1. Tour of the Cell 1

2. Prokaryote bacteria cells Eukaryote animal cells
Types of cells
- no organelles
- organelles
Eukaryote animal cells
Eukaryote plant cells

3. Why organelles? mitochondria chloroplast Golgi ER
Specialized structures
specialized functions
cilia or flagella for locomotion
Containers
partition cell into compartments
create different local environments
separate pH, or concentration of materials
distinct & incompatible functions
lysosome & its digestive enzymes
Membranes as sites for chemical reactions
unique combinations of lipids & proteins
embedded enzymes & reaction centers
chloroplasts & mitochondria
chloroplast
Golgi
Why organelles?
There are several reasons why cells evolved organelles. First, organelles can perform specialized functions. Second, membrane bound organelles can act as containers, separating parts of the cell from other parts of the cell. Third, the membranes of organelles can act as sites for chemical reactions.
Organelles as specialized structures
An example of the first type of organelle is cilia, these short filaments act as "paddles" to help some cells move.
Organelles as Containers
Nothing ever invented by man is as complex as a living cell. At any one time hundreds of incompatible chemical reactions may be occurring in a cell. If the cell contained a uniform mixture of all the chemicals it would not be able to survive. Organelles surrounded by membranes act as individual compartments for these chemical reactions. An example of the second type of organelle is the lysosome. This structure contains digestive enzymes, these enzymes if allowed to float free in the cell would kill it.
Organelle membranes as sites for chemical reactions
An example of the third type of organelle is the chloroplast. The molecules that conduct the light reactions of photosynthesis are found embedded in the membranes of the chloroplast. ER

4. Cells gotta work to live!
What jobs do cells have to do?
make proteins
proteins control every cell function
make energy
for daily life
for growth
make more cells
growth
repair
renewal

5. Building Proteins Organelles involved Nucleus Ribosomes Protects DNA
Bound by double membrane that is covered in pores (openings)
Darker center region that produces ribosomes
Contains nucleolus
Ribosomes
Complex of 2 subunits
Site of protein production
2 types
Free – suspended in cytoplasm
Synthesizes proteins that remain in cytoplasm
Bound – attached to rough ER
Synthesizes proteins to be exported or for membrane

6. Building Proteins continued…
endoplasmic reticulum (ER)
Processes proteins, manufactures membranes, used in synthesis and hydrolysis of compounds for rest of cell/body
2 kinds
Rough er – studded with ribosomes
Works with proteins that will be exported out of cell
Large amounts found in pancreatic cells which secrete enzymes for digestion
Smooth er – no attached ribosomes
Synthesizes lipids
Hydrolyzes macromolecules into smaller, usable molecules and detoxifies drugs and poisons
Golgi apparatus
Sorts and ships cell products
Both around and out of cell

7. ATP Cells need power! Making energy take in food & digest it
take in oxygen (O2)
make ATP
remove waste
ATP

8. Making Energy
Cells must convert incoming energy to forms that they can use for work
mitochondria: from glucose to ATP
chloroplasts: from sunlight to ATP & carbohydrates
ATP = active energy
carbohydrates = stored energy
ATP
ATP +

9. 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

10. 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
Lynn Margulis
From hypothesis to theory!
Paradigm shifting ideas in evolutionary biology.
Lynn Margulis
U of M, Amherst

11. Evolution of eukaryotes
Endosymbiosis theory
Evolution of eukaryotes

12. Vacuoles & vesicles Function little “transfer ships” Food vacuoles
phagocytosis, fuse with lysosomes
Contractile vacuoles
in freshwater protists, pump excess H2O out of cell
Central vacuoles
in many mature plant cells

13. Where old organelles go to die!
Lysosomes
Function
little “stomach” of the cell
digests macromolecules
“clean up crew” of the cell
cleans up broken down organelles
Structure
vesicles of digestive enzymes
synthesized by rER, transferred to Golgi
only in
animal cells

14. When things go bad… Diseases of lysosomes are often fatal
digestive enzyme not working in lysosome
picks up biomolecules, but can’t digest one
lysosomes fill up with undigested material
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

15. But sometimes cells need to die…
Lysosomes can be used to kill cells when they are supposed to be destroyed
some cells have to die for proper development in an organism
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.

16. 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

17. Cells need to make more cells!
Making more cells
to replace, repair & grow, the cell must…
copy their DNA
make extra organelles
divide the new DNA & new organelles between 2 new “daughter” cells
organelles that do this work…
nucleus
centrioles

18. Centrioles Function Structure help coordinate cell division
one pair in each cell
“motor” proteins