Zusammenfassung der Ressource
CH 10: How Cells Divide
- BACTERIAL CELL
DIVISION
- bacteria divide by
BINARY FISSION
- reproduction is
clonal
- EUKARYOTIC
CHROMOSOMES
- CHROMOSOMES
- made of chromatin
- complex of
DNA and
protein
- NON-DIVIDING
NUCLEUS
- HETEROCHROMATIN
not expressed
- EUCHROMATIN
expressed
- CHROMOSOME STRUCTURE
- NUCLEOSOME
- complex of DNA and
histone proteins
- HISTONES
- positively charged,
strongly attracted to
negatively charged
phosphate groups of DNA
- promote and
guide coiling DNA
- Eukaryotic Cell Cycle
- INTERPHASE
- G1 (gap phase 1)
- primary growth
phase, longest phase
- S (synthesis)
- replication of
DNA
- G2 (gap phase 2)
- organelles replicate,
microtubules organize
- DURATION
- typical mammal
cell around 24
hours
- M PHASE
- M (mitosis)
- subdivided
into four
phases
- PROPHASE
- chromosomes condense,
centrioles migrate to
opposite ends, nuclear
envelope breaks down
- PROMETAPHASE
- spindles attach to
kinetochore of
sister chromatids
- METAPHASE
- chromosomes
align at
metaphase plate
- ANAPHASE
- cohesion proteins
removed, spindle fibers
are shorter, chromosomes
pulled to opposite poles
- TELOPHASE
- nuclear envelop reforms
around each set of
chromosomes, chromosomes
uncoil, spindle apparatus
diassembles
- division of nucleus
- C (cytokinesis)
- separation of
new cells
- CANCER
- uncontrolled
cell
division
- WHY?
- FAILURE IN CELL
CYCLE CONTROL
- TUMOR-SUPPRESSOR GENES
- make proteins to stop cell cycle
- "BREAK PEDAL"
- P53
- P53 protein monitors integrity of DNA:
if it is damaged or not, if it can be
repaired
- if it can't be repaired
- APOPTOSIS
- cell is programmed
to kill itself
- LOSS OF FUNCTION
- cells will divide without repair
- then there is build up of multiple mutations
- CANCER
- two
tumor-suppressor
genes need to lose
function
- PROTO-ONCOGENES
- tells cell cycle to go
- "GAS PEDAL"
- GAIN OF FUNCTION
- ONCO: rapid cell
divison / cancer
- only one oncogene
needs to have
uncontrolled division
- MUTATIONS CAUSE THESE GENES NOT TO WORK
- CELLS PRODUCE MORE CELLS FOR GROWTH AND REPAIR