Cell History van Leeuwenhoek Hooke
Cell History All life is made of cells Discovered after microscope invented 1665: Robert Hooke first observed cork (dead plant bark) Cork reminded him of tiny rooms He named the empty boxes “cells”
Cell Theory Schleiden Schwann Virchow Three Parts: 1) All organisms are made of 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? Schwann Virchow
Cell Diversity Shape depends upon function Nerve Shape: Elongated branching Function: Sends messages to and from brain Red Blood Shape: Disc-like shape prevents clogging Function: Carries O2 throughout blood Skin Shape: Flat & broad; layers overlap Function: Covers and protects the body
Cell Categories 1) Prokaryote: Cells without a nucleus and other membrane-bound organelles Oldest cells known (~4 billion years old) Believed to have evolved first (oldest fossils) AKA: Bacteria
2) Eukaryote: Cells with a nucleus & membrane bound organelles Cell Categories 2) Eukaryote: Cells with a nucleus & membrane bound organelles More complex cells Evolved from prokaryotes Ex: Protists, Fungi, Plants, Animals
Eukaryote Evolution Endosymbiosis Theory: Chloroplast & mitochondria were free-living organisms Both were engulfed by a larger predator cell Both gave the larger cell an advantage (make food and energy) Predator cell provided each protection Over time, these cells could not survive without the mitochondria & chloroplast Evidence: Mitochondria & chloroplast contain own DNA, replicate, contain own ribosomes, make their own protein
Quick Review Cells shape is related to its job (function) Cells are the basic units of life Cells come from other cells
recap 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?