cells The cell is a unit of organization Units of life
Cell video • http://www.youtube.com/watch?v=1Z9pqST72is&feature=youtube_gdata_player
Cell vocabulary • vocabulary: Section 1 • 1. Cell, • 2. Cell theory, • 3. Plasma membrane, • 4. Organelle, • 5. Eukaryotic cell, • 6. Nucleus, • 7. Prokaryotic cell
History of studying cells • Because of the limitations of the human eye, much of the early biological research concentrated on developing tools to help us see very small things.
As imaging technology became more sophisticated, biological discoveries abounded. • Next is a timeline detailing some of those major events in biology.
1665 Robert Hooke • Robert Hooke observed “cellulae” or little rooms when he observed pieces of cork. • From his work came the term cell. the basic unit of structure and function for all living things!
What are the respective sizes of a virus and a plant cell? • A.3 mm, 30 mm • B.30 nm, 30 µm • C.30 µm, 30 nm • D.3 cm, 30 cm
The Cell Theory • When Schleiden and Schwann proposed the cell theory in 1838, cell biology research was forever changed. The cell theory states that:
SC.912.L.14.1 • Ch 7.* • Describe the scientific theory of cells (cell theory) and relate the history of its discovery to the process of science.
Cell theory • All life forms are made from one or more cells. • Cells only arise from pre-existing cells. • The cell is the smallest form of life.
It took the work of several scientist and likely many more to develop the cell theory. Like all theories, it takes support by many experiments over a long period of time to develop a theory!
The cell theory also provides us with an operational definition of "life".
Which of the following is not a part of the cell theory? • A.All animals are formed by cells. • B.Reproduction requires vegetative duplication or the sexual mixing of gametes. • C.Cells are the smallest form of life. • D.Abnormal cells self destruct by apoptosis.
1. How many scientists are listed in your book as contributing towards developing the cell theory? _______3__ • What were there names? __Schleiden, Schwann and Virchow___________________, • 2. Why do you think there were 3 scientist involved in this process? It takes the work of many scientists to develop a theory _over a long period of time and much testing must happen. • Could there have been others that contributed? ____yes________ Did this happen over a year or likely more time? ______more_______________. What does it take for an idea in science to become a theory? ___repeated tests with no evidence against the theory.______ • 3. What are the 3 main parts of the cell theory? • 1. All life forms are made from one or more cells. 2. Cells only arise from pre-existing cells. 3. The cell is the smallest form of life. • 4. Can cells appear spontaneously without genetic material from previous cells? no__ • 5. How was the cell theory developed? By combining the research from several scientists over several years.
Microscopes • SC.912.L.14.4 Compare and contrast the different types of microscopes (as N 1.1)
Dissection microscope • 3 D image, • Living or dead specimen • 20-40 X usually • Limited by size of scope
Compound Microscope • 10 to 1000X • Living and dead specimens can be viewed. • Slides of thin stained specimens must be made.
thin sections that light can pass through • Use two lenses to magnify the object. Multiply the power of each lens with the second to get the total power. • Can view living or dead specimens.
Transmission Electron Microscope • Magnify up to 500,000 X • Thin specimens treated with metal must be dead! • In a vacuum chamber!
Scanning Electron Microscope • 3D images • No lenses • Electrons instead of light • Only non living specimens! • 10X to 500,000X magnification!!!
1. Which type of microscope uses 2 lenses and visible light to magnify and view thin sections of specimens by passing light through the specimen? Compound light • 2. How do you determine the power of a compound microscope? Multiply the 2 lenses together • 3. What type of microscope uses a beam of electrons and a magnet to produce a black and white image of the specimen? Transmission electron microscope_ • 4. What is a problem with transmission microscopes with regard to viewing live specimens? The specimen must be in a vacuum chamber and prepped with metals so it must be dead! • 5. What type of microscope produces a 3D image of the specimen? The scanning electron microscope
Compare the 4 types of microscopes: compound light, dissecting, TEM and SEM, include the following information
SC.912.L.14.3 Compare and contrast the general structures of prokaryotic and eukaryotic cells.(MC AA)
Living things are classified in six kingdoms based on structure. • Eubacteria Prokaryotic • Archaea Prokaryotic • Protista Eukaryotic • Plantae Eukaryotic • Fungae Eukaryotic • Animalia Eukaryotic
Within prokaryotes • which appeared 3.5 billion years ago, are the kingdoms • Eubacteria and Archaea.
Within eukaryotes • which evolved 1.5 billion years ago, are the kingdoms • Protista, Plantae, Fungae, Animalia.
Autotrophs • are "self feeders" that use light or chemical energy to make food. Plants are an example of autotrophs.
heterotrophs • In contrast, heterotrophs ("other feeders") obtain energy from other autotrophs or heterotrophs. Many bacteria and animals are heterotrophs.
Multicellular Organisms • Multicellular organisms are created from a complex organization of cooperating cells. • There must be new mechanisms for cell to cell communication and regulation.
There also must be unique mechanisms for a single fertilized egg to develop into all the different kinds of tissues of the body. • In humans, there are 1014 cells comprising 200 kinds of tissues!
Cells are classified by fundamental units of structure and by the way they obtain energy. • Cells are classified as prokaryotes or eukaryotes
Prokaryotes • prokaryotes include the kingdoms of Eubacteria (simple bacteria) and Archaea.
Simply stated, prokaryotes are molecules surrounded by a membrane and cell wall. • Prokaryotic cells lack characteristic eukaryotic sub cellular membrane enclosed "organelles", but may contain membrane systems inside a cell wall.
Eukaryotes • Basic structure The basic eukaryotic cell contains the following: • plasma membrane • glycocalyx (components external to the plasma membrane) • cytoplasm (semi fluid) • cytoskeleton - microfilaments and microtubules that suspend organelles, give shape, and allow motion • presence of characteristic membrane enclosed subcellular organelles
1. What is the main purpose of the plasma membrane? To control what goes in and out of the cell. It is selectively permeable! • What is the structure of the plasma membrane? It is a bilayer of phospholipids with some proteins embedded.
Describe the main parts of a prokaryotic cell no nucleus, no membrane bound organelles, plasma membrane, cytoplasm, genetic information • 4. What does a eukaryotic cell have that a prokaryotic cell does not have? a nucleus and organelles.
5. What is the current theory as to why there are two types of cells, prokaryotic and eukaryotic? According to the endosymbiotic theory the prokaryotic cells started living inside each other and developed into the eukaryotic cells.
6. A cell with the DNA located in a nuclear membrane, mitochondria, ribosomes, and endoplasmic reticulum is most likely what type of cell? eukaryotic. • 7. Cells that lack a membrane bound nucleus and organelles are most likely what type of cells? prokaryotic
Section 2 • Read your reading essentials book section 2 or text book section 2! Vocabulary: 1. Selective permeability, 2. Phospholipid bilayer, 3. Transport protein, 4. Fluid mosaic model
SC.912.L.14.2 • Relate structure to function for the components of plant and animal cells. • Explain the role of cell membranes as a highly selective barrier (passive and active transport) (as 14.3)
Selective permeability Allows some substances to pass through and keeps others out. • This can change at different times! • This is not due to the size of the holes in the membrane! • Some things require energy to get them across • Some things are small enough to pass by themselves others need helper molecules.