Cells & Cellular Processes
Where Life Begins…
Cells...
 Are the simplest collection of matter that
can live
Are the basic unit of structure & function
for all living things
Communicate with one another
Sense & respond to environmental changes
Are descendents from earlier cells
All Cells Have…
 Plasma Membrane – semipermeable
layer that surrounds & protects every cell.
 Cytoskeleton – semifluid substance
within the membrane
 DNA – in the form of chromosomes that
contain specific genes coordinating cell
functions
 Ribosomes – tiny organelles that make
proteins using instructions from genes
Types of Cells
E.coli on the small intestine
1. Prokaryotes
–
–
–
Pro – before; karyon – nucleus
No true nucleus
Nucleoid region
•
Not a true membrane-bound nucleus but the area
where DNA is concentrated
–
Bacteria are
the only examples
E. coli
Salmonella
Lactobacillus
library.thinkquest.org
2. Eukaryotes
–
–
Contain a “true” nucleus enclosed by a
membrane
Also contain a variety of other membranebound organelles
http://nobelprize.org/nobel_prizes/medicine/laureates/1999/illpres/
www.answers.com/topic/cytoskeleton
(nucleus)
Organelles
“tiny organs”
1. Nucleus
http://www.public.iastate.edu/~ttt356/Nucleus.jpg
–
–
–
Control center that directs cellular activity
Contains most of the genes in eukaryotic cells
Enclosed by a nuclear membrane, or envelope,
that contains pores
– Contains DNA usually
in the form of chromatin
– Contains the nucleolus,
the area where ribosomes
are produced
www.nsf.gov/news/overviews/biology/interact05.jsp
2. Mitochondria
 Powerhouse of the cell
 Produces the bulk of the ATP in the cell during
aerobic respiration
 Contains its
own DNA
 Thought be
free-living bacteria
at one time
http://kentsimmons.uwinnipeg.ca/cm1504/Image110.gif
3. Ribosomes
 The tiniest organelles; produce in nucleolus
 Assemble proteins through the process of
translation
 Some are “free” in cytoplasm; others are attached
to Rough ER
http://genome.imim.es/courses/Madrid04/exercises/ensembl/images/ribosome.jpg
http://www.nsf.gov/news/overviews/biology/assets/interact05.jpg
4. Rough Endoplasmic Reticulum
 “Rough” because of the ribosomes attached
 Continuous with
the nuclear membrane
 Produces internal
membranes
 Folds, proof-reads &
transports proteins made by ribosomes
www.biologycorner.com
http://www.biology.arizona.edu/CELL_BIO/tutorials/pev/graphics/smooth_er.gif
http://www.mhhe.com/biosci/genbio/enger/student/olc/art_quizzes/genbiomedia/0064.jpg
5. Smooth ER
 Extension of RER without the ribosomes
 Makes lipids for the cell – fatty acids, steroids &
phospholipids
 Also functions in detoxification of poisons &
toxins within the cell
http://www.biology.arizona.edu/CELL_BIO/tutorials/pev/graphics/smooth_er.gif
www.biologycorner.com
http://ghr.nlm.nih.gov/handbook/illustrations/cellgolgi.jpg
6. Golgi Apparatus
 “Mailroom” of the cell
 Sorts, packages & exports proteins in vesicles
http://www.daviddarling.info/images/Golgi_apparatus.jpg
Golgi Implications in Disease
Alzheimers
Parkinson’s
Mad Cow
Lesch-Nyhan
ALS (Lou Gehrig’s)
Pick’s Disease
7. Vacuole
 Storage organelle for food, water & wastes
 Especially large in plant cells for the storage of
water
http://www.daviddarling.info/images/contractile_vacuole.gif
http://www4.alief.isd.tenet.edu/cahowe/PreAPBio/Projects/Cell_files/slide0013_image053.jpg
8. Lysosomes
 Enzyme-containing organelles that digest
(hydrolyze) cellular waste products, nonfunctional
proteins & return usable components to cytoplasm
 Enzymes are
made in SER
http://www.molecularexpressions.com/cells/lysosomes/images/lysosomesfigure1.jpg
Lysosomes in Tay Sachs
Mutated genes produce enzymes that are less
effective than normal at breaking down fatty cell
products known as gangliosides.
Gangliosides build up in the lysosomes and
overload cells.
http://www.sfn.org/index.cfm?pagename=brainBriefings_TreatingTaySachs
http://www.kellogg.umich.edu/theeyeshaveit/congenital/images/tay-sachs.jpg
9. Peroxisome
 Enzyme-containing organelles that transfer H+
from various compounds to oxygen
Some break down fatty acids; others break down
poisons such as alcohol
 H2O2 is often a waste product of peroxisome
reactions, and it is a toxin as well –
Our body breaks down H2O2 with an enzyme
called _______. The products are ____ & _____.
Peroxisomes & Disease
 ALD – featured in the movie “Lorenzo’s Oil”
Zellweger Syndrome
http://www.neuro.jhmi.edu/BrainWaves/2004_Fall/photos/oil.jpg
A Tour of the Cell
 The National Science Foundation Tour of
the Cell http://www.nsf.gov/news/overviews/biology/
interactive.jsp
An amazing animation of the Inner Life of
the Cell http://www.studiodaily.com/main/searchlist/6
850.html
The Cytoskeleton
 Semifluid medium that supports organelles
 Consists of a network of fibers that support the
cell and allow for organized movement of
material.
