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Mitochondria and Chloroplast are two important organelles of a cell body.
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Introducing
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CHLOROPLAST & MITOCHONDRIA
A Brief on
Mitochondria and Chloroplast
Mitochondrion
Mitochondria & Chloroplast
Mitochondrion
Definition: The mitochondrion (plural mitochondria) is a membrane-bound organelle found in most eukaryotic cells (the cells that make up plants, animals, fungi, and many other forms of life). Mitochondria range from 0.5 to 1.0 micrometer (μm) in diameter. These structures are sometimes described as "cellular power plants" because they generate most of the cell's supply of adenosine triphosphate (ATP), used as a source of chemical energy.
Mitochondria & Chloroplast
Origin & History
When life first began on our planet, single celled organisms produced energy in a way that was highly inefficient (anaerobic respiration, meaning without oxygen) compared to what most multi-cellular organisms use today (aerobic respiration, using oxygen).
Through evolutionary time, plants came about and were able to produce oxygen in the atmosphere giving rise to aerobic respiration which produced energy in a highly efficient manner.
Mitochondria & Chloroplast
Origin & History
The theory of endosymbiosis suggests that mitochondria were once
free living organisms on their own that used aerobic respiration. Larger anaerobic cells simply engulfed these aerobic mitochondria to use their energy, giving rise to complex cells we find today such as those in our bodies.
The first observations of intracellular structures that probably represent mitochondria were published in the 1840s.
Mitochondria & Chloroplast
Structure
A mitochondrion contains outer and inner membranes composed of phospholipid bilayers and proteins. The two membranes have different properties. Because of this double-membraned organization, there are five distinct parts to a mitochondrion.
Mitochondria & Chloroplast
Structure
Five distinct parts to a mitochondrion are: the outer mitochondrial membrane the intermembrane space (the space between the outer and inner membranes) the inner mitochondrial membrane the cristae space (formed by infoldings of the inner membrane) the matrix (space within the inner membrane)
Mitochondria stripped of their outer membrane are called mitoplasts.
Mitochondria & Chloroplast
Organization and distribution
Mitochondria are found in nearly all eukaryotes.
They vary in number and location according to cell type.
A single mitochondrion is often found in unicellular organisms.
Conversely, numerous mitochondria are found in human liver cells, with about 1000–2000 mitochondria per cell, making up 1/5 of the cell volume.
Mitochondria & Chloroplast
Function
Energy conversion • Pyruvate and the citric acid cycle • NADH and FADH2: the electron transport chain • Heat production
Storage of calcium ions
Additional functions
• Signaling through mitochondrial reactive oxygen species • Regulation of the membrane potential • Calcium signaling • Steroid synthesis.
Mitochondria & Chloroplast
Genome
The human mitochondrial genome is a circular DNA molecule of about 16 kilobases.
It encodes 37 genes: 13 for subunits of respiratory complexes I, III, IV and V, 22 for mitochondrial tRNA (for the 20 standard amino acids, plus an extra gene for leucine and serine), and 2 for rRNA.
One mitochondrion can contain two to ten copies of its DNA.
Mitochondria & Chloroplast
Replication and Inheritance
Mitochondria divide by binary fission, similar to bacterial cell division
Mitochondria must be duplicated during cell cycle and segregated to the daughter cell
Replication of mtDna maybe stochastic
Mitochondria & Chloroplast
Replication and Inheritance
Energy high-mitochondria grow and divide
Energy low-mitochondria destroyed and inactive
Most cases inherited only from mother which is known as maternal inheritance
Paternal inheritance may happen in some coniferous plants, some species and some insects.
Mitochondria & Chloroplast
When is replication not normal?
Mitochondrial Disease
Result from failures of the mitochondria
Less energy is generated within the cell. Cell injury and even cell death follow.
Genocopies of Mitochondrial Disease &Phenocopies of Mitochondrial Disease
Mitochondria & Chloroplast
Mitochondrial Disease
Primarily affects children but adult onset is becoming more common.
Damage to cells of the brain, heart, liver, skeletal muscles, kidney and the endocrine and respiratory systems.
Mitochondria & Chloroplast
Treatment
To alleviate symptoms and slow down the progression of the disease
Treatment may be beneficial and noted immediately in some disorders.
Sometimes, the benefits of treatment may take a few months to notice.
Mitochondria & Chloroplast
Therapy
Dietary Therapy Supportive Therapies Avoidance of Toxins Vitamins and Supplements That May Be Helpful Medication, Minerals, Vitamins and Substrates
That May Be Helpful Avoidance of Physiologic "Stress"
Mitochondria & Chloroplast
Possible Relationship to Aging
A number of changes can occur to mitochondria during the aging process
Tissues from elderly patients show a decrease in enzymatic activity of the proteins of the respiratory chain.
