Cell Theory Biology

Living organisms are made up of CELLS Living organisms can be made up of one cell or hundreds of millions of cells Unicellular – life forms consist of only one cell Multicellular – life forms are made of many cells

Some Unicellular Life Forms: E. Coli – a bacteria that lives in our gut Paramecium – a pond water creature that eats bacteria Amoeba – a pond water predator that may eat paramecium Size: 2 micrometers (millionth of a metre) Size: 100 - 350 micrometers Size: 100 - 350 micrometers

Some Multicellular Life Forms: Grass – a common plant Cow – a common creature that eats grass Human – a life form that may eat a cow September 17, 2018

Humans & Cells Made of trillions of cells Of those trillions there are only about 200 different varieties All humans began as one cell that grew & divided into trillions! September 17, 2018

September 17, 2018

Types of cells in the human body Each cell in our body is specialized for a specific role. Many cells have the same constituent parts, but radically divergent functions. Nerve cells Muscle cells Skin cells Fat cells Gametes Etc….-> http://en.wikipedia.org/wiki/Distinct_cell_types_in_the_adult_human_body September 17, 2018

We Are Not Alone! September 17, 2018

We Are Not Alone! Microorganisms live all over and inside our body! Skin (surface & deep layers) Saliva Intestine Stomach Eyes, nose & ears The number of human cells (trillions) are OUTNUMBERED by the number of bacteria, fungi & other microorganisms by at least a factor of 10 : 1 !! (For every 1 human cell, we have 10 microorganisms living with us) September 17, 2018

How many different bacterial species can you list???? List of clinically important bacteria: http://en.wikipedia.org/wiki/List_of_clinically_important_bacteria September 17, 2018

Two Types of Cells - 1. Prokaryotic Cells Evolutionarily ancient (3.8 billion years ago) first cells on earth & only life form for billions of years before more complex cells came along Have a membrane around its outside outer boundary keeping insides in Lack nuclear membrane genetic material floats around cell “pro” = before, “karyon” = nucleus Most often unicellular organisms ie: Bacteria September 17, 2018

Types of Cells - 2. Eukaryotes More complex cells – evolved from prokaryotic ancestor Outer membrane (same as prokaryotes) “Eu” = true, “karyon” = nucleus Nuclear membrane “organelles” Involved in metabolism & energy conservation of energy within the cell IE Mitochondria, Chloroplast, Golgi Apparatus September 17, 2018

Prokaryotes vs. Eukaryotes Notice the difference in complexity! September 17, 2018

Discovery of Cells – Robert Hooke 1665 – English scientist, Robert Hooke, discovered cells while looking through one of the first microscopes Looked at a thin slice of cork and described what he saw as “tiny boxes or honeycombs” Named the boxes “cells” as they reminded him of the cells in monasteries Thought cells only existed in plants September 17, 2018

Anton van Leuwenhoek 1673 - Anton van Leuwenhoek used a handmade microscope to observe pond scum & discovered single-celled organisms He called them “animalcules” He also observed blood cells from fish, birds, frogs, dogs, and humans Therefore, it was known that cells are found in animals as well as plants September 17, 2018

Spontaneous Generation???? Next 150 - 200 years - Very little research on cells because widely accepted view of life was maintained by the church, which frowned on modern science Spontaneous Generation – living organisms arose from non-living objects Their theory was based on observations such as… Dead logs were the source of mushrooms Rotting meat was the source of flies Mouldy hay was the source of mice September 17, 2018

How would you disprove Spontaneous Generation? Many scientists were sceptical of Spontaneous Generation & set about to understand how organisms come into existence (through the scientific method!) A jar of rotting meat People used to believe that flies came from the rotting meat How would you prove that flies were not a by-product of the rotting meat? September 17, 2018

Development of Cell Theory – 1800’s 1833 – Robert Brown Observed the nucleus in the epidermis of an orchid September 17, 2018

Schleiden and Schwann 1838 - Matthias Schleiden, a German professor of botany, conclusively identified the first plant cells and concluded that all parts of a plant are made of cells 1839 – Theodor Schwann, a German physiologist, who was a close friend of Schleiden, stated that all animal tissues are composed of cells. September 17, 2018

Rudolf Virchow 1855 – Rudolf Virchow, German physician, now known as the father of modern pathology Discovered that all disease results as an injury to the cell Proved that cells arise from other cells, not from non-living matter September 17, 2018

Current Microscopes Scanning Electron Microscopes (SEM) Bombards the object with a high-energy beam of electrons Electrons bounce off the atoms of the object and make a picture September 17, 2018

September 17, 2018

Sperm and egg cell September 17, 2018

Plant cells – shown: early anaphase September 17, 2018

Frog cell anaphase September 17, 2018

September 17, 2018

http://app. discoveryeducation http://app.discoveryeducation.com/search#selItemsPerPage=20&intCurrentPage=0&No=0&N=4294939027%252B4294939063%252B4294939055&Ne=&Ntt=cells&Ns=&Nr=&browseFilter=&indexVersion=&Ntk=All&Ntx=mode%252Bmatchallpartial http://videos.howstuffworks.com/discovery/28732-assignment-discovery-elements-of-cells-video.htm September 17, 2018