Procedure: You will be given a slide of Allium, which is an onion root tip. Growth occurs when cells divide, so the root tips should have several cells in the process of cell division. View the root tip under the microscope and search for organized blocks of cells where nuclei are plainly visible. Most activity will be occurring at the tip of the root. Move the slide around until you find a good spot that shows the cells in various stages of mitosis. Cells of the onion are growing so it is easy to find cells in various stages of mitosis.
The majority of the cells in your specimen were in which stage of the cell cycle? In allium, interphase lasts about 15 hours, and mitosis takes up 80 minutes. Assuming that each stage of mitosis takes the same amount of time, how many hours old is a cell that is just starting anaphase.
Yes, you'll need to do some algebra here - show your work 80 minutes means that each of the four stages PMAT takes 20 minutes. When a cell is just starting anaphase, it has already gone through prophase and metaphase, so it is 40 minutes old. Sketch one cell in any stage of mitosis. Label the stage and label any cell structures that are visible. The spindle fibers and chromosomes should be visible. Which stage of mitosis is the easiest in your opinion to see on the slide? What about it makes it easy to identify?
Answers vary, the majority of cells are in interphase, but you can usually find one or two in the other stages.Introduction There are two types of nuclear division, mitosis and meiosis. Mitosis is the first of these studied in this lab.
It is easily observed in cells that are growing at a rapid pace such as whitefish blastula or onion root tips, which are used in this lab. The root tips contain an area called the apical meristem that has the highest percentage of cells undergoing mitosis. The whitefish blastula is formed directly after the egg is fertilized. This is a period of rapid growth and numerous cellular divisions where mitosis can be observed. Just before mitosis the cell is in interphase.Mitosis and Meiosis Simulation
In this part of the cell cycle the cell will have a distinct nucleus and nucleoli where the thin threads of chromatin are duplicated. After duplication the cell is ready to begin mitosis and its starts with a step called prophase. In prophase, the chromatin thicken into distinct chromosomes and the nuclear envelope breaks open releasing them into the cytoplasm.
The first signs of the spindle begin to appear. Next the cell begins metaphase, where the spindle attaches to the centromere of each chromosome and moves them to the same level in the middle of the cell.
This level position is called the metaphase plate. Anaphase begins when the chromatids are separated and pulled to opposite poles. Then, the final stage is telophase. The nuclear envelope is reformed and the chromosomes gradually uncoil. Cytokinesis may occur, in which case, a cleavage furrow will form and the two daughter cells will separate. Meiosis is more complex and involves two nuclear divisions. The two divisions are called Meiosis I and Meiosis II and they result in the production of four haploid gametes.
This process allows increased genetic variation due to crossing over where genes can be exchanged. The process, like mitosis, depends on interphase to replicate the DNA. Meiosis begins with Prophase I. In this stage, homologous chromosomes move together to form a tetrad and synapsis begins. This is where crossing over occurs resulting in the recombination of genes. Metaphase I moves the tetrads to the metaphase plate in the middle of the cell, and Anaphase I reduces the tetrads to their original two stranded form and moves them to opposite poles.
Telophase I then prepares the cell for its second division. Meiosis II generally resembles mitosis except that the daughter cells are haploid instead of diploid. DNA replication does not occur in Interphase II, and prophase, metaphase, anaphase, and telophase occur as usual.
The only change is the number of chromosomes. The process of crossing over can be easily studied in Sordaria fimicola, an ascomycete fungus.We've moved! Formerly at Bryn Mawr College, Serendip is now an independent site partnering with faculty at multiple colleges and universities around the world.
Please update your bookmarks, and happy exploring. In this hands-on, minds-on activity, students use model chromosomes and answer analysis and discussion questions to learn about the processes of meiosis and fertilization. To learn how meiosis contributes to genetic variation, students analyze the results of crossing over and independent assortment. Students also compare and contrast meiosis and mitosis, and they learn how a mistake in meiosis can result in Down syndrome or death of an embryo.
