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Transcript
Cell Unit Notes Lecture I Cell Biology Standards in Lecture I 1c ~ students know how prokaryotic cells, eukaryotic cells, and viruses differ in complexity and in general structure 1e ~ students know the role of the endoplasmic reticulum and the Golgi apparatus in the secretion of proteins *1j ~ students know how eukaryotic cells are given shape and internal organization by a cytoskeleton, cell wall, or both The Scientists involved in the Cell Theory In 1665 Robert Hooke looked at a slice of cork under a microscope The tiny chambers reminded him of the “cells” in a monastery so he called them cells In 1674 Anton von Leeuwenhoek made better lenses for the microscope and was able to see cells in greater detail The Scientists involved in the Cell Theory In 1838 and 1839 Matthias Schleiden and Theodore Schwann observed that all living things are made up of cells Schleiden noted that all plants are made up of cells Schwann stated that all animals are made up of cells In 1855 Rudolf Virchow states that all cells come from pre-existing cells The Cell Theory All living things are composed of cells Cells are the basic functional units of life New cells are produced from existing cells Prokaryotes vs. Eukaryotes Prokaryotes smaller & simpler Contain a cell membrane & cytoplasm Sometimes a cell wall Also have ribosomes No nucleus All bacteria are prokaryotes DNA is “free – floating” Eukaryotes Have a nucleus containing DNA Most have specialized structures called organelles All plants, animals, protists, and fungi are eukaryotes Larger and more complex Prokaryote vs. Eukaryote Cell membrane Cytoplasm Prokaryotic Cell Cell membrane Eukaryotic Cell Cytoplasm Nucleus Organelles Prokaryotes & Viruses Prokaryotes are simple, living organisms that can reproduce on their own They have diverse ways of obtaining nutrients: Photosynthesis Chemosynthesis Heterotrophic consumers Prokaryotes & Viruses Bacteria (prokaryotes) live in every habitat possible and are the most numerous of all living things on our planet All living things depend upon bacteria – including, especially, humans! 3 Domains of Life on Earth Prokaryotes & Viruses represent the “ancient bacteria” and they live in extreme environments such as boiling water or extremely salty environments They are the oldest living organisms on this planet. Evidence suggests that they were present during the early stages of Earth over 3.9 billion years ago Archea Prokaryotes & Viruses Bacteria have cell membranes and most have a cell wall Their DNA is one circular molecule They often have many plasmids Small circular rings of DNA usually containing one gene Pili help bacteria “stick” to things Many bacteria have a flagellum or many flagella to help them move Prokaryotes & Viruses Viruses are extremely small particles not considered to be “alive” They act like parasites because they can ONLY reproduce in a host They consist of a protein coat and contain either DNA or RNA inside Eukaryote Cell Structures Cell Wall Found in many organisms including plants, algae, fungi, and nearly all prokaryotes Not found in animal cells Cell Wall The main function of the cell wall is to provide support and protection for the cell Plant cell walls are made of cellulose The Nucleus The nucleus is the “control center” of the cell The nucleus controls most cell processes and contains the hereditary information of DNA Almost all eukaryotic cells, including plant and animal, contain a nucleus The Nucleus Nucleolus – small dense region in nucleus where ribosomes are produced Nuclear envelope – double membrane layer surrounding the nucleus (aka. Nuclear membrane) The Cytoskeleton A network of protein filaments that help the cell maintain it’s shape It is also involved in many forms of Microtubule movement Microfilament The Cytoskeleton Made up of three types of structures: Microtubules – hollow tubes of protein that help maintain cell shape and serve as “tracks” for organelles to travel on Intermediate Filaments – smaller than microtubules – gives a cell its strength Microfilaments – long thin fibers that support cell movement and support Organelles in the Cytoplasm Ribosomes Organelle that “assembles” proteins A ribosome is made up of 2 parts: • a protein • rRNA (ribosomal RNA) Ribosomes make proteins from the “coded” instructions of the DNA inside the nucleus Ribosomes Endoplasmic Reticulum An internal membrane where parts of the cell membrane are made and some proteins are modified Rough endoplasmic reticulum The Rough Endoplasmic Reticulum is where protein synthesis occurs Ribosomes are on it’s surface making it appear “rough” Endoplasmic Reticulum The Smooth Endoplasmic Reticulum does not have any ribosomes on it’s surface It contains enzymes that make lipids (fats) Smooth endoplasmic reticulum Golgi Apparatus Golgi apparatus After proteins are assembled and produced by the Rough ER they move to the Golgi Complex where : Carbohydrates (sugars) and lipids (fats) are attached to the protein They are then sent to their final destination Lysosomes Small organelles that are filled with digestive and other enzymes They break down lipids (fats), carbohydrates (sugars), and proteins from food particles so it can be used by the rest of the cell Lysosomes also break down “old” organelles that have outlived their function Basically, they “take out the trash” Vacuoles Serve as a storage for water, salts, proteins, and “carbs” (plant and animal cells) In Plants : They usually have one large vacuole filled with water to support structures like leaves and flowers Vacuole Chloroplasts The producer! They use sunlight to power a familiar process called Photosynthesis The green pigment (color) chlorophyll is what gives leaves their color and is found inside chloroplasts Chloroplast Mitochondria The “powerhouse” of the animal and plant cell! Mitochondria use energy from food to make highenergy compounds (ATP) The cell uses these highenergy compounds for growth, development, and movement In that way, the mitochondria makes “fuel” for the cell Typical Plant Cell Typical Animal Cell