Presentation on theme: "Enzymes at work An important cause of deterioration in flavor, texture, and vitamin content of frozen fruits and vegetables during storage is the action."— Presentation transcript:
1 Enzymes at work An important cause of deterioration in flavor, texture, and vitamin content of frozen fruits and vegetables during storage is the action of proteolytic enzymes released from the vacuoles of the cells.. Blanching (a quick dip in boiling water) prior to freezing improves the keeping qualities of of produce. How do you suppose blanching works?
2 Chapter 7. The Cell: Mitochondria & Chloroplasts
3 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
4 Mitochondria & Chloroplasts Important to see the similaritiestransform energygenerate ATPdouble membranes = 2 membranessemi-autonomous organellesmove, change shape, divideinternal ribosomes, DNA & enzymes
5 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
6 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
9 Dividing Mitochondria Who else divides like that?What does this tell us about the evolution of eukaryotes?
10 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
13 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
14 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
16 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 Cytoplasmic streaming in Elodea shows chloroplasts moving to optimum position in cell CyclosisPrepare for overly dramatic introduction
18 ChloroplastsWhy are chloroplasts green?chlorophyll!
20 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 not bound within a nucleus?bacteria
21 Endosymbiosis theoryMitochondria & 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.https://www.youtube.com/watch?v=KlhW12dGfFkLynn MargulisU of M, Amherst
22 Evolution of eukaryotes Endosymbiosis theoryEvolution of eukaryotes