Partial preview of the text
Download Cell cycle questions and answers and more Exercises Cell Biology in PDF only on Docsity!
srone___ PGW KEM cn iy vee ON Bo seue, Govpat aremden cel of PHY VO 1s Cell Processes and Energy = Section Si ary 4. OF Gain “Hore oF Ayl Asgue wf speegte yh 2 Wi f we 0. OY AM SySTEn - Gump 9 geno u/ Y* "7% Cell Division MG el -unpesatiey en . Ueto Guide for Reading ; OY Regivnator ig. ite in . i u What events take place during the three stages of the cell cycle? type % Mtge PED ihefl” Dt W wv a On 43 SH YY « How does the structure of DNA help account for the way in which DNA OP ae 4 75 126 copies itself? — Double Helix Pett re Reales Cott Si ‘ The regular sequence of growth and division that cells undergo is known as “A frown OG y 4 WOM tre ceil cycle. The cell cycle is divided into three main stages. can 0 me ys: AW KG The first stage of the cell cycle is called interphase, During interphase, the f ‘pred, cell grows, makes a copy of its DNA, and prepares to divide into two cells. During the first part of interphase, the cell grows to full size and produces all y 6 tea the structures it needs. In the next part of interphase, the cell tnakes an exact cell cycle. ; #7 - copy of the DNA in its nucleus in a process called replication. At the endof |,Tn ter phase DNA replication, the cell contains two identical sets of DNA. 2. Mitosis Once interphase is complete, the second stage of the cell cycle begins. - prophase 4% Mitosis isthe stage during which the cell’s nucleus divides into two new -~meta phase nuclei. During mitosis, one copy of the DNA is distributed into each of the o daughter cells, Scientists divide {tosis into four parts, or phases: sana phase B's hase, metaphase, antiphase, and.téloghase. During"prophase, the - telophase. threadlike chromatin in the cell’s nucleus condenses to form double-rod ‘ . structures called chromosomes, Each identical rod ina chromosome is called 3. Cyto Kinesis a chromatid, The two chromatids are held together by a structure called a centromiere. As the cell progresses through metaphase, hase, and. \ telophase, the chromatids separate from each other and move to opposite A of the, “h an ends of the cell. Then two nuclei form around the chromatids at the two ends #13 ~ chvararin Aroma of the cell. | / oo, : Sister thvorslor After mitosis, the final stage of the cell cycle, called cytokinesis, completes chroma td wha. 8 cy cytokinesis, comp! duc larposd. the process of cell division. During cytokinesis, the cytoplasm divides, «(, 2 ae cal pte distributi les into each of the tw lis. Each daughter cell” (ei ‘ istributing the organelles into each of the two new cells. Each daughter cell” (i= / ‘ 7 d Thin th Ade has the same number of chromosomes as the original parent cell. At the end of ' luce, mater’ cytokinesis, each cell enters interphase, and the cycle begins again. The length 4 4 Whi uci? ofeach stage and cell cycle varies, depending on the type of cell. centromere ch Vp i 1 I t ad choweso DNA zeplication ensures that each daughter cell will have all of the Structuee tt fT} genetic information it needs to carry out its activities. The two sides of the \ae i DNA ladder are made up of alternating sugar and phosphate molecules. OSM Naa t Each rung of the DNA ladder is made up of a pair of molecules called ‘pac hoo nitrogen bases. There are four kinds of nitrogen bases: adenine, thymine, Chrornesome : guanine, and cytosine. Adenine only pairs with thymine, and guanine only ome pairs with cytosine. DNA replication begins when the two sides of the DNA (rung s) molecule unwind and separate. Next, nitrogen bases that are floating in the Nibrogen pase nucleus pair up with the bases on each half of the DNA molecule. Because of img the way in which the nitrogen bases pair with one another, the order of the Ac T bases in each new DNA molecule exactly matches the order in the original G--C DNA molecule. Once the new bases are attached, two new DNA molecules 2 are formed. “5 OOS: “ . Deoxy elegar psides a) ‘e é Cat cd ffersnticehars - process by AA COM betonvaem dyjeuret ty pt 7 tell “ex, form hired e492 pays cle phos phate. | 
