History, Types and General Characteristics of Cells Packet #10 Chapter #3 Wednesday, October 21, 20151

Cytology Wednesday, October 21,  Cytology is the study of cells.

Cell Theory  Various scientists arrived at three major thoughts  All living things are composed of cells  Cells are the basic units of structure and function in living things  All cells come from preexisting cells  These three thoughts became known as the cell theory. Wednesday, October 21, 20153

The Discovery Wednesday, October 21,  Cells discovered by Robert Hooke in 1665  However the subcellular structures could not be seen--the organelles  It wasn’t until the 1950’s, with the invention of the electron microscope that cell biology really took off

Isolation of Organelles Cell Fractionation  Cell fractionation allowed scientists to study cell components and involves a process known as centrifugation  The centrifuge is an instrument that is used to fractionize cells  Spins fast as much as 80,000 revolutions per minute and apply forces on particles up to 500,000 times the force of gravity  Differential centrifugation separate cellular components based on size and density.  Density gradient centrifugation allows further purification. Wednesday, October 21, 20155

 Micromanipulation  Another technique for the removal of parts of the cell  Can also insert material into a living cell  Done while looking through a microscope  In-Vitro Fertilization  In-Vivo Fertilization  Cell Cultures**  Isolate one type of cell and you grow it in large numbers-- bacteria for example Wednesday, October 21, Isolation of Organelles II Micromanipulation & Cell Cultures

SIZE OF ATOMS, MOLECULES, MACROMOLECULES, ORGANELLES, CELLS AND ORGANISMS The Hierarchy Revisited Wednesday, October 21, 20157

Hierarchy Revisited Wednesday, October 21,  Why do you think that the size of a cell is significant?  What makes the cell’s size special?  The small cell size allows maximum cell surface area.  HW

Introduction of Prokaryotic & Eukaryotic Cells  The discovery of cells, and their components, led to the distinction between prokaryotic cells and eukaryotic cells. Wednesday, October 21, 20159

Prokaryotic vs. Eukaryotic Wednesday, October 21,  Prokaryotic Cells  Prokaryotes are structurally simpler than eukaryotic cells.  Prokaryotic cells lack membrane-bound organelles and are typically smaller than eukaryotic cells.  Prokaryotic cells have a plasma membrane and typically a cell wall.  In prokaryotes, DNA is located in the nuclear area or nucleoid.  Prokaryotes have smaller ribosomes.  Chlorophyll may be present but no chloroplasts.  Mitosis, nor meiosis, does not occur  Cells reproduce by other asexual means

Prokaryotic versus Eukaryotic II Wednesday, October 21,  Eukaryotic Cells  Membrane bound organelles are present  Nucleus and nuclear membrane are present  Chlorophyll, when present, is contained in chloroplasts  Ribosomes are larger  Cell wall is present in some eukaryotic cells  Mitosis and meiosis occurs

Prokaryotic CellsEukaryotic Cells  No distinct nucleus  No chromosomes  Circular strands of DNA known as plastids  No membrane bound organelles  Ribosomes are smaller  No mitosis or meiosis occurs  Distinct, membrane-bounded nucleus  Chromosomes present on which DNA is located  Chloroplasts and mitochondria may be present  Ribosomes are larger  Mitosis and/or meiosis occurs Prokaryotes vs. Eukaryotes Wednesday, October 21,

TYPES OF EUKARYOTIC CELLS Plant cells vs. Animal Cells Wednesday, October 21,

Eukaryotic Cells Wednesday, October 21,  Most organisms are eukaryotes and are composed of eukaryotic cells.  There are two basic types of eukaryotic cells  Plant cells  Animal cells Organisms Prokaryotic Prokarytic Cells Eukaryotic Eukaryotic Cells Plant Cells Animal Cells Nerve cells Muscle cells Blood cells

Plant Cells Wednesday, October 21,  Have cell walls  Contain cellulose  Large vacuole filled with cell sap  Larger than animal cells  Shape  Different from animal cells  Cilia and flagella absent in higher plants  What kingdom(s) are the higher plants found?  What kingdom(s) are the lower plants found?

Animal Cells Wednesday, October 21,  No cellulose cell wall in MOST animal cells  Plasma membrane  Some vacuoles but they are usually small and numerous  Cytoplasm throughout the cell  Nucleus may be found anywhere in the cell  Is normally in the center of the cell  Cilia is common in animal cells of higher animals

Animal Cell II Cell Specialization Wednesday, October 21,  In animals, cells are often uniquely suited to perform a particular function within the organism  Nerve Cells  Muscle Cells  Rods and Cones in the eye  Sex cells  These specialized cells are determined by complex processes of turning on and off genes.

Wednesday, October 21, Plant Cell

Wednesday, October 21, Animal Cell

Plant Cell vs. Animal Cell Similarities  Both Eukaryotic Cells  Have membrane bound organelles Differences  Plant cells are “generally” larger than animal cells  Plant cells have a cell wall of cellulose  Adds stability and protection to the plant cell  Plant cells have vacuoles  That are used as space fillers  Fulfills digestive functions in plants--similar to lysosomes that are also found in animal cells.  Animal cells have centrioles Wednesday, October 21,

Review Wednesday, October 21,