DNA REPLICATION TRANSCRIPTION AND TRANSLATION DNA REPLICATION DNA

DNA REPLICATION, TRANSCRIPTION, AND TRANSLATION

DNA REPLICATION DNA replication: the process by which DNA is copied in a cell before cell division

STEPS IN DNA REPLICATION STEP 1: DNA Helicase separates 2 original DNA strands STEP 2: DNA Polymerase adds complementary nucleotides to each strand. STEP 3: Two identical DNA molecules are form

RNA • RNA: ribonucleic acid • Contains uracil instead of thymine • Single stranded instead of double stranded

TYPES OF RNA Carries the instructions for making proteins. Part of the Ribosomes Transfers amino acids to the ribosomes to make protein

TRANSCRIPTION • Process where genetic information in DNA is copied to m. RNA • Occurs in nucleus • DNA m. RNA Single Strand of DNA Transcribed copy of m. RNA

TRANSLATION • Process where information is transferred from m. RNA to t. RNA to make amino acids • Amino acids make proteins • m. RNA t. RNA Amino acids protein ADD: Occurs inside

CODONS • Codons: Every 3 bases in m. RNA make up a code for an amino acid • Anticodon: the three bases on t. RNA that complement the codon and code for an amino acids • Use a Codon Table to crack the code

CODONS

CODONS Stop Codon: Signal the stop to the making of a protein

MUTATIONS • Mutations: Changes in DNA that affect genetic information • Mutations happen regularly in our DNA • Mutations occur during DNA replication. • Chemicals & UV radiation cause mutations • Many mutations are repaired by enzymes

TYPES OF GENE MUTATIONS Point bases Mutations: changes in one or a few nucleotide Substitution: a base is replaced THE FAT CAT ATE THE RAT THE FAT HAT ATE THE RAT

GENE MUTATIONS Frameshift Mutations – mutation that inserts or deletes a base, messing up the m. RNA codons. Insertion: A base is inserted in the sequence THE FAT CAT ATE THE RAT THE FAT HCA TAT ETH ERA T H Deletion: a base is deleted from the sequence. THE FAT CAT ATE THE RAT TEF ATC ATA TET HER AT H H

Insertion Example Deletion Example

EFFECTS OF MUTATION NEUTRAL: Most mutations cause no changes If a base change happens, but the codon doesn’t change, or the codon codes for the same amino acid. Example: UUU and UUC = Phe, 6 codons code for Arg H

EFFECTS OF MUTATION HARMFUL: some mutations can cause cancers or genetic disorders. EXAMPLE: Leukemia, skin cancers, sickle cell anemia H

EFFECTS OF MUTATION HELPFUL: some mutations help improve an organisms chance of survival EXAMPLE: a mutation in fur color could help an animal better camouflage with the environment. Ted Ed: What Happens When DNA is Damaged H

MUTATION PRACTICE AUG CUG GAA CCG CUG A Met Leu Glu Pro Leu A

MUTATION PRACTICE AUG UGG AAU CGC UGA Met Trp Asn Arg Cys Stop

MUTATION PRACTICE AUG UGG AAC CGC UGA Met Trp Asn Arg Stop

MUTATION PRACTICE AUG UGG AAC CCU GA Met Trp Asn Pro Ala

MUTATION PRACTICE: CONCLUSIONS A geneticist found that a particular mutation had no effect on the protein 1. coded by a gene. What do you think is the most likely type of mutation in this gene? Why? 2. Examine your genetic code chart. Name one amino acid that has more than one codon. Name an amino acid that has only one codon. 3. Given the following three m. RNA sequences, determine which two code for the same protein. Circle them. Ser Leu. Ala Thr Arg. Ser Leu. Ala Thr Ser Ser Leu. Ala Thr Arg. Ser