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 1 mRNA DNA nucleus cytoplasm 2 3 ribosome amino acids mRNA protein

CTGACTGA CG G C AT GC CG A T A T CG A T G C A T A T GC GC A T T A DNA Genetic information is encoded in the sequence of bases Code is translated to amino acid sequence of 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

aDNA chromatin DNA replication...…has this effect at chromosomal level duplicated chromosome cell unduplicated chromosome (not actual shape) duplicated chromosome sister chromatids b

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 Chromosome duplication Chromosome distribution to daughter cells

cell nucleus DNA 1. REPLICATION 2. MITOSIS 3. CYTOKINESIS

DNA G 1 Cell growth S DNA replication G 2 Cell growth preparation for division Mitosis Cytokinesis Mitotic Phase (M) 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 INTERPHASEPROPHASE Centrosomes (with centriole pairs) Chromatin NucleolusNuclear envelope Plasma membrane Early mitotic spindle Centrosome Chromosome, consisting of two sister chromatids Fragments of nuclear envelope Kinetochore Spindle microtubules Figure 8.6

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings METAPHASETELOPHASE AND CYTOKINESIS Metaphase plate SpindleDaughter chromosomes Cleavage furrow Nucleolus forming Nuclear envelope forming 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 Cleavage furrow Contracting ring of microfilaments Daughter cells

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings In plants, vesicles build a new cell plate Vesicles containing cell wall material Cell plate forming Figure 8.7B Cell plateDaughter cells Wall of parent cell Daughter nucleus Cell wallNew 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 membrane parent 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) Dead cells Figure 8.11B Dividing cells 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