 Fibers include:
1. Microtubules
2. Actin microfilaments
3. Intermediate filaments
http://upload.wikimedia.org/wikipedia/commons/0/09/FluorescentCells.jpg
1. Microtubules
 Hollow tubes that form the thickest of the fibers
in cytoskeletal framework
Made in centrosome (MTOC)
 Shape & supports cell
Serve as tracks for movement of vesicles &
chromosomes
Organelle & vesicle movement along
microtubules is controlled by motor proteins
called dynein & kinesin
Dynamic Instability of Microtubules
Assembly
Disassembly
http://sparkleberrysprings.com/innerlifeofcell.html
http://www.nsf.gov/news/mmg/media/images/microtubule_traffic_h3.jpg
http://www.dnatube.com/view_video.php?viewkey=a8ae0be8b5306971900a&viewtype=?
http://www.hhmi.org/bulletin/may2007/chronicle/popups/molecules_1.html
Microtubules in the cell
 Centrioles
– Found in animal cells only
– Organize microtubules during cell division
– Have a 9 + 3 arrangement
• 9 sets of 3 microtubules
http://micro.magnet.fsu.edu/cells/centrioles/centrioles.html
Microtubules as Chemo Target
 Taxol, a chemo
drug, works by
stabilizing
microtubules (green)
used in cell division
 It halts cells in the
process of division
http://cose-stor.sfsu.edu/~huiyang/images/cell-fireworks.jpg
Cilia & Flagella
– Core of microtubules covered by an extension of the
cell membrane
– 9 + 2 pattern
– Anchored by a basal body that has the same 9 + 3
microtubule arrangement as centrioles
– Dynein arms are the “motors” responsible for the
bending movements of cilia & flagella
http://micro.magnet.fsu.edu/cells/centrioles/centrioles.html
2. Actin Microfilaments
 Solid rods that are much smaller than
microtubules
 Two-stranded helical polymers of actin
 Found just beneath the plasma membrane
http://sparkleberrysprings.com/innerlifeofcell.html
http://www.daviddarling.info/encyclopedia/A/actin.html
Microtubules & Actin Microfilaments
http://publications.nigms.nih.gov/insidethecell/chapter1.html
3. Intermediate Filaments
Mid sized filaments
that provide framework
for organelle position
 The most stable &
durable fibers in the
Cytoskeleton
 Main component
in tough coverings
(skin, hair, nails)
http://www.studiodaily.com/main/searchlist/6850.html
http://campus.queens.edu/faculty/jann
r/cells/cell%20pics/cytoskeleton.jpg
Membranes & Transport
Gateways of
cells & organelles
Structure
http://www.bioteach.ubc.ca/Bio-industry/Inex/
http://www.biology.iupui.edu/biocourses/N100H/cells.html
http://images.google.com/imgres?imgurl=http://www.iupac.org/didac/Slide%2520Images/Didac%252005/Thumbs/D5%2520CG06.jpg&imgrefurl=http:
//www.iupac.org/didac/Didac%2520Eng/Didac05/Content/CG06.htm&h=254&w=378&sz=61&hl=en&start=24&tbnid=ukwDqpIAGNcyMM:&tbnh=82&tbn
w=122&prev=/images%3Fq%3Dphospholipid%2Bbilayer%26start%3D20%26gbv%3D2%26ndsp%3D20%26svnum%3D10%26hl%3Den%26sa%3DN
http://commons.wikimedia.org/wiki/Image:Cell_membrane_detailed_diagram.svg
Passive Transport
 Does not require energy
 [High]  [Low]
1. Diffusion
2. Osmosis
3. Facilitated diffusion
1. Diffusion
Occurs across the phospholipids
– CO2
– O2
– Urea
Lab Information on Diffusion
Dialysis tubing acts as a semipermeable
membrane
Which materials can pass through the
pores?
Which cannot permeate the bag?
Animation
http://www.ualr.edu/botany/osmosis.jpg
2. Osmosis
Diffusion of water
Water moves from
– High [water]  low [water]
– Hypotonic [solute]  hypertonic [solute]
Animation
http://commons.wikimedia.org/wiki/Image:Osmotic_pressure_on_blood_cells_diagram.svg
http://commons.wikimedia.org/wiki/Image:Turgor_pressure_on_plant_cells_diagram.svg
3. Facilitated Diffusion
Molecules moving from [high]  [low] but
are too big to move between phospholipids
Requires a
membrane carrier
(facilitator)
Glucose uses this
http://www.biology.arizona.edu/chh/problem_sets/kidneysmetals/07t.html
Active Transport
Requires ATP energy
–
–
–
–
ATP pumps
Cotransport
Endocytosis
Exocytosis
Often goes against concentration gradient
ATP Pumps
Na+/K+ pump
Cotransport
2 molecules
transported on the
same protein
– 1 against the
gradient
– 1 with the
gradient
Endocytosis
Engulfing large
molecules by
wrapping a piece
of membrane
around it to form a
transport vesicle
3 Types of Endocytosis
Phagocytosis
– Engulfing solids
Pinocytosis
– Engulfing liquids
Receptor-mediated endocytosis
– Engulfing with specific receptors
• LDL cholesterol
Exocytosis
Spitting out large
molecules
Vesicles fuse
with membrane
Endo & Exocytosis
http://www.dnatube.com/view_video.php?viewkey=6ebda4840e7360ce6e7e
http://en.wikipedia.org/wiki/Phagocytosis
Review
Tutorial
http://www.dwm.ks.edu.tw/bio/activelearner/05/ch5intro.html
http://www.dnatube.com/view_video.php?viewkey=4fdd9ee93bdf998c6ca0