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CHAPTER 4: GROWTH AND DIVISION OF THE CELL, cell-cycle-1, Mitosis-vs…
CHAPTER 4: GROWTH AND DIVISION OF THE CELL
Concepts
cell cycle
mother cell
grows
divides
daughter cell
daughter cell
division phase
growth phase
stop dividing
cell cylce arrest
differentiate and mature
Controlled Growth
vs Cancerous Growth
growth needs to be controlled
rate
orientation
location
plants impose quiescence on some cells
can be ractivated
cancerous growth
uncontrolled division
release from cell cycle arrest
#
a lot less dangerous for plants than for animals
cancer can't migrate in plants
no vital organs
Chloroplast Division During Leaf Growth
plastid replication doesn't happen at the same rate as cell replication
#
Cell Division in Algae
Nuclei
Algae
gaps form in nuclear envelope
microtublues pass through nucleus
no histones
fungi
some have intranuclear and extranuclear spindle
nuclear envelope and nucleoi don't break down in many species
Cytokinesis
no cell wall
plasma membrane pinches in two
cleavage furrow
with cell wall
very similar to plants
phragmoplast
#
nuclear envelop breaks
different to plants
phycoplast forms
furrowing or cell plate formation
nuclear envelope remains
red algae
phragmoplast
wall grows inward
large hole (pit connection)
filled with protein and carbohydrates (pit plug)
Growth Phase of the Cell Cycle
interphase
S
Synthesis
chromosomes are replicated
chromatids connected at centromere
genes
chromosome
histone proteins give structure
centromere
telomeres
endoreducplication
multiple replications of DNA after stopping in G1
similarly, gene amplification
G2
Gap 2
prepare for division
spindle microtubules synthesized
G1
Gap 1
recovering from division
normal metabolism
synthesis of nucleotides
longest phase in cycle
(generally)
Division of Chloroplast and Mitochondria
infurrowing or pulled in two
both daughter cells need the organelles to have a full genome
division of organelles is more continuous
Cell Division of Prokaryotes
no mitosis or meiosis
(no nucleus to divide)
rings of DNA attached to plasma membrane
daughter loops are pulled apart as membrane grows
infurrowing
membrane pinches in two
Rates of Growth
arithmetic increase
only one cell divides
one additional cell each cycle
slow growth
hairs
basal cell
geometric increase
all cells divide
cells double each cycle
powers of 2
rapid growth
used in plants mostly only when extremely young
Division Phase of the Cell Cycle
Karyokinesis
division of nucleus
Mitosis
duplication division
"exact" copies
separates doubled chromosomes
#
Prophase
chromosomes condense
nuclear envelope breaks
microtubules (spindle)
pole to center
pole to centromere
kinetochore
Metaphase
chromosomes move to center
metaphase plate
prophase and metaphase often overlap
separase is activated
digests cohesin
chromatids are free of each other
Anaphase
microtubles shorten
sister chromatids pull apart
Telophase
nuclear envelopes form
chromosomes uncoil
new nucleoli appear
spindle depolymerizes
reverse of Prophase
Meiosis
sexual reproduction
sex cells (gametes) fuse
forms zygote
one set of chromosomes
haploid
two sets of chromosomes
diploid
four sets of chromosomes
tetraploid
production of reproductive cells
reduction division
two divisions
(no S phase between)
Meiosis I
Metaphase I
Anaphase I
1 more item...
Prophase I
1 more item...
Telophase I
3 more items...
Division of Homologs
Meiosis II
same steps
3 more items...
Division of Chromatids
results in 4 haploid cells
or 1 haploid cell and other 3 degenerate
egg cells
Cytokinesis
division of protoplast
not as precise as Mitosis
preprophase band
phragmoplast
where metaphase plate was
dictyosome vesicles
new primary walls and middle lamella begin to form
cell plate
vacuole division
phragmosomes
Less Common Types of Division in Plants
karyokinesis without cytokinesis
very large cell
hundreds or thousands of nuclei
coenocyte
cytokinesis without karyokinesis
multinucleate cell
new cell walls form around each nucleus
lily flowers
four nuclei
three on one side, one on other
forms two haploid nuclei and two triploid nuclei
