The Structure And Replication Of DNA 1.2 Flashcards
What are the individual units of DNA called
Nucleotides
What does a nucleotide contain
Phosphate
Deoxyribose sugar
A base (A,T,C or G)
What are the four bases (full names)
Thymine
Adenine
Cytosine
Guanine
What are the bases on each strand held together by
Weak hydrogen bonds
What is the bade pairing rule
The bases are complementary to one another
A-T and C-G
How many carbons is a deoxyribose sugar made up of
5
What carbon is the phosphate connected to
5’ carbon (5 prime carbon)
What are nucleotides held together by
Strong covalent bonds
DNA molecules are made up if two strands lying side by side, running in opposite directions what does that make the strands
Antiparallel
As the strands run in opposite directions what is each strand known as
One is 5’ to 3’ and the other is 3’ to 5’
What is DNA replicated by before cell division
DNA polymerase (enzyme)
Stage one of DNA replication
DNA double helix is unwound and unzipped, hydrogen bonds between bases are broken apart
What is stage two of DNA replication
- DNA polymerase needs primers to start replication. A primer is a short strand of nucleotides which binds to the 3’ end of the template DNA strand allowing polymerase to add DNA nucleotides
- DNA polymerase adds the free DNA nucleotides to the 3’ end of the primer. DNA polymerase works in a 3’ to 5’ direction.
Why is the leading strand continuous and the lagging strand isnt
The lagging strand is replicated in fragments because nucleotides can’t be added to the phosphate (5’) end because DNA polymerase can only add DNA nucleotides in a 3’ to 5’ direction
What is stage three of DNA replication
The fragments are then sealed together by an enzyme called ligase
What are the 5 things required for DNA replication
DNA
Primers
Free nucleotides
DNA polymerase
Ligase
What are the 5 things required for DNA replication
DNA
Primers
Free nucleotides
DNA polymerase
Ligase
What is polymerase chain reaction (PCR)
Polymerase chain reaction is a technique for the amplification of DNA
What does amplification of DNA mean
Increasing the amount of the DNA
What does PCR allow scientists to do easily
Turn a specific sequence of DNA into millions if copies which can then be used for analysis
What must DNA polymerase must with stand
High temperatures
What are the three stages of PCR
Denaturation
Annealing
Elongation/extension
What is denaturation
DNA is heated ti between 92-98 degrees which separates original DNA strands by breaking hydrogen bonds between strands
What is annealing
DNA is then cooled to between 50 - 60 degrees to allow primers to bind to the target sequence
