Peroxisomes Flashcards
concerning the structure of peroxisomes, they are [blank] in eukaryotes (plenty or few), peroxisomes are [blank] (size), [blank] (shape) organelles enclosed by a [blank] (single or duble) lipid bilayer, although they perform numerous vital functions.
plenty, small, spherical, single
peroxisome size range
0.2 to 2.5 micrometers
tell me about the genome of peroxisomes
they lack their own genome, all proteins imported from the cytosol
Tell me about the mobility of peroxisomes (dynamic or static)
Peroxisomes are dynamic
which filament do peroxisomes move on, on which motors?
actin filaments via myosin motors
speed of peroxisomes
7 micrometers
Name 4 biochemical functions of peroxisomes
fatty acid b oxidation, glyoxylate cycle, detoxification of reactive oxygen species, horone biosynthesis
explain the biochemical function of fatty acid b oxidation
Peroxisomes are involved in the breaking down of long-chain fatty acids into acetyl-CoA, which can enter the TCA cycle for ATP production.
explain the glyoxylate cycle
In seeds, peroxisomes converting fats into carbs through the glyoxylate cycle, which is essential for seedling growth until photosynthesis begins.
Explain the detoxification of reactive oxygen species
Peroxisomes contain catalase, an enzyme that breaks down hydrogen peroxide (H₂O₂) into water and oxygen, protecting the cell from oxidative damage.
explain hormone biosynthesis
Peroxisomes are involved in the biosynthesis of several plant hormones, including:
Jasmonic Acid: A signaling molecule involved in plant stress responses.
Indole-3-Acetic Acid (IAA): An auxin essential for plant growth regulation.
Speaking about protein import mechanisms, Proteins targeted to peroxisomes contain specific [blank]
peroxisomal targeting sequences (PTS), located at the C-terminus
asides from PTS, what kind of proteins assist in importing enxymes like catalase, fully synthesized and folded in the cytosol
PEX proteins
talking about peroxisome assembly, how do they form? 2 ways, which protein do they require for this
de novo, or from existing peroxisomes, PEX proteins
PEX proteins are involved in both [blank] and [blank] import
membrane and matrix
[blank] is a specialized protein complex allowing selective entry of peroxisomal matrix proteins.
the importomer
In the importormer complex, is PTS cleaved during entry
NO
structure of catalase crystals in peroxisomes
-large
-crystalline
-facilitate breakdown of uric acid.
peroxules
Peroxisomes form peroxule extensions to interact with other peroxisomes or organelles
-enhances material exchange and spatial organization within the cell.
dynamics of peroxisomes
dynamic shape changes
elongating, branching, and forming peroxules in response to metabolic demands
