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