the sequence of bases in DNA codes for the sequence of amino acids in a polypeptide
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protein synthesis occurs..
on ribosomes in the cytoplasm
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deffine RNA
a single strand of DNA that codes for a polypeptide, has URACIL, pentose sugar
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structure of mRNA
single helix, unstable, complementary to DNA, only exists until the protein is made
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structure of tRNA
small, single strand, twisted, clover, some H-bonds to help stabalise, has an anticodon
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protein synthesis in brief
transcription, RNA processing, translation
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Transcription
DNA strands seperated by DNA helicase, 'sense strand' used as a template for mRNA, RNA nucleotides line up by complementary base pairing
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splicing of pre-mRNA
enzymes remove introns to form mRNA, after this mRNA will leave the nuceus
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deffinition of exons
coding sections of DNA
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deffintion of introns
non-coding sections of DNA
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translation
on ribosomes, begins when two subunits bind ro the start codon on mRNA, specific tRNA anticodon pairs with start codon, tRNA molecules carry an amino acid, these form peptide bonds, process is repeated until the stop codon
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what happens to the polypeptide chain after:
it is free in the cytoplasm, bends and folds when specific H-bonds form
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regulation of transcription
specific transcriptional factors are needed to start transcription, each factor binds to a promotor region, allows attachment of RNA polymerase
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function of inhibitor molecules
blockes any switched off, prevents transcription of these genes
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mutations
the deletion and subsitution of bases, arrise spontaneously during DNA replication, but rate is increased by mutagenic agents
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do all mutations result in a change?
no, as the genetic code is degenerate, not all mutations change the amino acid sequence of the encoded polypeptide
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role of proto-oncogenes
control the rate of cell division, stimulate cell division
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role of tumor suppressor genes
control the rate of cell division, slow cell division
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mutated proto-oncogenes (oncogenes)..
stimulate the cell to divide too quickly
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mutated tumor suppressor genes..
are inactivated, allowing the rate of cell division to increase
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Other cards in this set
Card 2
Front
the sequence of bases in DNA codes for the sequence of amino acids in a polypeptide
Back
deffine a gene
Card 3
Front
on ribosomes in the cytoplasm
Back
Card 4
Front
a single strand of DNA that codes for a polypeptide, has URACIL, pentose sugar
Back
Card 5
Front
single helix, unstable, complementary to DNA, only exists until the protein is made
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