Labpaq Essay

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.

Centrosome:It where most of the microtubules are made. Plant and animal cells centrosomes have almost the same jobs during a cell's division. Only difference is that plants cell centrosomes does not contain centrioles.

The cell cycle refers to sequence of events that takes place in a cell leading to its division and duplication (replication). This process is important to genetics because through the cell cycle genetics information for all sorts are passed from parents to daughter cells. (Griffiths. A et al)

Prophase: This is the first phase in the Cell Cycle. Chromosomes become more coiled and can be seen through a light microscope. The nucleolus disappears during Prophase and inside the cytoplasm spindle fibers form, migrating to opposite poles of the cell. Picture URL: http://www.phschool.com/science/biology_place/labbench/lab3/images/prophase.gif

Cells in G1 phase have only one centrosome containing two loosely linked centrioles. At the end of G1 phase, the two centrioles each grow a new end of pro-centriole at the proximal end, which is called centriole initiation. During S phase, while cell duplicate its chromosomes, it also duplicate its centrosome by elongating the procentrioles. At the beginning of the elongation process, nine tubules, as the first one of the microtubule triplets, are nucleated by the γ-tubulin ring complex, in association with the cartwheel. These tubules grow only in one direction on the centriole, which is from the proximal to the distal end. The first tubules remain capped by the γ- tubulin ring complex throughout the elongation process. The other two tubules of the microtubule triplet next form through a γ- tubulin ring complex independent mechanism and grow to the same length of the first tubule. Eventually, the distal end of the novel centriole is assembled by elongated first and second tubules, appearing a structurally distinct distal domain, suggesting that the procentrioles get

Centriole - these two features made of hollow tubules play a key role in cell division.

This cycle is conventionally divided into five discrete phases: gap phase 1(G1), synthesis, gap phase 2 (G2), mitosis and cytokinesis. During G1, the cell grows and prepares itself for division. Cells often pause in G1 before DNA replication and enter a resting state called the G0 phase; cells may remain in this phase for days to years before resuming cell division (book). During the synthesis phase, the cell synthesizes the genome in chromosomes to produce two sister chromatids held together at the centromere by cohesion. Once the cell has undergone the synthesis phase, it goes to the G2 phase. In G2, the cell undergoes its second growth face and prepares for the separation of the newly replicated genome. The G1 and G2 segments of interphase are periods of active growth, during which proteins are synthesized and cell organelles are produced (book). G1, synthesis, and G2 together constitute

Centriole one of two minor structures situated in the cytoplasm of creature cells close to the atomic envelope. The sister chromatids are moving separated is anaphase. The nucleolus starts to blur from perspective is prophase. As the cell develops in size, its more troublesome for the cell to move required material in and waste items out. Mitosis controlled by cyclins sorts of proteins. 1 guardian cell parallels 2 hereditarily indistinguishable girl cells after cell division. Mitosis is divided into three sections Interphase,mitosis,and

Within prophase, various structures begin to be broken down by the cell while others are instead built up. This prepares the chromatin to be split into two rod-like structures known as chromosomes, each one the sister of the other. For example, the nucleolus entirely disappears. A structure comprised of microtubules, known as the mitotic spindle, begins to form with its primary function being to arrange the chromosomes. The mitotic spindle proceeds to compact the chromosomes into a very tight package-like structure. The nuclear envelope soon dissipates, allowing for the release of the chromosomes. In the metaphase, the chromosomes have been brought into the middle of the cell (a concept referred to as the “metaphase plate”) in preparation for division. Structures that are in charge of pulling sister chromatin apart known as kinetochores will attach to microtubules from the mitotic spindle so as to insure correct division. Anaphase is the phase in which the chromatin are officially separated from one another and in turn tugged to opposite ends of the cell. In order for this to happen, the cell breaks down a protein that behaves as an adhesive. This allows for the chromatin to become two separate chromosomes, each pair yielding to the opposite side. Telophase allows

Chromosomes (chroma, colour; soma, body) are thread-like colour bodies, as these are known, since these are stained by characteristic basic dyes. E.Strasburger (1875) observed thread like structures during cell division. W.Fleming described the splitting of chromosomes and termed the stained material as chromatin. Waldeyer (1888) named these structures as chromosomes.

A cell’s life is separated into two categories, interphase, and mitosis. It spends most of it’s life in interphase. During this time the cell goes through different stages; G1, where it grows larger; S, where it synthesizes DNA; and G2, where it grows some more. When it grows too large it goes through mitosis.

The cell cycle is the cycle of cell growth, replication of the genetic material and division into equal daughter cells. The cell cycle consists of interphase and mitosis. Interphase has three steps; G1, S, and G2

Interphase is the starting point of the Mitosis cycle. It is an in between and longest stage of the cells life, where the cell grows and begins to ready itself for mitosis. There are three stages in interphase G1, S, and G2. G1 is a developmental stage where the cell generates proteins and organelles. S is when the cell begins to copy its genetic material or DNA. G2 is when the cell is done copying its genetic material and begins producing more proteins and organelles until mitosis begins.

The two processes, with which a cell passes this DNA sequence onto other cells, are DNA replication and mitosis. The cell cycle is inclusive of mitosis and DNA replication, the latter of which occurs in the S phase (synthesis) of the cycle. The goal of the S phase is to create two identical semi-conservative chromosomes. The enzyme helicase unwinds the parental DNA double helix strand and uses it as a template so the enzyme DNA polymerase can attach free-floating nucleotides to the separate DNA ‘daughter’ strands using the complementary base pairing rule, in which A-T and C-G pair together. In this way, the process of DNA replication is deemed ‘semi-conservative’ as one parental strand is always passed on to daughter helix of DNA (Campbell & Reece, 2005).

At the center of the microtubules is the centrosome. This structure is where the microtubules branch off, which is near the middle of the cell. The centrosome is called the organizing center because it can break down the microtubules and allow the organelles to move around. At the center of the centrosome is where the commands are made called the centrioles, a pair of cylindrical structures.