Overview of mitochondria and
plastids function in energy
conversion
P t i
Patrice
H
Hamell
Department of Plant Cellular and Molecular Biology
PCMB 694 Winter 2007
Organelle, a little organ (“organitle”)
An organelle is a discrete cellular structure specialized functions. There are
many types of organelles, particularly in the eukaryotic cells of multicellular
organisms An organelle is to the cell what an organ is to the body (hence the
organisms.
name organelle, the suffix -elle being a diminutive).
Organelle, a little organ (“organitle”)
An organelle is a discrete cellular structure specialized functions. There are
many types of organelles, particularly in the eukaryotic cells of multicellular
organisms An organelle is to the cell what an organ is to the body (hence the
organisms.
name organelle, the suffix -elle being a diminutive).
Chlamydomonas reinhardtii cell
Organelle, a little organ (“organitle”)
Although the term "organelle" is considered by some cell biologists to be
synonymous
y
y
with "cell compartment",
p
some cell biologists
g
strictlyy limit the
term's definition to DNA-containing, formerly autonomous organisms
acquired via endosymbiosis (such as mitochondria and plastids and
hydrogenosomes and apicoplasts)
Mitochondria
Plastids
Mitochondria (“threadule”)
Mitochondrion (p
(plural mitochondria)) ((from g
greek μ
μιτοςς or mitos,, thread +
κουδριον or khondrion, granule) is a membrane-enclosed organelle, found in most
eukaryotes. Amitochondriate eukaryotes have a related organelle called
hydrogenosome or mitosome
The primary function of mitochondria is the oxidative phosphorylation. It is the
conversion of chemical energy contain in fuel molecules (via oxidation) into a "highenergy" storage molecule (ATP).
Additional function in amino acid synthesis, co-factor (heme and FeS cluster) etc..
Mitochondria contain its own genetic information (DNA).
(DNA) According to the
endosymbiotic theory, mitochondria are descended from free-living prokaryotes
(alpha-proteobacteria)
Plastids
Plastids are organelles found in photosynthetic eukaryotes (plants and algae). The
primary function of the plastid is photosynthesis. This is the conversion of light energy
into sugar
g molecules.
Some non-photosynthetic plants or algae still retain a plastid and its function is
unclear. A plastid-derived organelle, called the apicoplast is found in Apicomplexans
(parasites) Apicoplast have lost the ability to do photosynthesis.
(parasites).
photosynthesis
Depending on their morphology and function, plastids have the ability to differentiate,
or redifferentiate different forms. In plants, plastids may differentiate into several
forms, depending upon which function they need to play in the cell (for example
Chloroplasts: for photosynthesis, Chromoplasts: for pigment synthesis and storage)
Plastid contain its own genetic information (DNA). According to the endosymbiotic
theory, plastids are remnants from free-living prokaryotes (cyanobacteria)
Overview of oxidative phosphorylation
NADH
FADH2
Overview of oxidative phosphorylation
FAD
FADH2
Overview of photosynthesis
Photosynthesis uses the energy of light to make the sugar, glucose.
A simple general equation for photosynthesis follows.
6 CO2 + 12 H2O + light → C6H12O6 + 6 O2 + 6 H2O
carbon dioxide + water + light energy → glucose + oxygen + water
Overview of photosynthesis
Photosynthesis uses the energy of light to make the sugar, glucose.
A simple general equation for photosynthesis follows.
6 CO2 + 12 H2O + light → C6H12O6 + 6 O2 + 6 H2O
carbon dioxide + water + light energy → glucose + oxygen + water
Photosynthesis occurs in two stages. In the first phase light-dependent reactions
or photosynthetic reactions (also called the Light reactions) capture the energy of
light
g and use it to make high-energy
g
gy molecules.
During the second phase, the light-independent reactions (also called the CalvinBenson Cycle,
Cycle and formerly known as the Dark Reactions) use the high-energy
high energy
molecules to capture carbon dioxide (CO2) and make the precursors of glucose.
ATP
ADP + Pi
Fd
2NADP++ 2H+
4H+
stroma
FNR
2NADPH
PQ
PQ
lumen
4H+
2 H2O
4H+
PSII
+ O2
3 H+
ATP synthase
plastocyanin
PSI
cyt b6f
Mitochondria and plastids are related organelles
involved in the conversion of energy
Mitochondria
Respiration
(ATP)
Chloroplasts
y
Photosynthesis
(sugar)
Mitochondria and chloroplasts are related
organelles
g
involved in the conversion of energy
gy
nucleus
DNA
DNA
Mitochondria
Chloroplasts
p
Mitochondrial inner membrane
Thylakoid membrane
Specialized membranes containing multimeric complexes involved in electron transfer reaction