Mitosis is easily observed in cells that are growing at a rapid pace such as whitefish blastula or onion root tips, which was used in this lab experiment. The root tips contain and 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. In mitosis the cell is in interphase, and have a distinct nucleus and nucleoli where the thin threads of chromatin thicken into distinct chromosomes and the nuclear evvelope breaks open releasing them into the cytoplasm. The firs 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, a cleavage furrow will form and the two daughter cells will separate. Meiosis is more complex and involves two nuclear divisions. The…
* Meiosis – cell division for gamete production * In specialized tissues * Produces cells with the 1n chromosome number * Two Divisions * Meiosis I separates homologous chromosomes * Meiosis II separates sister chromisis * Asexual Reproduction * Mitotic division * Identical offspring * Sexual Reproduction * Fuse gametes from parents (syngamy) to produce a zygote *…
Eukaryotic cells go through Interphase and Mitosis. Interphase is further subdivided into 3 stages, G1 (first gap), S (synthesis of DNA), and G2 (second gap). In all 3 sub phases cell growth happens and organelles like mitochondria are replicated. DNA, however, is only synthesized during the S phase. DNA replication is started by Helicase which unwinds the double helix at replication forks. Topoisomerase is used to loosen the tension at the ends of the bubble, in order to correct for over winding ahead of the replication forks. Primase then synthesizes an RNA primer which the DNA polymerase III will use to lay down bases, synthesizing a new strand. DNA polymerase I will then remove the primer and DNA Ligase will join ends of DNA synthesized from different replication forks. Because DNA can only synthesize from 5'->3', there is a leading strand and lagging strand which creates Okazaki fragments that are later joined together by DNA Ligase. After DNA is replicated proofreading enzymes will check and repair any mistakes that occurred during replication. After S phase is the G2 phase where the cell grows even larger. G2 is followed by mitosis, which is subdivided into 5 parts: prophase, metaphase, anaphase, telophase, and cytokinesis. In prophase, chromatin condenses and the nucleoli disappears. What we know as chromosomes, which consist of two identical sister chromatids joined together at centromers, begin to appear. Mitotic spindle is formed and the centromers start moving to opposite poles, propelled by the lengthening microtubules that they shoot out. In metaphase, the longest stage of mitosis, the chromosomes line up on the metaphase plate and the centromeres have already migrated to opposite poles.…
Purpose: This activity is designed to familiarize you with the phases of mitosis and meiosis and compare these processes in a comparison chart. This activity will be three parts. For parts I and II, please scan your labeled work.…
The chromosomes replicate and each DNA strand unzips into two strands, while free floating bases attach to the strands. Chromosomes begin to condense and attach to the membrane of the nucleus pairing up with their corresponding chromosome. Enzymes cut the DNA from the chromosomes at this time. The spindle fibers from and centrioles begin to separate to opposite ends. The chromosomes will now line up on either side of the metaphase plate. The chromosomes split to other ends of the cell. New nuclear membranes form at other ends of the cell. The rest of the cell divides and the division of the cell's cytoplasm has occurred. The chromosomes condense again, spindles and centrioles form, and membrane fragments disperse. Spindle fibers attach to the chromosomes. Centrioles are at opposite ends. Fibers are pulled to opposite ends of the cell. Chromatids arrive at opposite ends and new nuclear membranes form. The rest of the cell continues to divide and there are now four daughter cells. Following these steps of meiosis will help us be able to have a better understanding and awareness of who the parents are of Mrs.…
Many similarities occur between meiosis and mitosis such that each process, after it has been gone through, result in no new gene combination. Each new cell also, after each process of mitosis or meiosis is gone through, has the same number of chromosomes. Each of the sister chromatids separate in anaphase in mitosis and anaphase two in meiosis since there are two major sets of phases in meiosis. This makes anaphase in mitosis very similar to anaphase two in meiosis. Meiosis two in meiosis is also very similar to mitosis. Also, when these processes have finally ended, they will form no homologous chromosomes in any of the new cells that have been formed.…
