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…
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.…
3 phases of Interphase: * G1 – the centrioles begin replicating * S – DNA is replicated * G2 – final preparations for mitosis are completed and…
Part 1: For this portion of the laboratory, please sketch a cell with 4 chromosomes going through each stage of mitosis starting with what the cell would look like following interphase. You should label your work and include a list of 2-3 events that are taking place during each of the phases of mitosis. You will also want to include the total number of chromosomes in the parent and daughter cells.…
During which phase of the cell cycle does DNA duplication, or replication, take place? – interphase…
* What are the stages of interphase? What happens in each stage?G1-cell growth,S phase-Synthesis,G2 prepare for division…
The cell cycle is important as old cells get damaged and have to be replaced with new cells for the functioning of the body. If new cells are not formed the human body will stop working within a few minutes. The cell cycle is defined as an orderly sequence of events in which a somatic cell duplicates its contents and divides in two. When a cell reproduces, it must replicate all its chromosomes to pass its genes to the next generation of cells. The cell cycle consists of two major periods: interphase, when a cell is not dividing, and the mitotic phase, when a cell is dividing. During interphase the cell replicates its DNA. Interphase is a stage of high metabolic activity. Interphase has three phases: G1, S, and G2. The G1 phase is the interval between the mitotic phase and the S phase. During this phase the cell is active. It replicates most of its organelles and cytosolic components but not its DNA. The replication of centrosomes also begins in the G1 phase. For a cell with a total cell cycle time of 24 hours, G1 lasts 8 to 10 hours. Cells that remain in G1 for a very long time are destined to divide again in G0 phase. Most nerve and muscle cells are in this phase. Once a cell enters the S phase, it is committed to go through the rest of the cycle. The S phase last about 8 hours. During the S phase, DNA replication occurs. As a result, the two identical cells formed during cell division later in the cycle will have the same genetic material. The G2 phase last about 4-6 hours. During G2, cell growth continues, enzymes and other proteins are synthesized in preparation for cell division, and the replication of centrosomes is completed. The mitotic phase of the cell cycle, which results in the formation of two new cells, consists of a nuclear division, which is called mitosis, and a cytoplasmic division, which is called cytokinesis, to form two identical cells. The process of mitosis results in the exact partitioning of genetic information. During prophase, 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…
13. The M phase is made up of what 2 stages. Cytokinesis and mitosis 15. Name the phase of mitosis that follows anaphase.…
You have conducted an experiment following the cell cycle of an animal cell. Each link below leads to a drawing of the slides you viewed from each phase of the cell’s reproduction. Click the link to a slide and identify the subphase of mitosis it shows. Then number the slides 1 to 4 in the order they occur.…
The cell cycle involves actively dividing eukaryotic cells passing through a series of stages known collectively as the cell cycle. The two gap phases (G1 and G2) and S (for synthesis) phase, in which the genetic material is duplicated and an M phase, in which mitosis partitions the genetic material and the cell divides, make up the cell cycle. In G1 cellular content is duplicated accept chromosomes. In S phase, each of the 46 chromosomes is duplicated by the cell. G2 double checks this looking to make some repairs if necessary. Mitosis is the process where by sister chromatids are split up to form two different cells. Once this has happened the whole process is free to start over making it a cycle.…
The cells prepares to divide by growing in size and prepares for DNA synthesis, when it enters the cell cycle. The cell cycle contains 5 phases, growing in size and preparing for DNA synthesis is the in the G phase and the G1 phase, next the cells then goes onto the S phase, this is where the DNA is replicated. Between the G1 and S phase is a check point where the cell cycle checks if the cell is proper to be divided. After the DNA is copied, the DNA copy and the cell goes through another checkpoint. If the cell does not pass through the checkpoint successfully the cell cycle will do one of the two, either try to repair the error in the cell or tell the cell to do apoptosis, the killing or destruction of the cell to prevent the cell from creating any other errors or messed up cells. The cell then move through the rest of the cell cycle and goes through the G2 phase where the cell prepares for mitosis. Mitosis is the process of division of cells in the cell cycle known as the M phase, this is how the cells in our body divides and grow. As the cell continues through the cell cycle to the M phase, here the cells goes through the stages of Mitosis and as the result it produces two diploid cells. Not every cell goes through Mitosis immediately, the cells need to either be told to prepare for division or it senses the cell next to it is missing and needs to divide to…
where G stands for gap, and in this phase the growth of cell parts occurs and materials needed for transcription, translation and DNA replication are made and if given the signal, preparation for S-phase occurs in this phase (Mrs. Weiland, 11/16/15). The second phase of interphase is S-Phase, or DNA synthesis, which is where DNA replication occurs. The chromosomes duplicate…
There are two main stages of the cell cycle, with multiple subdivisions within each. Interphase is the first stage, and it’s composed of G1 (contents of the cell are duplicated sans the chromosomes), S (chromosomal duplication), and G2 (checkpoints) phase. After interphase, there is the mitotic phase. The mitotic phase is composed of mitosis (division) and then cytokinesis (division of cytoplasm=2 daughter cells). The cell cycle ultimately produces two daughter cells. These processes allow the (complete) genetic material present in a cell/organism to be passed on to the daughter cells of cell division. The phases of Interphase ensure this for example. During the S phase, DNA is duplicated, aka 46 chromosomes. This allows the cells to split so they can have equal amounts of genetic material which are passed on to the daughter cells. The phase of G2 has cell checkpoints to ensure not errors occurred in the duplication process. After the volume is doubled, the cell undergoes the mitotic phases. Under these…
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…