...In prophase I of meiosis I, there are 5 sub-stages. The first one is leptotene where the chromosome starts to condense. Followed by zygotene was the pairing of the homologous chromosome and become closely associated during synapsis and the formation of the Synaptonemal complex. The third sub-stage is pachytene were the crossing over occur, forming chiasmata, which hold homologous chromosome together. In diplotene, the Synaptonemal complex start to disappear and in the last stage, diakinesis, the Synaptonemal complex is completely disappearing. In metaphase I, the pair of homologous chromosome aligns along the metaphase plate in double row. The formation of chiasmata before are to help keep the pairs together and position the pairs such that only one side of each homologue’s centromere faces outward toward of the cell’s poles. Thus kinetochore microtubules attach to only one side of each centromere; a kinetochore microtubules from one pole of the cell attaches to one homologue of the chromosome while a kinetochore microtubules from the other cell poles attaches to other homologue. In anaphase I, kinetochore microtubules shorten and homologous pairs are pulling apart. One duplicated homologue goes to the other poles. Sister chromatids do not separate. This is in contrast to mitosis, where duplicated homologues line up individually on the metaphase plate, kinetochore microtubules from opposite poles of the cell attach to opposite sides of one homologue’s centromere, and sister...
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...2/24/2013 Cell division • The human body is made up of trillions of cells… Mitosis and Meiosis • …But started with one Understanding Cell Division • What instructions are necessary for inheritance? • How are those instructions duplicated for distribution into daughter cells? • By what mechanisms are instructions parceled out to daughter cells? Reproduction • Parental cells produce a new generation of cells or multicelled individuals like themselves • Parents must provide daughter cells with hereditary instructions, encoded in DNA, and enough metabolic machinery to start up their own operation The roles of mitosis Chromosome • A DNA molecule & attached proteins • Duplicated in preparation for mitosis 1 2/24/2013 Chromosomal Organization A chromosomes is DNA associated with proteins. The entire complex is tightly wound and compressed into a discrete, linear structure. The Cell Cycle • • • • • Interphase Usually longest part of the cycle Cell increases in mass Number of cytoplasmic components doubles G1, S, and G2 phases Chromosomes duplicate in S phase of interphase Chromosome Duplication a One chromosome (unduplicated) Duplication allows a whole copy of the genome to reside in each daughter cell one chromatid one chromatid b One chromosome (duplicated) two sister chromatids Each duplicated chromosome will split. One sister chromatid will be in each new daughter cell 2 2/24/2013 Chromosome Number • Sum total...
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...Meiosis Quiz Question 1 Cats have a diploid number of 38. How many chromosomes are in a cat egg? * 76 24 38 19 Question 2 Crossing over occurs between homologous chromosomes during what stage of cell division? (Read each option carefully.) Interphase Prophase II of meiosis Prophase of mitosis * Prophase I of meiosis Question 3 A child with Down Syndrome has 3 copies of chromosome 21 (trisomy 21). Which statement could be true in regards to this child? The sperm could have had 2 copies of chromosome 21. One gamete had 2 copies of chromosome 21 and the other gamete had 1 copy. * All these answers could be true. The egg could have had 2 copies of chromosome 21. None of these answers could be true. Question 4 What is the purpose of meiosis? To allow an organism to replace damaged cells * To enable an organism to produce gametes To allow for growth Question 5 What advantage does sexual reproduction have over asexual reproduction? All other selections are true. Sexual reproduction doubles the number of chromosomes in a species Sexual reproduction is more efficient * Sexual reproduction provides more genetic variability Question 6 Mitosis results in ______ cells and meiosis results in _______ cells. haploid, haploid diploid, diploid * diploid, haploid haploid, diploid Question 7 Mitosis results in ________ and meiosis results in ________. gametes, somatic...
