Prophase – the nuclear envelope disintegrates and centrioles migrate to opposite poles of the cell.…
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.…
Create a Graph that represents the time spent in each stage of the cell cycle.…
1. How does a cell become differentiated? A cell becomes differentiated by using only the DNA that it needs. 2. Give an example of 2 differentiated cells.…
What are the two phases of the cell cycle? What are the three stages of interphase?…
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…
Cell structures come in various shapes and sizes dependent on their location within an organism and what life sustaining process it carries out. These can range from the globular protein of a red blood cell, designed to carry four oxygen molecules at a time to the tail like flagellum of a bacteria designed for mobility and penetration of organs within a body.…
8. Name the phase of the cell cycle in which cells spend most of their time doing their job.…
The cell cycle is a series of events a cell goes through as it grows and divides. During the cell cycle, a cell grows, prepares for division by making a copy of its DNA, and then divides to form two daughter cells. Each daughter cell then begins the cycle again.…
The more surface area, the more quickly the cell can exchange water, oxygen, food and wastes…
1. Why do bone injuries generally heal, while injuries to the spinal cord and brain do not?…
The mitotic index was brought up as diction in the lab. According to the reference in the lab, the mitotic index is the ratio of dividing cells to the total number of cells in the sample. Tissues that are cancerous have a higher mitotic index than that of normal tissues. This is due to the fact that cancerous cells have an uncontrollable reproduction rate which allows for quicker division among the cells. For example the amount of cells shown in…
The eukaryotic cell cycle is the process that starts just as a cell is first formed from a dividing parent cell and then carried on until its own cell division (Simon, Dickey, Reece, page 125). The first stage involved in the eukaryotic cell cycle is called interphase. Interphase is the period between divisions that has 3 separate phases. The first phase in interphase is G1,…
In order of all cells to be the same as a parent the mitosis in a must. Mitosis is the separation of copied chromosomes into single cells. The problem with unregulated cell division is that most of the time this will lead to cancer. Only when DNA replication as well as mitosis is working the correct way then cell cycle cell points are insured.…