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CELLS
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Definition of Cell A cell is the smallest unit that is capable of performing life functions. Smallest living unit ; most are microscopic
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Cell Theory Smallest living unit of structure and function of all organisms is the cell All living things are made of cells All cells arise from preexisting cells
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Characteristics of All Cells
A surrounding membrane plasma or cell membrane Protoplasm/Cytoplasm – cell contents in thick fluid Organelles – structures for cell function Control center with DNA
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Examples of Cells Plant Stem Bacteria Red Blood Cell Nerve Cell
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Prokaryotic First cell type on earth, smallest
Do not have structures surrounded by membranes Few internal structures One-celled organisms, Bacteria
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Eukaryotic Contain organelles surrounded by membranes
Most living organisms Animal Plant
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Eukaryotes are bigger and more complicated
Have nucleus Have organelles Have chromosomes can be multicellular include animal and plant cells
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Organelles are membrane-bound cell parts
Mini “organs” that have unique structures and functions Located in cytoplasm Cytoplasm liquid – the jell-o of the cell
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Cell Structures Cell membrane
Outer membrane that controls movement into and out of cell
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Nucleus Control center of the cell – stores chromosomes (DNA) Contains nucleolus – produces ribosomes
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Nucleolus inside nucleus Contains RNA to build proteins
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the more energy the cell needs, the more mitochondria it has
Provides/releases energy that powers cellular activities *cellular respiration the more energy the cell needs, the more mitochondria it has Produces energy through chemical reactions – breaking down fats & carbohydrates Controls level of water and other materials in cell Recycles and decomposes proteins, fats, and carbohydrates
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Each cell contains thousands Synthesize proteins
Ribosomes Each cell contains thousands Synthesize proteins may be free- floating or attached to ER Each cell contains thousands Make proteins Found on ribosomes & floating throughout the cell Made of RNA
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Cytoskeleton found throughout cytoplasm 3 functions:
mechanical support anchor organelles help move substances Within cytoplasm – acts as both a muscle and a skeleton ; for movement and stability
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Endoplasmic reticulum Folded membranes attached to nucleus
may be smooth: lacking ribosomes may be rough: has attached ribosomes Smooth “storage organelle” ;
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Ribosomes embedded on Rough endoplasmic reticulum
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takes in sacs of raw material from ER
Golgi Apparatus takes in sacs of raw material from ER sends out sacs containing finished cell products “packing and shipping” station Protein 'packaging and shipping station’ Move materials within the cell Move materials out of the cell
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sacs filled with digestive enzymes
Lysosomes sacs filled with digestive enzymes digest worn out cell parts digest food absorbed by cell If explodes, cell breaks down! Digestive 'plant' for proteins, fats, and carbohydrates Transports undigested material to cell membrane for removal Cell breaks down if lysosome explodes
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Cytoplasm “jell” or fluid in which organelles are found Site where chemical reactions occur within a cell
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Structures found ONLY in PLANT cells
Cell wall Tough, flexible, fairly rigid outer layer (chain link fence) protects cell from rupturing
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(central) Vacuole Membrane- bound storage sac Holds water, food, waste items Helps plants maintain shape
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Chloroplasts filled with chlorophyll turn light energy into food energy (photosynthesis
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How are plant and animal cells different?
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How are plant and animal cells different?
How are plant and animal cells similar? Differences Plants have…cell wall, chloroplasts, vacuole Similarities Both eukaryotic, surrounded by cell membrane
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How do animal cells move?
Some can crawl with pseudopods Some can swim with a flagellum Some can swim very fast with cilia
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Pseudopods means “fake feet” extensions of cell membrane
example: ameoba
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Flagellum/flagella large whiplike tail
pushes or pulls cell through water can be single, or a pair
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Cilia fine, hairlike extensions attached to cell membrane
beat in unison
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