Chapter 10 Cell Growth And Division. I. Cell Growth –A. Limits to Cell Growth –2 reasons cells...
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Transcript of Chapter 10 Cell Growth And Division. I. Cell Growth –A. Limits to Cell Growth –2 reasons cells...
Chapter 10
Cell Growth And Division
I. Cell Growth– A. Limits to Cell Growth– 2 reasons cells divide rather than
continuing to grow indefinitely:• 1) larger a cell grows,the more
demands on its _______– will not be making enough copies of
DNA as size increases---This would cause an information crisis.
• 2) difficult to move waste and nutrients across cell– rate @ which waste products leave
cell depends on _______________________ of cell=total area of cell membrane
DNA
Surface area
– rate @ which food and Oxygen are used up and waste produced depends on _____________________
– RATIO OF SURFACE AREA TO VOLUME-assuming a cube shape,surface area=l x w x 6…..volume= lx w x h…. ratio = SA /volume
Cell volume
Cell Size
Surface Area (length x width x 6)
Volume (length x width x height)
Ratio of Surface Area to Volume
Ratio of Surface Area to Volume in Cells
Section 10-1
• Volume increases faster than surface area/CAUSING RATIO TO __________________..causing serious problems for cell --Because a decrease in the relative amount of cell membrane available –compared to increase in cell volume--
decrease
B. Division of Cell-before a growing cell becomes too large
Cell division solves the problem of increasing size by reducing cell volume
-A cell divides into 2 daughter cells =_______________________________
– This happens before a cell can get too large
– DNA ___________________before cell division,solving info crisis.
Cell division replicates
C. Cell division and reproduction
• Asexual-takes one parent and produces genetically identical offspring-simple,efficient and effective
• What problems could it present…?• Some multicellular organisms
reproduce by budding---example-hydra
• Sexual-takes 2 parents-fusion of reproductive cells-new genetic info-some from each parent-greater diversity-advantage
• Comparing asexual and sexual-• Asexua l,since it is quick is a survival
strategy• Ok as long as conditions are favorable• Sexual advantage is diversity• Some do both-example-yeast
II. Cell Division Process
• ***simpler in prokaryotes– A. chromosomes –carries genetic info in
eukaryotes– made up of ____________ and proteins– cells of every organism have a
specific # of Chromosomes– humans have___ Chromosomes– fruit flies have 8– usually not visible except in cell
division,when they condense– ___________________before cell division
DNA
46
Replicates or copies
–each Chromosome consists of 2 identical __________________,which separate from each other in cell division
–chromatids attached @__________________,usually near middle
chromatids
centromere
II. Chromosomes & DNA Replication
• A-DNA & Chromosomes– In cytoplasm in prokaryotes– In _______________________found in cell
nucleus in the form of a number of chromosomes(46 humans,8 Drosophilia and 22 Sequoia trees)
eukaryotes
• 1--DNA length– 1.6 mm in E.coli(has 4,639,221 base
pairs)---obviously it must be tightly folded
B. Cell Cycle
– ________________________is in- between phase
– ______________________is the series of events that a cell goes through during growth and division….Where the cell grows,prepare for division,divides into 2 daughter cells
interphase Cell Cycle
–4 phases• M= _______________________________• S= ________________________________• G1 and G2=
________________________________________________________
Mitosis and cytokinesis Chromsomes
replicate & DNA synthesis,some proteins synthesize
G1=cell growth/G2= organelles and molecules produced
M phase
G2 phase
S phase
G1 phase
Figure 10–4 The Cell Cycle
Section 10-2
ANAPHASE
1) Prophase
– Longest phase– Chromosomes become visible– _______________________,2 tiny structures
near nuclear envelope-separate and take positions on opposite ends of nucleus
– Centrosome region helps organize __________________-microtubules that help separate chromosomes
– Chromosomes attach to __________________________
– @ end chromosomes coil tightly and nuclear envelope disappears
centrioles
spindle Spindle fibers
• 2) Metaphase-• chromosomes line up @ center• Centromeres go to 2 poles
• 3) Anaphase-• Centromeres split• Chromatids separate and become individual
_____________________• New chromosomes go to opposite poles and then
stop moving
chromosomes
• 4) Telophase-• Chromosomes disperse into tangle of
material• New nuclear envelopes• Spindle breaks apart• Nucleolus becomes visible
D. Cytokinesis-divison of cytoplasm– Usually along w/ Telophase– Cell plate forms in plants that becomes the
______________________________– Occurs at cleavage furrow in
animals,where it pinches inward---too rigid to pinch inward in plants
CELL WALL
III-Regulating Cell Cycle.• Most cells in lab divide until coming in contact
w/other cells-similar in body• _____________________= disorder in which some of
the body’s cells lose the ability to regulate growth• They do not respond to signals that regulate growth• Divide uncontrollably,making
___________________(masses of cells)/not all are cancerous
• _____________=protein that regulates normal cell cycle (in eukaryotes)cancer tumors
cyclins
• Cancer caused by defect in genes causing cell growth and division-oncogene-caused by carcinogens such as smoking,chew tobacco,radiation,viruses,chemicals-CARCINOGENS,many cancers linked to abnormality in p53 gene-normally halts cell cycle until all chromosomes have been replicated
• Cancer treated by-surgery for tumor removal,radiation-tarets DNA replication that is happening at accelerated rate, chemotherapy---both also affect normal cells
cyclins
• _________________=protein that regulates normal cell cycle (in eukaryotes)-tells cells it’s time to divide
• There are regulatory proteins internally and externally to the cell-for example(internally)-proteins that make sure replication has happened before mitosis/externally-GROWTH FACTORS-Stimulate growth or slow down growth-esp. important in embryo or wound healing
• APOSTASIS-process of programming cell death(which also can die by accidents)-key role in tissue and organ development-AIDS and Parkinson’s are examples of if apoptosis is not regulated