Dictionary > Gerontoplast

Gerontoplast

Definition
noun, plural: gerontoplasts
A plastid that forms from chloroplast during senescence
Supplement
Plastids are organelles involved in the synthesis and storage of food. They are found within the cells of photosynthetic eukaryotes. In plants, plastids may develop into these forms: (1) chloroplasts, (2) chromoplasts, (3) gerontoplasts, and (4) leucoplasts.
Gerontoplasts are plastids that form from chloroplasts during senescence. Chloroplasts are plastids that have high amounts of green pigments (chlorophyll). They have a three membrane systems. These are the outer membrane, the inner membrane, and the thylakoid system. The thylakoid system is the site of the light-dependent reactions of photosynthesis. It is a stack of disks (granum) connected to another granum by stromal thylakoids.
The gerontoplast forms in a formerly green plant tissue that is undergoing senescence. During senescence of a leaf, the gerontoplast develops from chloroplast under genetic control. The gerontoplast is similar to the chromoplast in having a reduced thylakoid system and several plastoglobuli. However, it is unable to divide. The gerontoplast is capable of reverting to a chloroplast, however, for only up to a certain point. Once the cell enters the terminal phase of senescence, it will go through cell death and therefore the development of gerontoplast from chloroplast becomes irreversible.1
See also:

Reference(s):

1 Wise, R. & Hoober, J. (2007). The Structure and function of plastids. Dordrecht: Springer. p.433-ff.


You will also like...

Circulation
Circulation

The circulatory system is key to the transport of vital biomolecules and nutrients throughout the body. Learn about the ..

complete-dominance
Dominance

This tutorial presents Gregor Mendel's law of dominance. Learn more about this form of inheritance and how it can be pre..

Flowers and tiny fruits of the pomegranate plant
Fruits, Flowers, and Seeds

This tutorial deals with the structure and function of flowers, fruits, and seeds. Also included here are the types of f..

Disturbance on a still water
Abiotic Factors – Water Conditions

A still body of water may be disturbed by a variety of factors. One of them is wind. In fact, it is considered as the pr..

Gene Regulation in Eukaryotes
Gene Regulation in Eukaryotes

Learn about the general structure of a eukaryotic gene, the transcription factors, and post-transcriptional regulation....

Electromagnetic spectrum of a brain
Sleep and Dreams – Neurology

While learning and intelligence are associated with the functions of a conscious mind, sleep and dreams are activities o..

Related Articles...

No related articles found

See all Related Topics