Mutated mtDNA can only be found in about 0.2% of very old cells.
Mitochondria & Chloroplast
Possible Relationship to Aging
Large deletions have been hypothesized to lead high levels of oxidative stress and neuronal death in Parkinson's disease.
Mitochondrial changes are causes of aging or merely characteristics of aging.
Mitochondria & Chloroplast
Chloroplast
Mitochondria & Chloroplast
Chloroplast
Chloroplasts are organelles found in plant cells and eukaryotic algae that conduct photosynthesis.
Cyanobacteria are considered the ancestors of chloroplasts.
Mitochondria & Chloroplast
Primary endosymbiosis
A eukaryote with mitochondria engulfed acyanobacterium in an event of serial primary endosymbiosis, creating a lineage of cells with both organelles. The cyanobacterial endosymbiont already had a double membrane— thephagosomal vacuole-derived membrane was lost.
Mitochondria & Chloroplast
Many other organisms obtained chloroplasts from the primary chloroplast lineages through secondary endosymbiosis.
Mitochondria & Chloroplast
Chromatophores
Being in the early stages of endosymbiosis, Paulinella chromatophora can offer some insights into how chloroplasts evolved.
Secondary and tertiary endosymbiosis
In some groups of mixotrophic protists, chloroplasts are separated from a captured alga or diatom and used temporarily. These klepto chloroplasts may only have a lifetime of a few days and are then replaced.
Mitochondria & Chloroplast
Chloroplast DNA
Chloroplasts have their own DNA. Its also known as the Plastome. Its existence was 1st proved in 1962.
Kleptoplastidy
Most chloroplasts have their entire chloroplast genome combined into a single large ring.
Inverted repeats: Chloroplast DNA contain 2 inverted repeats. 1. Long single copy section (LSC) 2. Short single copy section (SSC) Many nucleoids can be found in each chloroplast.
Mitochondria & Chloroplast
Protein synthesis
Protein synthesis within chloroplasts relies on two RNA polymerases.
Molecular structure
The movement of so many chloroplast genes to the nucleus means that lots of chloroplast proteins that were supposed to be translated in the chloroplast are now synthesized in the cytoplasm.
In most, but not all cases, nuclear-encoded chloroplast proteins are translated with a cleavable transit peptide that's added to the N-terminus of the protein precursor.
Mitochondria & Chloroplast
Protein targeting & import
Outer chloroplast membrane Inter-membrane space Inner chloroplast membrane Stroma Pyrenoids Thylakoid system
Mitochondria & Chloroplast
Structure
Lipid composition Phospholipids(48%) Galactolipid(46%) Sulfolipid(6%)
Semi-porous membrane Sometimes forms Stromule
Mitochondria & Chloroplast
Outer chloroplast membrane
Inter-membrane space
10-20 nanometers thick Exists between outer & inner wall
Lipid composition • Phospholipids(16%) • Galactolipids(79%) • Sulfolipids(5%)
Regulates passage of materials Fatty acids, lipids, carotenoids are synthesized
Mitochondria & Chloroplast
Inner chloroplast membrane
Colorless fluid surrounding grana Protein rich Location of chloroplast DNA & ribosomes Calvin cycle takes place
Mitochondria & Chloroplast
Stroma
Membrane bound compartment Site of light-dependent reactions Forms stack of disks(Grana) Grana are connected by inter-grana thylakoids
Mitochondria & Chloroplast
Thylakoid system
Chloroplasts use Rubisco Trouble distinguishing oxygen & carbon dioxide C4 plants evolved a solution Separating light reactions & Calvin cycle
Mitochondria & Chloroplast
Specialized chloroplast in c4 plants
Distribution in plants Cellular location
Mitochondria & Chloroplast
Location
Distribution in a plant All green parts contain chloroplast Usually parenchyma cells Can be found in collenchyma tissue Known as Chlorenchyma cell Concentrated in leaves
Can change orientation Low light condition
• Spread out in a sheet Intense light
• Aligns in vertical columns Reduces exposure Protects from photo-oxidative damage
Mitochondria & Chloroplast
Cellular location
Plant innate immunity Hypersensitive response Systemic Acquired Resistance
Photosynthesis:
Light reactions Photophosphorylation Dark reactions
pH level
Mitochondria & Chloroplast
Function and chemistry
Plastid interconversion
Chloroplast division
Chloroplast Inheritance
Mitochondria & Chloroplast
Differentiation, replication and inheritance
Mitochondria & Chloroplast
References
http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/C/Chloroplasts.html http://ccdb.ucsd.edu/sand/main?stype=lite&keyword=chloroplast&Submit=Go&e
vent=display&start=1 http://www.mitodb.com/ http://www.uni-mainz.de/FB/Medizin/Anatomie/workshop/EM/EMMitoE.html http://www.cytochemistry.net/Cell-biology/mitoch1.htm