Section 1 Cell Discovery and Theory Chapter 7 Section 1 Cell Discovery and Theory

CHAPTER 7 - Overview THEME FOCUS: Scientific inquiry led to the invention of the microscope, which made many discoveries possible. BIG Idea – Cells are the structural and functional units of all living organisms.  MAIN Idea (section 1) – Invention of microscope led to discovery of cell. 

CHAPTER 7 - Overview Introduction A cell is the structural and functional unit of all living organisms. They carry out all life process.

History of the Cell Theory 1665 – Robert Hooke was first to observe and use the term “Cell” when he observed a piece of cork, which is the dead cells of oak bark. What he observed was the cell wall of the cell. Late 1600’s – Anton Van Leeuwenhoek was first observe living cells found in pond water, milk, and other substances

The Cell Theory One of the fundamental ideas of modern biology which includes the following three principles. All organisms are composed of one or more cells. The cell is the basic unit of structure and organization of organisms All cells come from preexisting cells, with cells passing copies of their genetic material on to their daughter cells.

The Cell Theory Was derived from the observations and conclusions of the following scientist. 1838 – Mathias Schleiden concluded all plants are made of cells. 1839 – Theodor Schwann concluded that all animals were also made of cells. 1855 – Rudolph Virchow proposed that all cells are produced from the division of existing cells.

Microscope Technology Light Microscopes Utilize a series of glass lenses and visible light to magnify an image Each lens magnifies the image of the previous lens. i.e. Eyepiece lens 10x + objective lens 10x = total magnification of 100x Magnifies images up to 1,000 times the actual size

Microscope Technology Electron Microscopes Utilizes magnets to aim a beam of electrons at a cell to produce an image Magnifies images up to 500,000 times the actual size

Microscope Technology Transmission Electron Microscope (TEM) is the scope with the highest magnification Scanning Electron Microscope (SEM) can produce 3D images. TEM and SEM can only be used to observe nonliving cells and tissues. Scanning Tunneling Electron Microscope (STM) can create 3D images of objects as small as an atom and can be used with live specimens including DNA. Atomic Force Microscope (AMF) contains a needle that can be inserted into a single cell to make observations.

Basic Cell Types ALL cells share a common physical trait in that they have a plasma membrane, which is a boundary that controls what enters and/or exits a cell. MOST cells have genetic information that contains instructions for cell processes. Cells also breakdown molecules to generate energy such as in cellular respiration.

Basic Cell Types Cells can be grouped into either: eukaryotic or prokaryotic.

Basic Cell Types Eukaryotic cells contain a nucleus and membrane bound organelles. The nucleus contains DNA which is the hereditary information that directs the formation of proteins which carry out all cell activities. Organelles are specialized structures that perform specific cell functions. i.e. mitochondria, Golgi apparatus, Endoplasmic reticulum, and more Most organisms are made up of eukaryotic cells and called eukaryotes. i.e. Plants, animals, fungi, protozoa, algae, and yeast.

Basic Cell Types Prokaryotic cells are cells without a nucleus or membrane bound organelles. Most unicellular organisms are prokaryotes such as bacteria.

Cell Diversity Endosymbiont theory states that a symbiotic relationship involved one prokaryotic cell living inside another and both cells benefited from the relationship.

Cell Diversity The theory is that eukaryotic cells derived from prokaryotic cells. The development of the eukaryotic cell has allowed for cells to develop specific functions and allowed for more diversity in the complexity of cells and organisms. Support includes the fact that mitochondria have their own DNA, and new mitochondria arise only when existing ones divide. Thus it is believed that mitochondria developed from prokaryotic cells that came to live inside eukaryotic cells. The prokaryotes may have sought protection by living inside the eukaryotes in turn supplying energy.