Cell History

Cell History All life is made of cells Cells discovered after microscope invented 1665: Robert Hooke first observed cork (dead tree bark) Boxes he saw reminded him of tiny rooms He named the empty boxes “cells” Cell History Most likely not a picture of Robert Hooke. No known pictures have survived. Cork cells are dead. That’s why they look empty. All that remains is the outer cell wall. Cork is the bark of a type of oak tree. Lets zoom in…

Cell Theory Three Parts: 1) All organisms are made of 1 or more cells Matthias Schleiden Theodore Schwann Rudolf Virchow Cell Theory Three Parts: 1) All organisms are made of 1 or more cells 2) The cell is the most basic unit of life 3) Cells come from other cells What’s the big problem with this theory? Rudolf Virchow German doctor Concluded that cells arise from preexisting cells. Matthias Schleiden, German botanist Concluded that the structure of plants were composed of cell. Theodore Schwann, German physiologist Extended Schleiden’s view. All life is composed of cells. Cells have smaller parts. So why is the cell the basic unit of life and not the smaller parts? Where did the 1st ever cell come from?

Cell Diversity Shape depends upon function Typical Plant Cell Diagram Typical Animal Cell Diagram

Cell Diversity B A Shape depends upon function Nerve Cell Shape: Elongated branching Function: Sends messages to and from brain Advantage: Signals can travel a variety of directions B A Could you get from City A to City B, if Interstate 80 were suddenly closed?

Cell Diversity Vein Shape depends upon function Nerve Cell Shape: Elongated branching Function: Sends messages to and from brain Advantage: Signals can travel a variety of directions Red Blood Cell Shape: Disc-like Function: Carries O2 throughout blood Advantage: Roll through narrow veins & arteries Vein RBC RBC RBC

Cell Diversity Shape depends upon function Nerve Cell Shape: Elongated branching Function: Sends messages to and from brain Advantage: Signals can travel a variety of directions Red Blood Cell Shape: Disc-like Function: Carries O2 throughout blood Advantage: Roll through narrow veins & arteries Skin Cell Shape: Flat & broad Function: Covers and protects the body Advantage: Overlapping layers cover more area Skins cells act like the shingles on a roof.

Cell Categories 1) Prokaryote: Cells without a nucleus and other membrane-bound organelles First cells/life on Earth (oldest fossils = ~3.5 b.y.o) AKA: Bacteria

Amoeba (type of protista) Cell Categories Amoeba (type of protista) Mushroom (type of fungi) Tree (type of plant) Frog (type of animal) 2) Eukaryote: Cells with a nucleus & membrane bound organelles More complex cells Evolved from prokaryotes Ex: Protists, Fungi, Plants, Animals

Prokaryotes vs. Eukaryotes

Eukaryote Evolution Endosymbiosis Theory: Chloroplast & mitochondria were free-living organisms Evidence: Mitochondria & chloroplast contain own DNA, replicate, contain own ribosomes The Process Larger cell engulfed chloroplast & mitochondria Larger cell has an advantage Each continued to multiply Over time, each has become dependent on the other Chloroplast ancestor

Review Who first identified cells? What was he/she examining? Name the three parts to the cell theory. Explain how the shape of a blood cell allows it to perform it’s job better. Which category of cells contain nuclei? Why are bacteria considered the oldest forms of life on Earth? How do prokaryotes and eukaryotes differ? Which organelles are associated with the endosymbiosis theory? What evidence exists that the organelles from #8 were once free-living?