Enzymes: Helper Protein molecules

Transcription

1 Enzymes: Helper Protein molecules

2 Flow of energy through life Life is built on chemical reactions

3 Chemical reactions of life Processes of life building molecules synthesis + breaking down molecules digestion +

4 Nothing works without enzymes! How important are enzymes? all chemical reactions in living organisms require enzymes to work building molecules synthesis enzymes + enzyme We can t live without enzymes! breaking down molecules digestive enzymes enzyme + enzymes speed up reactions catalysts

5 Examples synthesis enzyme + digestion enzyme +

6 Enzymes are proteins Oh, I get it! They end in -ase Each enzyme is the specific helper to a specific reaction each enzyme needs to be the right shape for the job enzymes are named for the reaction they help sucrase breaks down sucrose proteases breakdown proteins lipases breakdown lipids DNA polymerase builds DNA

7 Enzymes aren t used up Enzymes are not changed by the reaction used only temporarily re-used again for the same reaction with other molecules very little enzyme needed to help in many reactions substrate product active site enzyme

8 It s shape that matters! Lock & Key model shape of protein allows enzyme & substrate to fit specific enzyme for each specific reaction

9 2 1 3

10 Enzyme vocabulary Enzyme helper protein molecule Substrate molecule that enzymes work on Products what the enzyme helps produce from the reaction Active site part of enzyme that substrate molecule fits into

11 What affects enzyme action Correct protein structure correct order of amino acids why? enzyme has to be right shape Temperature why? enzyme has to be right shape ph (acids & bases) why? enzyme has to be right shape

12 Temperature Effect on rates of enzyme activity Optimum temperature greatest number of collisions between enzyme & substrate human enzymes C (body temp = 37 C) Raise temperature (boiling) denature protein = unfold = lose shape Lower temperature T molecules move slower fewer collisions between enzyme & substrate

13 reaction rate Temperature human enzymes What s happening here?! 37 temperature

14 How do cold-blooded creatures do it?

15 ph Effect on rates of enzyme activity changes in ph changes protein shape most human enzymes = ph 6-8 depends on where in body pepsin (stomach) = ph 3 trypsin (small intestines) = ph 8

16 reaction rate ph stomach pepsin intestines trypsin What s happening here?! ph

17 For enzymes What matters? SHAPE!

18 Phospholipids Structure Glycerol + 2 fatty acids + phosphate group Functions Component of cell membranes Lipid transport as part of lipoproteins Emulsifiers Phosphatidylcholine Food sources Egg yolks, liver, soybeans,

19 Cell membranes are phospholipid bilayers

20 The basic structural unit of biological membranes is a lipid bilayer

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22 Energy. The Cell: Mitochondria & Chloroplasts

23 Overview Mitochondria & chloroplasts are the organelles that convert energy to forms that cells can use for work mitochondria: from glucose to ATP chloroplasts: from sunlight to ATP & carbohydrates ATP = active energy carbohydrates = stored energy ATP ATP

24 Mitochondria & Chloroplasts Important to see the similarities transform energy generate ATP double membranes = 2 membranes semi-autonomous organelles move, change shape, divide internal ribosomes, DNA & enzymes

25 Mitochondria Function cellular respiration generate ATP from breakdown of sugars, fats & other fuels in the presence of oxygen break down larger molecules into smaller to generate energy = catabolism generate energy in presence of O 2 = aerobic respiration

26 Mitochondria Structure 2 membranes smooth outer membrane highly folded inner membrane the cristae fluid-filled space between 2 membranes internal fluid-filled space mitochondrial matrix DNA, ribosomes & enzymes Why 2 membranes? increase surface area for membranebound enzymes that synthesize ATP

27 Mitochondria

28 Membrane-bound Enzymes

29 Dividing Mitochondria Who else divides like that? What does this tell us about the evolution of eukaryotes?

30 Mitochondria Almost all eukaryotic cells have mitochondria there may be 1 very large mitochondrion or 100s to 1000s of individual mitochondria number of mitochondria is correlated with aerobic metabolic activity more activity = more energy needed = more mitochondria What cells would have a lot of mitochondria? active cells: muscle cells nerve cells

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33 Chloroplasts Chloroplasts are plant organelles class of plant structures = plastids amyloplasts store starch in roots & tubers chromoplasts store pigments for fruits & flowers chloroplasts store chlorophyll & function in photosynthesis in leaves, other green structures of plants & in eukaryotic algae

34 Chloroplasts Structure 2 membranes outer membrane inner membrane internal fluid-filled space = stroma DNA, ribosomes & enzymes thylakoids = membranous sacs where ATP is made grana = stacks of thylakoids Why internal sac membranes? increase surface area for membrane-bound enzymes that synthesize ATP

35 Membrane-bound Enzymes

36 Chloroplasts Function photosynthesis generate ATP & synthesize sugars transform solar energy into chemical energy produce sugars from CO 2 & H 2 O Semi-autonomous moving, changing shape & dividing can reproduce by pinching in two Who else divides like that? bacteria!

37 Chloroplasts Why are chloroplasts green?

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39 Mitochondria & chloroplasts are different Organelles not part of endomembrane system Grow & reproduce semi-autonomous organelles Proteins primarily from free ribosomes in cytosol & a few from their own ribosomes Own circular chromosome directs synthesis of proteins produced by own internal ribosomes Who else has a circular chromosome no bound within a nucleus? bacteria

40 Endosymbiosis theory 1981?? Mitochondria & chloroplasts were once free living bacteria engulfed by ancestral eukaryote Endosymbiont cell that lives within another cell (host) as a partnership evolutionary advantage for both one supplies energy the other supplies raw materials & protection

41 Endosymbiosis theory Evolution of eukaryotes

42 Any Questions??