1. Cells grow larger and reproduce. 2. Development of whole organism from single cell (zygote)

1. Cells grow larger and reproduce

2. Development of whole organism from single cell (zygote)

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?

DNA - key molecule that carries information to direct all cell functions

THE PATH OF PROTEIN SYNTHESIS

1mRNA

DNA

nucleus

cytoplasm

2

3

ribosome

amino acids

mRNA

protein

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

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

• Chromosomes contain a very long DNA molecule with thousands of genes

Chromatin = DNA with associated proteins

Genome = complete set of chromosomes for an organism

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

• 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

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

• When chromosomes are duplicated, sister chromatids are produced

Centromere

Sister chromatids

Figure 8.4B

telomere

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 – 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

DNA

DNA

DNA

DNA

DNADNA

DNADNA

DNA

G1

Cell growth

SDNA replication

G2 Cell growth preparation

for division

Mitosis

Cyto

kinesis

Mitotic Phase (M)

Interphase

Interphase

Interphase

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

• Eukaryotic cell division consists of two stages:

– Mitosis

– Cytokinesis

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

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

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

METAPHASE TELOPHASE AND CYTOKINESIS

Metaphaseplate

Spindle Daughterchromosomes

Cleavagefurrow

Nucleolusforming

Nuclearenvelopeforming

ANAPHASE

Figure 8.6 (continued)

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

• 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

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

• 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

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

• E. coli dividing

Figure 8.3x

BINARY FISSION IN BACTERIA

cell wall

chromosome

cell membraneparent bacterial cell

two daughter cells

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

• Mitotic cell division functions in:

– Growth (here, onion root)

Review of functions of mitosis:

Figure 8.11A

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

• Cell replacement (seen here in skin)

Deadcells

Figure 8.11B

Dividingcells

Epidermis, the outer layer of the skin

Dermis

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

• Mitotic spindle

Figure 8.6x2