Structure of mitochondria, Biology

STRUCTURE

Mitochondria is a double unit membranous structure. It consists of outer & inner membranes.


2143_mitochondria.png

  • Outer membrane is smooth & made up of lipoproteins. It bears many non stalked particles. These particles are known as subunits of parson. In outer membrane carrier protein is also present. Carrier protein is similar to bacterial porins (proteins), which is present in gram negative bacteria.
  • Outer membrane has more phospholipids (Phosphatidyl choline) and cholesterol as compared to inner membrane.
  • Inner membrane is selectively permeable in comparison to outer membrane. Many types of enzymes are present in inner membrane, which are involved in ATP synthesis (oxidative phosphorylation). Outer surface of inner membrane is called C- face while inner surface called M- face. Inner membrane is folded into a number of finger like cristae. Cristae are tubular finger like but in fungi cristae' are plate like while in Euglena cristae are vesicle shaped. Cristae word coined by Palade. Inner membrane have electron acceptors arranged in a definite sequence and form electron transport system (ETS). Inner membrane is studded with pin head particles called oxysomes or elementary particles or particles or subunits of Fernandez Moran. (104  to 106 in number). Each F particle consists of three parts - Basal plate, Stalk and Head. ATP synthesis occur in head region of oxysome because here ATPase enzyme is present. Synthesis of ATP in head region can be proved by sonication experiment. There is a factor at the base of oxysome that is called F which attach particles to inner mitochondrial membrane. This factor also termed as Oligomycin Sensitivity Conferring Protein (OSCP) Oxysomes composed of ATPase enzymes and concerned with Oxidative phosphorylation (Recker 1967).

596_mitochondria1.png

  • Unit of mitochondria = Oxysomes.
  • Unit of ATP synthesis = Oxysomes
  • Inner membrane have less phospholipids. Phospholipid in inner membrane is mainly diphosphatidyl glycerole.
  • Each membrane has thickness of 60-75 Å Both membrane separated by a outer chamber or perimitochondrial space (80-100Å). This space is rich in coenzymes and enzymes required for oxidation of fats.
  • Inner chamber enclosed by inner membrane which consists of matrix. Mitrochondrial matrix have 70% of total cell enzymes, which are involved in Kreb's cycle. Beside these enzymes matrix have a complete protein synthesis apparatus. Matrix contains mtDNA, RNA and ribosomes.

mtDNA is circular or double stranded. It has :-

1. High G-C content

2. High melting point

3. High renaturation temperature

4. It can replicate itself during any stage of cell division (from G-2 to cytokinesis)

5. 2-6 copies present in each mitochondria.

6. Mitochondrial DNA can code the synthesis of 10 different types of proteins ( Membrane proteins). Rest of the proteins and enzymes of mitochondria are synthesized under the control of nuclear genes.

7. Mitochondrial DNA was discovered by Nash and Margit (1963).

8. Enzymes for replication and transcription of DNA like DNA- polymerase and RNA polymerase.

  • In mitochondria 70s types ribosomes are present, which are known as mitoribosomes. (Mitochondria of mammals have 55s ribosomes)
  • In scurvy disease several mitochondria fuse to form large bodies called chondriosphere.
Posted Date: 10/5/2012 6:59:41 AM | Location : United States







Related Discussions:- Structure of mitochondria, Assignment Help, Ask Question on Structure of mitochondria, Get Answer, Expert's Help, Structure of mitochondria Discussions

Write discussion on Structure of mitochondria
Your posts are moderated
Related Questions
Benthic Zone - Organisation of the Marine Ecosystem The benthic zone is divisible into sub zones horizontally. These are depicted in a cross section portion of the marine habi

Nerve Cell - The Basic Unit The basic unit of the nervous system is the nerve cell or neuron. A neuron is to the nervous system what a brick is to the building. It has a cell

Jaundice (Icterus) Jaundice is classified as pre-hepatic (hemolytic), hepatic and post-hepatic (obstructive) depending on origin of the problem, and is characterized by yellowi

The ph of urine can be quite variable. Why? Why is bromothymol blue used as a ph indicator instead of phenal red when titrating blood?

What are the chemical elements that form most of living biological matter? The elements are:- a)  oxygen (O), b)  carbon (C), c)  hydrogen (H) and d) Nitrogen (N).

Q. Do the phosphate and the pentose groups give heterogeneity or homogeneity to the nucleic acid chains? What about the nitrogen- containing groups? Supported by that, which of tho

Viruses Viruses are sub cellular, ultramicroscopic infectious agents of 20 nm-300 nm size range Many of them cause diseases like polio, dengue, small pox, measles, rabies, com

classification of phylum protozoa upto groups

What are some fungal diseases transmitted by animal feces? Bat and pigeon feces can carry Histoplasma capsulatum, the fungus agent of histoplasmosis. The infection is transmitt

IAA Stimulates Cell Enlargement Cell wall contains layer of cellulose fibrils and are normally quite rigid. Thus for a cell to grow, there must be a mechanism for relaxing th