BIMS 320 Lecture Notes - Lecture 4: Summer Squash, Phenylalanine, Abo Blood Group System

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skyferret287

6 Nov 2017

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7 tra its , one pa ir of a lle le s (1 domina nt, 1 re ce s s ive : no influe nce of e nvironme nt on phe notype. S uch tra its a re ve ry ra re in na ture ; in mos t ca s e phe notypic de te rmina tion is more comple x. In te ra c tio n s b e twe e n alle le s p ro d u c e do m in a n c e. Re la tio n s h ip s: me nde l chos e to e xa mine tra its with jus t two a lte rna tive forms. Functiona l e ffe cts of muta tion. From a functiona l pe rs pe ctive , a n orga nis m with two copie s of the wild type a lle le produce s a wild type phe notype.

Related Questions

Differentiate amongcomplete dominance, incomplete dominance andco-dominance.

3. Understand an allelicseries -How many possible alleles are there for any given gene? Isthere only one recessive allele for a gene? Is there only onedominant allele for a gene? Is an allele always recessive ordominant with respect to other alleles of the gene?

4. What is a lethalallele? Are lethal alleles usually dominant or recessive? Are thereany exceptions? (Hint: Huntington disease in humans). How do wemaintain stocks with lethal alleles?

5. How can you tell if anallele is lethal? If one of the parents has a lethal allele, wouldall the possible genotypes be present in the progeny? What wouldhappen to the phenotypic ratios of the progeny?

6. What ispleiotropy?

7. How can you tell if atrait is determined by more than one gene? What ratios ofphenotypes in the F2 generation would you expect if a trait isdetermined by a single gene?

8. What is epistasis? Howcan the genotype at a locus affect the phenotype determined by thegenotype at another locus? What are complementary gene action,duplicate gene action, dominant suppression, dominant epistasis,and recessive epistasis?

skyrat774

A strong understanding of the difference between gene and allele is needed now. We covered allele interactions in the lesson before this one. Allele interactions deal with a single gene and its alleles. Alleles, versions of a gene, can interact when placed together in a heterozygote.

We are now looking at two genes and how they interact. To more easily understand how two genes interact, we will only be considering the normal alleles and null alleles of both genes. Normal alleles will be dominant, null alleles will be recessive. In addition, the two genes are UNLINKED. The various interactions are made evident in standard F2 generations: Two purebred parents are crossed, a dihybrid F1 is formed, the dihybrid F1 is selfed, and F2 generation is examined. One must remember, the progeny of dihybrid selfs are always in a fixed genotype distribution: 9 A _ B_ : 3 A _ bb : 3: aa B _ : 1 aa bb. BUT, with genes interacting the phenotypic ratios are changed.

Please focus on how genes interact. You do not need to know specific pathways or organisms.

Answer the following questions.

2. There is a hypothetical plant called rat-ear. Red and pink varieties flourish in Hawaii and Long Island, NY. All the red and pink varieties can be bred true. Surprisingly, when the Hawaiian pink is bred with the Long Island pink, all the resulting progeny are red. When these red progeny are selfed the next generation has 333 red flowered and 259 pink flowered plants. The breeders breathe a sigh of relief. What do the breeders understand about the petal pigmentation of rat-ear plants?