The Phases of the Cell Cycle Essay examples

In a cell cycle, there are specific checkpoints between each phases caused by the occurrence of cyclin. Cyclin determines how concentration flunctuatues. If the regulation is disrupted by a decreasein cyclin, there would be no mitosis, meaning the cell cycle would continuously go thre G0 phase. However, if there is an increase

Chromosome pairs line up across the equator of the spindle at metaphase I (5). In anaphase I the chromosomes separate and travel to opposite ends of the spindle. The chromosomes migrate to the equators of two new spindles for metaphase 2 (7). Next the chromatids are pulled apart in anaphase 2 to form four clusters of chromosomes in telophase 2. The nuclear envelopes reform around four haploid nuclei that will give rise gamete

Exercise 3A is a study of mitosis. You will simulate the stages of mitosis by using chromosome models.You will use prepared slides of onion root tips to study plant mitosis and to calculate the relative duration of the phases of mitosis in the meristem of root tissue. Prepared slides of the whitefish blastula will be used to study mitosis in animal cells and to compare animal mitosis and plant mitosis.

Interphase: This particular stage is divided into three phases, G1 (first gap), S (synthesis), and G2 (second gap). During all three phases, the cell grows by producing proteins and other organelles within the cytoplasm. However, chromosomes are replicated only during the S phase. In all, a cell grows (G1), continues to grow as it duplicates its

These bivalents line up along the equator during metaphase I, the arrangement of the bivalent is completely random and relative to the orientation of the other bivalents, this is known as the independent assortment of chromosomes. This is followed by anaphase I where the homologous chromosomes separate and move to the opposite poles of the cell. At telophase I the cell divides into two, each cell contains one chromosome from each homologous pair. The second stage of meiosis is similar to mitosis.

A) Meiosis consists of two cell divisions and is broken up into Meiosis I and Meiosis II. At the beginning of the Cell Cycle, in this case there are four chromatids each from the homologous pairs being A, a, B, b. This is the Diploid number (4) meaning it is 2 times the haploid number that will be seen at the end of meiosis II. During the S phase of interphase, the chromatids replicate and reach the end of G2 phase. Now starting meiosis, during the first stage of prophase I the chromosomes condense and pair up through synapsis with their sister chromatids creating AA, aa, BB, bb. After they pair up they go through a process called crossing over, where the homologous chromosomes share a piece of their genetic material with each other. Crossing over allows for the genetic diversity of chromosomes. Now there are four homologous chromosomes Aa, Aa, Bb, Bb, each containing heterozygous alleles because the sister chromatids exchanged genetic information with their homologous pair. During late prophase I, spindle fibers being to form where they will later attach to a homologous chromosomes centromere. The next stage is Metaphase I. During metaphase I, the homologous pairs line up at the metaphase plate, also known to be the center of the cell. The homologous pairs form a tetrad which is considered a group of four homologous chromosomes. These homologous chromosomes orient themselves randomly, which is know as the process of independent

Without cell division and the cell cycle nearly all life would fail to exist. Cell division allows an organism to not only replace its own cells but to create offspring. The cell cycle consists of two main parts: interphase and mitotic phase. Within these two phases the processes can be broken down into further categories. Interphase can be broken down into three subphases that are the necessary preparations the cell makes in order to be ready to divide during mitosis. For this lab we looked mainly at the mitotic phase because of its fascinating and rapid changes to the cell. The cell types we looked at were prepared slides of whitefish and onion root tip.

Cytokinesis – the division of the parent cells by cytoplasm to form two daughter cells caring identical genetic information

The cell cycle is a series of stages that occurs when a new cells makes the division from the parent cell to two daughter cells. This is a stage in cellular reproduction. The cell cycle consists of three phases, interphase, mitosis, and cytokinesis. During Interphase, a cell will continue to perform its functions as usual. The time frame for Interphase varies; while an embryonic cell will take just a few hours to complete the cycle, a stem cell from an adult can take 24 hours (Mader, Windelspecht, 2015). After the interphase stage completes itself, a complete nuclear division happens and mitosis occurs. During the stage of mitosis, the daughter cells will receive the same amounts of the contents of the parent cell. Throughout the last stage, in the cytoplasm there is a division known as Cytokinesis (Mader, Windelspecht, 2015). Cytokinesis occurs differently in plant cells than it does in animal cells, as the cell wall around the plant prevents the process from happening the same way. Instead, a new plasma membrane and cell walls are built are built between the daughter cells. However, in animal cells a single cell will become two (Mader, Windelspecht, 2015).

The phase in mitosis which chromatin begins to coil and the mitotic spindle begins to form.

Page 17: Sam stared in amazement making the cell seem like a diamond. The creature continued,” Now, G2 or Gap 2 phase is where the cell continues to grow. Everything must be right in the cell in order for the cell to move on, being correct in size and having undamaged DNA.”

19) The phase of mitosis during which the nuclear envelope fragments and the nucleoli disappear is called

The cell cycle has four main stages. The cell cycle is the regular pattern of growth. The four stages consist of Gap 1 (G1), Synthesis (S), Gap 2 (G2), and Mitosis (M). Gap 1, consists of a cell that carries its normal functions. Calls also increase in size, and the organelles increase in number. A cell will spend the most time in this phase. But it also depends on the cell type to see how long it will spend in this phase. During this phase the cell has to pass a critical checkpoint before it can continue into the (S) stage, also called the Synthesis stage. It would be dangerous for a cell to keep dividing if the certain conditions were not met. The cells in this stage also need signals from the other cells to tell the if division is needed. Now the next stage is the Synthesis stage. During this phase the cell makes a copy of it’s nuclear DNA. By the end of the (S) phase DNA appears grainy in photos and the cell nucleus contains two complete sets of DNA. Gap 2, is the third stage of the cell cycle. The cells continue doing there thing and more growth occurs. This phase is like the checkpoint, everything in the cell has to be going right for the cell to be able to enter mitosis.

It is expected that the most common phase of mitosis seen will be interphase as the cell spends around ninety percent of its time in this phase. This is because interphase is the period between cell division in which the cells grows, DNA replicates and centrioles divide. It is such a long phase that it is even split into three sub-phases; G1 phase in which a cell grows, S phase or synthesis, in which a cell copies its chromosome and G2 phase in which the cell grows further and prepares for division.

The cell cycle is separated into multiple stages such as G0, G1, S, G2, and M phase. During the G0 phase is the stage in which there is no sign of the cell preparing to separate but, rather a stagnant cell. The G1 phase involves the expansion of the cell and gathering all the nutrients and energy to prepare for the upcoming processes of the cell cycle. In the S phase,