1. CHAPTER 6 A TOUR OF THE CELL

2. Cytology: science/study of cells
Light microscopy resolving power~ measure of clarity
Electron microscopy
TEM ~ electron beam to study cell ultrastructure
SEM ~ electron beam to study cell surfaces
Cell fractionation ~ cell separation; organelle study
Ultracentrifuge ~ cell fractionation; 130,000rpm

3. A cell is a living unit greater than the sum of its parts
While the cell has many structures that have specific functions, they must work together.

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

5. Cell Types: Prokaryotic
Nucleoid: DNA
concentration
No organelles with
membranes
Ribosomes:protein synthesis
Plasma membrane: (all
cells); semi-permeable
Cytoplasm/cytosol(all cells)

6. Cell types: Eukaryotic
Nucleus:membrane enclosed organelle containing chromosomes
Membrane bound organelles of specialized form and function
Generally larger than prokaryotic cells

7. Cell Size
As cell size increases, the surface area to volume ratio decreases
Rates of chemical exchange may then be inadequate for cell size
Cell size, therefore, remains small

8. 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

9. 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

10. Proteins do all the work!
cells
DNA
Repeat after me…
Proteins do all the work!
organism

11. Cells functions Building proteins read DNA instructions build proteins
process proteins
folding
modifying
removing amino acids
adding other molecules
e.g, making glycoproteins for cell membrane
address & transport proteins

12. Building Proteins Organelles involved nucleus ribosomes
endoplasmic reticulum (ER)
Golgi apparatus
vesicles
The Protein Assembly Line
Golgi apparatus
nucleus
ribosome ER
vesicles

13. What kind of molecules need to pass through?
histone protein
chromosome
DNA
Nucleus
Function
protects DNA
Structure
nuclear envelope
double membrane
membrane fused in spots to create pores
allows large macromolecules to pass through
nuclear
pores
pore
nuclear envelope
nucleolus
What kind of molecules need to pass through?

15. Nucleolus Function ribosome production
build ribosome subunits from rRNA & proteins
exit through nuclear pores to cytoplasm & combine to form functional ribosomes
small
subunit
large subunit
ribosome
rRNA &
proteins
nucleolus

16. Ribosomes Function Structure protein production rRNA & protein
small
subunit
large
Ribosomes
Function
protein production
Structure
rRNA & protein
2 subunits combine
0.08mm
Ribosomes
Rough ER
Smooth
The genes for rRNA have the greatest commonality among all living things. There is very little difference in the DNA sequence of the rRNA genes in a humans vs. a bacteria.
Means that this function (building of a ribosome) is so integral to life that every cell does it almost exactly the same way.
Change a base and this changes the structure of the RNA which causes it to not function.

17. Types of Ribosomes Free ribosomes Bound ribosomes suspended in cytosol
synthesize proteins that function in cytosol
Bound ribosomes
attached to endoplasmic reticulum
synthesize proteins for export or for membranes
membrane proteins

18. Endoplasmic Reticulum
Function
processes proteins
manufactures membranes
synthesis & hydrolysis of many compounds
Structure
membrane connected to nuclear envelope & extends throughout cell
accounts for 50% membranes in eukaryotic cell

19. Types of ER
rough
smooth

20. Smooth ER function Membrane production Many metabolic processes
synthesis
synthesize lipids
oils, phospholipids, steroids & sex hormones
hydrolysis
hydrolyze glycogen into glucose
in liver
detoxify drugs & poisons
ex. alcohol & barbiturates

21. Membrane Factory Build new membrane synthesize phospholipids
builds membranes
ER membrane expands
bud off & transfer to other parts of cell that need membranes

22. Which cells have lot of rough ER?
Rough ER function
Produce proteins for export out of cell
protein secreting cells
packaged into transport vesicles for export
Which cells have lot of rough ER?
Which cells have a lot of ER?
protein production cells like pancreas = production of digestive enzymes (rough endoplasmic reticulum from a cell of exocrine pancreas (88000X))

23. Golgi Apparatus

24. Vesicle transport vesicle budding from rough ER fusion of vesicle
with Golgi
apparatus
migrating
transport
protein
ribosome

25. Any Questions!!