Ms.Sastry1
Leigh High School
AP LAB # 3: MITOSIS AND MEIOSIS
Website to go for quizzes and activities: Print out the quizzes for mitosis and meiosis
OVERVIEW
Exercise 3A is a study of mitosis. You will simulate the stages of mitosis by using chromosome models.You will use prepared slides of onion root tips to study plant mitosis and to calculate the relative duration of the phases of mitosis in the meristem of root tissue. Prepared slides of the whitefish blastula will be used to study mitosis in animal cells and to compare animal mitosis and plant mitosis.
Exercise 3B is a study of meiosis. You will simulate the stages of meiosis by using chromosome models. You will study the crossing over and recombination that occurs during meiosis. You will observe the arrangements of ascospores in the asci from a cross between wild type and mutants for tan spore coat color in the fungus Sordaria fimicola. These arrangements will be used to estimate the percentage of crossing over that occurs between the centromere and the gene that controls that tan spore color.
OBJECTIVES
Section A: Before doing this laboratory you should understand:
* the key mechanical and genetic differences between meiosis and mitosis
* the events of mitosis in animal and plant cells
* the events of meiosis (gametogenesis) in animal and plant cells
Section B: After doing this laboratory you should be able to:
* recognize the stages of mitosis in a plant or animal cell
* calculate the relative duration of the cell cycle stages
* describe how independent assortment and crossing over can generate genetic variation among the products of meiosis
* use chromosome models to demonstrate the activity of chromosomes during Meiosis I and Meiosis II
* relate chromosome activity to Mendelian segregation and independent assortment
* calculate the map distance of a particular gene from a chromosome's center for between two genes using an organism of your choice in a controlled experiment
* demonstrate the role of meiosis in the formation of gametes using an organism of your choice, in a controlled experiment
* compare and contrast the results of meiosis and mitosis in plant cells
* compare and contrast the results of meiosis and mitosis in animal cells
PART 1: Identify the contents of the bag: 2 ‘homologous chromosomes’ (with 2 yellow sister chromatids that are connected at the centromere and 2 red sister chromatids that are connected at the centromere); 2 centrioles; spindle fibers (pole to kinetochore) – 4 threads.
1)Bead simulation: follow the procedure outlined in handout. Utilizing the beads, simulate stages of the cell cycle starting with interphase and ending with telophase.
2)As you simulate the stages, draw the beads as you see them in the different stages – be sure to color them in!
3)Label (use a text when necessary) – centrioles, sister chromatids, spindle apparatus, microtubule, metaphase plate, kinetochores, centromere, centrosome, actin microfilament in cleavage furrow (if you could see them where will they be?)
4)Did you simulate mitosis in an animal cell or plant cell – why? (Hint - 2 reasons)
5)What happened to the diploid condition of your parent cell – was it preserved in the daughter cell or not? How do you know?
PART 2: Microscope drawings of Onion root tip cells (plant cell) and Whitefish
blastula (animal cell). The Onion root tip will like this under low power – find
the root tip and ‘zoom” in using the 40x objective lens.
All stages will be found in this one slide of the onion root tip.
The whitefish blastula slides are a little more difficult to work with and see stages.
Use a website to help you draw the animal cell stages.
Draw (please no cut and paste work!) the different stages in a ‘T’ table (example below).
PART 3: How many cells in each stage:
Take one view of the Onion root tip and count how many cells you see for each stage (you have to see ALL stages – ‘0’ is not an option – switch views if you cannot find all stages).
1) Make a pie chart – and figure out if 360O of the piechart represented 24 hours – 1440 min. how long did the cell spend in each phase? (Interphase to cytokinesis).
2) Why are onion root tip and whitefish blastula areas that are ideal to view mitosis?
PART 4: Meiosis bead simulation:
a)As before follow instructions in the handout and draw pictures for each stage of Meiosis I an Meiosis II – color!
b)Label: Homologous chromososmes, sister chromatids, nonsister chromatids, chiasmata, synapsis, tetrad, centrioles, centromere, centrosome, metaphase plate, spindle fibers, microtubules, germ cell, gamete cells
c)If this process simulated oogenesis – what would the products be (hint: how many ova, how many polar bodies) and why?
d)If this process was spematogenesis – how many gametes would be produced?
e)What happened to the diploid condition of your parent cell – was it preserved in the daughter cell or not? How do you know?
f)Compare your drawings of Mitosis and Meiosis bead simulation in a T table– highlight differences.
PART 5: Go to the lab bench website and complete the Meiosis Sordoria activity and attach quiz.
More Practice for Sordaria counts –
2) What is the map distance between the spore color genes and the centromere in Sordaria – show your calculations; use the picture below: