Peroxisomes Flashcards

1
Q

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.

A

plenty, small, spherical, single

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2
Q

peroxisome size range

A

0.2 to 2.5 micrometers

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3
Q

tell me about the genome of peroxisomes

A

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

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4
Q

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

A

Peroxisomes are dynamic

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5
Q

which filament do peroxisomes move on, on which motors?

A

actin filaments via myosin motors

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6
Q

speed of peroxisomes

A

7 micrometers

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7
Q

Name 4 biochemical functions of peroxisomes

A

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

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8
Q

explain the biochemical function of fatty acid b oxidation

A

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

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9
Q

explain the glyoxylate cycle

A

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

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10
Q

Explain the detoxification of reactive oxygen species

A

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

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11
Q

explain hormone biosynthesis

A

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.

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12
Q

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

A

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

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13
Q

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

A

PEX proteins

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14
Q

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

A

de novo, or from existing peroxisomes, PEX proteins

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15
Q

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

A

membrane and matrix

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16
Q

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

A

the importomer

17
Q

In the importormer complex, is PTS cleaved during entry

18
Q

structure of catalase crystals in peroxisomes

A

-large
-crystalline
-facilitate breakdown of uric acid.

19
Q

peroxules

A

Peroxisomes form peroxule extensions to interact with other peroxisomes or organelles

-enhances material exchange and spatial organization within the cell.

20
Q

dynamics of peroxisomes

A

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