Cells are the basic structural units of living things A human being has about 75 trillion cells A fly has 1 million cells Each type of cell structure is related to its function But all cells have similar parts inside called organelles Each organelle has a specific function The Cell Theory 1 All living things are made of cells 2 Cells can reproduce new cells This theory came about after the invention of the microscope Robert Hooke 1660 He observed cork cells which are from cork tree bark He came up with the CELL Prokaryotic Cells cells that do not have a nucleus bacteria Eukaryotic Cells are everything else animals plants fungi and protists they have a nucleus 1 Cell Membrane double layered outer boundary Allows materials to enter and leave the cell like water oxygen carbon dioxide wastes food a The outside is hydrophilic likes water and the inside is hydrophobic doesn t like water 2 Nucleus Controls the functions of all the other organelles Contains DNA molecules called chromosomes that code for our inherited traits from our parents 3 Nucleolus located inside the nucleus produces RNA molecules that are involved with making proteins Ribosomes are also produced here and then enter the cytoplasm 4 Cytoplasm The fluid inside the cell Organelles move and float in the cytoplasm Made mostly of water 5 Vacuole Round organelles that store water or food or wastes Animal cells have several vacuoles Plant cells have one large vacuoles 6 Endoplasmic Reticulum ER Interconnected membranes located throughout the cell They connect the nucleus to the cell membrane These membranes transport molecules all over the cell and also produce fats and steroids a Rough ER has ribosomes on it Smooth ER does not have ribosomes 7 Ribosomes small round organelles located on the ER and loose in the cytoplasm Protein synthesis occurs on the ribosomes 8 Golgi Bodies Flattened sacs that are stacked together They store proteins and other molecules for later use by the cell or body 9 Lysosomes round organelles that contain digestive enzymes The enzymes break down wastes and recycle molecules When the cell dies the lysosomes break to release the enzymes to help clean up the cellular debris a Found only in animal cells b Cancer breaking them open prematurely 10 Mitochondria oval shaped organelles with internal membranes ATP energy molecules produced here during energy reactions such as cellular respiration fermentation glycolysis and lactic acid fermentation Depending on the cell type there can be over 10 000 per cell a Mitochondria have their own DNA this DNA is inherited intact from mother to child endosymbiotic theory could have been free living mitochondrial long ago 11 Centrioles found only in animal cells these two organelles function in cell division helping to pull a cell s nucleus in half after DNA has copied itself to create two new cells Plant cells have similar structures called centrosomes that function during cell division 12 Flagella and Cilia these are organelles of movement flagella are longer and few in number cilia are shorter but more numerous Plant Cells eukaryotic cells that can make their own food Plant cells are square or rectangular in shape They tend to grow side by side in layers Animal cells are round shaped and can be loosely arranged in a tissue Plant cells have all the same organelles as animal cells EXCEPT for the following differences 1 Plant cells have one large vacuoles that stores water Depending on the environment wet or dry the vacuole can gain or loss water 2 Plant cells do not have lysosomes 3 Plant cells have a thick rigid cell wall around the cell membrane that protects the cell during water gain or loss Plant cells are stronger than animal cells and can handle water stress better than breaking apart The cell wall is composed of cellulose 4 Chloroplast Green organelles chemical chlorophyll that traps light energy to create sugar molecules such as glucose in a process called photosynthesis a Most life on Earth depends on to do photosynthesis producing the food and oxygen needed by non photosynthetic organism like fungi and animals b Endosymbiotic Theory free living chloroplast long ago c Since chloroplast are large and brightly colored they are visible with our microscopes Also as they float in the cytoplasm a process called cytoplasmic streaming they allow us to see that the clear cytoplasm is very active in a cell
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