Bell ringer—Is It Made of Cells?

Which of these are alive? How did you decide? Virus Bacteria Human cheek cell Puppy 2

Objectives List and describe the discoveries that led to the development of THE CELL THEORY. Describe how one scientist's work influences the following scientist's work. 3

Theory vs. Law A law is a well-supported description of WHAT is happening (a set of observations) A theory is a well- supported explanation of HOW it happens. BOTH are well-supported by the result of many different experiments. BOTH are widely accepted by the vast majority of people in that field. BOTH help unify a field. 4

In The Beginning... In the beginning, the majority of the population believed in the idea of spontaneous generation. Spontaneous Generation : The belief that life can arise from inanimate objects. However, today we know this to be false! Why?! 5

But, what is the Cell Theory? And the Oscar goes to... A number of different scientists were involved in establishing the Cell Theory. Each one contributed a little more to the theory we know today. But, what is the Cell Theory? 6

The Cell Theory has 3 Principles… Principle 1: All living things are made of one or more cells. Unicellular (made of one cell) Multicellular (made of many cells) HINT: IF IT HAS A CELL/CELLS, IT IS A LIVING THING. 7

The Cell Theory Principle 2: Cells are the most basic unit of how an organism is built and how it functions. T 8

Living or Non-Living? Virus Dog Soil Soil Note: Viruses are not made up of cells.

The Cell Theory Principle 3: All cells come from pre-existing cells. IN OTHER WORDS… All cells develop from other cells due to cell division. 10

Redi, Set, Go! Francisco Redi was the first scientist to formally question spontaneous generation. In 1638, Redi observed that maggots appeared on meat that was left out overnight. He performed an experiment to see if rotted meat could produce maggots.

The Path To The Cell Theory From there, the cell theory began to grow from the work and research of many scientists. More was learned about cells as microscopes improved over the years. 12

Robert Hooke Used a light microscope to look at plant tissue. Noticed that a piece of dead cork had tiny chambers. Called them cells because they looked like the cells of a monastery. Hooke's Microscope Hooke's Drawings 13

Anton van Leeuwenhoek One of the first people to use a microscope to study living things in nature. Able to see things that no one had seen before. First person to see the tiny organisms living in pond water. 14

Other Important Scientists Matthias Schleiden All plants are made of cells. Theodor Schwann All animals are made of cells. Rudolf Virchow Looked at how cells reproduce. Cells come from cells that already exist. 15

The Classification of Cells Now that these scientists discovered cells, they needed a way to classify(distinguish between) them. There are two types of cells:

Prokaryotes vs. Eukaryotes Eukaryotes are/have: Big Ribosomes Complex Membrane-bound organelles A Nucleus The nucleus houses the cell's DNA. The nucleus is the control center of the cell. Prokaryotes are/have: Small Ribosomes Simple Naked DNA There isn't a need for a control center because the cell is so small!

Guided Practice Guiding Puppy will guide you to success!

Prokaryotes vs. Eukaryotes Word Bank Nucleus DNA No Nucleus (naked DNA) Membrane bound organelles Unicellular Multicellular More Complex Larger Less Complex Smaller Ribosomes 19

How does the modern cell theory differ from the origin of life theory?