nucleotides
- Created by: kierasanghera
- Created on: 22-05-16 21:10
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- nucleotides
- DNA
- deoxyribose nucleic acid
- two strands of repeating units called nucleotides
- two strands twisted into a double helix
- controls sequence of amino acids in proteins
- hereditary material responsible for passing genetic material on from cell to cell
- stable, two strands can sperate
- RNA
- ribonucleic acid
- single stranded
- ribosomal RNA
- decodes mRNA into amino acids
- ribosomal RNA
- as uracil base instead of thymine
- messenger RNA
- strand that is complementary to one strand of the DNA molecule
- transfer RNA
- carries amino acids to the ribosomes where they are bonded together into polypeptides
- nucleotides
- made up of: pentose sugar, nitrogenous base and a phosphate group, joined by covalent bonds
- joining nucleotides together
- a condensation reaction occurs between the phosphate group of one and the pentose sugar of another
- purines (larger)
- double rings of carbon and nitrogen atoms
- e.g adenine and guanine
- pyrimidines (smaller)
- single ring of carbon and nitrogen atoms
- e.g thymine, cytosine and uracil
- complementary base pairing
- adenine pairs with thymine
- cytosine pairs with guanine
- a purine in one strand is always opposite a pyrimidine in another
- held in place via hydrogen bonds
- DNA replication
- identical DNA produced
- DNA helicase unzips and unwinds DNA, forming two seperate strands
- free nucleotides complementary base pair to the exposed bases on the DNA strand
- DNA polymerase joins the new nucleotides together by strong covalent bonds, forming the sugar phosphate backbone
- semi conservative as one strand left over is always the original
- Protein synthesis
- trnascription
- DNA unzips as hydrogen bonds break
- one strand acts as a template, free RNA nucleotides complementary base pair to exposed bases on template DNA stand
- RNA polymerase joins nucleotides to form sugar phospahte backbone
- mRNA detatches from template strand
- dna molecules wind back into a helix
- mRNA detatches from template strand
- RNA polymerase joins nucleotides to form sugar phospahte backbone
- translation
- sequence of three bases on mRNA coding for a specific amino acid is called a codon
- process by which mRNA is translated into a protein
- after the mRNA has left the nucleus following transcription it goes into the cytoplasm to which a ribosome attatches
- the genetic code on the mRNA is read in codons
- tRNA molecules have specific anticodons for each of the amino aicds
- complementary tRNA anti codon is attracted to the mRNA codon so weak hydorgen bonds are formed
- this follows on for each codon and a peptide bond is formed between adjacent amino acids that have now been coded for
- a stop codon is then reached
- this follows on for each codon and a peptide bond is formed between adjacent amino acids that have now been coded for
- complementary tRNA anti codon is attracted to the mRNA codon so weak hydorgen bonds are formed
- tRNA molecules have specific anticodons for each of the amino aicds
- the genetic code on the mRNA is read in codons
- trnascription
- DNA
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