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56 Cards in this Set
- Front
- Back
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Genome
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- composed of one or more DNA molecules organized into chromosomes
- varies greatly among organisms |
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Transformation
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Uptake of foreign DNA in prokaryotes and eukaryotes repeatedly shows DNA is hereditary material
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DNA molecule
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- deoxyribose
- 5' phosphate -Nitrogenous base |
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purine
pure as gold |
adenine
guanine |
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pyrimidine
C.U.T |
cystosine
uracil thymine |
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nucleotide
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deoxyribose + phosphate + nitrogenous base
- smallest heritable unit |
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nucleoside
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deoxyribose + nitrogenous base
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DNA structure
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- db helix
- phosphodiester bonds holds nucleotides together by forming a bridge btwn OH and 2 adj sugar residues - hydrogen bonds - complementary base pairs |
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double helix
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T=A , G=C
A+t = G+C - sugar phosphate backbone is antiparallel 5' - 3' |
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DNA replication
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semiconservative
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Units of measurement for DNA
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-base pair (bp)
- kilobase (kb) - megabase (Mb) |
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information of DNA
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specified by sequence of nucleotides may be copied into RNA
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mutation
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insertion, replacement, delection of nucleotide = alter sequence
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prokaryote genomes
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-close together with little intergenic spacer
- operon: tandem cluster of coordinately regulated genes and is transcribed as one mRNA - introns are rare |
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eukaryote genomes
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- introns are common
- have spacer DNA btwn genes * some are repetitive and identical/nearly identical * tandem, dispersed |
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genes
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-encode functional RNA, mostly mRNA
- functional part of chromosome which is transcribed into RNA at the correct time and place in development - includes adj regulatory regions |
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RNA (ribonucleic acid)
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- single stranded nucleotide chain
- ribose -phosphate - nitrogenous base |
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classes of RNA
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-Informational RNA
- functional RNA |
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informational RNA
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mRNA - intermediate in the synthesis of a functional gene
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functional RNA
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Transfer RNA - tRNA - translation: brings AA to mRNA
ribosomal rRNA - guides coordinate assembly of amino acid chain of a protein small nuclear RNA -snRNAs - splicing premRNA to mRNA small cytoplasmic RNA - scRNA - protein trafficking microRNA -miRNA & small interfering RNA - siRNA |
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intron (eukaryotic genes)
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-noncoding region of gene
- excised - variable length -unkown function |
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exon (eukaryotic genes)
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coding region of gene
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prokaryotic gene structure
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- promoter
- 5 'UTR -translation initiation - coding region -translation termination - 3' UTR |
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promoter
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regulatory region where RNA pol usually binds
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UTR
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untranslated region at 5' & 3' end
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penetrance
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frequency a genotype actually expresses the phenotype
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expressivity
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degree to which a gene is expressed
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sex limitations traits
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- trait is encoded on autosome
- only one sex expresses certain trait |
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sex influenced traits
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- trait is encoded on autosome
- trait appears in both sexes but the frequency/degree of phenotypic is different |
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phenotype
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result of genotype interacting with environment
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multiple alleles
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all essential genes have more than 2 alleles
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incomplete dominance
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heterozygotes differs from both homozygotes
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codominance
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both phenotypes are expressed at the same time
ABO blood type |
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complementary gene action
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- 9 :7
- one dominant allele from each is required for full expression of the phenotype |
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deviations from mendalian ratios
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- variation in dominance
- multiple alleles - lethal alleles - 2 genes segregate independently and influence the same trait |
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recessive lethal alleles
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you must recalculate!
F1: 1:2 total live 3 F2 1:1 total live 8 F3: 9:6:3:2 total live 15 |
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mutational anaylsis
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studies gene function
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forward genetics
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-identify mutants and heritable phenotypes
- molecular analysis of products |
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reverse genetics
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- based on genome sequence
1. gene of potential interest is mutated 2. study mutated gene phenotype |
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classical genetics
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mutagens are widely used
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neoclassical genetics
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insertion mutagens
1. disrupt the gene 2. tag for isolation |
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modern genetics
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RNA interference (RNAi)
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forward mutations
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change from wild type to mutant
a+ → a |
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reverse mutations
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change from mutant back to wild type
a → a+ |
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genetic screens
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applied to any problem depending on ingenuity and resources
1. morphological mutations 2. biochemical mutations |
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morphological mutations
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change in shape/form
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biochemical mutations
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screen for auxotroph from mutagenized phototrophs by supplying various substrates for required growth
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phototrophe
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can grow on minimal media
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auxotroph
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mutate strain that cannot synthesize molecules required for growth and needs special substrate to grow
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lethal mutations
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- premature death
- recessive alleles are more useful - dominant lethals are difficult to obtain |
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conditional mutations
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- display wild type phenotype under permissive/nonrestrictive conditions
- display mutant phenotype under restrictive conditions ie temperature sensitive |
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mutational anaylses
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cross wildtype with mutant
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complementaion test
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cross homozygous recessive with homozygous recessive
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biochemical mutations
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mutations that alter gene function by altering structure and function in a product
- wildtype is normal + - mutation: has a change in nt sequence - |
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nutritional mutants
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- prototroph: wildtype normal: synthesizes nutrient
- auxotroph: mutant that fails to make nutrient |
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heterokaryon
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- fuses cells from distinct mutants
- use to test growth on complete media and media without methionine 1. if it doesnt grow: mutation on same gene 2. if it does grow: a. unlinked gene 2. two linked genes |
