Meiosis and genetic diversity in sordaria

Meiosis Save In meiosis, the chromosome or chromosomes duplicate during interphase and homologous chromosomes exchange genetic information chromosomal crossover during the first division, called meiosis I. The daughter cells divide again in meiosis II, splitting up sister chromatids to form haploid gametes.

Meiosis and genetic diversity in sordaria

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. 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.

Lab 3 sample ap mitosis & meiosis -

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.

Meiosis and genetic diversity in sordaria

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. Sordaria form a set of eight ascospores called an ascus. They are contained in a perithecium until they are mature and ready for release.

Crossing over can be observed in the arrangement and color of these asci. If an ascus has four tan ascospores in a row and four black ascospores in a row 4: However, if the asci has black and tan ascospores in sets of two 2: Hypothesis Mitosis occurs in whitefish blastula and onion root tip, and it is easily observable.

Meiosis and crossing over occurs in the production of gametes and spores.

Meiosis and genetic diversity in sordaria

Materials This lab requires prepared slides of whitefish blastula, onion root tips, and Sordaria, pencil, paper, a light microscope, and a chromosome simulation kit.

Observing Mitosis Prepared slides of whitefish blastula and onion root tips were observed under the 10X and 40X objectives. A cell in each stage of mitosis were identified, and then sketched. Time for Cell Replication Using a high power objective, every cell in a field of view was observed.

Each cell was counted as being in one of the stages of mitosis and recorded. At least cells and 3 fields of vision were counted and recorded. Next, the percentage of cells in each stage was recorded and the amount of time spent in each phase was calculated.

Simulation of Meiosis In this part of the lab, a chromosome simulation kit was used to demonstrate meiosis.Meiosis and Genetic Diversity in Sordaria Homework Name: Lucas Watson 1.

Meiosis and Genetic Diversity in Sordaria - Essay Samples

On the diagram below, indicate (with the appropriate letter) where plasmogamy (A), the dikaryon (B), karyogamy (C), meiosis (D), and mitosis (E) are Anomalous Combinations of Asci in Sordaria fimicola due to Meiosis Introduction Sordaria fimicola is a fungi that is a part of the Ascomycota phylum and is an excellent example of how variations are produced in /genetics-1/other/lab-report//view.

Recombination generates new combinations of existing genetic variation and therefore may be important in adaptation and evolution. We investigated whether there was natural genetic variation for recombination frequencies and whether any such variation .

4 November Section 24 TA- Erik Ohlson Meiosis and Genetic Diversity in the Model Organism, Sordaria fimicola Introduction Research groups from the Imperial College of Science, Technology and Medicine and the Institute of Evolution at the University of Haifa have been studying the model organism, Sordaria fimicola, in regards to controlling cross over frequency in response to environmental pressures.

Meiosis and Genetic Diversity.

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