Post on 29-Dec-2015
A Tour of the Cell
Read pg.98-99 ~ Create a double bubble to compare and contrast prokaryotic and eukaryotic cells
Prokaryotic
Eukary-otic
SIMILARITIES DIFFERENCESDIFFERENCES
Chp.6:Tour of the Cell
How big is a cell?
• Cells Alive! How Big is a Cell?
• Most cells are between 1 and 100 μm (10-6 or 1/ 1,000,000 m)
• Eukaryotic Cells are larger than prokaryotic cells
Prokaryotebacteria cellsProkaryote
bacteria cellsTypes of cells
Eukaryoteanimal cellsEukaryote
animal cells
- no organelles
- organelles
Eukaryoteplant cellsEukaryoteplant cells
Prokaryotic Cells
• No nucleus, no membrane-bound organelles
• But, they do have a cell membrane and they do have an organelle– Ribosomes!
• Also have Nucleoid region, Cell Wall, and Cytosol (fluid)
Eukaryotic Cells
• Eukaryotic Cells contain a nucleus and membrane-bound organelles
• The membrane is key!
Limits to Cell Size• As a cell grows, its surface area
to volume ratio decreases
• This means the cell has more volume that needs to get oxygen, food, get rid of waste but less SA to do it over (in proportion)
Why organelles?• 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
mitochondria
chloroplast
Golgi
ER
Cells gotta work to live!
• What jobs do cells have to do?– Make proteins
• proteins control every cell function
– Store energy• for daily life• for growth
– Make more cells• growth• repair• renewal
Proteins do all the work!
cellscellsDNADNA
proteinsproteins
organismorganismRepeat after me…
Proteins do all the work!
Cell functions • Building proteins
1. read DNA instructions
2. build proteins
3. process proteins• folding• modifying
– removing amino acids– adding other molecules
» e.g, making glycoproteinsfor cell membrane
4. address & transport proteins
Building Proteins• Organelles involved
– nucleus– ribosomes– endoplasmic reticulum
(ER)– Golgi apparatus– vesicles
nucleus ribosome ERGolgi
apparatus vesicles
The Protein Assembly Line
nuclearpores
nuclearpore
nuclear envelopenucleolus
histone protein
chromosome
DNA
• Function– protects DNA
• Structure– nuclear envelope
• double membrane• membrane fused in spots to create pores
– allows large macromolecules to pass through
Nucleus
DNA
NucleusmRNA
nuclearmembrane
smallribosomal
subunit
largeribosomal
subunit
cytoplasm
mRNA
nuclear pore
production of mRNA from DNA in nucleusproduction of mRNA from DNA in nucleus
mRNA travels from nucleus to ribosome in cytoplasm through nuclear pore
mRNA travels from nucleus to ribosome in cytoplasm through nuclear pore
1
2
Nucleolus• Function
– ribosome production• build ribosome subunits from rRNA & proteins• exit through nuclear pores to cytoplasm &
combine to form functional ribosomes
smallsubunit
large subunit
ribosome
rRNA &proteins
nucleolus
smallsubunit
largesubunit
Ribosomes • Function
– protein production
• Structure– rRNA & protein– 2 subunits combine 0.08m
RibosomesRough
ER
SmoothER
membrane proteins
Types of Ribosomes
• Free ribosomes– suspended in cytosol– synthesize proteins that
function in cytosol
• Bound ribosomes– attached to endoplasmic
reticulum– synthesize proteins
for export or for membranes
Endoplasmic Reticulum
• Function – processes proteins– manufactures membranes– synthesis & hydrolysis of many compounds
• Structure– membrane connected to nuclear envelope &
extends throughout cell
Types of ER
rough smooth
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– in liver– ex. alcohol & barbiturates
Membrane Factory
• Build new membrane– synthesize
phospholipids• builds membranes
– ER membrane expands
• bud off & transfer to other parts of cell that need membranes
Rough ER function• Produce proteins for export out of cell
– protein secreting cells– packaged into transport vesicles for export
Synthesizing proteins
cytoplasm
cisternalspace
mRNA
ribosome
membrane ofendoplasmic reticulum
polypeptide
signalsequence
ribosome
Golgi Apparatus
transport vesicles
secretoryvesicles
• Function– finishes, sorts, tags & ships cell products
• like “UPS shipping department”
– ships products in vesicles• membrane sacs• “UPS trucks”
Golgi Apparatus
Vesicle transport
vesiclebuddingfrom roughER
fusionof vesiclewith Golgiapparatus
migratingtransportvesicle
protein
ribosome
DNA
RNA
ribosomes
endoplasmicreticulum
vesicle
Golgi apparatus
vesicle
proteinon its way!
