chapter 10 cell growth & division. cell division there are 2 main reasons cell divides: there...
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Cell Cycle The sequence of growth and division of a cell The sequence of growth and division of a cell An average cycle may be 22 hours An average cycle may be 22 hours Two general periods: Two general periods: 1. growth phase 2. division phaseTRANSCRIPT
Chapter 10Chapter 10Cell Growth & DivisionCell Growth & Division
Cell DivisionCell Division There are 2 main reasons cell divides:There are 2 main reasons cell divides:
1.1. The cell has more trouble trying to move The cell has more trouble trying to move nutrients and wastes across the cell nutrients and wastes across the cell membrane.membrane.
2.2. The larger a cell becomes, the more The larger a cell becomes, the more demands it puts on its DNA.demands it puts on its DNA.
Bottom line – cells need to be replacedBottom line – cells need to be replaced
Cell CycleCell Cycle• The sequence of The sequence of
growth and division of growth and division of a cella cell
• An average cycle may An average cycle may be 22 hoursbe 22 hours
• Two general periods:Two general periods: 1. growth phase1. growth phase 2. division phase2. division phase
Interphase (Growth phase)Interphase (Growth phase)
Most of the cell’s Most of the cell’s life is spent in life is spent in interphaseinterphase
Longest phase –Longest phase –(90% of cell’s (90% of cell’s growth)growth)
Centrioles – help to Centrioles – help to organize cell divisionorganize cell division
Chromatin – DNA bound Chromatin – DNA bound protein within the nucleusprotein within the nucleus
Interphase (Growth phase)Interphase (Growth phase)
New DNA is formed New DNA is formed during 3 phases:during 3 phases:
GG11 – 1 – 1stst period of growth period of growth 1. Increase in size.1. Increase in size.
2. Makes new proteins and 2. Makes new proteins and organelles.organelles.
SS1 1 – DNA is synthesized or – DNA is synthesized or replicated replicated
1. Chromosomes are replicated.1. Chromosomes are replicated. 2. New DNA molecules are 2. New DNA molecules are
made. made.
GG2 2 – final cell growth– final cell growth1. Shortest phase1. Shortest phase2. Prepares cell for mitosis2. Prepares cell for mitosis
Terms to knowTerms to know Chromosome – Chromosome –
contains genetic contains genetic information (DNA) information (DNA) passed from one passed from one generation to the nextgeneration to the next
Spindle – microtubule Spindle – microtubule that helps separate that helps separate chromosomeschromosomes
A – centromere: A – centromere: center of chromosomecenter of chromosome B – chromatids: two B – chromatids: two
identical “sister” parts identical “sister” parts of the chromosomeof the chromosome
Mitosis (Division phase)Mitosis (Division phase)
4 phases:4 phases:(PMAT)(PMAT)
1)1) PProphaserophase2)2) MMetaphaseetaphase3)3) AAnaphasenaphase4)4) TTelophaseelophase
MitosisMitosis
Takes place within the nucleus of the cellTakes place within the nucleus of the cell
4 phases that blend from one to another4 phases that blend from one to another
ProphaseProphase 11stst and longest phase and longest phase
of mitosisof mitosis Chromatin become Chromatin become
chromosomeschromosomes Chromatids are joined Chromatids are joined
by centromereby centromere Nucleus disappearsNucleus disappears Centrioles migrate to Centrioles migrate to
polespoles Spindles are formedSpindles are formed
MetaphaseMetaphase
22ndnd phase of mitosis phase of mitosis Chromosomes meet Chromosomes meet
in the middle of cellin the middle of cell Pulled by spindlesPulled by spindles Each chromosome is Each chromosome is
attached to top of attached to top of spindlespindle
AnaphaseAnaphase
33rdrd phase of mitosis phase of mitosis Centromeres are split Centromeres are split
apartapart Chromatids are pulled Chromatids are pulled
apart and begin to apart and begin to drift to opposite polesdrift to opposite poles
TelophaseTelophase Final phase of mitosisFinal phase of mitosis Begins when chromatids Begins when chromatids
reach polesreach poles New nucleus starts to New nucleus starts to
formform Chromosomes start to Chromosomes start to
unwindunwind Spindles disappearSpindles disappear Cytoplasm begins to Cytoplasm begins to
dividedivide
CytokinesisCytokinesis Cytoplasm Cytoplasm
pinches in pinches in halfhalf
Each daughter cell has Each daughter cell has an identical set of an identical set of chromosomeschromosomes
Plants
apical meristem
Rat – epithelial cellsRat – epithelial cells
Prophase, Metaphase, Anaphase, Prophase, Metaphase, Anaphase, or Telophase?or Telophase?