Genetics

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  • Created by: Sopha8
  • Created on: 20-05-15 14:27
Describe the structure of DNA
2 strands of polynucleotides joined by H bonds between complimentary base pairs make double helix. each nucleotide has phosphate, deoxyribose sugar and a nitrogenous base-either thyamine, adenin, cytosine or guamine
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What is the genetic code?
sequence of base triplets which code for specific amino acids. sequence is non-overlapping and degenerate (20 amino acids, 64 possible triplets)
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What is mRNA and why is it produced?
messenger RNA- polynuceotide strand copied from section of DNA to carry code for making proteins as DNA is too large to move out of the nucleus to ribosomes which assemble proteins
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How does RNA differ for DNA?
1- ribose sugar 2-single polynuceotide strand 3-Uracil instead of thyamine
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What is tRNA?
Transfer RNA- transfers amino acids to ribosomes during translation. Has anticodon at one end which has specific sequence of 3 bases and amino acid binding site at other
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What are the stages of transcription?
1-RNA polymerase breaks H bonds in DNA at start of a gene 2-RNA free nucleotides pair up with complimentary bases on DNA strand 3- RNA polymerase moves down DNA forming mRNA and putting double helix back together 4-RNA polymerase reaches stop signal
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What has to be done to mRNA before it can leave the nucleus?
introns removed by splicing then exons joined up
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What happens during translation?
1- mRNA attaches to ribosome 2-tRNA attches to complimentary codon of mRNA 3-amino acids on tRNA are joined by peptide bonds 4-tRNA move away leaving chain of amino acids 5-keep producing chain untill stop signal on mRNA
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What are transcription factors?
control expression of genes by controlling the rate of transcription. bind to promoters on DNA, they are either activators which help RNA polymerase to bind or repressors which bind to start of gene to prevent RNA polymerase from binding
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What other molecules, other than transcription factors, effect gene expression?
Oestrogen- binds to oestrogen receptor which can either be activator or repressor and siRNA-RNA interference where siRNA binds and protein bind to target mRNA, protein cuts in to sections so can no longer be translated
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Other cards in this set

Card 2

Front

What is the genetic code?

Back

sequence of base triplets which code for specific amino acids. sequence is non-overlapping and degenerate (20 amino acids, 64 possible triplets)

Card 3

Front

What is mRNA and why is it produced?

Back

Preview of the front of card 3

Card 4

Front

How does RNA differ for DNA?

Back

Preview of the front of card 4

Card 5

Front

What is tRNA?

Back

Preview of the front of card 5
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