12.1 DNA Griffith – Questioned how bacteria made people sick/ pneumonia – Smooth strains caused, harmless strains rough – Heat killed; however, heat killed + harmless caused it! Transformation- heat-killed passed ability to/ changed other Avery – Looking for molecule in heat-killed that’s responsible – Enzymes to destroy; only if broke down DNA not happen Hershey-Chase Experiment – Used “bacteria eater”; used radioactive P (DNA injected) /S (protein injected) as markers for virus; injected virus into bacteria and saw P DNA “characteristics” – DNA made of nucleotide – Nucleotide= deoxyribose molecule, phosphate group, nitrogenous base (adenine, guanine, cytosine, and thymine) – Double Helix is base paring: A-T, G-C

12.2 Chromosomes and DNA Replication DNA and Chromosomes – Length: for the size of the space, it’s huge! – Chromosome Structure Human cell 1000x base pairs of a bacteria! Chromatin is DNA tightly woven around histones (protein) DNA Replication – Watson/ Crick double helix is how DNA is replicated- separated into 2 strands and base pairs create new strands – Prokaryotes happens at 1 site; Eukaryotes unzipping/ replication happens at hundreds of sites – DNA polymerase- enzyme that unzips DNA and proofreads new strands

12.3 RNA and Protein Synthesis Structure Differences: – Sugar is ribose, single-stands, uricil- U (instead of thymine-T) 3 Types – mRNA (instructions to assemble aa to proteins); rRNA (proteins assembled); tRNA (construction of protein, coding/ transfer) Transcription – RNA polymerase binds to/ separates DNA; uses 1 strand as template to assemble into strand of RNA; only binds to DNA areas known as promoters (specific base sequence) Editing- RNA is copying DNA – Introns- mRNA sequences not involved in coding of proteins – Exons- expressed mRNA sequences in synthesis of proteins

12.3 continued Genetic Code – Codon-3 consecutive nucleotides that specify an aa; sticky note (pg 303) Translation (aka protein synthesis)- use mRNA to produce protein – mRNA is transcribed; tRNA codon and anticodon (complementary to mRNA); joining/ breaking of aa; process continues until reaches stop codon Roles DNA/ RNA-DNA ‘master plan’ and RNA ‘blueprints’; DNA is safe in nucleus while RNA goes to protein building sites in cytoplasm (ribosome) Genes and Proteins: many proteins are enzymes; proteins used as tools

12.4 Mutations Kinds – Point Mutations: change one/ few nucleotide; substitution (change base) or insertions/ deletion (base inserted or removed) – Frameshift Mutitations: nucleotide +/- still group in 3 to make aa, groupings for codons shifted; shift of “reading frame” changes every aa that follows – Chromosomal Mutations: changes # or structure of chromosomes; deletions, duplications, inversions (reverse direction), or translocation (parts break off one and attach to other) Significance – Many are neutral; little/ no effect on expression – Dramatic change in protein structure = harmful – Genetic variation can be helpful – Polyploidy: extra set of chromosomes, “super” crops

12.5 Gene Regulation Gene Regulation – Operon: group of genes operate together; must be expressed lac operon – Lac genes turned off by repressors and on by lactose – Operator: region for repressor to bind to, preventing transcription of gene Eukaryotic Gene Regulation – Have TATA box to help position RNA polymerase/ marking point just before transcription begins – Reason more complex is because of cell specialization! Development and Differentiation – Differentiation of cells = cells specialized – Hox genes: control differentiation of cells/ tissues as embryo develop