MitosisinAnimalandPlantCells – Observe the prepared slide of the whitefishblastula

MitosisandMeiosis

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OBSERVATIONS

Exercise 1:
MitosisinAnimalandPlantCells
PROCEDURE

1. Observe
the prepared slide of the whitefishblastula
under the microscope.

2. Drawcells
thatrepresentthevarious
stagesofmitosis:Interphase,
Prophase,Metaphase, Anaphase, and Telophase. Place your drawings here:

3. Foreachdrawing,labelthepartsofthecellsthatyoucanidentify suchasthenuclear
membrane,chromosomes,cellular
membrane,cytoplasm,spindlefibers,
chromatids, cleavagefurrowformation duringCytokinesis,
andcentrioles.Itisunlikelythatyouwillfind all of these structures. Why?

4. Observe
the slide of the onion root tipunder the microscope.

5. Drawcellsthatrepresentthevarious
stagesofmitosis:Interphase,
Prophase,Metaphase, Anaphase and Telophase. Place your
drawings
here:

6. Label
thepartsofthecells
thatyoucanidentifysuchasthenuclear
membrane,chromosomes,
cellularmembrane,cytoplasm,spindle
fibers, chromatids,
cellwallformationregion,and centrioles.
It it is unlikely that you
will findall of these structures.
Why?

RESULTS

Forboththewhitefish
andtheonion,whatisthe2nnumberofchromosomesthatwereobserved?
Hint:separate
chromosomes are easiest to view
and count during Prometaphase.

QUESTIONS

A. What
is the purpose of mitosis?

B. What
other term is commonly used in place of “mitosis”?

C. What
is a blastula?

D. What
are the differencesin the mitoticprocesses between animal and plant cells?

E. Whymighttherebemoremitoticdivisioninanonionroottipthaninotherareasoftheplant?

F.
Asummaryofmitosis–fillinthecorrectanswer.Thenucleusintheundivided
cellhasthe diploid(2n)numberofchromosomes,andthenuclei
inthetwosplitcellsalsohave numberofchromosomes.Inmitosis,thechromosomenumber(checkthecorrectchoice) stays
thesameor halves.

Exercise 2:
MeiosisinAnimals
QUESTIONS

A. Which organ,
the ovary or the testes,
contained the greater number of gametes? B.
What
may be a reason for this?

Exercise 3:
SimulatingMeiosis
QUESTIONS

A. What
does mitosis accomplish?

B. When and where does mitosis occur?

C. What
does meiosis accomplish?

D. When and where does meiosis occur?

E. How
do these two processes differ?

F. How do Prophase
in Mitosis and Prophase I in Meiosis differ?

G.
Does
Meiosis occur anywhere
else in the body beside within the gonads?

H.
Howdoesmeiosis
conferadvantagestoanorganism
whencomparedtoasexualreproduction
such as budding?

I. How
might crossing-over be a benefit to an organism?

J. How might
crossing-over be detrimental to
an organism?

K. Crossing
over
can also occur during mitosis where
chromosomes exchange segments.
Is crossingover more
advantageoustoorganismsurvivalifitoccurs
duringmitosisor meiosis?
Explain.

LABORATORYSUMMARY

What have you
learned from doing this laboratory?