1. Uniqueness of Mitochondria and chloroplasts (Ch. 6)

2. 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

3. 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

4. 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

5. 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.

6. Fetal development
syndactyly
6 weeks
15 weeks

7. 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 +

8. 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

9. 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

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

11. 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

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

13. Mitochondria are everywhere!!
animal cells
plant cells

14. 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

15. 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!

16. 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

17. Chloroplasts
Why are chloroplasts green?

19. 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

20. 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  +

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

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

23. 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

24. 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

25. 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

26. Putting it all together
animal cells
plant cells

27. Any Questions??

28. Review Questions

29. 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

30. 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

31. 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