Flow of Genetic Information
Nucleus of root tip cell
1) The nuclear envelope is a dynamic structure with many functions
NE: nuclear envelopes
NP: nuclear pores
2) Nuclear pore complexes function both as molecular sieves
and as active transporters
n Protein & r Protein
RNA
Basic process of transport in Nuclear Pore Complex
1. Permit free diffusion of small molecules through 9 nm diameter channel
2. A larger regulated central channel functions in the active transport of
proteins and RNA molecules
3) The nucleolus, a prominent organelle in the interphase nucleus,
is the ribosome factory of the cell
-Not membrane bounded
-Specialized regions of the nucleous
-A product of active ribosomal genes
->100 different proteins and nucleic acids
-Transcibing rDNA
- Processing rRNA transcript
- assembling rRNA
- import rProteins into ribonucleoprotein
4) During mitosis, the nuclear envelope disassembles into vesicles
that participate in the formation of new envelopes around the daughter nuclei.
1.9 Peroxysome
: called “peroxysome”
because they generate and destroy hydrogen peroxide (H2O2)
The roles of peroxysome
- Participate in lipid mobilization in germinating fat–storing seeds
- Play a key role in photorespiration in leaves of C3 plants
- Invoved in the conversion of recently fixed N2 into nitrogen-rich
organic compounds.
the presence of catalase
(stained by diaminobezimidine)
Unspecialized peroxysome
Contains catalase , glycolate oxidase
urate oxydase, enzyme for oxydation
1) The toxic H2O2 produced by peroxysomal oxidases
is destoryed in situ by catalase
Production of H2O2
RH2 + O2
R + H2O2
Catalatic reaction
2H2O2
O2 + 2H2O
Peroxydatic reaction
R’H2 +H2O2
R’ + 2H2O
2) Leaf peroxysomes participate with chloroplasts and mitochondria
in the glycolate pathway (photorespiration)
C:
P:
M:
2) Glyoxysomes are specialized peroxysomes
that assist in breaking down fatty acid
during the germination of fat storing seeds.
Produce H2O2
4) In some leguminous root nodules, peroxysomes play an essential role in
the conversion of recently fixed N2 into ureides for nitrogen export.
Ureides
Urate oxydase
produce H2O2
New peroxysome arise by
1) division of preexisting peroxysomes
2) import of peroxysomal proteins from cytosol