Explore BrainMass


Genetic Problems - Lethal Gene

1. A short-tailed mutant of mouse was discovered. Multiple crosses of this mouse to normal mice produced 27 normal, long-tailed mice and 25 short-tailed mice. A series of crosses among short tailed mice were made and 21 short-tailed mice and 11 long-tailed mice were produced. Determine which phenotype is dominant and explain

A problem set containing lots of basic genetics questions.

1. Two black guinea pigs were mated repeatedly over several years. They produced 29 black progeny and 9 white progeny. Explain these results, giving the genotypes of parents and progeny. 2. In horses, black is dependent on a dominant gene (B) and chestnut upon its recessive allele (b). The trotting gait is due to a dominan

Genetics - Genotypes, Punnett Squares

In fruit flies, the phenotype for eye color is determined by a certain locus. E indicates the dominant allele and e indicates the recessive allele. The cross between a male wild type fruit fly and a female white-eyed fruit fly produced the following offspring. Wild-type Wild-type White-eyed White-eyed Brown-eyed male f

Human Nutrition

How does one's food pattern over time contribute to the development of diseases? What do you think is the interplay between genetics and eating habits? How early should one be concerned with preventing diseases? Infancy?


Using the table below, build a genetic distance matrix which gives the total number of genetic differences between pairs of unique haplotypes in the sample. The first box is filled in for you, by way of an example. Haplotypes 1 2 3 4 5 1 -- 2 2 -- 3 -- 4 -- 5

Genetics: Observed Frequencies

The observed genotype frequencies for SNP7 in this sample are f(AA)= 0.80 , f(AC)= 0.00, and f(CC)=0.20. Is variation at this SNP consistent with the expectations of Hardy-Weinberg equilibrium? Why or why not?

Recombinant Mapping

If Curly wings are recessive to normal wings and Barred Eyes is recessive to normal eyes, cross Curly Barred to a normal normal fly. What would be the expected ratios if they were linked or unlinked? If you had 2,500 flies, how many would you expect to see?

Genotypes and frequencies of phenotypes

In a particular species of guppy, tails can either be long or short and either feathered or straight. A cross between a true-breeding long, feather-tailed male guppy and a true-breeding short, straight-tailed female guppy produces progeny that all have short, straight tails. a) express the genotypes of the adults in the cr

Population Genetics

5. In ladybugs, wings with 4 spots are recessive to those with 2. Assume 11% of the ladybugs have 4 spot wings. If the mutation rate of 2 spot to 4 spot alleles is 0.047, what percentage of the next generation will be heterozygous? 6. You look at two populations of moose, one from Canada, and one from Newfoundland, an islan

Population Genetics

3. In plants, flower color is controlled by incomplete dominance, where red and blue are the two homozygous conditions and purple indicates heterozygous. An initial population contains 14 red, 70 purple, and 24 blue individuals. Give exact allele and expected genotype frequencies for this population. Now assume that the heter

Population Genetics

1. In Chihuahuas, being loud and obnoxious is dominant over calm and passive. If 17% of a population of feral Chihuahuas is quiet, what percentage would you expect to be heterozygous for this trait? If your population contained 2,300 dogs, how many homozygous noisy dogs would there be? 2. In frogs, being spotted is dominant

Genetic Material

All living organisms contain genetic information that provides several functions inherent to the individual organism and the perpetuation of its species. a) Describe how genetic material contributes to the regulation of physiological function and development b) Discuss how the nature of genetic material both perpetuates

MONOHYBRID CROSS for brown eyes and blue eyes in humans

In humans, brown eyes (B) are dominant over blue (b)*. A brown-eyed man marries a blue-eyed woman and they have three children, two of whom are brown-eyed and one of whom is blue-eyed. Draw the Punnett square that illustrates this marriage. What is the man's genotype? What are the genotypes of the children? (* Ac

Question about meiosis for someone who is heterozygous for two genes.

