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Getting from DNA to proteins
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Information flow in cells Protein CB 5.26
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a gene - DNA used to produce RNA or protein The relationship between DNA and genes promotercoding regionterminatornon-gene DNA
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Five Perspectives about Genes: 1.Genes act as units of heredity 2.Genes are seen as a cause of disease 3.Genes code for proteins 4.Genes act as switches, controlling development 5.Genes are replicators (selfish gene)
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Genes act as units of heredity…storing and passing on information. CB 14.15
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Genes act as units of heredity… storing and passing on information.
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Genes are seen as a cause of disease Mutations in the gene GPR143 lead to one form of albinism (http://www.albinism.org/publications/what_is_albinism.html)
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Genes are seen as a cause of disease
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Protein Genes code for proteins CB 5.26
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Proteins are the “doers” of the cell. They act as: Enzymes Structural Support Transporters Signals Genes code for proteins…
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Genes act as switches, controlling development
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Genes are replicators (selfish gene) CB 21.7
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CB 19.4 Viruses infect living cells, take over, and produce more virus.
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Bodies are vessels for the transmission of genes
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a gene - DNA used to produce RNA or protein The relationship between DNA and genes promotercoding regionterminatornon-gene DNA
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Five Perspectives about Genes: 1.Genes act as units of heredity 2.Genes are seen as a cause of disease 3.Genes code for proteins 4.Genes act as switches, controlling development 5.Genes are replicators (selfish gene)
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Protein Genes code for proteins CB 5.26
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Chains of DNA nucleotides store information:
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CB 16.7 In cells, DNA is a double-stranded helix
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? 4 nucleotides in DNA 20 amino acids in proteins
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How can 4 nucleotides code for 20 amino acids? If Ratio (nucleotide:amino acid)Possible combinations 1:14 1 = 4
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How can 4 nucleotides code for 20 amino acids? If Ratio (nucleotide:amino acid)Possible combinations 1:14 1 = 4 2:14 2 = 16
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How can 4 nucleotides code for 20 amino acids? If Ratio (nucleotide:amino acid)Possible combinations 1:14 1 = 4 2:14 2 = 16 3:14 3 = 64
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CB 17.4 Combinations of 3 nucleotides code for each 1 amino acid in a protein.
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How can 4 nucleotides code for 20 amino acids? If Ratio (nucleotide:amino acid)Possible combinations 1:14 1 = 4 2:14 2 = 16 3:14 3 = 64 There are more possible combinations of nucleotides than amino acids: redundancy
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CB 17.5 the Genetic Code
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Sickle-cell anemia is caused by a single nucleotide change in the hemoglobin gene CB 5.22
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Changes in DNA can change the protein
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CB 17.4 Changing the number of nucleotides in a gene is more dramatic than changing a nucleotide
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The fat cat ate the rat. change one letter The zat cat ate the rat.
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The fat cat ate the rat. change one letter The zat cat ate the rat. The atc ata tet her at. delete one letter
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CB 17.4 Combinations of 3 nucleotides code for each 1 amino acid in a protein. What does RNA do?
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Protein RNA moves the information from the nucleus to the cytoplasm, where the protein is made? Both proteins and RNA are involved in the processes CB 5.26
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Differences between DNA and RNA
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CB 17.4 DNA is long and contains many genes; RNA is short and represents one gene.
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Only a small percent of DNA codes for proteins CB 19.14
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DNA Composition: In humans: Each cell contains ~6 billion nucleotides of DNA. This DNA is ~2 meters long and 2 nm wide.
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Width of DNA Length of human DNA in each cell The length of DNA in each of your cells is longer than you are tall.
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DNA Composition: In humans: Each cell contains ~6 billion base pairs of DNA. This DNA is ~2 meters long and 2 nm wide. ~1.5% directly codes for amino acids ~25% is genes In a single human cell only about 5-10% of genes are expressed at a time.
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There are 2 explanations for why so little of your DNA directly codes for proteins... CB 19.14
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CB 5.26 Genes act as switches. The information in genes is what to make and when to make it. Protein
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a gene Genes have three basic parts promotercoding regionterminatornon-gene DNA The promoter marks where the gene begins AND when the gene is expressed
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CB 5.26 Genes act as switches. When to express a gene is critical for the cell/organism to function correctly. Protein
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Development: differentiating cells to become an organism
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Cells function differently because they express different genes.
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The proper control of gene expression is critical for proper development.
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What happens during development?
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Developmental mutants of Drosophila melanogaster produced by altering single genes
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Increases in cell number play a role…
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…so does cell death.
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CB 21.19 Development of a mouse paw: yellow areas show dying cells
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Development in animals is one way. Why?
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