Nucleic Acids
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?- Created by: Buffya
- Created on: 28-05-13 16:51
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- Nucleic acids
- DNA
- Contains the sugar dexoyribose
- DNA is a stable polynucleotide molecule. It acts as an information store because the bases projecting from the backbone act as a coded sequence
- Two polynucleotide strands run parallel to each other with hydrogen bonds between the bases
- The strands run in opposite directions - antiparallel and twist - double helix
- A is complementary to T, C is to G
- Copying in interphase
- Double helix untwisted
- Hydrogen bonds broken exposing bases
- Free DNA nucleotides hydrogen bond with exposed bases
- Covalent bonds seal the sugar-phosphate backbone
- Semi-conservative replication catalysed by DNA polymerase
- Covalent bonds seal the sugar-phosphate backbone
- Free DNA nucleotides hydrogen bond with exposed bases
- Hydrogen bonds broken exposing bases
- Double helix untwisted
- A gene is a length of DNA that codes for one polypeptide - occupies a locus on chromosomes
- RNA
- Contains the sugar ribose
- Contains uracil instead of thymine. Base pairing of A-U, C-G
- There are three forms
- ribosomal RNA (rRNA)
- Shown as a two-lobed structure
- transfer RNA (tRNA)
- Is around 80 nucleotides long which folds up and is stabilised by hydrogen bonds
- messenger RNA (mRNA)
- A single strand complementary to the DNA template strand
- ribosomal RNA (rRNA)
- A gene can be exposed by splitting hydrogen bonds in that region
- RNA nucleotides form a complementary strand (mRNA)
- mRNA leaves through nuclear pore and attaches to a ribosome
- tRNA brings amino acids in order according to base sequence on mRNA
- mRNA leaves through nuclear pore and attaches to a ribosome
- RNA nucleotides form a complementary strand (mRNA)
- Nucleotides
- Made of one phosphate group, one sugar molecule and one organic nitrogenous base
- Five possible bases
- Pyrimidines
- Thymine
- Uracil
- Cytosine
- Purines
- Adenine
- Guanine
- Excess purines form uric acid which can cause gout
- Pyrimidines
- A condensation reaction between the phosphate of one and the sugar of another joins them
- DNA
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