There is a gene R on the long arm of the same chromosome as the huntington gene. (1) Draw a labelled diagram to show the chromatids of a diploid cell at the end of anaphase 1 of meiosis, for a person who is heterozygous for both characters. (2) Draw a labelled diagram to show the product cells derived from this cell at tel


How would a pair of sister chromosomes differ from homologous chromosomes? If the reproductive cell only has 23 chromosomes, then how come all of our body cells (somatic cells) have 46 chromosomes? Briefly describe the constituent molecules found within a chromosome. You may use a diagram to illustrate your answer. Refer

Determining probability of inheriting disease gene

Part I: Imagine you have a friend who is getting married and plans on starting a family right away. She asks your advice about preconception genetic screening because she is concerned about the chance that her future children could have cystic fibrosis. Her fiancé has a sister that has cystic fibrosis, and she has a cousin wh

Genetics Problems

1) Consider a genetic locus that could hold either of the alleles P or p (where P is dominant, p is recessive). Consider a second genetic locus (for some other unrelated trait) that could hold either of the alleles R or r. Listed below are some genotypes of individuals for each of these loci: a) PPRR b) PpRR


2. The inbred mouse strains BALB/c and C57BL have different Ig heavy chain allotypes: The BALB/c allele is IgHa, whereas the C57BL allele is IgHb. C57BL mice make good immune responses to the antigen "Z", but BALB/c mice respond poorly. Assume you produced (BALB/c X C57Bl)F1 mice, then back-crossed these F1s to BALB/c. You te

What can you conclude about the gene(s) encoding VH and CH?

Recall that allelic forms of Ig constant regions exist. In the mouse, the locus encoding Ig heavy chain constant regions is named IgH. The inbred mouse strains BALB/c and C57BL/6 have different IgH alleles: BALB/c mice are IgHa and C57BL/6 mice are IgHb. They also differ in their humoral response to phosphorylcholine (PC). While

Which Cell is the Cancer Cell?

Herbie is a typical American college freshman who loves to eat. His second most favorite food is hotdogs. He cuts them into his Kraft macaroni and cheese at a 1:1 ratio, going through a score of hotdogs each week. He doesn't know his brand is preserved with sodium nitrite, but his stomach is slowly finding out as it's acid conve

Modification of Mendelian Rations

In pings, coat color may be sandy, red, or white. A geneticist spent several years mating true-breeding pigs of all different color combinations, even going so far as to obtain true-breeding lines from different parts of the country. For crosses 1 and 4 below, she encountered a major problem: her computer crashed and she lost


A. What is your evidence that DNA is the genetic molecule of heredity? b. The Human Genome Project began with two goals: to know the sequence of genes on all the human chromosomes and to know the sequence of bases on all the human chromosomes. With this, individuals with genetic defects could have proper treatment. Pre

Biology questions about RNA, mitosis, and definitions of genetics terms

1. What are the three types of RNA? What is the function of each? 2. Define mitosis and cytokinesis. What would a daughter cell look like if cytokinesis did not occur after mitosis? 3. Define the following terms: gene, allele, dominant, recessive, true breeding, homozygous, heterozygous, cross-fertilization, self-fertiliza

Genetics: Blood Groups

Five human matings numbered 1-5 are shown in the following table. Include both maternal and paternal phenotypes for ABO, MN, and Rh blood-group antigen status (Rh+ is the dominant trait): Parental phenotypes 1. A, M, Rh- x A, N, Rh- 2. B, M, Rh- x B, M, Rh+ 3. O, N, Rh+ x B, N, Rh+ 4. AB, M, Rh+ x O, N, Rh+ 5. AB, MN, Rh

Mode of inheritance

Labrador retrievers may be black, brown, or golden in color. While each color may breed true, many different outcomes occur if numerous litters are examined from a variety of matings, where the parents are not necessarily true-breeding. The results below show some of the possibilities. Propose a mode of inheritance that consiste

Colorblindness is explained.

Since colorblindness is a sex-linked recessive trait: A) fathers of all colorblind sons must be colorblind B) fathers of all colorblind daughters must be colorblind C) mothers of all colorblind daughters must be colorblind D) mothers of all colorblind sons must be colorblind E) all the sons of carrier female