Presentation on theme: "Chapter 6. The Cell: Mitochondria & Chloroplasts"— Presentation transcript:
1 Chapter 6. The Cell: Mitochondria & Chloroplasts Modified from: Kim Folgia, Explore Biology
2 OverviewMitochondria & chloroplasts are the organelles that convert energy to forms that cells can use for workmitochondria: from glucose to ATPchloroplasts: from sunlight to ATP & carbohydratesATP = active energycarbohydrates = stored energyATP+ATP
3 Mitochondria & Chloroplasts Important to see the similaritiestransform energygenerate ATPdouble membranes = 2 membranessemi-autonomous organellesmove, change shape, divideinternal ribosomes, DNA & enzymes
4 Mitochondria Function cellular respiration generate ATP from breakdown of sugars, fats & other fuelsin the presence of oxygenbreak down larger molecules into smaller to generate energy = catabolismgenerate energy in presence of O2 = aerobic respiration
5 Mitochondria Structure 2 membranes smooth outer membranehighly folded inner membranethe cristaefluid-filled space between 2 membranesinternal fluid-filled spacemitochondrial matrixDNA, ribosomes & enzymesWhy 2 membranes?increase surface area for membrane-bound enzymes that synthesize ATP
8 Dividing Mitochondria Who else divides like that?What does this tell us about the evolution of eukaryotes?
9 Mitochondria Almost all eukaryotic cells have mitochondria there may be 1 very large mitochondrion or 100s to 1000s of individual mitochondrianumber of mitochondria is correlated with aerobic metabolic activitymore activity = more energy needed = more mitochondriaWhat cells would have a lot of mitochondria?active cells:• muscle cells• nerve cells
12 Chloroplasts Chloroplasts are plant organelles class of plant structures = plastidsamyloplastsstore starch in roots & tuberschromoplastsstore pigments for fruits & flowerschloroplastsstore chlorophyll & function in photosynthesisin leaves, other green structures of plants & in eukaryotic algae
13 Chloroplasts Structure 2 membranes outer membraneinner membraneinternal fluid-filled space = stromaDNA, ribosomes & enzymesthylakoids = membranous sacs where ATP is madegrana = stacks of thylakoidsWhy internal sac membranes?increase surface area for membrane-bound enzymes that synthesize ATP
15 Who else divides like that? ChloroplastsFunctionphotosynthesisgenerate ATP & synthesize sugarstransform solar energy into chemical energyproduce sugars from CO2 & H2OSemi-autonomousmoving, changing shape & dividingcan reproduce by pinching in twoWho else divides like that?bacteria!
17 Mitochondria & chloroplasts are different Organelles not part of endomembrane systemGrow & reproducesemi-autonomous organellesProteins primarily from free ribosomes in cytosol & a few from their own ribosomesOwn circular chromosomedirects synthesis of proteins produced by own internal ribosomesWho else has a circular chromosome no bound within a nucleus?bacteria
18 Endosymbiosis theory 1981 | ?? Mitochondria & chloroplasts were once free living bacteriaengulfed by ancestral eukaryoteEndosymbiontcell that lives within another cell (host)as a partnershipevolutionary advantage for bothone supplies energythe other supplies raw materials & protectionLynn MargulisFrom hypothesis to theory!Paradigm shifting ideas in evolutionary biology.Lynn MargulisU of M, Amherst
19 Evolution of eukaryotes Endosymbiosis theoryEvolution of eukaryotes