Download cell division, mitosis

1. Cells grow larger
and reproduce
2. Development of whole
organism from single cell
(zygote)
3. Worn-out cells are replaced.
What controls these processes?
C
DNA
Genetic information
is encoded in the
sequence of bases
G
G
A
T
G
G
C
C
A
T
T
C
T
G
A
C
A
Code is translated to
amino acid sequence
of proteins
C G
T
A
G
C
A
T
A
G
G
T
A
A
T
T
C
C
THE PATH OF PROTEIN SYNTHESIS
DNA
1
mRNA
nucleus
amino acids
2
ribosome
mRNA
3
cytoplasm
protein
• Chromosomes consist of a long DNA molecule
with thousands of genes
Chromatin = DNA with associated proteins
Genome = one complete set of chromosomes for
an organism
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
The large, complex chromosomes of eukaryotes
duplicate with each cell division
• A eukaryotic cell has many more genes than a
prokaryotic cell
Figure 8.4A
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
1. Original DNA
molecule unwinds.
2. New DNA strands are synthesized
from the two original strands.
a DNA in uncondensed form
a
DNA
chromatin
DNA replication...
duplicated chromosome
cell
…has this effect at chromosomal level
unduplicated
chromosome (not
actual shape)
duplicated
chromosome
b
sister chromatids
• When chromosomes
are duplicated, sister
chromatids are
produced
Sister chromatids
Centromere
telomere
Figure 8.4B
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Human bands
Figure 8.19x1
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Human karyotype
Figure 8.19x2
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• When the cell
divides, the sister
chromatids separate
Chromosome
duplication
– Two daughter
cells are produced
– Each has a
complete and
identical set of
chromosomes
Sister
chromatids
Centromere
Chromosome
distribution
to
daughter
cells
Figure 8.4C
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
cell
nucleus
DNA
1. REPLICATION
DNA
DNA
• Eukaryotic cell
division consists
of two stages:
– Mitosis
– Cytokinesis
2. MITOSIS
DNA
DNA
3. CYTOKINESIS
DNA
DNA
DNA
Mitotic Phase (M)
DNA
DNA
DNA
Interphase
DNA
DNA
G2
Cell growth
preparation for
division
Interphase
G1
Cell growth
S
DNA replication
DNA
DNA
Interphase
DNA
INTERPHASE
PROPHASE
Centrosomes
(with centriole pairs)
Early mitotic
spindle
Centrosome
Chromatin
Nucleolus Nuclear
envelope
Plasma
membrane
Chromosome,
consisting of two
sister chromatids
Figure 8.6
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Fragments
of nuclear
envelope
Centrosome
Kinetochore
Spindle
microtubules
METAPHASE
ANAPHASE
Cleavage
furrow
Metaphase
plate
Spindle
TELOPHASE AND CYTOKINESIS
Daughter
chromosomes
Figure 8.6 (continued)
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Nuclear
envelope
forming
Nucleolus
forming
• Mitotic spindle
Figure 8.6x2
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Cytokinesis differs for plant and animal cells
• In animals, cytokinesis
occurs by cleavage
– which pinches the cell
apart
Cleavage
furrow
Cleavage
furrow
Figure 8.7A
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Contracting ring of
microfilaments
Daughter cells
• In plants, vesicles
build a new cell plate
Cell plate
forming
Wall of
parent cell
Cell wall
Figure 8.7B
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Vesicles containing
cell wall material
Daughter
nucleus
New cell wall
Cell plate
Daughter
cells
• Binary fission - example: E. coli dividing
Figure 8.3x
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
BINARY FISSION IN BACTERIA
cell wall
two
daughter
cells
chromosome
cell membrane
parent
bacterial
cell
Review of functions of mitosis:
• Mitotic cell division functions in:
– Growth (ex. onion root)
Figure 8.11A
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Cell replacement (ex. skin)
Dead
cells
Epidermis,
the outer
layer of the
skin
Dividing
cells
Dermis
Figure 8.11B
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Asexual reproduction (seen here in a hydra)
Figure 8.11C
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Development (Sea urchin )
Figure 8.0x
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings