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Copyright Pearson Prentice Hall

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1 Copyright Pearson Prentice Hall
Cells: Prokaryotes v. Eukaryotes (extracts of 7-1 & ch19) Photo Credit: © Quest/Science Photo Library/Photo Researchers, Inc. Copyright Pearson Prentice Hall

2 The Discovery of the Cell
Early Microscopes In 1665, Robert Hooke used an early compound light microscope to look at a thin slice of cork, a plant material. Copyright Pearson Prentice Hall

3 The Discovery of the Cell
Early Microscopes At the same time, Anton van Leeuwenhoek used a microscope to observe pond water and other things. Daphnia – water insect Copyright Pearson Prentice Hall

4 The Discovery of the Cell
What is the cell theory? In 1838, Matthias Schleiden – all plants were made of cells. In 1839, Theodor Schwann – all animals were made of cells. In 1855, Rudolph Virchow – new cells were created only from division of existing cells. These discoveries led to the cell theory. Copyright Pearson Prentice Hall

5 The Discovery of the Cell
Cell Theory is a SCIENTIFIC THEORY! Scientific Theory: A well tested explanation that unifies a broad range of observations. Scientific Theory used to make accurate predictions about new observations and situations. Scientific Theory can be revised according to new evidence Copyright Pearson Prentice Hall

6 The Discovery of the Cell
cell theory All living things are composed of one or more cells. Cells are the basic units of structure and function in living things. Use genetic code (DNA) Over generations mutations accumulate and lead to changes over time Get energy and materials from environment to run cellular metabolism Respond to the external environment Maintain homeostasis (stable internal environment) New cells are produced from existing cells. Grow and develop Copyright Pearson Prentice Hall

7 Copyright Pearson Prentice Hall
Exploring the Cell Light microscope V. Electron microscope Electron Microscope Up to 100,000X Preserved cells only Scanning EM (3D image) Transmission EM (2D cross section) Light micrograph (LM) Up to 1000X Live or preserved cells TEM SEM Top) Transmission electron micrograph (TEM) of  Mycobacterium tuberculosis bacilli, the causative agent for tuberculosis. Image courtesy of CDC / Elizabeth "Libby" White. (Botton) Scanning electron micrograph (SEM) of four Salmonella infantis bacteria. BLUE is micrograph of DNA using a SCANNING PROBE microscope (320,000X) Confocal light microscope uses florescent labels to image HeLa cell (also Hela or hela cell) is an immortal cell line used in medical research. The cell line was derived from cervical cancer cells taken from Henrietta Lacks, who died from her cancer on October 4, 1951. Copyright Pearson Prentice Hall

8 Copyright Pearson Prentice Hall
DNA kept separate from the cell’s cytoplasm by the nuclear membrane Figure 4.4 Copyright Pearson Prentice Hall

9 First cells (prokaryotic) 3.5 billion years ago
Scientist’s study of different organisms’ cell structure and DNA lead them to group organisms into 3 different domains Archae-bacteria: Oldest bacteria type UC Eubacteria: common bacteria UC Protists Plants Fungi Animals UC&MC MC UC&MC MC First Eukaryotes (Has nucleus) UC = unicellular MC= multicellular First cells (prokaryotic) 3.5 billion years ago

10 Prokaryotes and Eukaryotes
Prokaryote focus: The smallest, simplest life forms are prokaryotes—unicellular organisms that lack a nucleus. Biologists divided them into two different domains: the Eubacteria and the Archaebacteria. Copyright Pearson Prentice Hall

11 Classifying Prokaryotes
Archaebacteria- Ancient bacteria Achaebacteria’s DNA is more similar to eukaryotes than eubacteria!. They live in extreme environments (why also known as extremeophiles) Methanogens live in oxygen-free environments, such as thick mud and animal digestive tracts. Other archaebacteria live in salty environments or in hot springs where water temperatures approach the boiling point. Copyright Pearson Prentice Hall

