Summary
A recycling pathway in which cytoplasmic components are enclosed in autophagosomes and degraded by lysosomes.
In depth
Cells form a double-membraned autophagosome around damaged organelles or protein aggregates; it fuses with a lysosome and the contents are degraded and recycled. It is activated by starvation through mTOR inhibition.
Autophagy removes damaged mitochondria (mitophagy) and pathogens, and defects are linked to neurodegeneration and cancer. Yoshinori Ohsumi won the 2016 Nobel Prize for revealing its mechanisms.
There are three forms: macroautophagy (the best known, using autophagosomes), microautophagy (the lysosome engulfs cytoplasm directly) and chaperone-mediated autophagy (specific proteins are fed into the lysosome). Proteins such as ATG family members and LC3 build and mark the autophagosome; Yoshinori Ohsumi won the 2016 Nobel Prize for identifying these genes in yeast.
Autophagy supports health: it clears protein aggregates in neurons, controls inflammation, and recycles nutrients during fasting. Cancer cells can use it to survive stress, so it may either protect against or support tumours.
Example: during starvation, a cell digests part of its own cytoplasm to supply amino acids for essential proteins.
Frequently asked questions
What is Autophagy?
A recycling pathway in which cytoplasmic components are enclosed in autophagosomes and degraded by lysosomes.
Which area of biology covers Autophagy, and how advanced is it?
Autophagy is one of the 52 topics in Cell Biology. It is rated Advanced, so it suits learners who want specialist depth. Related topics in this area include Apoptosis, Cytoplasm, Endocytosis.
Can you give an example of Autophagy?
During fasting, autophagy supplies amino acids for essential protein synthesis.
What should I learn before Autophagy?
Work through the Beginner topics in Cell Biology first, such as Cell Theory, Prokaryotic Cell, Eukaryotic Cell, then return to Autophagy. Advanced topics assume the Intermediate vocabulary.
What topics are related to Autophagy?
The closest topics to Autophagy are Apoptosis, Cytoplasm, Endocytosis, Active Transport. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Autophagy?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Autophagy. To practise the whole of Cell Biology, use the Cell Biology quiz.
How is Autophagy different from Apoptosis?
Autophagy: A recycling pathway in which cytoplasmic components are enclosed in autophagosomes and degraded by lysosomes. Apoptosis: Programmed cell death carried out by caspase enzymes, removing damaged or unneeded cells without inflammation. Read both side by side and note what each one explains.
How should I study Autophagy step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Apoptosis and explain the difference aloud. Finally, take the Cell Biology quiz and come back to this page for any question you miss.