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1、10.1 Pre-Read Questions Name 2 limitations to cell growth. How does DNA limit cell growth? Why is the ratio of surface area to volume important? Describe the process of cell division.Ch 10: Cell Growth and Division10.1: Cell GrowthCells Does not continue to grow bigger Cells just continue to produce
2、 more cellsLimits to Cell Growth 2 main reasons Larger a cell becomes, the more demands the cell places on its DNALimits to Cell Growth 2 main reasons 2. Cell has more trouble moving enough nutrients and wastes in and out of cellReason #1 DNA “overload” DNA = information that controls a cells functi
3、on if cells grow, DNA does not make extra copies DNA would not be able to serve the needs of the cellReason #2: Exchanging Materials how fast materials leave or enter the cell depends on surface area food and oxygen depend on cell volumeRatio of Surface Area to Volume as surface area increases, its
4、volume increases at a faster rateRatio of Surface Area to VolumeConsequence = cells have a more difficult time to move needed materials in and waste products outCell Division how cells reproduce one cell divides into 2 new cells daughter cellsCell Divisionbefore cell division - cell copies DNA Each
5、daughter cell gets own copy of DNA10.2A12 / 5 / 062 StagesMitosis = division of the cell nucleusCytokinesis = division of the cytoplasmMitosis asexual source of new cellsChromosomes carries the genetic information consists of DNA cells have specific number of chromosomesChromosome not visible until
6、cell division replicated before cell division chromosomes change form to chromatidsChromatids Separate from each other and go into daughter cells attached at a centromere located near the middle of the chromatidsCentromereChromatidCell Cycle cell reproduction forms two daughter cells in between peri
7、od = interphaseCell Cycle: 4 phases consists of 4 phases M phase = mitosis and cytokinesis S phase = chromosome replication (S = synthesis) G1 and G2 (G = gap) - growth and activityInterphase 3 of the 4 phases occur G1 S phase G2G1 Phase cell growing increase in size and synthesize new proteins and
8、organellesS Phase chromosom e replication proteins synthesizedG2 Phase DNA replication complete at beginning shortest phaseG2 Phase organelles produced prepare for cell division10.2 Post Read Questions Describe the 2 stages of cell division. Draw a chromosome and label and describe its parts. What a
9、re the different phases of interphase? Describe each one. What is the cell cycle?10.2 B 12 / 06 / 06Interphase In between periods of cell division Cell growth and DNA replication occurProphase first and longest phase (50%- 60%) chromosome becomes visible centrioles take position on opposite sides of
10、 nucleus at the centrosomeProphase Centrioles lie in centrosome so they can organize the spindle Spindle = fanlike microtubule structure that helps separate the chromosomesProphase end = chromosomes coil and nuclear envelope break downMetaphase lasts only a few minutes chromosomes line up across the
11、 center of the cellMetaphase (cont) microtubules connect the centromere of each chromosome to the two poles of the spindleAnaphase centromeres that join the sister chromatids split into individual chromosomes and are moved apart to opposite polesTelophase chromosomes become dense material spindle br
12、eaks apart nucleolus appearsCytokinesis Division of cytoplasm usually occurs the same time as telophase Animal Cell = cell membrane draw inward and pinched off Plant cell = cell plate forms midway between the 2 nuclei; cell wall appearsIP M A T N T E R P H A S ER O P H A S EE T A P H A S EN A P H A
13、S EE L O P H A S EABCDEPut the pictures in orderANSWERDCEABCh 10 Review Questions (Cont) What is cytokinesis? When does it occur? Compare how cytokinesis works between animal and plant cells. Describe metaphase. Describe anaphase. If you were to look at a picture of telophase and anaphase, how can y
14、ou distinguish the difference between the two?10.312 / 7 / 06Review: Cell Cycle Preparing for Cell Division INTERPHASE G1 S G2Review: Cell Cycle Steps of Cell Division Mitosis Prophase Metaphase Anaphase Telophase / Cytokinesis Look at Figure 10.7 Observe what is going on What is happening in each s
15、tep?Cyclin protein regulates the timing of the cell cycle in eukaryotic cellsRegulatory Proteins Two types Internal Regulators External RegulatorsInternal Regulators proteins that respond to events inside the cell signals cell cycle to continue ONLY WHEN OTHER THINGS ARE COMPLETEExternal Regulator proteins that respond to events outside the cell direct cells to speed up or slow down the cell cycle example: growth regulatorsUncontrolled Cell Growth Cancer body loses ability to control
