Biochemistry 4463G Chapter Notes - Chapter 7: Dominance (Genetics), Y Chromosome, Proband

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crimsonplatypus799

2 Feb 2018

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For autosomal loci and x-li(cid:374)ked lo(cid:272)i i(cid:374) fe(cid:373)ales, a perso(cid:374)(cid:859)s genotype at a locus consists of both of the alleles occupying that locus on the two homologous chromosomes. Haplotype refers to the set of alleles at two or more neighbouring loci on one of the two homologous chromosomes. Phenotype is the expression of genotype as a morphological, clinical, cellular, or biochemical trait. These can be clinically observable or may only be detected by blood/tissue testing. A person with a pair of identical alleles at a locus, is homozygous. When the allele pairs are different, the person is heterozygous (if both the alleles are mutant alleles with no wild-type, it is referred to as being compound heterozygous). These terms can only be applied for the nuclear genome. Mitochondrial genome is circular, and some genes are located in plasmids thus, heterozygous and homozygous gene classification cannot be applied to the mitochondrial genome.

Related Questions

Consider two gene loci in the mouse, locus 1 and locus2. Each locus is on a different, nonhomologous autosomalchromosome . Alleles at locus 1 influence furcolor. Allele A is for black and allele ais for white. Allele A is completely dominant toallele a . Alleles at locus 2 influencestature; allele B is for tall and allele b is forshort. Allele B is completely dominant to alleleb.

Mouse 1, genotype Aa Bb, mates with femalemice , genotype Aa Bb; 100 progeny areproduced.

___: What fraction of the gametes from mouse 1 is expected to begenotype Ab ?

___: What fraction of the gametes from mouse 1 is expected tohave allele a ?

___: What fraction of the progeny is expected to betrue-breeding for both stature and black fur?

___: How many progeny are expected to be tall with white fur?Show yourcalculations.

___: How many progeny are expected to be heterozygous at bothloci? Show yourcalculations.

___: If you randomly choose two progeny mice, one at a time,what is the probability that both mice are tall andwhite? Show yourcalculations.

Mouse 1, genotype Aa Bb, mates with femalemice , genotype Aa Bb; 100 progeny areproduced.

___: What fraction of the gametes from mouse 1 is expected to begenotype Ab ?

___: What fraction of the gametes from mouse 1 is expected tohave allele a ?

___: What fraction of the progeny is expected to betrue-breeding for both stature and black fur?

___: How many progeny are expected to be tall with white fur?Show yourcalculations.

___: How many progeny are expected to be heterozygous at bothloci? Show yourcalculations.

___: If you randomly choose two progeny mice, one at a time,what is the probability that both mice are tall andwhite? Show yourcalculations.

olivehare365

These all relate to exceptions to the inheritance patterns encountered by Mendel.â

Why do multiple and lethal alleles often result in modifications of the classic Mendelian monohybrid and dihybrid ratios?

Select the four correct statements.

-When an essential gene is mutated, it can result in a lethal phenotype. There are no classic Mendelian monohybrid and dihybrid ratios.

-In the case of codominance, heterozygotes produce gene products from both alleles of a gene. Classic Mendelian monohybrid and dihybrid ratios are modified by codominance.

-In the case of incomplete dominance, the phenotype of the heterozygote is distinct from and often intermediate to the phenotypes of homozygous individuals. Classic Mendelian monohybrid and dihybrid ratios are modified by incomplete dominance.

-Genes exist in a large number of allelic versions and a diploid organism has two homologous gene loci that may be occupied by different alleles of the same gene. This can result in many different phenotypes for traits, which may not follow typical Mendelian ratios.

-When an essential gene is mutated, it can result in a lethal phenotype. This results in a modification of classic Mendelian ratios.

-The phenotype of the heterozygous genotype is distinct from and often intermediate to the phenotypes of the homozygous genotypes. The joint expression of both alleles in a heterozygote is called codominance. There are no classic Mendelian monohybrid and dihybrid ratios.

-Genes exist in a large number of allelic versions, but in a diploid organism, only one allele of the gene can occupy one homologous gene loci. Classic Mendelian inheritance cannot explain this phenomenon.

-Each gene produces a unique gene product. The effect of one allele in a heterozygote completely masks the effect of the other. Classic Mendelian genetics cannot explain this phenomenon.

2. Consider two gene loci in the mouse, locus1 and locus 2. Each locus is on a different, nonhomologousautosomal chromosome . Alleles at locus 1 influence fur color.Allele A is for black and allele a is for white.Allele A is completely dominant to allele a . Allelesat locus 2 influence stature; allele B is for tall andallele b is for short. Allele B is completelydominant to allele b.

Mouse 1, genotype Aa Bb, mates withfemale mice , genotype Aa Bb; 100 progeny are produced.

___: What fraction of the gametes from mouse 1is expected to be genotype Ab ?

___: What fraction of the gametes from mouse 1is expected to have allele a ?

___: What fraction of the progeny is expectedto be true-breeding for both stature and black fur?

___: How many progeny are expected to be tallwith white fur? Show your calculations.

___: How many progeny are expected to beheterozygous at both loci? Show yourcalculations.

___: If you randomly choose two progeny mice,one at a time, what is the probability that both mice are tall andwhite? Show your calculations.

3. Using the geneloci, alleles and phenotypes as described in question 2, considerthis mating between Mouse 3, black and tall, and mouse 4, black andtall. That mating produced these progeny: 58 black and short, 165black and tall, 25 white and short, 62 white and tall.

____: what is the expectednumber of progeny of the phenotypic class, black and short?Show your work.

____: What is the Chi-squarevalue for these observed and expected data? Show yourwork.

___: How many degrees offreedom are used for the Chi-square test in thissituation?

______: What is theapproximate Chi-square probability for this Chi-square value anddegrees of freedom?

_____: Mouse 3 mated withmice that had the phenotype short & white, and produced 200progeny. How many progeny are expected to have the phenotype, blackand tall?

____: In addition tothe gene loci, alleles and phenotypes described in question 1,consider a third gene locus with alleles D and d; D for long fur,and d for short fur. D is completely dominant to allele d. Thisgene locus segregates independently of the other two loci. Mouse 5,genotype Aa Bb Dd, mates with mouse 6 of the same genotype.What fraction of the progeny are expected to have the phenotype,black fur, tall & long fur?

I don't need the answers to question #2, justquestion #3. (the hilghted) However question 3 asks for informationfrom question 2, so that is why it is there

Thank you

plumbuffalo108

Biochemistry 4463G Chapter Notes - Chapter 7: Dominance (Genetics), Y Chromosome, Proband

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