Meiosis is the process by which eukaryotic organisms produce egg and sperm having half the genetic information (haploid) of the other cells in the organism’s body (diploid). You will notice some similarities to mitosis but some definite differences in meiosis that result in genetic diversity in the gametes as well as the offspring formed by the eventual fusion of the egg and sperm.…
10. At the beginning of meiosis, two homologous chromosomes pair up. These two homologous chromosomes are separated during meiosis I. Drag the chromosomes Below into the cells on the…
The cell cycle begins in the G1 phase. This phase is where the cell carries out its normal functions. During this phase, however, the cell passes through a vital check point before it enters the synthesis phase. Synthesis, by definition, means combining parts to make a whole. During this stage the cell makes a copy of its DNA. By the end of the “S” stage the nucleus of the cell has two complete sets of DNA. During the G2 stage cells continue normal functions and have additional growth. This stage also contains a check point to make sure all is well with the cell before continuing to the next stage, mitosis. Mitosis is where the cell’s nucleus and its contents divide. Through this stage the nuclear membrane dissolves and DNA condenses around…
Approaching the end of the process, anaphase is the point in which the paired chromosomes begin being dragged by the spindle fibers towards the poles. Eventually, during telophase the fibers disappear and the cell has been stretched, in preparation for cell division. Part of the parent cells membrane surrounds the new daughter cells, as the newly generated organelles move inside the daughter cells and the chromosomes move into the newly developed nuclei and the cell…
* A gene's specific location along the length of a chromosome is called the gene's locus…
Mitosis is the process by which the nucleus of the cell is divided into two nuclei, each with the same number and kinds of chromosomes as the parent cell.…
There is two stages in M-phase; the first stage is called mitosis. Mitosis is the nuclear division of the cell, separating the two copies of the genome and forming daughter nuclei. There are four stages in mitosis: prophase, metaphase, anaphase and telophase. Multiple changes occur in prophase including the coiling of the chromatin into chromosomes, the disappearance of the nuclear envelope and nucleoli, the migration of the centrosomes toward opposite poles and the construction of spindle apparatus, which are composed of protein fibers called microtubules. The next stage is called metaphase, where the chromosomes line up at the middle of the cell because the microtubules push and pull them there. The third stage, anaphase, consists of sister chromatids separating and being pulled toward opposite poles. The last phase of mitosis is telophase, which is when the chromosomes uncoil resulting in chromatin. During telophase two new nuclear enveloped appear and spindle apparatus breaks down (Mrs. Weiland, 11/19/15).…
The cell cycle, or cell-division cycle, is the series of events that take place in a cell leading to its division and duplication that produces two daughter cells. In cells without a nucleus, the cell cycle occurs via a process termed binary fission. In cells with a nucleus, the cell cycle can be divided in three periods: interphase—during which the cell grows, accumulating nutrients needed for mitosis preparing it for cell division and duplicating its DNA—and the mitotic phase, during which the cell splits itself into two distinct cells, often called "daughter cells" and the final phase, cytokinesis, where the new cell is completely divided. The cell-division cycle is a vital process by which a single-celled fertilized egg develops into a mature organism, as well as the process by which hair, skin, blood cells, and some internal organs are renewed.…
Meiosis I begins with Prophase I. In Prophase I, the chromatin becomes smaller and creates chromosomes. The pair of chromosomes are known as sister chromatids that are joined together at the center which is called the centromere. Spindles also form during the phase from long proteins called microtubules on both sides of the cell. After this, crossing over occurs and breaks then reconnects DNA to make a new combination of genes. Metaphase I is when the chromosomes line up on both sides of the middle of the cell then during Anaphase I the spindle fibers pull the homologous chromosomes away from each other and toward the outside of the cell. By Telophase I, the cell goes through the process of Cytokinesis which divides the cytoplasm of the parent cell and makes two daughter cells. Each of them is a haploid cell and has only half the number of chromosomes as…