3. worn-out cells are replaced. 1. cells grow larger and reproduce 2. development of whole organism...
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3. Worn-out cells are replaced.
1. Cells grow larger and reproduce
2. Development of whole organism from single cell (zygote)
What controls these processes?
CTGA
C G
G C
A T
G C
CG
AT
AT
C G
ATG C
A T
AT
G C
G C
A TT A
DNAGenetic information is encoded in thesequence of bases
Code is translated to amino acid sequenceof proteins
THE PATH OF PROTEIN SYNTHESIS
1mRNA
DNA
nucleus
cytoplasm
2
3
ribosome
amino acids
mRNA
protein
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• 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
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• A eukaryotic cell has many more genes than a prokaryotic cell
The large, complex chromosomes of eukaryotes duplicate with each cell division
Figure 8.4A
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... …has this effect at chromosomal level
duplicated chromosome cell
unduplicated chromosome (not actual shape)
duplicated chromosome
sister chromatidsb
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• When chromosomes are duplicated, sister chromatids are produced
Centromere
Sister chromatids
Figure 8.4B
telomere
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• Human bands
Figure 8.19x1
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• Human karyotype
Figure 8.19x2
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• When the cell divides, the sister chromatids separate – Two daughter cells are produced
– Each has a complete and identical set of chromosomes
Centromere Sister chromatids
Figure 8.4C
Chromosomeduplication
Chromosomedistribution
todaughter
cells
cell
nucleus DNA
DNADNA
DNA DNA
DNA DNA
1. REPLICATION
2. MITOSIS
3. CYTOKINESIS
• Eukaryotic cell division consists of two stages:– Mitosis– Cytokinesis
DNA
DNA
DNA
DNA
DNADNA
DNADNA
DNA
G1
Cell growth
SDNA replication
G2 Cell growth preparation for
division
Mitosis
Cytokinesis
Mitotic Phase (M)
Interphase
Interphase
Interphase
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INTERPHASE PROPHASE
Centrosomes(with centriole pairs)
Chromatin
Nucleolus Nuclearenvelope
Plasmamembrane
Early mitoticspindle
Centrosome
CentrosomeChromosome,consisting of twosister chromatids
Fragmentsof nuclearenvelope
Kinetochore
Spindlemicrotubules
Figure 8.6
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METAPHASE TELOPHASE AND CYTOKINESIS
Metaphaseplate
Spindle Daughterchromosomes
Cleavagefurrow
Nucleolusforming
Nuclearenvelopeforming
ANAPHASE
Figure 8.6 (continued)
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• Mitotic spindle
Figure 8.6x2
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• In animals, cytokinesis occurs by cleavage
– which pinches the cell apart
Cytokinesis differs for plant and animal cells
Figure 8.7A
Cleavagefurrow
Cleavagefurrow
Contracting ring ofmicrofilaments
Daughter cells
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• In plants, vesicles build a new cell plate
Vesicles containingcell wall material
Cell plateforming
Figure 8.7BCell plate Daughter
cells
Wall ofparent cell
Daughternucleus
Cell wall New cell wall
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• Binary fission - example: E. coli dividing
Figure 8.3x
BINARY FISSION IN BACTERIA
cell wall
chromosome
cell membraneparent bacterial cell
two daughter cells
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• Mitotic cell division functions in:
– Growth (ex. onion root)
Review of functions of mitosis:
Figure 8.11A
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• Cell replacement (ex. skin)
Deadcells
Figure 8.11B
Dividingcells
Epidermis, the outer layer of the skin
Dermis
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• Asexual reproduction (seen here in a hydra)
Figure 8.11C
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• Development (Sea urchin )
Figure 8.0x
