Biology 9
Cell Reproduction Lab
(This exercise was adapted in part from activities developed by “The Biology Corner” and “The Biology Project”)
Objectives:
• To observe and understand the phases of the cell cycle and the time spent in each phase
• To observe and understand the phases of mitosis
• To observe and understand the phases of meiosis and to differentiate between the processes of oogenesis and
spermatogenesis
• To understand the use of karyotyping in the diagnosis of genetic disorders
Note that all the links for this lab are posted at the course website
PART 1: Cell Cycle
• Watch the animation “How the Cell Cycle Works” at http://highered.mcgrawhill.com/classware/ala.do?isbn=0072986867&alaid=ala_1013380&showSelfStudyTree=true
• State the event of each phase of the cell cycle below:
o G1 ________________________________________________________________________
o S ________________________________________________________________________
o G2 ________________________________________________________________________
o M ________________________________________________________________________
(for the M phase, be very precise and concise!)
PART 2: Mitosis
• Go to the “Cells Alive” website at http://www.cellsalive.com/.
• On the left side of the screen is a navigation bar. Click on the “Mitosis” link. Read the text on this page and
view the animation. You can slow down the video by clicking step by step through the phases.
• In which phase does each of the following events occur?
o Chromatin condenses into chromosomes: ______________________________________________________
o Chromosomes align in center of cell: _________________________________________________________
o Nuclear envelope breaks down: _____________________________________________________________
o Cell is cleaved into two new daughter cells: ___________________________________________________
o Daughter chromosomes arrive at the poles: ____________________________________________________
• Watch the video again carefully and answer the following questions. The colored chromosomes represent
chromatids. There are two chromatids of each color because they are exact duplicates of each other.
o How many chromosomes are visible at the beginning of mitosis? ___________________________________
o How many are in each daughter cell at the end of mitosis? ________________________________________
PART 3: Determining Time Spent in Different Phases of the Cell Cycle: Onion Root Tip
• Go to http://www.biology.arizona.edu/cell_bio/activities/cell_cycle/cell_cycle.html
• In this activity, you will be presented with cells from the tip of an onion root. You will classify each cell based on
what phase of the cell cycle it is in. At the end you will count up the cells found in each phase and use the
numbers to predict how much time a dividing cell spends in each phase. Assume your calculation is based on a
total cell cycle of 24 hours.
• Read the introduction then click the “next” button. You will have 36 cells to classify. When you’re finished,
record your data in the chart below.
Interphase
Prophase
Metaphase
Number of cells
Percent of cells*
*(calculate: number of cells divided by total cells x 100 )
Anaphase
Telophase
Total
36
100%
Did you forget a calculator - no problem. Go to www.calculator.com and click on the “fractions” calculator. A
window with a virtual calculator will open and you can do the math from there.
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PART 4: Meiosis
• Go to http://www.biology.arizona.edu/cell_bio/tutorials/meiosis/main.html for the meiosis tutorial. Read each
section under “Contents” on the left hand side of the screen and watch the Meiosis 1 and Meiosis 2 animations on
page three of the tutorial. The “Test Yourself” portion of the tutorial (page 5) is not required but is
recommended. Answer the following questions.
o What is the diploid chromosome number for humans? ___________________________________________
o The daughter cells resulting from meiosis are? haploid or diploid (circle the correct answer)
• Watch the Meiosis 1 and Meiosis 2 animations on the third page of the tutorial.
• Name the phase of MEIOSIS 1 where each of the following occurs. Be precise!
o Homologous chromosomes pair and form synapses: _____________________________________________
o Homologous chromosomes align at the center of the cell: ________________________________________
o Nuclear envelope reforms: __________________________________________________________
o Chromosomes move to separate poles: _______________________________________________________
o Do the chromosomes inherited from the mother or father have to stay together following meiosis 1? _______
• At the end of meiosis 2, each HUMAN cell contains how many chromosomes? __________________________
• Name TWO ways that meiosis contributes to genetic recombination or variation.
o ______________________________________________________________________________________
o ______________________________________________________________________________________
• Name TWO errors that can occur during meiosis.
o ______________________________________________________________________________________
o ______________________________________________________________________________________
PART 5: Gametogenesis
Gametogenesis is the formation of gametes (sex cells) through the process of meiosis. In humans and other
mammals, the gametes are sperm and eggs. Spermatogenesis produces sperm and oogenesis produces ooctyes
(eggs). Fertilization occurs when the nucleus of a sperm fuses with the nucleus of an egg.
