Where DNA is unzipped and its bases are exposed, then free nucleotides bind to their complimentary bases and hydrogen bonds form, then the phosphodiester bonds form, thus creating the sugar-phosphate backbone
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Why is DNA replication said to be semi-conservative?
Because the new molecule of DNA contains 1 new strand and 1 old strand
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What is the role of the DNA helicase?
It breaks the hydrogen bonds in the unzipping phase
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What is the role of DNA polymerase?
It catalyses the formation of the phosphodiester bonds between the nucleotides after the free nucleotides have bonded with the exposed bases
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What is continuous replication?
Where DNA can be continuously replicated as the strand unzips, this occours in the strand that unzips at the 3' end because DNA polymerase can only bind to the 3' end
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What is the leading strand?
The strand which continuous replication occurs on, due to the way polymerase only binds to one end, so the DNA helicase runs in the opposite direction to the DNA polymerase
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What is discontinuous replication?
Where DNA polymerase runs in the same direction as the unzipping so replication is fragmented due to the DNA polymerase waiting for the next section to be unzipped
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What is the lagging strand?
The strand where discontinuous replication occurs due to DNA polymerase binding on the 3' end (which is the opposite end to the unzipping), so it lags because it needs to wait until the strand has been unzipped
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What are replication errors and what do they lead to?
Where the sequence of bases isnt exactly matched and it can cause mutations, this happens spontaneously and randomly
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What is the genetic code?
The sequence of bases which code for a sequence of amino acids (so that proteins can be made)
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What is a triplet code?
3 bases which code for an amino acid
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What is a codon?
The same as a triplet code, just another name for it
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What is the name given to a section of DNA(with a complete series of codons) which codes for an entire protein?
A gene
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What is the start codon?
It is a codon that signals the start of a sequence, however if it is in the middle of a sequence it is methionine
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What is a stop codon?
There are 3 stop codons which signal the end of a sequence, unlike the start codon, the stop codons never code for an amino acid.
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How many possible codons are there?
4 bases and 3 bases to 1 codon: 4x4x4=64, 64 condons
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Why are there stop and start codons?
So that the code can be read properly
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Why is the genetic code degenerate?
Because there are more codons than amino acids so more than 1 codon codes for an amino acid
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Other cards in this set
Card 2
Front
Why is DNA replication said to be semi-conservative?
Back
Because the new molecule of DNA contains 1 new strand and 1 old strand
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