Nucleotides

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Application booklet
Structure of DNA ­ Reference pages 3-5 knowledge booklet
ACTIVITY 1
Read the information on page 3 about the structure of DNA in silence and
highlight all the key scientific words. Pick out the relevant keyword cards from
your envelope.

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Page 2

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Working in pairs & using the DNA modelling kit
a) synthesise a double stranded DNA molecule
b) hydrolyse a double stranded DNA molecule
Use your knowledge of condensation and hydrolysis to show how water is
involved in these reactions.
Place your DNA molecule onto a mini white board and together label the
following parts. Make sure you use precise names.…read more

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PURINE PHOSPHATE DNA MOLECULE NUCLEOTIDE PYRIMIDINE
Smallest Largest
PHOSPHATE ­ PYRIMIDINE ­ PURINE ­ NUCLEOTIDE ­ GENE - DNA
MOLECULE
Q3. What is meant by the term complementary base pairing?
......Adenine always pairs with Thymine & vice versa
Cytosine always pairs with guanine & vice versa .................................
Q4. If the bases on one strand of DNA are TGGAAGACT, what is the base
sequence on the other strand?
.........ACCTTCTGA ..........................................................................
...................................................................................................
...............
Q5. Adenine and cytosine never pair up, and guanine and cytosine never
pair up.…read more

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Ignore phosphorus, Ignore molecule
3
(iii)
Name of base Percentage
Thymine 34
Cytosine / Guanine 16
Adenine 34
Cytosine / Guanine 16
Spelling must be correct to gain MP1
First mark = names correct
Second mark = % correct, with adenine as 34%
M3. (a) nucleotide
1
(b) (i) 21.4, 21.4 28.6
2
(ii) amounts of A and T /C and G/complementary bases different
therefore no basepairing
2 max
[5]
M4. (a) Phosphate
Deoxyribose
Q Candidates must specify deoxyribose. This term
is a specification requirement.…read more

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If (c)(i) incorrect accept [50 ­ (c)(i)]
1
(d) Different proteins
Different genes
Different (DNA) base sequences
2 max
[7]
M5 . (i) A = 31 and JT = 31
C = 19
2
(ii) viral DNA singlestranded / not doublestranded
evidence from table e.g.…read more

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DNA Polymerase ............ - forms a
polynucleotide strand;
the two new DNA molecules are identical to each other and to the original
DNA;
each newly formed DNA molecule contains one of the original
polynucleotide strands, hence the term
semi........-conservative ............... replication.
ACTIVITY 9
Q1. . If the bases on a portion of the original strand of DNA are ATGCTACG, what would the
equivalent sequence of bases be on the newly formed strand? TACGATGC
Q2. Why is the process of DNA replication described as semiconservative?
...…read more

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The DNA in the
bacteria of generation 1 was extracted and spun in a high-speed centrifuge.
The bacteria in the 14
N medium were allowed to divide one more time. The DNA
was also extracted from these bacteria (generation 2) and spun in a high speed
centrifuge. The diagram shows the results of this investigation.
(i) Which part of the DNA molecule contains nitrogen?..t
he organic bases (A,T,G.C)
(ii) Explain why the DNA from generation 1 is found in the position shown.
....…read more

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DNA one new strand and one original/parent strand
(b) (i)15
N/ tube B
(DNA), more/greater density
1
(reject heavier)
(ii)DNA with one heavy and one light strand 2
new/synthesised strand, made with 14N/ light strand
Total 5
marks
Genetic Code ­ Reference pages 7-8 Knowledge booklet
ACTIVITY 10
In the exam you will be expected to interpret the genetic code within a section of
DNA and identify the correct amino acids in the correct sequence.…read more

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Met__ __Pro__ __Asn__ __Tyr__ __Pro___ __Arg__ __Pro___ __Asn__
__Asp_
Step 3 Double check that you have the correct number of amino acids to triplets.
Typical questions
How many different amino acids does the gene code for?
Be careful with this one, remember that the code is degenerate and more than
one codon/triplet codes for the same amino acid.…read more

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