Lysosomes
Mr. Nichols
PHHS
What are lysosomes?
The “garbage disposals” of your cells; they are responsible for
digesting and recycling materials that the cell no longer needs or
has to get rid of.
They are found in both plant and animal cells.
Lysosomes are very common in white blood cells, where disease
and sickness are fought so a lot bacteria needs to be digested.
Their shape and size vary depending on what material is digested.
They contain about 40 different enzymes (ex. nucleases, proteases,
lipases, and carbohydrases).
How are they structured?
-enzyme-filled sacs
-generally spherical
-acidic pH of about 4.8
-500 nanometer diameter
-surrounded by single
membrane
(To learn how enzymes are created, go to page 60 in the textbook.)
Why this structure?
The membrane surrounding the lysosome protects
the rest of the cell from the lysosome’s digestive
enzymes;
Without this protective membrane, enzymes could escape and
accidentally destroy other parts of the cell.
The lysosome’s optimum pH is acidic for protection;
Its enzymes work most efficiently in an acidic environment, so
if enzymes were to escape from the lysosome, they couldn’t
easily digest other parts of the cell (which is not so acidic).
Main Functions of
Lysosomes
1. Digestion of ingested material
(by releasing enzymes into the new vacuole)
2. Autophagy & Cell Death
(by digesting internal parts of the cell, such as
organelles)
In each example above, the red lysosomes combine with the grey unwanted
material and then release their enzymes into the material so that the enzymes can
digest it.
How does endocytosis
function?
Incoming material (from outside the cell) is encased
in a vacuole by a process called endocytosis
The lysosome combines with the incoming vacuole and within this
compartment, the
enzymes are released by the
lysosome to digest material in the vacuole.
How do autophagy & cell
death function?
Autophagy and cell death are the processes by
which lysosomes digest parts of their own cell.
The material to be digested is enclosed in a vacuole, which the lysosome
combines with and then releases its enzymes into in order to digest the
material.
In Autophagy, the “recycled” or digested materials can
then be used in the cytoplasm or for new cell material.
In cell death, the lysosome digests all the organelles in
the cell, killing it.
What can be digested by
the lysosome’s enzymes?
Carbohydrates
Complex molecules
Cell waste products
Sugars
Dead cells
Proteins
Extra material or organelles
Nucleic Acids
Macromolecules
Lipids
Generally, how are
lysosomes made?
Lysosomes are created in the ER and packaged in the Golgi bodies
(see page 60 for more detailed information on this):
Human Diseases
caused by lysosome malfunctions
Tay-Sachs Disease
An essential enzyme within the lysosomes is not
produced by a genetic defect, so the lipid it would
normally break down accumulates.
Effects: mental retardation, early death, damage to
the nervous system
Arthritis Inflammation
Enzymes escape from the lysosome
Effects: inflammation and pain
SOURCES
for images, content, and videos
http://www.cartage.org.lb/en/themes/sciences/zoology/animalphysiology/anatomy/animalcellstructure/Lysosomes/Lysosomes.
http://www.zik-fg.de/Group_Bioinformatics_Toponomics_DE/data/images/Saureus-Lysosomes.mpg
http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/A/Autophagy.html
http://missbakersbiologyclasswiki.wikispaces.com/5th+Period's+Cell
http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=cooper&part=A1519
http://www.cellsalive.com/cells/lysosome.htm
http://www.biology4kids.com/files/cell_lysosome.html
http://library.thinkquest.org/12413/structures.html
http://www.buzzle.com/articles/lysosome-structure.html
http://www.utm.utoronto.ca/~w3bio315/picts/lectures/lecture15/Lysosome-Functions1.jpg
http://www.utm.utoronto.ca/~w3bio315/picts/lectures/lecture15/Lysosome-Formation1.jpg
http://library.thinkquest.org/C004535/lysosomes.html
http://micro.magnet.fsu.edu/cells/lysosomes/lysosomes.html
http://student.ccbcmd.edu/courses/bio141/lecguide/unit3/eustruct/lyso.html
http://www.zik-fg.de/Group_Bioinformatics_Toponomics/gallery.html
http://images.protopage.com/view/721389/1854gk07so11gu766lauptjlr.jpg
http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__lysosomes.html