Cell Theory 7.1 Questions of the day! What are the seven characteristics of life? Cells have a specific set of rules that they always follow. What do you think they are? How can scientists determine what these rules are? What tools might they use? How is a theory different from a hypothesis? Why would the rules for cells be called “cell theory”?

Cell Theory 7.1 Cells discovered by Robert Hooke in 1665 by looking at cork. Named cells because they looked like rooms (cells). 50 years later, animal cells were found. Robert Hooke's cells

Cell Theory 7.1 Brain cells We have learned that life requires 7 characteristics in order to be considered living. Likewise, cells have rules that they ALWAYS follow Brain cells

Cell Theory 7.1 Cell Theory Series of statements that ALL cells follow. All organisms are made of cells. Cells are the basic unit of organization in an organism. All cells are derived from existing cells.

Cell Theory 7.1

Cell Theory 7.1 Microscopes Compound light microscope Light and lenses used to magnify 1000 x is the greatest magnification Doesn’t kill the specimen Eye lens x objective lens = total magnification 10 X x 10X = 100X

Cell Theory 7.1

Cell Theory 7.1 Plant Cell – light microscope Bacteria – light microscope

Cell Theory 7.1 Electron microscopes Use electrons to magnify Specimens are blasted with electrons Image projected on a screen

Cell Theory 7.1 Transmission electron microscope (TEM) Cells are dead View internal structures 500,000 X greatest magnification Scanning electron microscope (SEM) Look at surface structures Kills cell 250,000 X magnification

Cell Theory 7.1 TEM Image of a cell SEM Image of a Tardigrade (color was added)

Cell Theory 7.1 Scanning tunneling electron microscope (STEM) Doesn’t kill Looks at atoms and DNA STEM Image of DNA

Cell Theory 7.1 Cell Types There are 2 types of cells Prokaryotic are simple (bacteria) Eukaryotic are complex (plants and animals) Both have similarities and important differences

Cell Theory 7.1 Prokaryotic and Eukaryotic Cells both have... DNA Ribosomes/Protein Membrane Phospholipid bilayer (Controls what goes in and out of cell) Follows cell theory Form follows function – shape determined by job.

Cell Theory 7.1 Prokaryotic Cells Small Bacteria No Nucleus No membrane bound organelles Circular DNA (plasmid) Divides through binary fission

Cell Theory 7.1 Eukaryotic Cells Have a Nucleus Have membrane bound organelles Undergoes mitosis DNA is linear Complex Plants and Animals

Cell Theory 7.1

Cell Theory 7.1 CONCLUSION! Cells allows follow the rules of cell theory Microscopes show scientists how cells function and what small structures on organisms look like There are 2 main cell types that have similarities but important differences. Prokaryotic cells are simple Eukaryotic cells are complex

Cell Theory 7.1 TASKS! Draw a prokaryotic and eukaryotic cell labeling the main differences. If you encountered an alien cell, discuss how you would tell if it was a prokaryotic or a eukaryotic cell. What is “cell theory”? What does it state?