The Genetic Code

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  • Created by: Lotto65
  • Created on: 04-02-17 15:33
How many codons would there be if a codon consisted of just two bases?
16
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Why is it not sufficient to have a codon made of two bases?
That makes 16 codons but we need 20 amino acids
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How many codons would there be if a codon consisted of 3 bases?
64
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How do you calculate the number of codons from a sequence of a certain number of bases?
4 (number of possible bases) to the power of how many in the sequence/ codon
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If we have 64 different codons, how come we only have 20 amino acids?
There are 2 or more codons per amino acid
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How many amino acids in human insulin?
51
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What do we mean by 'universality of the genetic code'?
An amino acid sequence produced in humans is the same as the amino acid sequence produced in e.g. bacteria. Each codon means the same amino acid in all organisms
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Give some minor variations of the genetic code in other organisms
In yeasts, CUG means Serine rather than Leucine; In some organisms, the stop codon codes for a non-standard amino acid
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What is the polymerase chain reaction used for?
Copying DNA artificially
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Why would you need to copy DNA?
For gene transfer procedures; For forensic analysis when larger amounts of a small quantity is required
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Which enzyme is used in the polymerase chain reaction?
DNA polymerase
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How much DNA is produced in each cycle?
Double the amount produced in the previous cycle
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Where is DNA copied in the PCR?
In small tubes called Eppendorfs
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How do they speed up PCR?
Do it at high temperatures
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What is taq DNA polymerase?
A special type of heat stable DNA polymerase
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How is taq DNA polymerase obtained?
From a bacterium adapted to living in hot springs
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How many copies of DNA can be produced after a few hours?
Millions (more than 100 million)
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How much DNA is needed at the start of PCR?
Only a small quantity
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What happens at two stages of PCR?
The DNA strands are separated into two single strands and then single strands combine to form double stranded DNA
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Are hydrogen bonds strong or weak?
Weak
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How come hydrogen bonds are not broken at the temperatures in cells?
There are many of them to it holds the strands together
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What does re-annealing mean?
When DNA is cooled and hydrogen bonds reform between two strands so they can pair up again
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At what temperature does the PCR machine separate DNA strands and for how long?
95 degrees celcius for 15 seconds
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What temperature is required to cool the DNA strands in PCR?
54 degrees celcius
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What else is present after re-annealing?
Primers
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What does an excess of primers mean?
The prevention of re-annealing of the parent strand
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Copying of the parent strands starts from...
The primers
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What is used as templates to make double stranded DNA?
Primers
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At what temperature does taq DNA polymerase assemble nucleotides?
72 degrees celcius
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Why 72 degrees celcius at this stage of PCR?
That is tag DNA polymerase' optimum temperature
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How long does one cycle of PCR take?
2 mins
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What do we mean by the genetic code being 'degenerate'?
Multiple codes code for the same amino acid
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What amino acid codes AUG (the start codon)?
Methionine
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Are ribosomes catalysts?
Yes
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True/ false: Mistakes are common in translation
False- they are very rare
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What has been widely used to help diabetes sufferers?
Porcine, bovine and shark insulin
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Why might we want to use human insulin for diabetes sufferers?
Some people are allergic to animal insulin
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How does insulin lower blood glucose concentration?
It binds to insulin receptors
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What was initially used to produce human insulin?
E.Coli bacteria
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What is now used to produce human insulin?
Yeast or safflower plants
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How is another organism used to produce human insulin?
The gene for making human insulin is transferred to the organism where it transcribes and translates that gene sequence
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What in the genetic code makes gene transfer possible?
The universality of the genetic code
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What is the function of gel electrophoresis?
Splits mixtures of DNA, RNA and protein
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What is used to unravel proteins in GE?
Sodium dodecyl sulfate
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Other cards in this set

Card 2

Front

Why is it not sufficient to have a codon made of two bases?

Back

That makes 16 codons but we need 20 amino acids

Card 3

Front

How many codons would there be if a codon consisted of 3 bases?

Back

Preview of the front of card 3

Card 4

Front

How do you calculate the number of codons from a sequence of a certain number of bases?

Back

Preview of the front of card 4

Card 5

Front

If we have 64 different codons, how come we only have 20 amino acids?

Back

Preview of the front of card 5
View more cards

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