Structure And Replication Of DNA Flashcards
(21 cards)
What type of acid is DNA?
Nucleic acid
What is the structure of DNA?
Double stranded helix, antiparallel
What is DNA made up of?
Nucleotides joined by a sugar phosphate backbone
What are nucleotides made up of?
Deoxyribose sugar, phosphate and a base
What are the base pairings in nucleotides?
Adenine-thymine
Guanine-cytosine
What bonds are the bases held together by?
Weak hydrogen bonds
Which part of the nucleotide is the 3’ end and 5’ end at?
3’ end- deoxyribose sugar
5’end- phosphate
What does the base sequence of DNA form?
The genetic code(encodes genetic info of heredity in a chemical language)
What is DNA replicated by before the cell divided
DNA polymerase
What does DNA polymerase need to start replicating?
A primer
What is a primer?
A short strand of complementary nucleotides that binds to the 3’ end of the template DNA strand, this allows DNA polymerase to add DNA nucleotides
What 4 things do you need for DNA replication?
Enzymes(Ligase, polymerase)
Primer
ATP
Free DNA nucleotides
Why is DNA replication important?
Ensures each cell receive a full set of chromosomes therefore no genetic information will be lost
What are the stages of DNA replication?
DNA is unwound and hydrogen bonds between bases are broken, forming two template strands
The primer binds to the 3’end of the template DNA strand allowing DNA polymerase to add DNA nucleotides to the 3,end of the new DNA strand forming(strand forms in 5’-3’ direction)
This results in a continuous strand being replicated called the leading strand and the opposite strand being replicated in fragments called the lagging strand
The lagging strand fragments of DNA are joined together by and enzyme called ligase
How does PCR amplify(copy) DNA?
Uses complementary primers for specific target sequences within the DNA
What are the primers in PCR?
They’re short strand of nucleotides which are complementary to specific target sequences at two end of the region of the DNA to be amplified
What happens after each cycle of PCR?
A DNA strand produces two new DNA strands
Example- 1-2-4-8 etc
What are the three stages of PCR?
DNA is heated to between 92°c-98°c to separate the strands
It is then cooled to 50°c-65°c to allow the primers to bind to the target sequences
It is then heated to between 70°c-80°c for heat tolerant DNA polymerase to replicate the region of DNA
What are the three practical uses of PCR?
Helps solve crimes- amplified DNA can be used to create a DNA profile for a person
Settle paternity suits-amplified DNA can be used to determine father of the baby
Diagnose genetic disorders-amplified DNA from patient can be generated to allow it to be screened for a genetic disorder
What does heat tolerant DNA polymerase do?
Ensures enzymes don’t denature at high temperature of PCR
What does gel electrophoresis determine?
Determines criminality or paternity by analysing DNA samples
