November 23, 2014

practical Cell biology Lab 5

MitochondriaThe energy required to power living cells comes from the sun. Plants capture

this energy and convert it to organic molecules. Animals can gain this energy by

eating plants or other animals. The most efficient way for cells to harvest energy

stored in food is through cellular respiration, a catabolic pathway for the

production of adenosine triphosphate (ATP).Glucose, derived from food, is broken

down during cellular respiration to provide energy in the form of ATP and heat.

Cellular respiration has three main stages: glycolysis, the citric acid cycle and

electron transport. The Krebs cycle and electron transport occur within

mitochondria, Mitochondria are known as the powerhouses of the cell.

Mitochondria are bounded by a double membrane.Each of these membranes

is a phospholipid bilayer with embedded proteins. The outermost membrane is

smooth while the inner membrane has many folds. That folding increases the

surface area inside the organelle. Many of the chemical reactions happen on the

inner membrane of the mitochondria.

The double membranes divide the mitochondrion into two distinct parts: the

intermembrane space and the mitochondrial matrix. The intermembrane space is

the narrow liquid part between the two membranes while the mitochondrial matrix

is the part enclosed by the innermost membrane. Several of the steps in cellular

respiration occur in the matrix due to its high concentration of enzymes also matrix

contains mitochondrial deoxyribonucleic acid (mtDNA) and mitochondria

reproduce independently of the cell by fission.

 

A

B

November 23, 2014

practical Cell biology Lab 5

In general, the number of mitochondria per cell and the number of

cristae per mitochondrion are related to the energy requirement for the function

carried out by that cell type. So the number of mitochondria in a cell depends on

the cell's function. Cells with particularly heavy energy demands, such as muscle

cells, have more mitochondria than other cells

The mitochondrion in figure A has small number of cristae. In the figure B, the mitochondrion contains many long and closely packed cristae.