Which of the following statements about DNA replication is correct?
Polymerase adds nucleotides to the 3’ end of a DNA strand
During the polymerase chain reaction (PCR) samples of DNA are repeatedly heated and cooled. Why are the samples cooled?
To allow primers to bind to target
sequences
Nucleotide contains: deoxyribose sugar, phosphate group, and nitrogenbase
Backbone composed by: sugar phosphate, nitrogen bases, and hydrogen bonds
The total number of deoxyribose sugars in a fragment of DNA is DOUBLE
A DNA molecule replicates three times during three cell division processes. How many of the 8 resulting DNA molecules will contain the original DNA strands?
2
The number of sugar molecules to bases in a nucleotide is HALF
Name the type of bond which links the primer to backbone
Hydrogen bond
Name the chemical group found at the 5’ end of a DNA strand
Phosphate group
Strand B is replicated continuously while strand A can only be replicated in fragments. Explain why the strands are replicated in different ways.
Nucleotides can only be added to the 3’ end (of a new strand/primer) OR DNA can only be replicated from 5’ to 3’
there are 3 amino acids in a single dna bond
State the function of PCR.
amplification of DNA
what happens in the first stage of PCR?
heated 92-98, denaturesDNA, breakinghydrogen bonds to separate strands
what happens in the second stage of PCR?
DNA cooled to 50-65, allow primers to bind to targetsequences
what happens in the last step of PCR?
heated to 70-80, heat-tolerant DNA polymerase replicates DNA, two strands form
During replication, what bonds between the two DNA strands
are broken.
hydrogen
what are the requirements for DNA replication?
Nucleotides, DNA polymerase, primer, template DNA, and energy.
what is an original DNA template?
double helix made of two complementary strands, each strand used as a template to create new DNA molecules
what is DNA polymerase?
an enzyme that adds new nucleotides to a growing strand of DNA
what is a primer?
short strand of nucleotides that will bind to 3' end of template strand allowing DNA polymerase to add free DNA nucleotides
Explain why DNA replication must take place before a cell
divides.
to maintain DNA chromosome compliment
Give the term used to describe the unit made up of sugar,
phosphate and base.
nucleotide
Name the sugar found in a strand of DNA.
deoxyribose
Describe the directional arrangement of the two strands in
DNA.
Have an antiparallel structure.
With deoxyribose at 3’ end and phosphate at 5’ end of each strand.
During DNA replication, hydrogen bonding is broken. Name the
enzyme which does this.
DNA polymerase.
Name the type of bond which links the base of one nucleotide
to the base of another.
hydrogen
What is the first event in the process of DNA replication?
DNA untwists and strands separate.
Name the 2 enzymes involved in DNA replication and state
their functions.
DNA polymerase – adds nucleotides to 3’ end of primer
DNA ligase – joins fragments of DNA.
State the name of the molecule required to begin DNA
replication.
primer
Herring and human have the same percentage of bases,
yet are very different organisms. Suggest a reason for this.
new cells have identical DNA to the original.
State the end of the strand to which DNA
polymerase adds nucleotides.
3'
Give one practical application of PCR.
Paternity suits / forensics / genetic sequencing.
The diagram shows the contents of a tube used in PCR. Describe the contents of a suitable control tube designed to show that primers are needed in the reaction.
Test tube with DNA, DNA nucleotides, enzyme and buffer (no primers).
State the structural difference between the 3’ and 5’
end of a DNA strand.
The 3’ end of the strand contains deoxyribose (sugar) and the 5’ end contains phosphate.