Chapter 1 Hierarchy of Life

1
Chapter 1Hierarchy of Life

• Atoms
• Molecules
• Cells
• Tissue
• Organs (systems)
• Organism
• Population
• Communities
• Bioshpere

2
What is Life

• Definition An organized genetic unit capable of
  metabolism, reproduction and evolution.
• What is evolution Any genetic and resulting
  phenotypic change in organisms from generation to
  generation.

3
What is the smallest Unit of Life

• The Cell
• Cell Theory- All organisms consist of cells and
  that all cells come from preexisting cells.
• So, then, where did life begin?

4
Evolution

• Start with a soup of chemicals that eventually
  interacted into enclosed compartments and became
  cells (3.8 billion years ago).
• For 2 billion years, cells were unicellular and
  prokaryotic and many were photosynthetic
• Photosynthesis deposited oxygen into the
  atmoshpere, helping to dampen the suns damaging
  rays (how????) and life could move onto land.

5
Evolution (cont.)

• Some cells became eukaryotic (how?)
• Multicellularity (1 billion years ago) arose, and
  cells could now specialize.
• Sexual reproduction changed everything! And
  speeded up evolution.
• Darwin explained it all with his Theory of
  Natural Selection.

6
Tree of Life

• Three Domains
• Bacteria
• Archaea
• Eukarya
• Bacteria split from the other two very early and
  while Archaea are also prokaryotes, they share a
  common ancestor with Eukarya.