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21 Cards in this Set
- Front
- Back
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7 functions of proteins
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1. Support e.g. structural proteins give 3D network
2. Movement e.g. contractile proteins in muscles 3. Transport e.g. transport proteins 4. Buffering e.g. buffering action of proteins 5. Metabolic regulation e.g enzymes 6. Coordination and control e.g. protein hormones 7. Defense e.g. antibodies and clotting proteins |
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How many bases in each cell?
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3 billion
- 3% divided into genes (24,000) |
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All cells have the same DNA
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- different cells transcribe different sets of genes
- same genome, different transcriptome |
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Transcriptional profiling by micro-array analysis
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- Measurement of the expression of thousands of genes at once, to show entire cellular function
- This can be used in disease pathogenesis, cancer and to measure a patients response to therapy |
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Genome definition
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The genetic material of an organism, including the coding and non-coding sequences of RNA and DNA
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Transcriptome definition
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The set of RNA molecules, including non-coding RNA produced in a cell
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Proteome definition
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The entire set of proteins expressed by a genome, cell, tissue etc
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The genetic code
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- Proteins are encoded by mRNA
- The code in read as codons with 3 base pairs - There are 20 amino acids (some degeneracy in the code) |
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Reading frames in transcription
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- Transcription starts with methionine
- The open reading frame codes the protein (deletions/mutations) |
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Amino acid codes and families
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1. Small amino acids
2. Hydrophobic amino acids 3. Aromatic amino acids 4. Nucleophilic amino acids 5. Amide amino acids 6. Basic amino acids 7. Acidic amino acids |
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More than 1 protein per gene
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1. Glycosolation - interaction with other proteins, half-life, orientation
2. Phosphorylation - receptor signalling, intracellular communication, control of enzyme function 3. Numerous forms of post-translational processing |
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Protein activation by proteolysis
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- Proproteins can be cleaved by a protease to be activated
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How are proteins assembled?
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3 RNA species are needed:
1. Ribosomal RNA 2. Transfer RNA 3. Messenger RNA |
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DNA controls protein synthesis, cell structure and cell function
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- RNA polymerase must bind to the gene
- After transcription, a strand of mRNA carries instructions from the nucleus to the cytoplasm - Translation by complementary base pairing of anticodons to mRNA codons. tRNA molecules bring amino acids to the ribosomal complex - The DNA of the nucleus has both direct and indirect control over protein synthesis |
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Define transcription
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The production of RNA from a DNA template
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Define translation
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Production of a functional polypeptide using the information contained in the sequence of codons along an mRNA strand
- The sequence of codons determines the sequence of amino acids in the polpeptide |
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Role of RNA polymerase
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Promotes hydrogen bonding between the nitrogenous bases of the template strand and the complementary nucleotides in the nucleoplasm.
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Role of the ERs
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Smooth ER: lipid synthesis and metabolism
Rough ER: protein secretion |
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Where are soluble intracellular proteins synthesised?
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Free ribosomes
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How do newly made proteins know where to go?
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1. Signal peptides are used for entry into the ER
2. Nuclear translocation signals |
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Folding of proteins
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1. Amino acid sequence is primary structure
2. Amino acids then fold into secondary structures of alpha-helices and beta-sheets 3. Tertiary structure is the proper folding of a protein into its final shape 4. Quaternary structure is the coming together of subunits to form the overall functional protein |
