Download Lysosomes are organelles that digest macromolecules

Lysosomes are organelles that digest macromolecules, repair cell
membranes, and respond to foreign substances entering the cell.
LEARNING OBJECTIVE [ edit ]
Describe how lysosomes function as the cell's waste disposal system
KEY POINTS [ edit ]
Lysosomes breakdown/digest macromolecules (carbohydrates,lipids, proteins, and nucleic acids),
repair cell membranes, and respond against foreign substances such as bacteria, viruses and
other antigens.
Lysosomes contain enzymes that break down the macromolecules and foreign invaders.
Lysosomes are composed of lipids and proteins, with a single membrane covering the internal
enzymes to prevent the lysosome from digesting the cell itself.
Lysosomes are found in all animal cells, but are rarely found within plant cells due to the tough
cell wall surrounding a plant cell that keeps out foreign substances.
TERMS [ edit ]
enzyme
a globular protein that catalyses a biological chemical reaction
lysosome
An organelle found in all types of animal cells which contains a large range of digestive enzymes
capable of splitting most biological macromolecules.
Give us feedback on this content: FULL TEXT [edit ]
Lysosomes
A lysosome has three main functions: the breakdown/digestion of macromolecules
(carbohydrates, lipids, proteins, and
nucleic acids), cell membrane repairs, and
responses against foreign substances such
as bacteria, viruses and other antigens.
When food is eaten or absorbed by the
cell, the lysosome releases its enzymes to
break down complex molecules including
sugars and proteins into
usable energy needed by the cell to
survive. If no food is provided, the
lysosome's enzymes digest
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otherorganelles within the cell in order to obtain the necessarynutrients.
In addition to their role as the digestive component and organelle-recycling facility of animal
cells, lysosomes are considered to be parts of the endomembrane system. Lysosomes also use
their hydrolytic enzymes to destroypathogens (disease-causing organisms) that might enter
the cell. A good example of this occurs in a group of white blood cells called macrophages,
which are part of your body's immune system. In a process known as phagocytosis or
endocytosis, a section of the plasma membrane of the macrophage invaginates (folds in) and
engulfs a pathogen. The invaginated section, with the pathogen inside, then pinches itself off
from the plasma membrane and becomes a vesicle. The vesicle fuses with a lysosome. The
lysosome's hydrolytic enzymes then destroy the pathogen .
Lysosomes digest foreign substances that might harm the cell
A macrophage has engulfed (phagocytized) a potentially pathogenic bacterium and then fuses with
a lysosomes within the cell to destroy the pathogen. Other organelles are present in the cell but for
simplicity are not shown.
A lysosome is composed of lipids, which make up the membrane, and proteins, which make
up the enzymes within the membrane. Usually, lysosomes are between 0.1 to 1.2μm, but the
size varies based on the cell type. The general structure of a lysosome consists of a collection
of enzymes surrounded by a single-layer membrane. The membrane is a crucial aspect of its
structure because without it the enzymes within the lysosome that are used to breakdown
foreign substances would leak out and digest the entire cell, causing it to die.
Lysosomes are found in nearly every animal-like eukaryotic cell. They are so common in
animal cells because, when animal cells take in or absorb food, they need the enzymes found
in lysosomes in order to digest and use the food for energy. On the other hand, lysosomes are
not commonly-found in plant cells. Lysosomes are not needed in plant cells because they
have cell walls that are tough enough to keep the large/foreign substances that lysosomes
would usually digest out of the cell.