This activity can be used to introduce meiosis and fertilization or to review these processes. The Teacher Preparation Notes provide instructional suggestions and background information and explain how this activity is aligned with the Next Generation Science Standards. In addition to the more complete Student Handout described above, we offer a shorter version of the Student Handout in the attachments below. This version omits the modeling and analysis of independent assortment, but includes a section on asexual vs.
If you would prefer to send your comments or questions in a private message, please write Ingrid Waldron at iwaldron sas. To enhance student understanding and retention of basic concepts, we have enhanced the graphical representations, clarified some of the verbal explanations, and revised many of the questions.
Please see the Teacher Preparation Notes for much useful information, including the directions for requesting a copy of the key. The Student Handout has been substantially revised to engage students in more active learning and clarify the instructions, questions and explanations. In addition we have sharpened the focus on how genes are inherited via meiosis and fertilization. Where is it? Based on teacher feedback, the questions, explanations and figures in the Student Handout have been revised and reorganized for greater clarity and better focus on the most important concepts.
In addition, we have developed a shorter and somewhat simplified version of the Student Handout which is appropriate for middle school and some high school students. The Teacher Preparation Notes have been revised for greater clarity and completeness.
Hi, I have been looking at your website and was thinking of doing this activity with my students, however I do not see a link to download the answersheet to the worksheet. Where could I find this? I encourage you to read the Teacher Preparation Notes available at the link above. These Teacher Preparation Notes include information about how to get a copy of the key, instructional suggestions, background biology and learning goals, all of which I think will be helpful for you as you consider using this activity.
We are grateful to the middle school and high school teachers who provided helpful suggestions for improvements. Resources for Teaching about Coronavirus has descriptions and links for multiple resources to use in teaching and learning about coronavirus. This page also includes some resources for teaching remotely. Narrative is determined not by a desire to narrate but by a desire to exchange. Attachment Size MeiosisFertilizationProtocol shorter.
Crossing Over Lab Activity
Hey I plan on teaching this on Monday, can you get the answer key to me by then? Thanks, Aidan. I am usually, but not always, able to send a key within hours. Ingrid Waldron. I cannot find the answer key.Genetic diversity is a very important part of evolution. Without different genetics available in the gene pool, species would not be able to adapt to an ever-changing environment and evolve to survive as those changes happen.
Statistically, there is no one in the world with your exact same combination of DNA unless you are an identical twin. This makes you unique. There are several mechanisms that contribute to the large amounts of genetic diversity of humans, and all species, on Earth.
Independent assortment of chromosomes during Metaphase I in Meiosis I and random fertilization meaning, which gamete fuses with a mate's gamete during fertilization is randomly selected are two ways your genetics can be mixed during the formation of your gametes. This ensures that every gamete you produce is different from all of the other gametes you produce.
Another way to increase genetic diversity within an individual's gametes is a process called crossing over.
Lab - 10 Meiosis
During Prophase I in Meiosis I, homologous pairs of chromosomes come together and may exchange genetic information. While this process is sometimes difficult for students to grasp and visualize, it is easy to model using common supplies found in pretty much every classroom or home. The following lab procedure and analysis questions can be used to help those struggling to grasp this idea. Share Flipboard Email. Heather Scoville. Science Expert. Heather Scoville is a former medical researcher and current high school science teacher who writes science curriculum for online science courses.
Updated January 07, Choose two different colors of paper and cut two strips out of each color that are 15 cm long and 3 cm wide. Each strip is a sister chromatid. Secure them in place with glue, tape, staple, a brass fastener, or another method of attachment. Use your model and prior knowledge about crossing over and meiosis to answer the following questions. When is the only time crossing over can occur? What does each letter on your model represent?
Write down what letter combinations were on each of the 4 sister chromatids before crossing over happened. Compare your answers to number 5 and number 6. Which showed the most genetic diversity and why?Sometimes students struggle with some concepts that relate to evolution.
Meiosis is a somewhat complicated process, but necessary to mix up genetics of offspring so natural selection can work on a population by choosing the most desirable traits to be passed down to the next generation. Hands-on activities can help some students grasp the concepts.
Especially in cellular processes when it is difficult to imagine something so small.