protein finishedprotein
Making Proteins
TO:
TO:
TO:
TO:
nucleus
proteins
transportvesicle
Golgiapparatus
vesicle
smooth ER
rough ER
nuclear porenucleus
ribosome
cellmembrane protein secreted
cytoplasm
Making proteinsPutting it together…
Lysosomes
•Sac of hydrolytic enzymes; intracellular digestion of macromolecules
• Phagocytosis• Autophagy: recycle cell’s own organic material• Apoptosis: programmed cell death
Vacuoles
• Membrane-bound sacs– digestion & release of
cellular waste
– Food (phagocytosis)
– Contractile (pump excess water)
– Central (storage in plants)
Mitochondria• Quantity in cell correlated
with metabolic activity– cellular respiration
• double membrane (phospholipid); – Outer membrane is smooth– Inner membrane is highly
convoluted forming folds called cristae
• Contains enzymes used for ATP production
•contain own DNA
Chloroplast• Contains chlorophyll, captures energy from Sun and
converts it to chemical bond energy via photosynthesis
• Structure: double membrane, contains thylakoids (flattened disks), grana (stacked thylakoids), stroma.
• own DNA
Microscope Review
Types of Microscopes
• Compound Light Microscopes (like what we use in class)-uses 2 or more lenses to magnify objects.– Max magnification 1500X.
• Electron Microscopes-uses a beam of electrons to image a specimen.Scanning EM(SEM)– Surface– Magnification 60,000X
Transmission EM(TEM)– Inside– Magnification 100,000 X +
Course Adjustment Knob
Fine Adjustment Knob
Arm
Base
Stage
Diaphragm
Light Source
Body Tube
Low Power Objective
Eyepiece
Revolving Nosepiece
Medium Power Objective
High Power Objective
Stage Clip
Using a Microscope• Always carry the microscope by the arm and the base.• To calculate magnification, multiply the eyepiece
magnification by the objective magnification.• Always make sure the stage is all the way up when focusing
and slowly bring the stage down.• When on low power, use the course adjustment knob (the
big knob)• When on medium and high power, use the fine adjustment
knob (the little knob) ONLY!!!• NEVER use the course adjustment knob on medium or high
power!!! Why? You are so close to the slide that you will run into it with the objective!!
• When you are finished with the microscope, wrap the cord around the base and put the lowest objective down. Make sure the stage is all the way down.
How to Draw a Diagram from a Microscope
Drawing the Diagram1. If it is not already provided, draw your “field of view”
• This is the circle that you see when you look through the microscope
2. Draw exactly what you see• make sure it’s not a water spot or air bubble!!!3. Add color exactly like the colors you observe in the
specimen.4. Mark the diagram with the specimen name and
magnification.Labels5. Printed neatly6. Horizontal to the upper edge of the paper7. Lines connecting labels to the diagram should be straight.
Ameoba 400X
Pseudopod
Food vacuole
Assignment
• Cell Observations: Prokaryotic vs. Eukaryotic Cells– Examine at least one of each of the following
types of cells• Bacteria• Protist• Plant • Animal
– Draw your observations under high power– Complete analysis questions on the back