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10 Cards in this Set
- Front
- Back
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Explain why a strand of mRNA is shorter than a strand of DNA |
Introns present in DNA |
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2 differences between mRNA and tRNA |
complementary base pairing in tRNA/tRNA is clover shaped tRNA is shorter/fewer nucleotides tRNA has amino acid binding site mRNA different for each gene, only 64 diff tRNA |
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Describe the role of tRNA in the process of translation |
tRNA molecule carries a specific amino acid anticodon of tRNA pairs with a complementary codon on mRNA molecule tRNA attaches to ribosome/holds amino acid in place allows correct sequence of amino acid to form - sequence is determined by bases in mRNA |
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How do different sequences of bases code for different proteins? |
Protein made of chain of amino acids Each amino acide has its own triplet code |
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Starting with mRNA in the nucleus of a cell, describe how a molecule of protein is synthesised. (6) |
1. mRNA leaves nucleus through nuclear pore 2. moves to ribosome 3. tRNA molecules bring amino acids to ribosome 4. Specific tRNA molecule carries specific amino acid 5. Anticodon of tRNA complementary to codon on mRNA 6. Peptide bond forms between amino acids 7. tRNA detaches and collects another amino acid 8. Ribosome moves to next codon until stop codon |
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What is the role of RNA polymerase in transcription? |
join nucleotides together to form a strand |
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Explain why medical screening of cancer causing genes is recommended |
Identify high risk individulas Early diagnosis/avoid risk factors Identify risk in families |
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Describe what is meant by a mutation, and explain how a mutation in a supressor gene leads to a malignant tumour |
Mutation is change in the base sequence of DNA Suppressor gene codes for a protein that inhibits cell division Mutation in gene leads to different base sequence/code diff amino acid sequence non-functional protein Cell divide by mitosis Cell undergoes uncontrolled division Tumour spreads via lymph |
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Explain why cancer is more likely to be treated successfully if the disease is detected early |
Cancer less likely to have spread smaller tumour/smaller growth less cell damage |
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Explain how examining mRNA may show if cancer is present. |
Change in codon sequence of mRNA indicates change in base sequence of DNA oncogene active or tumour suppressor gene inactive |