The materials in this activity are common and easily found. A cell with only one set of chromosomes are considered haploid. Gametes, like the egg and sperm in humans, are examples haploid.
Lab - 10 Meiosis
Gametes fuse during sexual reproduction to form a zygote which is once again diploid with one set of chromosomes from each parent. Meiosis is similar to mitosis and must have the cell's DNA replicate before it can begin. This creates chromosomes that are made up of two sister chromatids connected by a centromere. Unlike mitosis, meiosis requires two rounds of division to get half the number of chromosomes into all of the daughter cells. Meiosis begins with meiosis 1 when homologous pairs of chromosomes will be split.
The stages of meiosis 1 are similarly named to the stages in mitosis and also have similar milestones:. Meiosis 2 will see the sister chromatids split apart. This process is just like mitosis.
The names of the stages are the same as mitosis, but they have the number 2 after them prophase 2, metaphase 2, anaphase 2, telophase 2. The main difference is that the DNA does not go through replication before the start of meiosis 2.
Have students answer the following questions to understand the concepts explored in this activity. Share Flipboard Email. Heather Scoville. Science Expert. Heather Scoville is a former medical researcher and current high school science teacher who writes science curriculum for online science courses.
Updated February 05, Pre-Lab Vocabulary. Before starting the lab, make sure students can define the following terms:. Purpose of the Lesson. To understand and describe the process of meiosis and its purpose using models. Background Information. The nuceli now only have 1 set of duplicated chromosomes. You will need the following materials:. String 4 different colors of paper preferably light blue, dark blue, light green, dark green Ruler or Meter Stick Scissors Marker 4 paper clips Tape.
Using 1 m piece of string, make a circle on your desk to represent the cell membrane. Using a 40 cm piece of string, make another circle inside the cell for the nuclear membrane. Cut 1 strip of paper that is 6 cm long, and 4 cm wide from each color of paper one light blue, one dark blue, one light green, and one dark green Fold each of the four strips of paper in half, lengthwise.
Then place the folded strips of each color inside the nucleus to represent a chromosome before replication.Pearson, as an active contributor to the biology learning community, is pleased to provide free access to the Classic edition of The Biology Place to all educators and their students.
The purpose of the activities is to help you review material you have already studied in class or have read in your text. Some of the material will extend your knowledge beyond your classwork or textbook reading. At the end of each activity, you can assess your progress through a Self-Quiz. To begin, click on an activity title. Meiosis follows phases similar to those in mitosis, but the outcome of the process is very different. The DNA of the parent cells is replicated in interphase preceding both mitosis and meiosis.
However, in meiosis, replication is followed by two divisions. Meiosis reduces the chromosome number of the parent cell so that four daughter cells are produced, each with one-half the chromosome number of the parent cell.
Each daughter cell contains only one chromosome from each homologous pair. In your laboratory you will do a simulation activity that helps you verify your understanding of the events of meiosis.
Lab Meiosis. Edit a Copy. Study these flashcards. Betsy E. Mitosis vs Meiosis? Mitosis - Production of somatic cells body cells Meiosis - Production of gametes sex cells. A cell having two sets of chromosomes. A cell with one complete set of chromosomes. An allele that contributes to the phenotype only when two copies of it are present rr. Independent assortment. The random distribution of the chromosomes to the gametes during meiosis. Anaphase I. Anaphase II.
Number of cells made in telophase I? Number of cells made in telophase II? The structure formed by synapsed homologous chromosomes during prophase of meiosis I. Crossing over. A cell that forms from fertilization or syngamy. Order of phases in Meiosis. Genetic diversity. Mitosis makes diploid cells and Meiosis makes haploid cells.
Which division, meiosis 1 or 2, is most like mitosis? Meiosis 2 because in mitosis and meiosis 2 the centromeres split and sister chromatids separate. In mitosis, daughter cells are genetically identical to the parent cell.
True or false? Popular Study Materials from Biology Lab lab diffusion and osmosis lab diffusion and osmosis lab 9: cellular respiration lab diffusion and osmosis lab mitosis lab photosynthesis mitosis quiz quiz. Sign up for free and study better.