12 Classifying Prokaryotes
Grand Prismatic Spring Yellowstone. Thermophiles of Yellowstone Produce Beautiful colors This type of Extremophile requires temperatures above 45oC (113oF) to survive. Wow: for most organisms, proteins and nucleic acids would denature at these hot temperatures. Thermophiles source of enzymes used in DNA biotechnology This type of Extremophile requires temperatures above 45oC (113oF) to survive. Being adapted to this temperature range is noteworthy since, for most organisms, proteins and nucleic acids would denature at these hot temperatures. Copyright Pearson Prentice Hall

13 Classifying Prokaryotes
Eubacteria include organisms that live in a variety of environments, including: in fresh and salt water on land in the human body Copyright Pearson Prentice Hall

14 Structures of Prokaryotic Cells
Nucleoid region – area where DNA is coiled in the cytoplasm. DNA is in direct contact with the rest of the cell Plasmid – smaller circular DNA molecules – stores genes easily shared with other bacteria Ribosomes – where proteins are made cell membrane – encloses the cytoplasm of the prokaryotic cell, regulates what chemicals enter and leave the cell. Ribosome Flagella DNA Pili Plasmid

15 Structures of the Prokaryotic Cell
Cell wall – rigid, composed of lipids, carbohydrates and protein. Protects the cell and maintains its shape Pili – short surface projections found in some prokaryotes. Helps attach bacteria to surfaces Flagella – long whiplike extensions found in some prokaryotes. Propel cell through liquid environments Not all bacteria the a same shape! Bacilli (rod) Cocci (round) Spirilla (spiral)

16 Importance of Bacteria
Bacteria are vital to the living world. Autotrophs: Some are producers that capture energy by photosynthesis. Heterotrophs: using living organisms as food source. decomposers Nitrogen fixing bacteria Pathogens: cause disease Some bacteria damage the cells and tissues directly by breaking down the cells for food. Others By produce toxins that makes you sick Copyright Pearson Prentice Hall

17 Bacterial Disease in Humans
19–3 Diseases Caused by Bacteria and Viruses Bacterial Disease in Humans Bacterial Disease Growth of pathogenic bacteria disrupts the body’s equilibrium by interfering with its normal activities and producing disease. Antibiotics Chemicals that kill bacteria w/o harming your cells Ex: Penicillin disrupts bacterial cell wall production Does not work on Viral infections Bacterial Diseases Copyright Pearson Prentice Hall

18 Importance of Bacteria
Still other bacteria have human uses. foods Genetically engineered bacteria used to produce medicine production of some vitamins especially vitamins K in human intestines Copyright Pearson Prentice Hall

19 Prokaryotes and Eukaryotes
Compare & Contrast: What are the characteristics of prokaryotes and eukaryotes? Copyright Pearson Prentice Hall

20 Prokaryotes and Eukaryotes
Prokaryotic cells have genetic material that is not contained in a nucleus. do not have membrane-bound organelles. cells are generally smaller and simpler than eukaryotic cells. Bacteria (both archaebacteria and eubacteria) are prokaryotes. Copyright Pearson Prentice Hall

21 Prokaryotes and Eukaryotes
All cells have DNA to store hereditary information but where is it in the cells? Eukaryotes have a nucleus – DNA surrounded by a a nuclear envelope membrane separating DNA from the rest of the cell Eukaryotes have membrane bound organelles – like mitochondria and Endoplasmic Reticulum Copyright Pearson Prentice Hall

22 Prokaryotes and Eukaryotes
Cells highly specialized In multicellular species groups of cells can form tissues Copyright Pearson Prentice Hall

23 Prokaryotes and Eukaryotes
Eukaryotic cells: Build the structures of Plants, animals, fungi, and protists. Copyright Pearson Prentice Hall

24 Prokaryotes and Eukaryotes
Compare and contrast Pro Both Eu Copyright Pearson Prentice Hall


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