General Biology: Cell Structure Cell differences between the plant and animal kingdoms. Thomas Sobat, Stephanie Hines, Adam Hott, Kirk Roth and Cheryl Kellog. PIE Scientists, Biology Department, Ball State University, Muncie Indiana 47306 STANDARDS ADDRESSED: 6.4.2 Give examples of organisms that cannot be neatly classified as either plants or animals, such as fungi and bacteria. 6.4.5 Investigate and explain that all living things are composed of cells whose details are usually visible only through a microscope. 6.4.6 Distinguish the main differences between plant and animal cells, such as the presence of chlorophyll* and cell walls in plant cells and their absence in animal cells. OBJECTIVES Students will demonstrate competency in microscopy. Students will be able to distinguish between and discuss characteristics of bacteria, protists, plants and animals. Students will demonstrate an understanding of the differences between and similarities within the plants and animals at both the organismal and cellular levels. MATERIALS Microscopes at least one per group (group size is immaterial), 12 would be ideal. Animal epidermis cross-section microscope slides, up to six different animals. Animal specimens either preserved, whole mount, live or an image (same six animals used for slides). Plant epidermis cross-section microscope slides, up to six different plants. Plant specimens either preserved, whole mount, live or an image (same six plants used for slides). Individually wrapped pieces of cheese and/or Slim Jims snack sticks, one of either per student. Apples, strawberries, carrots etc. pre-washed, one per student Potatoes, one per student group Plastic cups, one per student group optional Toothpicks, three per student group INTRODUCTION Although the human body contains over 75 trillion cells, the majority of life forms exist as single cells that perform the functions necessary for independent existence. Most cells are far too small to be seen with the naked eye and require the use of microscopes. It wasn't until the 1600’s that biologists observed through microscopes that plant tissues were divided into tiny compartments, or cells. It took another 175 years before scientists began to understand the true importance of cells. In 1839, Matthias Jakob Schleiden and Theodor Schwann proposed that all living things are made up of cells; their theory gave rise to modern cellular biology. Bacteria Bacteria are as unrelated to human beings as living things can be, but bacteria are essential to human life and life on Earth. Although they are notorious for their role in causing human diseases, from tooth decay to the Black Plague, there are beneficial species that are essential to good health. Bacteria are prokaryotes, lacking well-defined nuclei and membranebound organelles, and with chromosomes composed of a single DNA circle. Two outer layers, an inner membrane protected by an outer wall, bind all bacterial cells. Many have a third outer protective layer known as the capsule. They come in many shapes and sizes, from minute spheres, cylinders and spiral threads, to flagellated rods, and filamentous chains. They are found practically everywhere on Earth and live in some of the most unusual and seemingly inhospitable places. Evidence suggests that bacteria were in existence as long as 3.5 billion years ago, making them one of the oldest living organisms on the Earth. There are two different ways of grouping bacteria. They can be divided into two types based on their response to gaseous oxygen. Aerobic bacteria require oxygen for their health and existence and will die without it. Anaerobic bacteria can't tolerate gaseous oxygen at all and die when exposed to it. The second way of grouping them is by how they obtain their energy. Bacteria that have to consume and break down complex organic compounds are heterotrophs. This includes species that are found in decaying material as well as those that utilize fermentation or respiration. Finally, bacteria that create their own energy, fueled by light or through chemical reactions, are autotrophs. Protists The protists (Kingdom Protista) are the simplest eukaryotes, yet they represent an incredibly diverse group. Most are unicellular, while others are colonial and closely related to single protist cells. It is the unicellular character that separates protists from the Kingdoms Animalia, Plantae, and Fungi whose members are multicellular by definition. One group of protists, the a

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