ANTH 1013 1st Edition Lecture 5Outline of Last Lecture I. Mendel’s Law of Independent AssortmentII. Examples of Medelian InheritanceIII. Mendelian Inheritance Lost and RediscoveredIV. GenesV. Cell Biology Related to Mendel’s TheoriesVI. Meiosis Big PictureOutline of Current Lecture I. DNAII. ProteinsIII. Protein SynthesisIV. Coding vs. Noncoding DNA SequencesV. MutationsCurrent LectureI. DNAi. Explains diversity of life on earth, makes us what we areii. DNA carries the instructions for building proteins and influences most of the characteristics of an organismiii. Structure of DNA discovered in 1953 as a result of work by Rosalind Franklin, James Watson, and Francis Cricka. Took pictures of DNA, awarded Nobel Prizeb. Double-helix of complimentary strandsc. Rungs of the ladder are made of repeating subunits called nucleotidesiv. Structurea. Complimentary structure – 2 sides of strand matchupb. Sides of ladder = phosphate and sugarc. Rungs of ladder = bases 1. Adenine, guanine, thymine, cytosine2. Cytosine and Guanine, Adenine andThymine always pair up togetherd. There are approximately 3 billion base pairs in thehuman genomev. ReplicationThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.a. Replication occurs during interphase1. DNA strand unzips itself2. Free floating nucleotides come in and pair up with individual strands, creating 2 identical double stranded DNA moleculesII. Proteinsi. Humans are protein!a. DNA encodes for proteinsb. Hemoglobin: blood, collagen: connective tissue, actin and myosin: skeletal muscleii. Moving from DNA to proteina. DNA creates amino acids, which create proteins1. There are 20 amino acids2. Proteins are determined by specific sequences of amino acids3. Protein Synthesis: creation of protein from DNAb. Protein Synthesis1. The sequence of bases determines the protein produced2. Codon: sequence of 3 bases that codes for a specific amino acid3. Protein synthesis requires the following:a. DNA with a sequence of base pairs making p a geneb. mRNA, which has been copied fromthe genec. aribosome, which is the site of proteinsynthesisd. 20 different types of amino acidse. 20 different types of tRNA which carrythe amino acids used in building theproteinIII. Protein Synthesisi. DNA vs. RNAa. DNA: double stranded, deoxyribos sugar, utilizesthymine baseb. RNA: single stranded, ribos sugar, utilizes uracil baseii. Protein synthesis occurs in 2 steps:a. Transcription: genetic info is copied from the nuclear DNA into messenger RNA (mRNA)1. “To copy”2. During transcription, nuclear DNA is unzipped in the region of a gene and used to create mRNA3. mRNA is complimentary to the original DNA strand4. Occurs inside the nucleusb. Translation: the mRNA serves as a template to construct a protein1. “to convert”2. tRNAmolecules used to identify the amino acid coded for by mRNA3. There are 20 different tRNA molecules, which carry a specific amino acid4. Steps:a. mRNA moves through ribosome, exposing codons in sequenceb. free-floating tRNA’s carrying amino acids move into ribosomec. tRNA anticodon bonds with mRNA codon, and its amino acid is bonded with the growing proteind. tRNA is ejectedc. Protein synthesis halts when a STOP codon is reachedIV. Coding vs. Noncoding DNA sequencesi. Gene: a sequence of DNA bases that specifies the order of amino acids in an entire protein, or a portion of a protein, or any functional product, such as RNAa. 24000 genes in humansii. Not all DNA codes for proteinsa. Its estimated that only 2% of the human genome is coding1. This means that 98% of our genome doesn’t participate in protein synthesis!b. Humans appear to have more non-coding DNA than almost any other species studied so farc. What is this “junk DNA” do then?1. Used for “DNA fingerprinting” (like on TV shows)2. May serve regulatory function – tells coding DNA where to start3. Pseudogenes – inactive genes – if something goes wrong in the starting process4. Genes for noncoding RNA5. Repetitive DNA – chunks get inserted that are just repeatsV. Mutationsi. A change in the nucleotide sequencea. Can be caused by copying errors during DNA replication, or exposure to chemical mutagens, radiation, or virusesb. Can occur in either somatic cells or gametesii. Point mutation: single point mutation can change entire amino acida. Example: sickle cell hemoglobin sequenceiii. Insertion or deletion mutationa. Accidentally insert or delete more than one base (several)b. May have dramatic effect because all of the codons “downstream” of the mutation are shifted, so many amino acids will be alterediv. Mutations are rarea. Extremely rare, but there are 3.2 billion nucleotides in the human genome, so on average, each person has point mutations at 58 positions relative to their parentsb. So – everyone is a mutant!v. Effects of mutationsa. Some effects of mutation:1. Non-viable zygote2. Protein non-functional 3. Protein has reduced function4. Neutral effect5. Protein has improved function6. Protein has new functionb. Whether a mutation is bad or good depends on the environment. Bad or good are therefore relative and have meaning only in relation to their effect on fitness (reproductive success)vi. Examplesa. Autosomal dominant b. 1/10,000 births, almost entirely from new