• Go to http://www.kumc.edu/instruction/medicine/anatomy/histoweb/male/male.htm to view images of the testis
and the process of spermatogenesis. View images 3 and 8. Note the many circular structures. These are the
seminiferous tubules where sperm formation takes place.
o View images 4, 5, and 7. Find mature sperm in the lumen of a tubule.
o The process of spermatogenesis involves meiosis 1 and meiosis 2. One primary spermatocyte undergoing
spermatogenesis results in the formation of how many sperm? _____________________________________
• Go to http://embryology.med.unsw.edu.au/medicine/BGDlab3_3.htm to view images of the ovary and the
process of oogenesis. Scroll down the page. View the graph that shows the changes in the number of oocytes
with age.
o Continue to scroll down the page. Observe the cross-section of the whole ovary (cat).
o Scroll down and view the remaining high power images showing follicles in various stages of development.
Look for a large, fluid-filled vesicular (Graafian) follicle, which contains a mature secondary oocyte located
at one side of the follicle. The vesicular follicle are generally next to the outer surface of the ovary because
this type of follicle releases the egg during ovulation.
o How does the number of vesicular follicles compare with the number of sperm cells you observed in the
previous images of the seminiferous tubules of the testis? _________________________________________
o The process of oogenesis involves meiosis 1 and meiosis 2. One primary oocyte undergoing oogenesis will
result in the formation of how many eggs? _____________________________________________________
PART 6: Karyotyping Activity
• Karyotyping is one of many techniques that allow us to look for several thousand possible genetic diseases in
humans. In this activity, you will use a computer model to look at chromosomes and prepare a karyotype. You
will evaluate three patients' case histories, complete their karyotypes, and diagnose their disorders based on any
missing or extra chromosomes.
• Go to http://www.biology.arizona.edu/human_bio/activities/karyotyping/karyotyping.html and read the
background information and instructions.
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Click on “Patient Histories” and follow the directions to read and assess the patient histories. You will complete
a karyotype for Patient A, B, and C and answer the following questions.
Patient A - Click on the link to "Complete Patient A's Karyotype". Match the chromosomes to their homologs.
After all the matches are complete you'll analyze the patient’s karyotype and provide a diagnosis. Scroll down
the page to view the completed karyotype.
o What is Patient A's history (summarize)? ______________________________________________________
_______________________________________________________________________________________
o How many total chromosomes are in the karyotype? ____________________________________________
o The last set of chromosomes is the sex chromosomes, if you have two large chromosomes, your patient is
XX (female), one large and one small indicates and XY (male). What sex chromosomes does the patient
have? __________________________________________________________________________________
o Which chromosome set has an extra? _________________________________________________________
o What notation would you use to characterize Patient A's karyotype? ________________________________
o What diagnosis would you give this patient (what disease)? _______________________________________
Patient B - Click on the link to go to Patient B and repeat the above process.
o What is Patient B's history (summarize)? ______________________________________________________
_______________________________________________________________________________________
o How many total chromosomes are in the karyotype? ____________________________________________
o What sex chromosomes does the patient have? _________________________________________________
o Which chromosome set has an extra? _________________________________________________________
o What notation would you use to characterize Patient B's karyotype? ________________________________
o What diagnosis would you give this patient (what disease)? _______________________________________
Patient C - Click on the link to go to Patient C and repeat the above process.
o What is Patient C's history (summarize)? ______________________________________________________
_______________________________________________________________________________________
o How many total chromosomes are in the karyotype? ____________________________________________
o What sex chromosomes does the patient have? _________________________________________________
o Which chromosome set has an extra? _________________________________________________________
o Write out the correct notation for this karyotype: _______________________________________________
o What diagnosis would you give this patient (what disease)? _______________________________________
o Name FOUR manifestations of this syndrome? You need to look it up. Be sure to also look up any terms
you do not understand.
_______________________________________________________________________________________
_______________________________________________________________________________________
_______________________________________________________________________________________
_______________________________________________________________________________________
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