BIOLOGY 1A Lecture Notes - Lecture 16: Kinetochore, Telomere, Cell Division
Eukaryotic Cell Cycle: Machinery
-Transitory apparatus: made every cell cycle then destroyed
Microtubule cytoskeleton: spindle to separate chromosomes
1.
Contractile Ring with Actin: divides two cells into two
2.
Organelles: daughters get all of the parts
Abundant organelles: equal partitions
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Chloroplasts and Mitochondria: small number, have internal division (fission)
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Golgi and ER: break apart and daughters get pieces
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Centrosome: special case! Templates its own duplication
Protein structures that template their own duplication
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Cell division
Somatic division- mitosis 1 to 2
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Gametes: meiosis 1 to 4
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Live cell only replicates 1 every year. Intestinal cells replicate 1 a day
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Cell cycle is very fast in embryo- 8 minutes
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In our neurons we only replace 1 every 100 years
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Cancer: cell divides 1 every day. Inappropriate division
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G1>S>G2>M
G1 is growth phase; cell is determining if it can go through cell division.
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S is when DNA is replicated
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G2 is quality control
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M is mitosis and is typically the shortest; separate DNA
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Parts of Chromosome
Centromere is a DNA site where kinetochore attaches so microtubules can
attach
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Kinetochore is a group of proteins to centromere
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Multiple origins of replication
cant replicate last end bc there is no way to come around from the
other side without telomere
Szotak, Greider and Bladburn?
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Telomere: Cell will think it is damaged if the DNA is broken so set of
proteins cap it off so cell does not recognize
Proteins= telomerase
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Chromosomes= proteins and DNA
N= set of different chromosomes
1N= haploid, 1 set of chromosomes
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2N= diploid, 2 sets of chromosomes
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C= how many DNA molecules are in a chromosome
Pombe has 3 chromosomes (3N) but has 12x 10^6 bp.
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Munkjak has 3N but 3x10^9 bp
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How is N and C measures?
Add dye to measure number of chromosomes during mitosis
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C- have a dye that quantitatively dyes to number of DNA
Cell grows in dish. Dye bonds. Put it in FACS. Dye binds to how much
DNA is in there. Bright red vs. light red
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Laser will tell how much C is in it
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S phase: 2 homologous chromosomes then duplicates to 2 sister chromatids in
each homologous chromosome
DNA molecules before and after replication is 4 to 8
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C content goes from 2C to 4C
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N goes from 2 to 2 and chromosome number is 4 to 4
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Mitosis:
Metaphase: chromosomes line up in plane
Microtubules grow from - to +
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They attach to kinetochore and sometimes miss and keep going
past metaphase plate
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Pulling apart forces:
Cohesion holds the two sister chromatids together
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20 cM to 2uM
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Spindles that miss each other
Proteins bind to them and move stuff
Kinesin binds to microtubules and moves toward + end
of microtubules
So the centrioles are pushed away from each
other
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Dynein moves toward - end
Drags chromosome toward centriole
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Lecture 16 2/26
Thursday, March 8, 2018
4:48 PM
Document Summary
Transitory apparatus: made every cell cycle then destroyed. Contractile ring with actin: divides two cells into two. Chloroplasts and mitochondria: small number, have internal division (fission) Golgi and er: break apart and daughters get pieces. Cell cycle is very fast in embryo- 8 minutes. In our neurons we only replace 1 every 100 years. G1 is growth phase; cell is determining if it can go through cell division. M is mitosis and is typically the shortest; separate dna. Centromere is a dna site where kinetochore attaches so microtubules can attach. Kinetochore is a group of proteins to centromere. Multiple origins of replication cant replicate last end bc there is no way to come around from the other side without telomere other side without telomere. Telomere: cell will think it is damaged if the dna is broken so set of proteins cap it off so cell does not recognize. C= how many dna molecules are in a chromosome.
