Welcome to Zoology World

balindrakumar033@gmail.com   24/05/2018,Thursday


The science or study of animal life. Together with botany, the study of plant life, it forms the science of biology. Zoology is such a vast subject that most zoologists specialize or focus on the study of particular organisms or taxonomic groups. tion of animals.

Semi-autonomous nature of mitochondria

Mitochondria contain all requirements of protein synthesis.

1.70s ribosome.

2.DNA molecules(rich in G-C ratio) to form mRNA and also replicate.

ATP molecules to provide energy.

The mitochondria can form some of the required proteins but for most of proteins,these are depedent upon nuclear DNA and cytoplasmic ribosomes,so the mitochondria are called semi-autonomous organelles.

According to endosymboitic origin of mitochondria were intially a free living.aerobic bacteria which during to the process of evolution entered an anaerobic cell and become established as mitochondria.This theory is supported by many similarities which exist between bacteria and mitochondria.

Chemical composition of Mitochondria

Cohngave the chemical composition of mitochondria:
Protein=65%-70%; Lipids=25-30%(90%phospholipids and 10% cholestrol,Vit.E,etc); RNA=5-7%;Some amount of DNA 2-5%.
The mitochondria matrix has many catabolic enzymes like cytochrome oxidase and reductase, fatty acid oxidase ,transaminase,etc.

Enzymes of Mitochondria:

Outer membrane:

Monoamine oxidase,glycerophosphatase, acyltransferase ,phospholipase A.

outer membrane and innner membrane of mitochondria

Inner membrane:

Cytochrome b,c1,c,a (cyt.b,cyt.c1,cyt.c,cyt.a, cyt.a3) NADH,dehydrogenase, succinate, dehydrogenase,ubiquinone ,flavoprotein,ATPase.

Perimitochondria space:

Adenylate kinase,nucleoside diphosphokinase.

Inner matrix:

Pyruvate dehydrogenase, citrate synthase,aconitase, isocitrate dehydrogenase, fumerase, malate dehydrogenase, dehydrogenase.


Mitochondria are self-duplicating organelles due to presence of DNA molecules so new mitochondria are always formed by growth and division of pre-existing mitochondria by binary fission.

Function of Mitochondria:

1.Mitochondria are called power house or storage batteries or ATP mills formation of ATP is called oxidative phosphorylation.

2.Intermediate products of cell respiration are used in the formation of steroids,cytochromes, chlorophyll etc.

3.These are also seat of some amino acid biosynthesis.

4.Mitochondria also regulates th calcium ion concentration inside the cell.

5.Site of thermiogenesis.

6.Yolk nucleus(a mitochodrial cloud and golgi bodies) controls vitellogenesis.

7.Mitochodria of spermatid form nebenkern(middle piece) of sperm during spermiogenesis

8.Mitochondria release energy during respiration.

9.Mitochodria contain electron transport system.