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...Ronald Mathis Grand Canyon University Biology 100 July 10th 2011 The Cell Cycle Directions: Answer the following questions. Cite references as needed. Be sure to read the required Module 3 readings and view the required Web sites before completing the assignment. Cell Cycle Questions for Cell Cycle 1) . Briefly describe all phases of the cell cycle and tell what happens in each. a) Interphase: G1 phase, S phase, G2 phase Interphase: Before a cell can enter cell division, it needs to take in nutrients. All of the preparations are done during the interphase. Interphase proceeds in three stages, G1 phase, S phase, G2 phase. Cell division operates in a cycle. Therefore, interphase is preceded by previous cycle mitosis and cytokinesis (Module 3 Readings). a. G1 phase: The cell increases the supply of proteins and increases its organelles. b. S phase: Linear chromosome is replicated. c. G2 phase: Increases protein preparing to replicate. (Module 3 Readings) b) M phase: M phase is a method of indirect cell division by means of which the two daughter nuclei normally receive identical complements of the number of chromosomes of the somatic cells of the species. 2) Which phase is the shortest? Anaphase is the shortest phase of mitosis because its where the chromatids twins are all pulled apart at the centromere by the spindle fibers. 3) What is G0 (Gap 0/Resting phase)? A resting phase is when or where the cell has left the cycle...
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...There are two types of cell divisions in eukaryotes: mitosis, regarding somatic cells and which provides an identical cell to the parent cell during the asexual multiplication cells (it thus preserves genetic information) and meiosis resulting in production of sexual cells or gametes for reproduction. For animals, meiosis is a process that takes place during gametogenesis (spermatogenesis or ovogenesis), that is to say during the development of gametes (sperm in males and eggs in females) in the so-called species diploid. In plants, meiosis produces spores which give by mitosis haploid generation (pollen, leafy foot foam, etc. . ) It gives haploid cells (cells containing n chromosomes) from diploid cells (cell containing 2n chromosomes - in humans, a normal cell contains 2n = 46 chromosomes (ie 23 pairs), while a gamete contains n = 23 chromosomes in two divisions). In haploid species (such as Sordaria macrospora ), meiosis occurs after fertilization to divide the egg cell ( 2n chromosomes). But in addition to the role of division, meiosis has an important role in genetic mixing (miscegenation), thanks to two mechanisms shuffling: the interchromosomal and intrachromosomal shuffling) . Thus, during meiosis, the amount of DNA within the cell varies over time. Each cell will therefore separate genetic heritage (contained in chromosomes) in two to transmit only half of their genes to daughter cells. It takes place in several stages forming a set of two cell divisions...
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...Meiosis and mitosis are two processes forms of eukaryotic cell division, together they distribute the genes in the cell that results in producing different daughter cells. Durin mitosis, two identical daugther cells are created and each contain the same number of chromosomes as their parents. In the other hand, meiosis creaes four unidentical daughter cells, and each one of them has the half number of chromosomes as their parents cells. In meiosis I, a process in which the first cycle of nuclear division occurs during the formation of gamets, it results in reducing the number of chromosomes to the half as their parents. It consists of four phases: prophase I, metaphase I, anaphase I, and telophase I. The chromosomes condense and become visible...
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...Unit 5: Meiosis & Mendel Test Review Packet Chapter 13: What is the difference between diploid and haploid? How are they represented? Which type of reproduction will result in genetically identical offspring? What is the difference between a somatic and germ cell? What is a karyotype? Explain what is meant by homologous chromosomes. Sketch a diagram that correctly represents: sister chromatids, homologous chromosomes, centromere and then answer the following questions about your diagram. How many chromosomes does your cell have? How many homologous pairs of chromosomes? How many chromatids? Is the cell haploid or diploid? What is the process that produces gametes? What is another term for a fertilized egg? How does the chromosome number of a...
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...Name Class Date Guided Inquiry • Skills Lab Chapter 11 Lab Modeling Meiosis Problem How does meiosis increase genetic variation? Introduction Most cells in organisms that reproduce sexually are diploid. They have two sets of chromosomes and two complete sets of genes. Gametes are an exception. Gametes are the cells that combine during sexual reproduction. In animals, these cells are called sperm and eggs. Gametes are haploid cells with only one set of chromosomes. Meiosis is the process in which haploid cells form from diploid cells. In this lab, you will model the steps in meiosis. You will make drawings of your models. You will also identify points in the process that can lead to greater genetic variation. Skills Focus Use Models, Sequence, Draw Conclusions Materials • pop beads • magnetic centromeres • large sheet of paper • colored pencils • scissors Safety Do not direct the points of the scissors toward yourself or others. Use the scissors only as instructed. Pre-Lab Questions 1. Control Variables Why must you use the same number of beads when you construct the second chromosome in Step 1? Name Class Date 2. Infer Why is the longer chromosome pair used to model crossing-over? 3. Calculate A diploid cell has two pairs of homologous chromosomes. How many different combinations of chromosomes could there be in the gametes? Procedure The diploid cell in your model will...
