cells are the smallest living units ofan organismall cells have three things in common nomatter what type of cell they areall cells have a cell membranewhich separates the inside of the cellfrom its environmentcytoplasm which is a jelly-like fluidand dna which is the cell's geneticmaterialthere are two broad categories of cellsthe first category is eukaryotic cellsthey have organelles which include thenucleus and other special partseukaryotic cells are more advancedcomplex cells such as those found inplants and animalsthe second category is prokaryotic cellsthey don't have a nucleus ormembrane-enclosed organelles they dohave genetic material but it's notcontained within a nucleusprokaryotic cells are always one cell orunicellular organisms such as bacteriaso what are organellesorganelle means littleorganorganelles are the specialized parts ofa cell that have unique jobs to performlet's start with the nucleus the controlcenter of the cellthe nucleus contains dna or geneticmaterialdna dictates what the cell is going todo and how it's going to do itchromatin is the tangled spread out formof dna found inside the nuclear membranewhen a cell is ready to divide dnacondenses into structures known aschromosomesthe nucleus also contains a nucleoluswhich is a structure where ribosomes aremade[Music]after ribosomes leave the nucleus theywill have the important job ofsynthesizing or making proteinsoutside the nucleus the ribosomes andthe rest of the organelles float aroundin cytoplasm which is the jelly-likesubstanceribosomes may wander freely within thecytoplasmor attach to the endoplasmic reticulumsometimes abbreviated as erthere are two types of errough er has ribosomes attached to itand smooth er doesn't have ribosomesattached to it[Music]the endoplasmic reticulum is amembrane-enclosed passageway fortransporting materials such as theproteins synthesized by ribosomesproteins and other materials emerge fromthe endoplasmic reticulum in smallvesicles[Music]where the golgi apparatus sometimescalled the golgi body receives themas proteins move through the golgi bodythey're customized into forms that thecell can usethe golgi body does this by folding theproteins into usable shapesor adding other materials onto them suchas lipidsor carbohydrates[Music]vacuoles are sac-like structures thatstore different materialshere in this plant cell the centralvacuole stores watergoing back to the animal cell you willsee an organelle called a lysosomelysosomes are the garbage collectorsthat take in damaged or worn out cellpartsthey are filled with enzymes that breakdown this cellular debristhe mitochondrion is an organelle thatis the powerhouse for both animal andplant cellsduring a process called cellularrespiration the mitochondria make atpmolecules that provide the energy forall of the cells activitiescells that need more energy have moremitochondriameanwhile the cell maintains its shapethrough a cytoskeletonthe cytoskeleton includes thethread-like microfilaments which aremade of proteinand microtubules which are thin hollowtubessome organisms such as plants that arephotoautotrophicmeaning they capture sunlight for energy[Music]have cells with an organelle called achloroplastthe chloroplast is where photosynthesishappens it's green because it has agreen pigment called chlorophyllplant cells also have a cell walloutside of their cell membranes thatshape support and protect the plant cellanimal cells never have a cell wallthere are many other unique structuresthat only some cells havehere are just a fewin humans for example the respiratorytract is lined with cells that haveciliathese are microscopic hair-likeprojections that can move in wavesthis feature helps trap inhaledparticles in the air and expels themwhen you coughanother unique feature in some cells isflagellasome bacteria have flagella a flagellumis like a little tail that can help acell move or propel itselfthe only human cell that has a flagellumis a sperm cell[Music]in summaryremember eukaryotic cells are plant andanimal cells with a nucleus and membraneenclosed organelleswhile prokaryotic cells are unicellularorganisms without these thingsall cells have a cell membrane cytoplasmand genetic materialand even though only plant cells havechloroplasts both plant and animal cellshave mitochondria[Music]you