| What must take place prior to cell division? | DNA must be replicated exactly by DNA polymerase to ensure each daughter cell receives all the needed genetic information to carry out its activities and functions. |
| Describe the DNA replication process in vivo (living cells) | DNA is unwound and hydrogen bonds between bases are broken to form two template strands
The enzyme DNA polymerase needs primers to start replication.
Primer allows DNA polymerase to add DNA nucleotides using complementary base pairing to the 3' deoxyribose end of the primer
DNA polymerase can only add nucleotides in one direction (3' - 5') resulting in the leading strand being replicated continuously and the lagging strand being replicated in fragments.
The fragments of DNA on the lagging strand are joined together by the enzyme ligase |
| what is a primer | a short strand of nucleotides which binds to the 3' end of the template DNA strand |
| What is PCR | Polymerase Chain Reaction
An automated process that amplifies DNA using complementary primers for specific target sequences |
| what are practical applications of PCR | It can amplify DNA to help solve crimes, settle paternity suits and diagnose genetic disorders |
| What is a primer in PCR | short strands of nucleotides which are complementary to specific target sequences at the two ends of the region of the DNA to be amplified |
| What happens (vaguely)during the PCR process | there are repeated cycles of heating and cooling to amplify the DNA
each cycle doubles the number of DNA molecules that are present |
| describe in detail each stage of the PCR process | double stranded DNA is heated to between 92-98 degrees celcius to separate the DNA strands (completely)
DNA is then cooled to between 50 and 65 degrees celcius to allow primers to bind to target sequences
It is then heated to between 70 and 80 degrees celcius for head tolerant DNA polymerase to replicate the region of DNA |