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...Meiosis plays a very important role in producing gametes or sex cells. They do this by making haploid cells from diploid cells. Diploid cells consist of two sets of chromosomes, whereas haploid cells only have one set of chromosomes. For diploid cells to change to haploid cells, the cell needs to go through two rounds of cell division. When the first division occurs, homologous chromosomes separate and move to opposite sides of the cell. If these homologous chromosomes do not separate correctly, they can lead to the development of aneuploid gametes. These gametes can cause fertility problems and chromosomal abnormalities (Pawlowski and Tiang, 1). To make sure homologous chromosomes separate correctly, these chromosomes must come together and...
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...Introduction: Meiosis involves two types of nuclear division that result in four haploid daughter cells. These divisions according to Chapter 15 Meiosis and Sexual Life: Campbell Biology: Tenth Edition are called Meiosis I and Meiosis II, during the first nuclear division the homologous chromosomes separate while during the second division the sister chromatids separate. The stages of Meiosis are: Prophase I, Metaphase I, Anaphase I and Telophase I, this are part of the first division while Prophase II, Metaphase II, Anaphase II and Telophase II are part of the second division of the cell. During this lab, we wanted to know what the stages of meiosis in a plant were and which stages were present in a lily anther. The first generation of lily anther will always produce spores and then this grow and produce gametes, leading the male structure to produce sperm and the female structure to produce eggs. This process leads to the “transmission of traits” from one generation to another. We hypothesized that all the lily anther cells will be in the stages of Telophase I and Telophase II. We also predicted that if the cells were in Telophase I or Telophase II, then the cells were dividing ready to form different ones. Methods:...
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...Title: Genetic Recombination By: Elizabeth Daniel 03/10/07 Abstract: This study was done so that we, the students, would be able to learn about the life cycle of Sordaria fimicola and also so that we would be able to see the role that mitosis and meiosis played during that cycle. We simply crossed over the wild type strand and the mutant strand, and the outcome was one that enabled us to look into the life of this interesting fungus. We believed that the fungus would crossover and create arrangements that would match up with what the expected outcome of a regular sordaria strain would be, and we were correct. We were able to accept the null hypothesis, which stated that there was no difference between the data we observed and the data we expected. Introduction: The main purpose of this experiment was to see the Sordaria fungus and determine the arrangements and map distance that it had. We then would see whether our observed data matched up with the expected data. The study needed to be done so that the students would learn the role and part that mitosis and meiosis played in the life cycle of a Sordaria fungus. Using the information learned here, the students would be able see how meiosis and mitosis effected cells and how the process was done. During the experiment, the students also would learn the different arrangements that the crossing over led to and how to calculate frequency and map distance on the chromosome which the genes are found. We hypothesized...
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...Normal cell division meiosis and gamete production via meiosis. Explain why the process of mitosis and meiosis are both important to a living organism. When would an organism need to undergo the process of mitosis? Meiosis? What would happen if meiosis did not occur? Mitosis is the cell process of growth and division whereas meiosis is the process of developing reproductive cells. The sperm and egg are critical components for almost all living organisms. Every living organism begins with one cell that came from our father’s sperm fertilizing our mother’s egg. This beginning cell then divided by mitosis into two cells (called daughter cells) which then grow and divided into four cells. Mitosis continues through when we were born and continues again until we “fully” grown. Mitosis occurs regularly to replace old dead skin cells. “Mitosis has five stages which include: prophase, prometaphase, metaphase, anaphase, and telophase, which constitute the period in which the cell makes preparations for cell division.” (Sparknotes, 2009) Meiosis is a special form that is similar to mitosis. Meiosis occurs only in a special arrangement of our cells to create eggs and sperm. In meiosis, one cell is divided twice in a row to form four daughter cells from one cell. The divided cells are then tailored to become eggs or sperm. If meiosis did not occur there would be an elimination of reproduction and all living organism would die. Life would not exist as we know it today. Mitosis...
