DNA REPLICATION:: PART 4

ENZYMES REQUIRED IN DNA REPLICATION

-         Topoisomerase: - This unwinds the DNA and releases the super
                                    coiled structure of the double helix.

                                                

-         Helicase: - It breaks the hydrogen bonds between the two
                          strands of the DNA.

                                                   

DNA REPLICATION :: PART 3

-         First generation of E.coli.

o   The DNA from E.coli was extracted.

o   The isolated DNA had equal amounts of N15 and N14 in their DNA.

-         Second generation of E.coli. 

o   DNA from E.coli was extracted.

o   It had two DNA strands containing only N14 and two hybrid DNA strands containing N14 and N15.

DNA REPLICATION :: PART 2

SEMI-CONSERVATIVE MODE OF DNA REPLICATION

-         This is called semi conservative because the new strand of DNA contains one parental strand and one newly synthesized strand.

-         EXPERIMENT

o   N15 is a heavy isotope of nitrogen.

o   E.coli was grown in a nutrient medium that contained N15 instead of N14.

o   Hence N15 got incorporated into the purines and pyrimidines bases of the DNA.

                         

o   After this E.coli were removed from N15 medium and kept in N14 medium.

DNA REPLICATION:: PART 1

INTRODUCTION

-          This a cellular mechanism that involves the multiplication of a DNA fragments into two.

-          This process of multiplication of DNA into two is called DNA replication.

-          DNA replication involves a large number of enzymes.

-          DNA replication is called semi-conservative.

                                                          

-          This process of replication is important to pass on the genetic material to its future generations.

STEM CELLS:: PART 4

-         Adult stem cells

o   These are found in developed organism.

o   These have twin properties of self renewal and differentiation.

o   These orient from the bone marrow.

o   These are Multipotent and help in regeneration of some organs like skin.

STEM CELLS::PART 3

Types based on origin: -

-         Embryonic stem cells

o   These are derived from the inner mass of the blastocyst.

o   Blastocyst is that stage of an embryo when it is 4-8 cells old.

                                 

o   These are Pluripotent and can differentiate into almost 2000 types of cells.

o   These are used in regenerative medicine and artificial organs.

STEM CELLS:: PART 2

Types based on ability to differentiate: -

-         Totipotent: - These stem cells can differentiate into all
                            cell types.

                                       

-         Pluripotent: - These stem cells can differentiate into
                             many cells but not all cells.

-         Multipotent: - These stem cells can differentiate into
                               some cells but not many.

-         Unipotent: - These stem cells can differentiate into only
                             one type of cell.

STEM CELLS:: PART 1

INTRODUCTION

-         Stem cells are undifferentiated cells of a multicellular
       organism.

                                      

-         These cells can differentiate into many types of cells.

-         These cells also have the ability of self renewal.

BIOCHEMICAL TECHNIQUES::PART 9

LAMBERT-BEER LAW

                                                  
       When a monochromatic light of intensity I0 passes through a medium there is a change in its intensity depending upon the concentration ‘C’ of the medium and the path length ‘L’ of the sample.

                                 

                                          

BIOCHEMICAL TECHNIQUES:: PART 8

WORKING

-         This technique uses a medium called Agarose gel.

-         The DNA fragments are digested with the help of restriction enzymes and placed in the wells made in the gel setup.

-         An electric field is applied across the gel.

-         Since the DNA molecule is negatively charged it moves towards the positive electrode.

                             

-         The smallest strand of DNA covers the maximum distance in a given period of time than the larger strands.

-         The DNA strands can be stained with Ethidium bromide and visualized.