Cells: The Basic Units of LIFE

Early Discoveries of Life The first person to study nature under a microscope was Anton Van Leeuwenhoek Robert Hooke later took bark from a tree and discovered small chambers he called cells Other scientists then began to look at more plants and animals under microscopes, all discovering cells were the basic units of all living things!

What is a Cell?! It took a long time for people to discover cells and figure out what they were all about. They need sophisticated equipment (microscopes) to be able to see cells. Every thing we know about cells we call “cell theory”.

Cell Theory says that… 1.All living things are composed of cells. 2. Cells are the basic units of structure and function in all living things. 3. New cells are produced from existing cells.

Basic Cell Structure: All cells have the same basic structure. Some are simple and some are very complex, but we always see… –Cell Membranes –Cytoplasm Many cells also have a… –Cell Wall –Nucleus

Cells come in all shapes and sizes!

There are two types of cells: Prokaryotic Cells and Eukaryotic Cells

These are two distinct types of cells with STRUCTURAL differences. Prokaryotes Bacteria Eukaryotes AnimalPlant

Prokaryote Cell A single celled organism that does not have a nucleus. It does have a cell membrane and cytoplasm

Traits of Prokaryotes: (pro-care-ee-ohts) 1.They do not have a nucleus, and their genetic material is not stored in the nucleus. 2.They have some organelles, a cell membrane and cytoplasm but not much else. 3.They are smaller, simper, and less complicated that eukaryotes. 4.All bacteria are prokaryotes. (Escherichia Coli and Staphylococcus aureus)

Bacteria may be small but they are powerful! During the 14 th century, 25% or ¼ of Europe was killed by a killed by a bacteria called the Bubonic Plague, also called Black Death. This bacteria was spread through fleas and rodents.

The Black Death was one of the most devastating pandemics in human history, resulting in the deaths of an estimated 75 to 200 million people and peaking in Europe in the years 1346–53. Although there were several competing theories as to the etiology of the Black Death, analysis of DNA from victims in northern and southern Europe published in 2010 and 2011 indicates that the pathogen responsible was the Yersinia pestis bacterium, probably causing several forms of plague. The Black Death is thought to have originated in the arid plains of Central Asia, where it then travelled along the Silk Road, reaching Crimea by From there, it was most likely carried by Oriental rat fleas living on the black rats that were regular passengers on merchant ships. Spreading throughout the Mediterranean and Europe, the Black Death is estimated to have killed 30–60% of Europe's total population. In total, the plague reduced the world population from an estimated 450 million down to 350–375 million in the 14th century. The world population as a whole did not recover to pre-plague levels until the 17th century.

But at the same time we need bacteria to live! 1.Bacteria are decomposers and without them all other organisms would not be able to survive. 2.We use bacteria in our digestive system to help digest our food. There are approximately ten times as many bacterial cells as human cells in the human body! 3.We could not make cheese or yogurt without bacteria.

Eukaryote Cell A more complex cell with a nucleus and many organelles.

Traits of Eukaryotes: (you-care-ee-othts) 1. They all have a nucleus where the genetic material of the cell is stored. 2. They have many organelles that work together to help the cell function, along with a nucleus, cell membrane, and cytoplasm.

More traits of Eukaryotes: (you-care-ee-othts) 3. Eukaryotic cells are much more complex then prokaryotic cells. 4.They can be just one cell or can make up more complex multi-cellular organisms. 5. All plants, animals, fungi, and protists are eukaryotic cells.

The nucleus! Prokaryotic cells do not have a nucleus and eukaryotic cells do have a nucleus. This allows eukaryotic cells to make multi-cellular organisms and perform more complex functions.