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...involved in a gamete formation. gametic cell- a cell that fuses with another cell during fertilization in organisms that reproduce sexually, homologous chromosome , sister chromatid, karyotype, autosome and sex chromosome. How many chromosomes are in a human somatic cell? 46 How many homologous chromosome pairs are in a human somatic cell? 22 How many chromosomes are in a human gamete? 23 How many homologous chromosome pairs are in a human gamete (trick question)? 46 Which stage of the human life cycle is diploid (2n)? Which is haploid (n)? Which processes form the transition from haploid to diploid and diploid to haploid? Meiosis- The goal of meiosis is to produce four haploid gametes from one diploid somatic cell. This occurs through two cell divisions: meiosis I and meiosis II. Interphase - as in mitosis, the DNA content of the cell doubles from 2n to 4n. Meiosis I- Prophase I. DNA supercoils, tetrads form and crossing over occurs between maternal and paternal homologous chromosomes. Metaphase I. Homologous chromosome pairs line up along the equator of the cell in stacks instead of end to end. The random alignment of the homologous chromosomes during metaphase I is known as independent assortment. Anaphase I. Homologous chromosome pairs separate toward opposite poles of the cell. Nondisjunction can occur at this stage. Telophase I/cytokinesis. Nuclei reform in each of the two daughter cells as the mother cell is split in half by cytokinesis. Prophase II. DNA supercoils. Metaphase...
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...1. Is it possible for a female carrier to have a daughter who has hemophilia? Explain your answer using terms such as sex-linked inheritance, sex-linked genes, dominant, recessive, and X and Y chromosomes. Sex-linked inheritance is when a gene is located on a sex chromosome, usually a mutated gene that can cause a disorder. The sex chromosomes are X and Y. The combination of two sex chromosomes determines a person’s sex. XX is female and XY is male. Hemophilia is a rare, sex-linked inherited blood clotting disorder that causes blood to clot abnormally resulting in slower clotting. Hemophilia is a recessive disorder that is passed along the X chromosome (National, 2013). A recessive gene will not manifest itself unless paired with a like recessive gene or in an absence of a dominate gene to suppress it. A carrier is a person who has the gene for a disorder, has the ability to pass on the disorder, but does not develop the disorder because there is not a matching recessive gene to activate it and there is a dominant gene to block it. A woman who is a carrier for hemophilia will be represented as XXh. If a male is XhY the hemophilia gene on the lone X chromosome is enough for the condition to manifest itself (National, 2013). A woman who is a carrier of hemophilia can give birth to a daughter who has hemophilia only if the male has hemophilia and transmits the recessive gene on his X chromosome. If a woman who is a carrier mates with a man who has the disorder they could have...
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...Educating Learners with Diverse Needs Benchmark Assessment Teaching for Exceptionalities Grand Canyon University: SPE 526 Educating Learners with Diverse Needs February 27, 2013 Kerry Fitzmaurice, Instructor Lesson Plan: Mrs. J. Koneri, Mrs. D. Curry, Mrs. T. Brown Unit: Cellular Division: Mitosis and Meiosis Dougherty High School Essential QuestionsObjectives:Students will be able to: | 1. Which cells in an organism undergo mitosis?2. What are the stages of mitosis and what occurs at each step?3. In what part of the body does meiosis take place? 4. How many chromosomes are found in a somatic cell compared to a sex cell? (gametes)5. What do haploid and. Diploid mean? 6. How does meiosis differ from mitosis? 1. Define, draw, locate using a microscope and give examples of the phases of mitosis, meiosis, cytokinesis, and replication. 2. Compare and Contrast mitosis and meiosis. 3. Explain crossing over and how it contributes to the production of unique individuals. 4. Summarize the major characteristics of spermatogenesis and oogenesis. 5. Describe the structure of a chromosome 6. Explain the differences between sex chromosomes and autosomes. | Standards: | SCSh4. Students use tools and instruments for observing, measuring, and manipulating scientific Equipment and materials.SCSh8. Students will understand important features of the process of...
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