The Structure of DNA (2.1.2)

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What are the 2 forms of nucleic acid found in the nucleus?
DNA (deoxyribonucleic acid) and RNA (ribonucleic acid).
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What do the nucleic acids code for?
Building the structure of all living organisms.
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What are DNA & RNA made from?
They are polymers made up from monomer units called nucleotides.
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What is DNA made up of?
2 long chains of nucleotides.
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What is the structure of a single nucleotide?
A phosphate group, a pentose sugar (deoxyribose) and a nitrogenous organic base (A,T, C, G).
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How are nucleotides joined?
By condensation reactions to form polynucleotide chains.
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What does each chain have?
A sugar-phosphate backbone, with the bases projected outwawrds.
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What does it mean that the two chains are anti-parallel?
They run in opposite directions to each other, allowing the bases between the two chains to pair up in the middle.
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What direction do the chains run in?
One runs in the 3' to 5' direction and the other one runs in the 5' to 3' direction. This refers to the numbering of the carbon atoms in the sugar molecule.
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What is complementary base pairing?
The bases that meet in the middle can only pair up in a specific way. Adenine pairs with Thymine- 2 hydrogen bonds between them. Cytosine pairs with guanine- 3 hydrogen bonds between them.
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What shape are the chains in?
They twist into a double helix which is held in place by hydrogen bonds.
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What are the advantages of the double-stranded structure over a single-stranded one?
Very stable structure- important as it carries genetic instructions to make an organism. Enables DNA to be copied perfectly repeatedly so can be passed from cell-cell. Allows easy access to code for when it needs to be read to make a protein.
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Card 2

Front

What do the nucleic acids code for?

Back

Building the structure of all living organisms.

Card 3

Front

What are DNA & RNA made from?

Back

Preview of the front of card 3

Card 4

Front

What is DNA made up of?

Back

Preview of the front of card 4

Card 5

Front

What is the structure of a single nucleotide?

Back

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