Mitochondria are in both cells!! animal cells plant cells mitochondria chloroplast
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
Mitochondria and chloroplasts change energy from one form to another Organisms transform energy they acquire from their surroundings. In eukaryotic cells, mitochondria and chloroplasts are the organelles that convert energy to forms that cells can use for work. Mitochondria (singular, mitochondrion) are the sites of cellular respiration, the metabolic process that generates ATP by extracting energy from sugars, fats, and other fuels with the help of oxygen. Chloroplasts, found only in plants and algae, are the sites of photosynthesis. They convert solar energy to chemical energy by absorbing sunlight and using it to drive the synthesis of organic compounds such as sugars from carbon dioxide and water.
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
Function – make ATP energy from cellular respiration sugar + O 2 ATP fuels the work of life Structure – double membrane Mitochondria in both animal & plant cells ATP
Mitochondria Structure – 2 membranes smooth outer membrane highly folded inner membrane – cristae – fluid-filled space between 2 membranes – internal fluid-filled space mitochondrial matrix DNA, ribosomes & enzymes Why 2 membranes? increase surface area for membrane-bound enzymes that synthesize ATP
Membrane-bound Enzymes glucose + oxygen carbon + water + energy dioxide C 6 H 12 O 6 6O 2 6CO 2 6H 2 OATP +++
Dividing Mitochondria Who else divides like that? What does this tell us about the evolution of eukaryotes?
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
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
Chloroplasts Structure – 2 membranes – stroma = internal fluid-filled space 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
Membrane-bound Enzymes + water + energy glucose + oxygen carbon dioxide 6CO 2 6H 2 O C 6 H 12 O 6 6O 2 light energy +++
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!
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 ribosomes like bacterial ribosomes Who else has a circular chromosome not bound within a nucleus? bacteria
Endosymbiosis theory 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 Lynn Margulis U of M, Amherst 1981 | ??
glucose + oxygen carbon + water + energy dioxide C 6 H 12 O 6 6O 2 6CO 2 6H 2 OATP +++ + water + energy glucose + oxygen carbon dioxide 6CO 2 6H 2 O C 6 H 12 O 6 6O 2 light energy +++ Compare the equations Photosynthesis Respiration
The Great ENERGY Circle of Life sun ATP Photosynthesis Respiration O2O2 glucose sugar CO 2 H2OH2O + + plants animals & plants ATP
Peroxisomes Other digestive enzyme sacs – in both animals & plants – breakdown fatty acids to sugars easier to transport & use as energy source – detoxify cell detoxifies alcohol & other poisons – produce peroxide (H 2 O 2 ) must breakdown H 2 O 2 H 2 O
The peroxisome is a specialized metabolic compartment bounded by a single membrane. Peroxisomes contain enzymes that transfer hydrogen from various substrates to oxygen, producing hydrogen peroxide (H 2 O 2 ) as a by–product. Reactions …different functions. Some peroxisomes use oxygen to break fatty acids down into smaller molecules… Peroxisomes in the liver detoxify alcohol and other harmful compounds by transferring hydrogen from the poisons to oxygen. The H 2 O 2 formed by peroxisome metabolism is itself toxic…… cell′s compartmental structure is crucial to its functions
Specialized peroxisomes… glyoxysomes found in the fat–storing tissues of plant seeds. These organelles contain enzymes that initiate the conversion of fatty acids to sugar
Difference between Lysosomes and peroxysomes Unlike lysosomes, peroxisomes do not bud from the endomembrane system. They grow larger by incorporating proteins made primarily in the cytosol, lipids made in the ER, and lipids synthesized within the peroxisome itself. Peroxisomes may increase in number by splitting in two when they reach a certain size
Putting it all together animal cells plant cells