Uniqueness of Mitochondria and chloroplasts (Ch. 6)

Lysosomes – think of Lysol Where old organelles go to die! Function – cleans up! digests macromolecules cleans up broken down organelles Structure vesicles of digestive enzymes synthesized by rER, transferred to Golgi

Cellular digestion Lysosomes fuse with food vacuoles polymers digested into monomers become nutrients of cell Work best at pH of 5 vacuole lyso– = breaking things apart –some = body

When things go bad… lysosomal storage diseases Diseases of lysosomes are often fatal digestive enzyme not working grow larger & larger until disrupts cell & organ function lysosomal storage diseases more than 40 known diseases example: Tay-Sachs disease: build up undigested fat in brain cells Death by age 5 or younger! More prevalent in Ashkenazi Jews Recessive disorder Carriers don’t know they have it

But sometimes cells need to die… Lysosomes can be used to kill cells when they are supposed to be destroyed Cells need to die on cue for proper functioning apoptosis “auto-destruct” process lysosomes break open & kill cell ex: tadpole tail gets re-absorbed when it turns into a frog ex: loss of webbing between your fingers during fetal development Feedback mechanism There are sensors in the cell that monitor growth. They trigger self-destruct when they sense processes. Brown spots on leaves too. Virus infected plant cell auto-destructs and even cells around it to wall off virus.

Fetal development syndactyly 6 weeks 15 weeks

Making Energy Cells convert incoming energy to forms that they can use mitochondria: from glucose to ATP chloroplasts: from sunlight to ATP & carbohydrates ATP ATP +

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

Mitochondria Structure – Form fits function 2 membranes smooth outer highly folded inner Cristae mitochondrial matrix All come from MOMS egg cell so easy to trace ancestry! Why 2 membranes? increase surface area for membrane-bound enzymes that synthesize ATP

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

Endosymbiosis theory 1981 | ?? Mitochondria & chloroplasts were once free living bacteria, engulfed by ancestral eukaryote Endosymbiont cell that lives within another cell (host) Partnership, evolutionary advantage for both Energy for raw material, protection Lynn Margulis From hypothesis to theory! Paradigm shifting ideas in evolutionary biology. Lynn Margulis U of M, Amherst

Evolution of eukaryotes – plant and animal Endosymbiosis theory Evolution of eukaryotes – plant and animal

Mitochondria are everywhere!! animal cells plant cells

Chloroplasts Chloroplasts are plant organelles class of plant structures = plastids amyloplasts store starch in roots, tubers chromoplasts store pigments in fruits, flowers chloroplasts store chlorophyll, function in photosynthesis

Who else divides like that? Chloroplasts Function photosynthesis generate ATP & synthesize sugars transform solar energy into chemical energy produce sugars from CO2 & H2O Semi-autonomous moving, changing shape & dividing Who else divides like that? bacteria!

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

Chloroplasts Why are chloroplasts green?

Mitochondria & chloroplasts are different Not part of endomembrane system Grow & reproduce semi autonomously Have their own ribosomes Have their own circular chromosome direct synthesis of proteins produced by own internal ribosomes ribosomes similar to bacterial ribosomes Who else has a circular chromosome not bound within a nucleus? bacteria

Compare the equations   Photosynthesis + water + energy  glucose + oxygen carbon dioxide 6CO2 6H2O C6H12O6 6O2 light energy  + Respiration glucose + oxygen  carbon + water + energy dioxide C6H12O6 6O2 6CO2 6H2O ATP  +

The Great ENERGY Circle of Life sun ATP Photosynthesis Respiration O2 glucose sugar CO2 H2O + plants animals & plants

Food & water storage plant cells animal cells food vacuoles central vacuole animal cells contractile vacuole

Vacuoles & vesicles Function: Storage Food vacuoles phagocytosis, fuse with lysosomes Contractile vacuoles in freshwater protists, pump excess H2O out of cell Central vacuoles in many mature plant cells

Vacuoles in plants Functions storage stockpiling proteins, inorganic ions depositing metabolic byproducts storing pigments, defensive compounds Tonoplast: selective membrane control what comes in or goes out

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 (H2O2) must breakdown H2O2  H2O

Putting it all together animal cells plant cells

Any Questions?? 2007-2008

Review Questions

1. In which cell would you expect to find the most lysosomes? Muscle cell in the thigh muscle of a long-distance runner Pancreatic cell that manufactures digestive enzymes Macrophage (white blood cell) that engulfs bacteria Epithelial cells lining the digestive tract Ovarian cell that produces estrogen (a steroid hormone) Answer: c Source: Taylor - Student Study Guide for Biology, Sixth Edition, Test Your Knowledge Question #17

2. In which cell would you expect to find the most mitochondria? Muscle cell in the thigh muscle of a long-distance runner Pancreatic cell that manufactures digestive enzymes Macrophage (white blood cell) that engulfs bacteria Epithelial cells lining the digestive tract Ovarian cell that produces estrogen (a steroid hormone) Answer: a Source: Taylor - Student Study Guide for Biology, Sixth Edition, Test Your Knowledge Question #20

A. Found in plant-like cells, only B. Found in animal-like cells, only Choose the answer that best applies for each of the following questions. A. Found in plant-like cells, only B. Found in animal-like cells, only C. Found in all eukaryotic cells. D. Found in all cells. E. Found in prokaryotic cells, only. Mitochondria Chloroplasts Ribosomes Vacuoles. Answer: a Source: Taylor - Student Study Guide for Biology, Sixth Edition, Test Your Knowledge Question #20