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a+ --> a- mutation (forward mutation). a- --> a+ reverse mutation ( revers ion). Presence of pink pigment + / -.
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a+ --> a- mutation (forward mutation) a- --> a+ reverse mutation (reversion)
Presence of pink pigment + / - Incomplete dominancethe term used to describe the general casein which the phenotype of a heterozygote is intermediate between those of the two homozygotes,on some quantitative scale of measurement Four-o’clock plants
Point mutations at the molecular level Purine replaced by a different purine; pyrimidine replaced by a different pyrimidine: TRANSITIONS Purine replaced by a pyrimidine; pyrimidine replaced by a purin: TRANSVERSIONS
Animation ed.9: 9.2&9.17 TRANSLATION
Animation ed.9: 9.2&9.17 TRANSLATION
Selection of auxotrophs by filter enrichment Forward mutation-A mutation that converts a wild-type allele into a mutant allele
Reverse mutation-The production of a wild-type gene from a mutant gene
Intragenic suppressor Equivalent reversion UCC (Ser)forwardUGC (Cys)reverseAGC (Ser) Wild type Mutant Wild type CGC (Arg, basic) forwardCCC (Proline) reverseCAC (His, basic) Wild type Mutant Pseudo-wild type
Intergenic suppressor Nonsense suppressor
non-essential Chromosome Fragment SUP11 M WT ade2-101 CIN mutant ade2-101 ade1-101 Chromosome transmission fidelity (Ctf) assay ade2-101 kar3D sic1D rad50D xrs2D
Animation ed9: 9.19a Nonsense mutation
Animation ed9: 9.19b Nonsense suppressor
Animation 9.19c Nonsense suppression rodns and suppressor-tRNA together give WT phenotype
Coding Regulatory
When doing GENETIC mapping,Molecular Markers can be used as a locus Single Nucleotide Polymorphisms (SNPs) AACGTCATCG vs. AACGTTATCG Microsatellites (variable # of short repeats) CGCGCG vs. CGCGCGCGCG vs. CGCG Restriction Fragment Length Polymorphism (RFLP) SNP leading to a loss/gain of a restriction cut site
When doing GENETIC mapping,Molecular Markers can be used as a locus Almost all SNPs, Microsatellites, etc. are SILENT, and there are millions of them They are mile-markers, not destinations! אבני דרך, ולא יעדים!
A specific gene, the breast cancer gene BRCA1 was found By using the genomic map at increasing levels of resolution
Is there linkage between a mutant gene/phenotype and a SNP? USE standard genetic mapping technique, with SNP alternative sequences as “phenotype” B= bad hair, Dominant B 2’ / b 2 SNP1 ..ACGTC.. SNP1’ ..ACGCC.. SNP2 ..GCTAA.. SNP2’ ..GCAAA.. SNP3 ..GTAAC.. SNP3’ ..GTCAC.. X 1/1’1/1 B/b b/b 2/2’ 2/2 3/3’ 3/3 2/2’ 47% 2/2 3% 2/2’ 3% 2/2 47% 3/3’ 25% 3/3 25% 3/3’ 25% 3/3 25% 1/1’ 25% 1/1 25% 1/1’ 25% 1/1 25% B/b B/b b/b b/b SO…B is 6 cM from SNP2, and is unlinked to SNP 1 or 3
Is there linkage between a mutant gene/phenotype and a SNP? USE standard genetic mapping technique, with SNP alternative sequences as “phenotype” B= bad hair, Dominant SNP1 ..ACGTC.. SNP1’ ..ACGCC.. SNP2 ..GCTAA.. SNP2’ ..GCAAA.. SNP3 ..GTAAC.. SNP3’ ..GTCAC.. X 1/1’1/1 B/b b/b 2/2’ 2/2 3/3’ 3/3 We have the ENTIRE genome sequence of mouse, so we know where the SNPs are Now-do this while checking the sequence of THOUSANDS of SNPs SO…B is 6 cM from SNP2, and is unlinked to SNP 1 or 3
Physical maps are maps of the order, overlap, and orientation of physically isolated pieces of the genome-in other words, maps of the distribution of the cloned genomic DNA from genomic clone libraries
Part of the automated production line of a major human genome sequencing center
A specific gene can be found in the genomic sequence by matching linkage and cytological maps with the Genome sequence
CGCGCG vs. CGCGCGCGCG vs. CGCG
Complementation groups Mutagenesis Plate to select for phenotype of interest
Complementation groups First, we need to catalogue our mutants to complementation groups (Total of 138 mutants were isolated in the original CTF screen). Mutant#1 Mutant#2 Diploid x x x GENE1 x GENE1 GENE1 Mate GENE1 Diploid still shows CTF phenotype Mutant#1 and Mutant#2 are mutated in the same gene Same complementation group
Complementation groups Mutant#3 Mutant#4 Diploid x GENE9 x x GENE9 x GENE10 GENE9 Mate GENE10 GENE9 GENE10 GENE10 Diploid dont show CTF phenotype Mutant#3 and Mutant#4 are mutated in different genes Different complementation groups