12 A. Cells need to stay small because: The larger a cell becomes, the more demands on its DNATrouble moving enough nutrients and wastes across the cell membraneOrganization!
13 DNA “Overload” DNA is the cell’s “library” of information. Imagine a very large city using one local library for all materials
14 A big bag is weaker, harder to find things Large cell, difficult to maneuver organelles
15 More volume = bigger need The larger the volume ofthe balloon, the weaker itis. The balloon skin staysthe same.
16 Large surface area SPEEDS UP the movement of materials B. What is Surface area?The total area of thesurface of a three-dimensional object2 cmWhat is the surface area of this cube?2 cm24 cm2The villi of small intestines and the cristae of mitochondria are examples of maximizing surface area for chemical reaction and diffusion to take placeLarge surface area SPEEDS UP the movement of materials
17 200 cm3 C. What is Volume? The amount of 3-dimensional space that an object occupies, “capacity”Large volume SLOWS downmovement of materialsWhat is the VOLUME of the shape here?200 cm3cm
18 D. Ratio of Surface Area to Volume As the length of cell increases,volume increases faster surface area(cm3 compared to cm2)HIGH ratio desired: quick movement of materialsEx: 6000/1 is better than 2/1
19 It’s better to have lots of small cellsinstead of fewerlarge cells!
20 II. Chromosomes All genes located in DNA in nucleus of eukaryotic cell B. Chromosomesare condensedforms of DNA
21 Chromosomes Chromosome number is unique to every species Humans: 46 chr.Chimpanzees: 48 chr.Yeast: 32 chr.Adders-Tongue Fern: 1440 chr.!
22 Anatomy of a Chromosome Chromatids attached atthe centromereCopied duringInterphaseD. After duplicationphase, eachchromosomeconsists of twoidentical “sister”chromatids
23 II. Cell DivisionA.46 chr46chromosomes46 chrB. Chromosome # stays the same[Cells growths, doubles chromosomes, then splits, forming two daughter cells with original # of chromosomes]
24 C. Common Locations for Cell Division Intestinal lining- every 24 hoursSkinBlood cells/bone marrow- 120 daysLiver- sometimes
25 D. Cells that Rarely Divide (In G0 phase) Muscle CellsCardiac cellsKidneyNerve cells
27 Gap0 “resting phase”, cell is not growing A. Interphase: “I-ball”90% of the time!Gap “resting phase”, cell is not growingGap cell grows, doubles organellesSynthesis duplication of the DNA inthe cell's chromosomesGap cell grows, microtubules assembledG0- is “quiescent” phase.. Some cells stay here after terminal differentiation, while others are here and can move into G1
28 C. CheckpointsG1 Checkpoint:DNA to be replicated is healthy; cell sizeG2 Checkpoint: Checks that DNA that was replicated is healthy; rest of cell ready for divisionM checkpoint:Chromosomes are properly attached to the spindle fibers.
29 What happens if the cell cannot pass through the checkpoint? Repair the damageORB) Self-destruct: APOPTOSIS(Programmed Cell Death)There are proteins in the cell that regulate these processes and determine which way the cell will go.
42 MITOSIS Video Daughter Parent Cell Cells Why cant a cell just split into two?Parent Cell to daughter cells- Note daughter cells look genetically identical to parent cellsDNA replication
43 V. TermsA. Spindle: network of microtubules that move chromosomes during mitosis and meiosisB. Equator: center line of cell where chromosomes line up during metaphaseC. Poles: the opposite ends of cellD. Centrioles: animal cells only, move the spindle and chromosomes during division
44 E. Cleavage Furrow: the pinching in of animal cells during cytokinesis F. cell plate: disk in plant cells that divide the cell into two daughter cells during cytokinesisG. Centromere: region where two sister chromatids are joined tightly together