Using homework and pg 108-109, fill-in the following chart
Asexual Reproduction:
II. When one parent passes a ________ copy of its genetic information to each offspring.
The offspring produces from the parent are _________ identical to the parent.
Often times we refer to this ability as cloning.
Examples of this include:
 Bacteria (Prokaryotes) : _____________ _______________
 Hydra- ____________
 Starfish- ____________
 Potatoes- ____________
Sexual Reproduction:
III. Two parents give genetics material to produce offspring that are ____________ from
their parents.
 Each parent produces ___________ cells called __________.
 Through a process called ___________, a female gamete (_______) from on
parent fuses with a male gamete (________) from the other parent to form a
zygote.
 Because each parent gives genetic material, the offspring is not identical to either
parent (as each offspring has its own _________ version of chromosomes/DNA).
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Your body has different kinds of cells!
Now, think back to Section 1 of Chapter 10, when we began talking about mitosis.
Question number 2 (which was everyone’s favorite question!) outlined how chromosomes
are formed. In the space below, fill in the blanks to refresh.
Key: Sister chromatids, string of nucleosomes coil to form a fiber histones, DNA wraps
around a histone to form nucleosome, condensed chromosome is formed making itself
visible during cell division, fiber loops and condenses.
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Chromosomes:
DNA+ histone proteins = packaged DNA (coils and ______).
Each chromosome contains ________ of genes.



A _____ is a section of a chromosome that ________ for the production of a specific
protein.
Examples: eye color genes, ear lobe genes, hair color genes, height genes
Organisms’ physical ___________ are the result of proteins that are produced within
the cells of that organism.
 Chromosomes (carry genes)  code for Proteins  Exhibit Traits/Characteristics
Different _________ have different chromosomes and different #’s of chromosomes
(see example chart)
Just because you
perceive an
organism to be
more complex,
does not mean it
necessarily has
more
chromosomes!
Haploid vs. Diploid
Think back to the section on mitosis, and fill in the following
chart using the human gene number.
Human exampleMother’s egg ( ___ chromosomes)
 22 autosomal chromosomes
Define autosomal:
 1 sex chromosome:
Father’s sperm (___ chromosomes)
 22 autosomal chromosomes
 1 sex chromosome
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When during reproduction, when the fusing occurs, the final equation is:
 Egg (____ chromsomes) + Sperm (___ chromosomes) = Zygote (___ chromosomes)
It doesn’t stop there! We have homologous chromosomes that form pairs!
From the equation above, notice that both mom and dad donate their chromosomes. They
are both human beings (obviously), so the chromosomes must be similar in shape and the
genes they possess. Therefore, these chromosomes are ______ up to form a homologous
pair.
Homologous= ____________ , Humans have ___ pairs of homologous chromosomes
Why do we do this?
• Scientists have taken mom’s chromosome 1 and paired it with dad’s chromosome 1.
• They do this because they code for the same trait.
Example: chromosome 1 contains a gene that codes for you brain size. This is
contributed both from mom and dad (I am eternally grateful to my parents for making me
so smart!).
Notice that 22 of the 23 chromosomes are of a similar size and shape. Yet, there seems to
be one outlier. What kind of chromosome is that? _________________
•
When chromosomes are in pairs, such as in the karyotype above, we refer that as
Diploid (2n)
– Cells containing __ sets of each type of chromosomes (1-23)
– In humans, 2n=46
• Haploid (n)
– Cells contain only __ set of each, contributing by a single parent
– In humans, n =23
– In humans, only sex cells are haploid (all other cells are diploid)
Thought: Are they cells produced after mitosis haploid or diploid? _________
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Oogenesis:
Through the process of meiosis (which we will get to eventually), an egg is formed. This
egg is referred to as a ____ cell, or a ______. This process of creating an egg in female
hosts is referred to as oogenesis.
Spermatogenesis:
Through the same process of meiosis, a male forms sex cells, but they are of a different
size and function. The process of creating sperm in a male host is referred to as
spermatogenesis.
Spermatogenesis
Oogenesis
With a partner, fill out the following flow chart.
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Word Bank (some boxes with have more than one in each): Sperm, egg, 1N, 2N, gamete,
zygote, fertilization, mitosis.
Mitosis Review: With a partner, fill in the corresponding boxes of mitosis. Draw
pictures of cell with chromosome movement.
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Mitosis  Meiosis
 Mitosis makes EXACT copies. This is not quite the case for meiosis…
•
•
•
•
•
•
•
We talked earlier about haploid and diploid cells.
Skin cells are an example of (haploid or diploid) cells.
Cells involved in reproduction are examples of (haploid or diploid) cells.
Since germ cells are haploid, mitosis cannot be how the cell reproduces. Since
haploid means that there is only _____ the chromosomal information present.
Another process must be occurring.
This process is referred to as_________. It is very similar to mitosis in many
ways, but there are ___ rounds of division instead of just one.
Meiosis is necessary to reduce the chromosome count to half of its original
number.
46/2=
2n
n=
23
Meiosis
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Meiosis-cell division that _________the # of chromosomes in half - diploid(__) to
haploid(__).
 Meiosis 1- ______with a diploid cell, ______ with 2 diploid cells.

 Prophase 1-chromosomes _________, nuclear envelope disappears
 Metaphase 1-Homologous chromosomes line up ____________along the nuclear
equator
 Anaphase 1-Homologous _______________move to opposite poles
 Telophase 1-Chromosomes reach the poles and the __________begins to divide.
Review quiz:
http://www.biologycorner.com/quiz/qz_meiosis.html
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 Prophase II- A new ________ forms around the chromosomes.
\
 Metaphase II- Chromosomes line up at the ____________.
 Anaphase II- Centromeres divide and _____________move to opposite poles.
 Telophase II- A new ________ __________ forms around each set of
chromosomes, the cells divide.
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Genetic Variation:
 If there was not genetic variation in human beings, we would all be identical. The
term be yourself would not really mean anything, WE WOULD ALL BE THE
SAME!
 Thankfully, nature took care of that for us, and gave our cells a couple of ways to
encourage genetic variability (variety).
 Crossing Over:
 During __________, homologous chromosomes line up next to each other.
Each chromosome is made of 2 _______ ___________ attached a centromere.
 Crossing over occurs when one “arm” of the sister chromatid crosses over the
other sister chromatid.
 The chromosomes break at the point of the crossover, reforms, and resumes
meiosis.
 The chromosome is reformed with a piece from the other chromosome, thus
NO LONGER BEING ___________.
 Independent Assortment
 During ____________, homologous pairs of chromosomes line up at the
equator of the cell.
 The pairs can then line up in either of two equally probable ways.
 In humans, each gamete receives one chromosome from each of the __ pairs
of homologous chromosomes.
 Each pair separates independently, therefore there are over 223 different
possibilities!
 Random Fertilization
 Fertilization is a random process that adds _________ variation.
 The ________ formation is made by the joining of a mother’s gamete (___)
and a father’s gamete (________).
 Due to the random nature, the possible outcomes is squared! Therefore, 223 x
223 = over 70 TRILLION combinations! (Aren’t you happy you beat the
odds?)
 Nondisjunction:
 When issues during cell division occurs, bad things can happen to the organism.
 These are __________, and the occurrence varies dependent on the condition.
 One of the more common chromosomal mutations that occur is the failure of
chromosomes to separate properly during meiosis I and II.
 This is evident at the 21st chromosome, as there is no longer a pair (2), but __
chromosomes.
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