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Prayer Attendance Homework Check CHAPTERS 3.1-3.11 WHAT IS A CELL? Ms. Doshi What is a cell? cell -is the basic unit of all organisms We see cells in our fridge. Example: eggs Most expensive egg cell: caviar (Human sperm cells cost: 1 cent for 20,000 cells) Eggs are the largest and most expensive cells in the world. Cell Theory 1. All living organisms are made of one or more cells. 2. All cells arise from other, pre-existing cells. 2 Types of Cells Eukaryotic cell -has a nucleus, which contains the cell’s DNA. Eukaryote -an organism composed of eukaryotic cells Prokaryotic cell -does not have a nucleus, its DNA is in the cytoplasm. Prokaryote -an organism composed of prokaryotic cells Four Structures in all Prokaryotes 1. plasma membrane – – – – surrounds the cells also known as the “cell membrane” everything inside the cell is “intracellular.” everything outside the cell is “extracellular” 2. cytoplasm – – jelly-like fluid fills the inside of a cell 3. ribosomes – – – little granular bodies make proteins in cytoplasm – each prokaryote has circle DNA or linear DNA 4. DNA Additional Structures in Prokaryotes cell wall -rigid -protects and gives shape to the cell capsule -protective outer coating flagellum -looks like a tail -helps move the cell pili -helps cell to attach to other surfaces -helps cell to exchange DNA with other cells; function as tubes The Prokaryote: Basic Structure Prokaryotes in our Bodies All bacteria are prokaryotes. Examples: E.coli -live in your intestine -helps your body make some essential vitamins Streptococcus pyogenes -cause strep throat Eukaryotic vs. Prokaryotic Cell EUKARYOTES PROKARYOTES DNA is in a NUCLEUS They are LARGER THAN prokaryotes (10x more) CYTOPLASM contains ORGANELLES No NUCLEUS; DNA is in the CYTOPLASM No ORGANELLES VERY SMALL Structures found in animal and plant cells. Where did eukaryotic cells come from? First, came prokaryotes. Then came eukaryotes. Where did all the organelles come from? Two theories: 1. Endosymbiosis 2. Invagination Endosymbiosis (Theory) Best explanation for two organelles in eukaryotes: -chloroplasts in plants and algae -mitochondria in plants and animals What do these 2 organelles do? Chloroplasts -help plants and algae convert (change) sunlight into energy for cells. Mitochondria -help plants and animals convert food and oxygen into energy for cells. Endosymbiosis Invagination Best explanation for Nucleus and Rough Endoplasmic Reticulum in eukaryotic cells. Questions 1. 2. 3. 4. 5. 6. What is a cell? What is the cell theory? What are the 2 types of cells? What are the 4 structures in all prokaryotes? What are some prokaryotes in our bodies? What are the differences between a eukaryotic and prokaryotic cell? 7. Draw a prokaryotic cell. Label all of its parts. 8. Draw a eukaryotic cell . Label all of its parts. 9. What is the best explanation of where mitochondria and chloroplasts come from? 10. What is the best explanation of where the nucleus and RER come from?