Biological Molecules OCR AS - Nucleotides, DNA And RNA

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Biological Molecules OCR AS - Nucleotides, DNA And RNA

Quiz On Biological Molecules OCR AS - Nucleotides

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What are the monomers of nucleic acids?
What are nucleotides made up of?
3 covenlently bonded subunits;
- one phosphate group
- one sugar molecule
- one organic nitrogenous base
What are nucleotides joined and split by?
Joined by condensation and split by hydrolysis.
What are the two types of Purine?
Adenine and Guanine
What are the three types of pyrimidine?
Thymine, uracil and cytosine.
Which are larger; purines or pyrimidines?
What is the name of the sugar molecule in the nucleotides of DNA?
How do the nucleic acid strands run in relation to each other in DNA?
What are the complementary base pairs in DNA?
Adenine and Thymine.
Guanine and Cytosine.
What are the main stages of DNA replication during interphase?
- double helix is untwisted.
- hydrogen bonds between the bases are broken to expose the bases.
- 'free' DNA nucleotides are hydrogen bonded onto the exposed bases according to the base pairing rules.
- covelent bond are formed between the phosphate of one group and the sugar of the next to seal the backbone.
- this continues all the way down the molecule until two new DNA molecules are formed.
What is the process of DNA replication also known as?
semi-conservative replication.
What is the sugar molecule found in the nuceotides of RNA?
What nitrogenous bases are found in RNA and how do they pair?
Adenine - Uracil
Cytosine - Guanine
What are the three forms of RNA?
- Messenger
- Ribosomal
- Transfer
What do the sequences of bases on DNA mean?
They code for the sequence of amino acids in the assembally of a protein.
What does RNA play a part in?
Protein synthesis.
What are the main stages of protein synthesis in relation to RNA?
- The sequence for a particular protein (gene) is exposed by the splitting the hydrogen bonds in that region.
- RNA molecules form a complementary strand.
- mRNA peels away from the DNA and leaves through a nuclear pore.
- mRNA attached to a ribosome.
- tRNA bring amino acids to the ribosome in the correct order
- amino acids are joined by peptide bonds.
If a DNA template strand code reads ATTCGCGTTAAT, what will the mRNA strand read?

Why is mRNA less stable than DNA and why is this a neccessary feature of mRNA?
RNA is single-stranded and therefore less stable, as nucleotide bases are exposed and not paired. It also contains Uracil instead of thymine, which may contribute to the lower stability.
Also, as it is involved in protein production, disintegration of mRNA prevents overproduction.
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