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10 Cards in this Set
- Front
- Back
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Basic flow of info in all cells?
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-DNA (replication)
-DNA to RNA (transcription) -RNA to protein (translation) |
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Main functions of three main classes of DNA
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-mRNA (messenger RNA) template for protein synthesis
-tRNA (transfer RNA) transports AA to ribosomes during protein synthesis -rRNA (ribosomal RNA) component of ribosomes with enzymatic activity |
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Key events in the three phases of transcription
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Initiation- transcription factors bind DNA to promoter that is rich in A/T, RNA polymerase engages DNA, short stretch is unzipped and RNA synthesis begins
Elongation- RNA polymerase catalyzes linkage of nucleotides creating RNA complimentary of DNA (5' to 3') Termination: Dissociation of newly synthesized DNA from RNA polymerase |
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Significance of high proportion of A-T base pairs in both the origin of replication and the start sites of transcription
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A-T base pairs have two hydrogen bonds which C-G have three. It will be easier to break the A-T bond as opposed to the C-G
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What is the genetic code?
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Made up of 3 nucleotide bases (A, T, C, G) called a codon. Three nucleotides in the RNA encode for one AA.
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Start and stop codons
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UAA, UGA and UAG are stops. AUG is start
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What happens in each of the APE sites in the ribosome
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A- aminoacyl site: successive AA bearing TNAs will bind
P- peptide site: where peptide bonds form E- exit site: where empty tRNAS will exit the ribosome |
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Key events in phases of translation
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Initiation- small ribosomal subunit associates with large ribosomal subunit due to charged tRNA-Met and mRNA; this is occupying the P site of the ribosome complex
Elongation- amino acids are added one by one to the preceding amino acid Termination- a release factor binds directly to the stop codon, causing the addition of a water molecule instead an amino acid, breaking the chain. |
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How might a change in gene DNA sequence cause a change in protein sequence
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Alteration of a single AA in a crucial area of protein will significantly alter protein activity
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How is it possible that a change in gene (DNA sequence) might not change protein sequence
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Base-Pair subsition mutations occur when there is a replacement of a nucleotide and its partnered with a different pair of nucleotides.
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