BIOLOGY 151 Lecture Notes - Lecture 29: Mendelian Inheritance, Zygosity, Meiosis

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15 Apr 2016

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Heterozygous +heterozygous- big t"s separate into one gene, litle t"s go into another. Two factor cross- follow inheritance of 2 diferent traits. Possible paterns- plant that"s tall with yellow and round and a plant that"s green and wrinkled. 1 possibility- one with yellow and round or green and wrinkled. All combinaions are possible. trait on the same chromosome- traits are linked and stay together. They"re not always on the same chromosome though. Independent assortment- alleles of diferent genes assort independently during gamete formaion during meiosis if they are on diferent chromosomes. Mendelian geneics: inheritance patern of genes that segregate and assort independently. Simple mendelian inheritance: the manner by which genes and traits are passed from parents to their children. The modes of mendelian inheritance are often dominant, recessive, x-linked dominant, and x-linked recessive. Wild-type allele: prevalent allele in a populaion, encodes a protein made in the proper amount and funcions normally. Defecive in its ability to express a funcional protein.

Related Questions

Question 1 Select one answer. 10 points Crossing over occurs:_______________.

during both meiosis I and meiosis II

during mitosis but not meiosis

during meiosis II only

during meiosis I only

Question 2 Select one answer. 10 points Homologous pairs ofchromosomes line up at the center of the cell in during which stageof meiosis?

Metaphase I,

Metaphase II,

Telophase I,

Telophase II

Question 3 Select one answer. 10 points A haploid organism hashow many copies of each chromosome?

1, 2, 3, 4

Question 4 Select one answer. 10 points The sister chromatidsseparate during which stage of meiosis?

Anaphase I, Anaphase II, Prophase I, Prophase II

Question 5 Select one answer. 10 points Describe the importanceof independent assortment: ________________________.

will assort independently of each other,

will sort to the same gamete,

are called alleles

All of these are true

Question 6 Select one answer. 10 points How many differentgametes are produced by a cell with the genotype AABb?

1, 2, 3,4

Question 7 Select one answer. 10 points The next two questionsare based on the following information. Part 1 of 2: In beansyellow (Y) is dominant to green (y) and smooth (S) is dominant towrinkled (s). What are the possible genotypes for the offspring ofthe following cross: YySS and YYSs.

Yy, SS, YY, Ss

YYSS, YySS, YYSs, YySs

YYSS, YYss, yySS, yyss

YS, yS, YS, yS

Question 8 Select one answer. 10 points Part 2 of 2: In beanswith yellow (Y) dominant to green (y) and smooth (S) dominant towrinkled (s): What are the phenotypes for the offspring in theexample in the previous question?

100% green wrinkled,

50% yellow smooth and 50% greensmooth,

100% yellow smooth,

50% yellow smooth and 50% yellowwrinkled

Question 9 Select one answer. 10 points Alleles are differentversions of a _______________.

chromosome,

genotype,

phenotype,

gene

pucesnake469

Problem A. You cross two homozygous parents: RRYY (round yellow) and rryy (wrinkled green) to produce an F1 generation. Round seeds are dominant, yellow seeds are dominant. You cross two F1s to produce the F2 generation. In the F2 generation, you find an individual with round yellow seeds. You do a testcross to find out the genotype of this âmysteryâ dominant/dominant phenotype. In the offspring of the cross, you find 1?2 have round yellow seeds and 1?2 have wrinkled yellow seeds.

1. Based on these data what was the genotype of the mystery F2?

Problem B. You carry out a dihybrid cross between a red-flowered rose with long pollen grains (A1A1 LL) and a white-flowered rose with round pollen (A2A2 l l). The flower color gene (A) shows incomplete dominance, and long pollen is completely dominant to round pollen. The genes for these traits are on different chromosomes so assort independently

2. What would be the phenotypes of the F1 generation?

3. What fraction of the F2 generation is expected to have red flowers and long pollen? (As always when traits are independent, what rule can you apply to save time?)

Problem D. In the example of epistasis presented in class, the agouti allele in mice (A) codes for striped hairs and is dominant to the allele for all black hairs (a). A loss-of-function allele for the pigment gene (b) produces no pigment and is recessive to the normal, dominant allele (B). The recessive allele at b masks the effect of the A gene. A dihybrid cross of AABB and aabb is carried out.

5. Name all of the genotypes in the F2 generation that can produce an albino (no pigment) phenotype.

Problem E. A cross is made between homozygous fruit flies that differ for eye color (the st gene) and

body color (the e gene). The F1 double heterozygote is shown below using chromosome notation.

st+ e

--------------------------------------

st e+

st = the recessive allele for scarlet eyes; st+ = the dominant wildtype allele for red eyes e = the recessive allele for ebony body; e+ is the dominant wildtype allele for gray body

6. Are the chromosomes shown in the genotype above in cis or trans configuration?

7. Based on this notation, what were the genotypes and phenotypes of the two parents of the F1? (Think carefully here...)

8. With what phenotype would you cross this F1 to measure recombination frequency?

cyansnail823

Which of these statements is incorrect?

Syntenic genes are located on the same chromosome.

Independent assortment results in recombinant chromosomes.

You can reliably predict the relative genetic distance fromgenesâ physical distance on a chromosome.

Linked genes are always syntenic.

What is the relative genetic distance between two linked genesif the recombination frequency is 0.49?

0.49 cM

4.9 cM

49 cM

490 cM

What statement best explains the distortion in Mendelian ratiosobserved by Bateson & Punnett in 1905? (Reminder: they found anoverrepresentation of F2 offspring showing both dominant orrecessive phenotypes, and an underrepresentation of offspringdisplaying one dominant and one recessive phenotype)

Human error: they should have been more careful about theirexperimental setup.

Gene linkage: Genes for flower color and pollen shape arephysically close on the same chromosome, leading to a breakdown inthe independent assortment of the alleles for these traits.

Chromosome crossover: Homologous recombination of twochromatids during meiosis caused the alleles to shuffle, resultingin a breakdown of the independent assortment of the alleles forthose genes.

Random variation: No two situations are alike. In finitepopulations, you are going to get some variation across a mean.

When determining the relative genetic distance between twogenes, why is dihybrid back-cross preferable over traditionaldihybrid cross?

9:3:3:1 phenotypic ratio is easier to work with than 1:1:1:1ratio.

Genotypes of the offspring can be determined based on theirphenotype.

If the genes are independently assorted, the dihybrid back-crosswould result in only 2 genotypes in the F1 generation.

B and C

Why do we map genes?

To understand how genes interact with each other

Comparative genomics analysis

To determine the genotype of an organism

All of the above

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BIOLOGY 151 Lecture Notes - Lecture 29: Mendelian Inheritance, Zygosity, Meiosis

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