DNA replication Flashcards
(6 cards)
dna replication
Before a cell divides each DNA, it is needed for the molecule to replicate, this happens during the S part of interphase.
The DNA helix unwinds due the enzyme helicase
This leads to exposed nucleotides that are to bind
Free roaming nucelotides within the nuceloplasm of the nucleus, and binds to the exposed nucelotides through the bases forming H bonds w its complementary base.
This is then catalysed by the enzyme polymerase.
Covalent bonds form between the sugar of one nucelotide and phosphate group adjacent to the sugar- creating a backbone , this is catalysed by the enzyme ligase.
Why is it called semi conservative replication?
Because each DNA strand are identical to each other but carry one old strand and a new strand.
Dna structure
Double polynucleotide strand , containing bases that are binded together through hydrogen bonds, each base only bonds with its complementary base
This is called complementary base pairing
T,A,C,G = bases
polynucleotide chains run opposite each other , these are called anti parallel, and they form a double helix.
The H bonds causes the strands to become very strong and stable but also allows the strands to unzip/unwind so it can be replicated or transcribed.
DNA + RNA differences
DNA is a double stranded polynucleotide, contain thymine, only contains T,A,C,G
locations: mitochondria, nucelus, chloroplast
RNA is a single stranded polynucleotide, only contains U,A,C,G doesnt contain thymine
Types of RNA- MRNA , TRNA ( Involved in translation only)
Locations: Nucleus, Cyptoplasm
How is DNA found in prokaryotic cells and eukaryotic cells.
Prokaryotes- Held in plasmids
Eukaryotes-Organised into chromosomes, that contain histone proteins = associated w DNA
Nucleic acids.
DNA + RNA = polymers
Monomers of DNA+ RNA are called nucleotides.
Nucelotides contain a pentose sugar, nitrogenous base + phosphate group
Condensation reaction occurs between the hydroxyl group OH and phosphate groups HO, expelling water
Polymers- large molecules that are made from small repeating units called monomers
Many nucleotides bonds together to create a polynucleotide.
Phosphate group from one nucleotide forms a covalent bond w the hydroxl group attached to carbon 3 of the next nucleotide- this is called a phosphodiester bond.
Nitrogenous bases don’t take part in polymerisation + extends out from polynucleotide structures
Pyramidines- T, U, C
- complex ring structure
purines - A,G
- simple ring structure structure
