Meiosis and Reproduction Notes:
Paste the following pages into your IntNB. You will need to paste the odd numbered
pages into the left side of your IntNB and the even numbered pages into the right side.
Warm-up:
Humans have 46 chromosomes in all of their body cells. The first cell of the organism is
made by joining egg and sperm.
1. How many chromosomes in a human egg or sperm cell? Explain.
__________________________________________________________________
__________________________________________________________________
__________________________________________________________________
2. Can cell division by mitosis (duplication of cells) produce egg or sperm? Explain.
__________________________________________________________________
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Meiosis and Sexual Reproduction:
Asexual Reproduction
What is Asexual
Reproduction?
Called _________________ reproduction in plants
•
A form of duplication using only ____________.
–
Example: _________________________
_________________________________
What are the limitations of
asexual reproduction?
Produces only genetically ___________________
offspring since all divisions are by mitosis.
•
Offspring called
meaning that each
is an exact copy of the original organism
•
This method of reproduction is __________ and
effective allowing the spread of an organism
–
•
Example: _________________________
Since the offspring are identical, there is no
mechanism for introducing
•
What are some specific
examples of asexual
reproduction?
______ .
In prokaryotes and some one-celled eukaryotes, cells
undergo ____________ _____________
•
Hydra reproduce by _______________
•
Planaria reproduce by ____________________
•
Several plants reproduce through _______________
reproduction.
–
Most of these organisms can reproduce
_______________ as well.
Understanding haploid and diploid
If N=2, 2N would look like:
1. Draw the chromosomes in a diploid cell of an organism where N=3.
2. How many combinations of haploid (eggs or sperm) cells are possible if N=2?
Draw the possible combinations.
3. How many combinations of haploid cells are possible if N=3?
Draw the possible combinations.
Sexual Reproduction
Why do organisms have sex?
Sexual reproduction increases ______________ by
producing new ______________ combinations.
What does sexual
reproduction consist of?
1. ______________: Formation of two haploid sex
cells (or _______________).
•
Meiosis is a process to convert a ________ cell
to a ________ gamete, and cause a change in the
genetic information to increase diversity in the
offspring.
•
In humans, meiosis only occurs in the ________
–
Spermatogenesis: In the ___________
(in males)
–
Oogenesis: In the _________________
(in females)
2. Fertilization: Combination of genetic information
from two separate cells that have one ________ the
original genetic information.
Where do gametes come
from?
•
______________ for fertilization usually come from
separate parents
o Female produces an ___________
o Male produces _____________
What are is the ploidy levels
of gametes?
•
Both gametes are haploid (1__), with a single set of
____________________ .
What happens when two
gametes combine?
•
The new individual is called a _____________, with
two sets of chromosomes (____________ or 2___).
•
Once the zygote begins to divide, it is called an
_________________.
What is the name for the way these chromosomes are organized? ___________________
Circle the sex chromosomes. What is the gender of this person? ____________________
Chromosomes and Karyotypes
How many chromosomes do
humans have?
Humans have ______ chromosomes.
What are some characteristics
of chromosomes?
•
There is a __________ set for humans; __n = 46
•
There are two types:
1. ______________ (#1 – 22)
2. _______ Chromosomes (#____)
What are some characteristics
of autosomes?
•
______________ chromosomes
•
Humans have _____ sets of 2.
o One from each parent
What are some characteristics
of sex chromosomes?
•
Humans have 1 set of ____.
•
Female sex chromosomes are
___________________ (X__)
•
Male sex chromosomes are
_____________________(X__)
What can Chromosomes tell
us?
Scientists can organize chromosomes in a cell into a
________________.
In a karyotype, chromosomes are arranged in order of:
1. _____________
2. _____________ _________________
3. ___________________ ______________
Meiosis is often called
/
Meiosis can be broken up into two phases:
and
.
Meiosis I:
Prophase I is much like the prophase of mitosis:
1.
___________________________________________
2. _______________________________________
_________________________________________
3. ______________________________________
_________________________________________
However, unlike mitosis, where the chromosomes
of a homologous pair are randomly scattered within
the nucleus, in meiosis, 1. ________________________
_____________________________________________________
2. ___________________________________________________________________
______________________________________________________________________
Metaphase I
Anaphase I
Telophase I
Metaphase I:
metaphase plate.
Microtubules are attached to the
align at the
.
Anaphase I: Homologous pairs separate with
remaining together.
Telophase I: Two daughter cells are formed with each daughter containing only one
of the homologous pair.
Each daughter cell is now
.
Meiosis II:
formation
Prophase II:
does not replicate, this is just like mitotic prophase.
Metaphase II: Chromosomes align at the
Anaphase II:
separately to each pole.
Telophase II: Cell division is complete.
daughter cells are obtained.
divide and sister chromatids migrate