Peroxisomes

Question 1

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.

Answer 1

plenty, small, spherical, single

Question 2

peroxisome size range

Answer 2

0.2 to 2.5 micrometers

Question 3

tell me about the genome of peroxisomes

Answer 3

they lack their own genome, all proteins imported from the cytosol

Question 4

Tell me about the mobility of peroxisomes (dynamic or static)

Answer 4

Peroxisomes are dynamic

Question 5

which filament do peroxisomes move on, on which motors?

Answer 5

actin filaments via myosin motors

Question 6

speed of peroxisomes

Answer 6

7 micrometers

Question 7

Name 4 biochemical functions of peroxisomes

Answer 7

fatty acid b oxidation, glyoxylate cycle, detoxification of reactive oxygen species, horone biosynthesis

Question 8

explain the biochemical function of fatty acid b oxidation

Answer 8

Peroxisomes are involved in the breaking down of long-chain fatty acids into acetyl-CoA, which can enter the TCA cycle for ATP production.

Question 9

explain the glyoxylate cycle

Answer 9

In seeds, peroxisomes converting fats into carbs through the glyoxylate cycle, which is essential for seedling growth until photosynthesis begins.

Question 10

Explain the detoxification of reactive oxygen species

Answer 10

Peroxisomes contain catalase, an enzyme that breaks down hydrogen peroxide (H₂O₂) into water and oxygen, protecting the cell from oxidative damage.

Question 11

explain hormone biosynthesis

Answer 11

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.

Question 12

Speaking about protein import mechanisms, Proteins targeted to peroxisomes contain specific [blank]

Answer 12

peroxisomal targeting sequences (PTS), located at the C-terminus

Question 13

asides from PTS, what kind of proteins assist in importing enxymes like catalase, fully synthesized and folded in the cytosol

Answer 13

PEX proteins

Question 14

talking about peroxisome assembly, how do they form? 2 ways, which protein do they require for this

Answer 14

de novo, or from existing peroxisomes, PEX proteins

Question 15

PEX proteins are involved in both [blank] and [blank] import

Answer 15

membrane and matrix

Question 16

[blank] is a specialized protein complex allowing selective entry of peroxisomal matrix proteins.

Answer 16

the importomer

Question 17

In the importormer complex, is PTS cleaved during entry

Answer 17

NO

Question 18

structure of catalase crystals in peroxisomes

Answer 18

-large
-crystalline
-facilitate breakdown of uric acid.

Question 19

peroxules

Answer 19

Peroxisomes form peroxule extensions to interact with other peroxisomes or organelles

-enhances material exchange and spatial organization within the cell.

Question 20

dynamics of peroxisomes

Answer 20

dynamic shape changes
elongating, branching, and forming peroxules in response to metabolic demands