5 The photosynthetic grana and stroma thylakoid membranes

5) The photosynthetic grana and stroma thylakoid membranes form a physically continuous three-demensional network

TEM depicting a single granum and associated stroma thylakoids

The spatial relationship between stacked granna and interconnecting stroma thylakoids

PS II PS I and ATP synthase TEM revealing difference in grana and stroma thylakoids

6) Plastids are partially autonomous, encoding and synthesizing some of their own proteins

7) Plastids reproduced by division of existing plastids TEM of dividing etioplast

8) Plastids are inherited maternally in most flowering plants but paternally in gymnosperms

9) Plastids synthesize chlorophylls, cartenoids and fatty acids and reduce some inorganic nutrients

Mitochondria : contain the respiratory machinery that generates ATP

TEM of a mitochondrion in a bean root tip cell

1) Similarity in the basic architecture of all mitochondria reflects the university of their mechanism for generating energy

An unusual phopholipid component of inner mitochondrial membrane

TEM depicting a longitudinal section through a transfer cell mitochondria Arrows indicate ribosomes

2) Small solutes cross the outer and inner mitochondrial membranes sequencially, whereas large proteins destined for matrix cross both membrane simultaneously

3) Mitochondria resemble prokaryotes in numerous important properties. - Mitochondria possess the genetic capacity to make some of their own proteins. - Mitochondrial ribosomes resemble those of prokaryotes. - Mitochondria reproduce by fission.

TEM of a mitochondrion in a bean root tip cell, showing the final phase of division

4) Like plastids, mitochondria are semiautonomous and possess the genetic machinery to make some of their own proteins Distinctive features of plant mitochondria genome 1. large size and complexity (about 10 fold larger than animal ones) 2. Genome: do not contain a set of t. RNA genes (16 t. RNAs specific to 12 -14 amino acids) 3. Contains some chloroplast DNA sequences (t. RNA genes, but not functional)