2.3.2- How DNA Replicates Flashcards
Explain what helicase is.
The enzyme that catalyses the breaking of Hydrogen Bonds between the nitrogenous party’s of bases in the DNA molecule- The unzipping.
Explain what semi conservative replication is.
How DNA Replicates. Results in two new molecules, each with one old strand and one new strand. One old strand is conserved in each molecule.
What is the function of the guesses enzyme?
It catalyses the unwinding of the double helix during DNA replication
Where are free phosphorylated nucleotides going in a cell?
Within the nucleus, in the nucleoplasm.
During DNA replication, free phosphorylated nucleotides are bonded to exposed base pairs following what rules?
Complementary base pairing rules.
In what direction are new nucleotide bases added to a DNA template strand?
The 5’ to the 3’ direction.
Explain how the sugar phosphate back bone can form between the synthesised strand during DNA replication.
The activate nucleotides a re hydrolysed, releasing extra phosphate groups, supplying the energy to make phosphodiester bonds between the sugar residue of one nucleotide and the phosphate group of the next one.
Explain the process of semi conservative DNA replication, including the enzymes involved at each stage of this.
- double helix unwinds but at a time, catalysed by GYRASE enzyme.
- hydrogen bonds are broken between two strands- molecule unzipped. Catalyses by DNA HELICASE ENZYME
- free nucleotides in the nucleoplasm are bonded to exposed bases in the 5’ to 3’ direction- catalysed by DNA POLYMERASE and using the unzipped DNA as a template
- lagging strand is synthesised in fragments and are joined later, catalysed by LIGASE.
- activated nucleotides are hydrolysed to release extra phosphate groups- supplying the energy to make phosphodiester bonds between sugar of one nucleotide and the phosphate of the next one
What is the produce of DNA replication?
Two genetically identical DNA molecules, identical to each other and the parent molecule.
Explain briefly how the small DNA loops in prokaryotes and inside mitochondria and chloroplasts semi conservatively replicate.
A bubble sprouts from the loop which then unwinds and unzips, then joins to exposed nucleotides, following complementary base rules. The whole loop’s eventually copied.
How may a mitigation occur during DNA replication?
The wrong nucleotide may be inserted, which would change the genetic code- is a point mutation.
How is the rate of mutations that are produced during DNA replication reduced?
There are enzymes that proofread and edit out incorrect nucleotides during the replication process.
Define what DNA polymerase is.
An enzyme that catalysed the formation of DNA from activated deoxyribose nucleotides, using single stranded DNA as a template.
