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DNA, RNA, and Proteins
DNA and Protein Synthesis • DNA contains the genetic information to • make amino acids • Amino acids combine to make proteins • These proteins determine the physical traits • of an organism and control cellular functions. • Proteins do everything, • and DNA gets all the • credit! • Think of them as tiny minions • who do all the work
DNA and Protein Synthesis • Codon: three bases code for a specific protein: • ex: AAA = Lysine • The codons code for 20 amino acids • Just like the alphabet has 26 letters to make all • the words we know, the 20 amino acids make • all the different proteins found in living • organisms • The codons are the template for protein synthesis, • which takes place on the ribosomes (rRNA) in the • cytoplasm
DNA and Protein Synthesis – Codons and amino acids Name the Amino Acid: UAU CCG AGU GCA Tyrosine Proline Serine Alanine
DNA and Protein Synthesis But… How does the information get from the DNA to the cytoplasm? mRNA
DNA and Protein Synthesis - Transcription • Transcription: • 1) DNA unzips • 2) mRNA (messenger ribonucleic acid) copies info from DNA using base pairings • RNA is different from DNA • Single stranded, not double stranded • Instead of deoxyribose, it has ribose • instead of Thymine, it uses Uracil • 3) Carries the genetic code from the nucleus to the • ribosome in the cytoplasm
DNA and Protein Synthesis - Translation • Translation: • rRNA (ribosomal RNA) attaches to mRNA and starts reading the codons • tRNA (transfer RNA) – carries amino acids and attaches them to the growing protein chain • When protein production is complete, the ribosome releases the protein chain
DNA and Protein Synthesis Practice making mRNA using the DNA template DNA G A T T A C A CU AAUGU mRNA
DNA and Protein Synthesis • Amino acids are linked together in the same • order as the codons , creating a protein chain • Just like linking letters to make words, linking • amino acids makes proteins mRNA CUAAUGUGC Amino Acid Amino Acid Amino Acid
DNA and Mutations • Mutations are any changes that take place in DNA: • Can be spontaneous or caused by mutagens • ex: Chemicals, high temperatures, UV light, • radiation • Can change the genetic code, and be replicated • when forming new body cells. • In sex cells, can be passed on to offspring. • Mutations can be neutral, beneficial, or harmful • ex: Blue eyes – a mutation that occurred 6-10,000 years ago, can be traced back to one ancestor • what kind of mutation is that?
DNA and Mutations – Lets looks at different mutations THE DOG BIT THE CAT
DNA and Mutations - Substitution • THE DOG BIT THE CAT • Substitution - Replace just one letter: • THE DOG BIT THE CAR
DNA and Mutations - Deletion • THE DOG BIT THE CAT • Deletion: Delete just one letter (T): • THE DOG BIT HEC AT
DNA and Mutations-Insertions • THE DOG BIT THE CAT • Insertion - Add just one letter (E): • THE DOE GBI TTH ECA T • Cells have “proof reading” proteins that constantly check the DNA and fix errors, so most are corrected