1. Genetics Unit Module 9: Transcription and Translation
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Content developed by the Institute for Science and Mathematics Education, University of Washington, Seattle, Washington, U.S.A.
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2. Basic Molecular Biology
Information in cells flows from DNA to RNA to protein
Transcription:
Synthesis of messenger RNA (mRNA)
Uses DNA as template
Takes place in nucleus
Translation:
Synthesis of protein via transfer RNA (tRNA) and amino acids
Uses mRNA as template
Takes place in ribosomes
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3. Steps of Transcription
Double strands of DNA “unzip” by protein action
2. mRNA strand is built, using DNA as template following base-pairing rules
3. mRNA leaves nucleus for the ribosomes in the cytoplasm
Image from
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mRNA
mRNA is similar in structure to DNA
EXCEPT THAT mRNA IS:
Single stranded
Sugar = ribose, instead of deoxyribose
Uses the nitrogenous base uracil instead of thymine
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5. Protein Synthesis: Translation
1. mRNA is used to synthesize amino acids in the ribosome. Every 3 letters of the mRNA is a codon sequence.
2. Codons are equated (using base-pairing rules) by tRNA into anticodons.
3. Anticodons are translated into amino acids, brought to the ribosome by tRNA.
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6. Protein Synthesis: Translation
4. Amino acids are strung together forming a polypeptide, which makes up part of, or a whole, protein.
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7. Protein Synthesis: Structure
The sequence of amino acids in a polypeptide determines the primary structure of the protein, through:
Chemical interactions between amino acids
Physical properties of the amino acids
example: Hydrophobicity is the inability of a molecule to interact with water
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8. Protein Synthesis: Structure
Other physical interactions help to determine the protein’s structure at different organizational levels: that is coiling into helix, folding of coils, attaching of side chains.
wikipedia
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Protein Synthesis
Example: Enzymes are types of proteins that fit at an active site with other specific molecules (substrates) to accelerate chemical reactions - If there are any structural changes in the active site, the enzyme won’t function
The structure of a protein determines its function
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Proteins
Of all molecules in animals, proteins are the most abundant.
They are found in muscle tissues, enzymes, and antibodies.
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11. Transcription and Translation Animation
Watch the excerpt from “Secret of Life”
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12. Visualizing Molecular Processes
Optionally, watch the Dr. Drew Berry TEDx Talk to help you “see” these complex cellular process at work:
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