L, M, O
R EAL-W ORLD CONNECTION
Discuss the effects of Mendel’s two laws
(segregation and independent assortment). Give an example. Accept all reasonable responses.
The law of segregation states that every individual has two alleles of each gene and each gamete receives one of these
alleles. The law of independent assortment states that genes for different traits are inherited independently of each other.
For example, when a pea plant with the genotype RrYy produces gametes, the alleles R and r will seperate from each other
as well as from the alleles Y and y. Every individual is a unique combination of the traits of its parents.
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Mendel’s Laws of Heredity
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
tt 25%
Name
Date
Mendel and Meiosis
Section 10.2 Meiosis
Main Idea
Details
Organize Information As you read Section 2, list the ways in
which meiosis explains Mendel’s results.
Accept all reasonable responses. Sample response: Meiosis produces haploid
cells which each have one allele of each gene. Chromosomes follow the law of
independent assortment. Genes for traits can be seen now with microscopes.
Review
Vocabulary
mitosis
Use your text to define the following term.
period of nuclear cell division in which two daughter cells are
formed, each containing a complete set of chromosomes
New
Vocabulary
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
crossing over
Use the terms in the left margin to complete the graphic organizer
below.
diploid
A first step in sexual reproduction occurs when
egg
a diploid cell with homologous chromosomes,
or two of each pair, undergoes meiosis
genetic recombination
haploid
homologous
chromosome
which produces four cells containing
half the number of chromosomes,
haploid cells, called
meiosis
egg
nondisjunction
and
sperm .
sexual reproduction
sperm
Describe three things that can happen to homologous chromosomes
during meiosis. Accept all reasonable responses.
crossing over
genetic recombination nondisjunction
What happens
non-sister chromatids
reassortment of
from homologous
chromosomes and genetic
chromosomes break and information during meiosis
exchange genetic material
failure of homologous
chromosomes to separate
properly during meiosis
Results in
new combinations
of alleles on a
chromosome
gametes with too many or
too few chromosomes
variation among
organisms
Mendel and Meiosis
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Name
Date
Main Idea
Genes,
Chromosomes,
and Numbers
I found this information
on page
.
(continued)
Details
Summarize at least six pieces of information about chromosomes
by creating a concept map below.
Accept all reasonable responses.
Sample concept map:
thousand or
more genes
lined up
SE, pp. 263–265
RE, p. 108
one of each
chromosome
one from each
parent gamete
haploid cell
gametes
The Phases of
Meiosis
I found this information
on page
.
SE, pp. 266–269
RE, p. 109
similar to those in the text.
Sketch
Description
Prophase I
Metaphase I
centromere
attaches to
spindle fiber,
pulls
chromosomes to
center of cell,
lines up tetrads
Anaphase I
chromosomes
move apart from
each other
toward “poles”
of cell
Telophase I
spindle is broken
down,
chromosomes
uncoil, cytoplasm
divides
Meiosis
diploid cell
Compare and contrast the phases of Meiosis I and Meiosis II.
Sketch each phase. Accept all reasonable responses. Sketches should be
DNA of
chromosomes
coil up, pair up
with homologous
chromosomes,
spindle forms
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two of each
Sketch
Description
Compare and
Contrast
Prophase II
a spindle forms
in each of the
new cells and
chromosomes
are pulled to
center of cell
in Prophase II, the
chromosomes are
already coiled
Metaphase II
chromosomes
line up randomly
at center of cell
Metaphase I is more
organized
Anaphase II
centromere of
each
chromosome
splits, sister
chromatids move
to opposite poles
of cell
Anaphase II is
forming two haploid
cells, Anaphase I
forms two diploid
cells
Telophase II
nuclei re-form,
spindle breaks
down, cytoplasm
divides
in Telophase II,
haploid cells are
formed, in
Telophase I, diploid
cells are formed
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
Section 10.2 Meiosis
Name
Date
Section 10.2 Meiosis
Main Idea
The Phases of
Meiosis
I found this information
on page
.
SE, pp. 266–269
RE, p. 109
(continued)
Details
Identify the phase of meiosis when crossing over may occur.
Describe the process.
During Prophase I, the two sister chromatids in a tetrad pair tightly.
Non-sister chromatids from homologous chromosomes break off
and change places.
Meiosis Provides
for Genetic
Variation
List two factors that increase genetic variation. Name the process.
I found this information
on page
.
2. crossing over
SE, pp. 269–270
RE, p. 111
Nondisjunction
1. cell division
Process: genetic recombination
Identify an advantage and a disadvantage of nondisjunction.
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
I found this information
on page
.
SE, p. 271
RE, p. 111
Gene Linkage
and Maps
I found this information
on page
.
SE, pp. 272–273
RE, p. 111
Advantage
Disadvantage
Plants with more than the normal Organisms lacking one or
number of chromosomes
more chromosomes often
produce flowers and fruits that
do not survive.
are often larger than normal and
the plant is healthier.
Explain gene linkage by completing the paragraph below.
• chromosomes
• farther
• inherited
• crossing over
• genes
• linked
• sequence
Genes close together on the same chromosome are usually linked .
Linked genes are usually inherited together.
not
individual genes
Chromosomes
,
, follow Mendel’s law of independent
assortment. Linked genes might become separated, as a result of
crossing over
genes are
the
farther
. Crossing over is more likely to happen if
apart on a chromosome. Scientists use
frequencies of new gene combinations
relative locations of the genes
to map the
on a chromosome.
Mendel and Meiosis
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