Explore BrainMass

DNA, Chromosomes and the Genomes

Genetics punnet square , sex lethal etc

In sheep the polled condition ( hornless ) is controlled by a single gene locus with two alleles. Heterozygous females are polled but heterozygous males have horns. Suppose two Heterozygous sheep were crossed. Refer to attachment for multiple choice questions.

Base composition in Aspergillus niger and TMV are figured.

Analysis of base composition from DNA extraction in Aspergillus niger was seen to contain 37% cytosine. Using this data predict the % of adenine. If the same were detected in Tobacco Mosaic Virus [TMV], will it be possible to predict the % of adenine. This job gives reasons.

Predicting DNA structure

A double stranded DNA virus has 200,000 base pairs. Determine the number of nucleotides present and the total number of complete spirals. How long will this DNA be?

DNA length in human beings

Molecular weight of DNA in an autosome of human beings is 0.5 à? 10 power 12. Determine the number of deoxyribonucleotide pairs in this DNA and calculate the length in both micrometers and inches.

Identifying amino acids produced using fixed proportions of nucleotide residues

A solution containing 80% cytosine and 20% uracil was used to make synthetic RNAs. A bacterial cell free system produced proteins using these mRNAs in the following proportions: a) 4 times as many serine as leucine residues. b) 16 times as many serine residues as phenylalanine residues. c) 16 times as many proline resid

Polypeptide equivalents and their functionality

Convert the following mRNA segments into their polypeptide equivalents; a) 5′ GAAAUGGCAGUUUAC 3′ b) 3′ UUUUCGAGAUGUCAA 5′ c) 5′ AAAACCUAGAACCCA 3′ d) 3′ UGACCAGAUCUACCGAAA 5′

Amino acids and codons

A certain gene consists of 450 nucleotide pairs. The protein product of the gene consists of 150 amino acid residues. How many codons make the 150 residues?

Amino acid number prediction following mRNA sequence

How many different mRNAs would specify the following amino acid sequences - a) met - phe - ser - pro b) ile - arg - phe - leu - ala [use the triplet codon chart to find the number of codons representing the amino acids]

General formula for calculating length of DNA

Suppose 25,000 μm is 1 inch. Enumerate a formula to find the length of a DNA molecule in inches a) if the length is known in μm and b) only the number of nucleotide pairs is given.

Composition of bases in yeast

DNA of a certain species of yeast has thymidilic acid content of 32.6%. If the A/T ratio is 0.97, what is the composition of deoxyadenylic acid?

Prediction of DNA strandedness is achieved.

In one set of Φ X phages the deoxyribonucleotide composition was A = 24.7, T = 32.7, G = 24.1 and C = 18.5. Another set of phages had the following deoxyribonucleotide composition - A = 27.6, T = 27.8, G = 22.3 and C = 22.3. a) Find the A/T, G/C ratio of the 2nd set of phages. b) What is the structure of the phage DNA wit

Probability in drosophila mutation experiment

In a mutation experiment in drosophila, 45 mutations were detected amongst 543 males that received 2500 Roentgens (R) and 67 mutations in 649 males that received 4000R. What is the number of progeny expected in 1000 progeny of males exposed to 6000R?

Predicting triplets in laboratory conditions

Under laboratory conditions, a synthetic polyribonucleiotide was produced using a mixture of A and G with a relative frequency of 5:1 respectively. How would a scientist predict the relative frequencies in which the triplets are expected to form when the ribonucleotides form in a random linear array? Indicate which amino acid(s)

Triplet codons and probability

Find the number of triplet codons feasible from 4 ribonucleotides A, U, G and C containing a) no uracil, b) one or more uracils.

Chromosome number in different body cells

An animal cell has 46 post-mitotic chromosomes in each of its somatic cells. How many chromosomes should be present in the following cells- a) Mature egg, b) 1st polar body, c) Sperm, d) Spermatid, e) Primary spermatocyte, f) Brain cell, g) Secondary oocyte, h) Spermatogonium.

Chi-square testing

Cross between pure red tomato and yellow tomato produced all red F1 progeny. From the F2 progeny of 400 plants, 90 were yellow. Hypothesize that a single pair of allele is involved such that Y- = Red and yy = Yellow. Test this hypothesis using Chi square test.

F2 progeny ratio

In squash, disc shaped fruit is dependent on dominant gene D and elongated fruit on recessive allele d. Yellow color is controlled by dominant gene R and green color by recessive allele r. Draw a cross between the homozygous squash fruits and summarize the expected results of F2.

Crosses in garden pea

Garden pea producing round seeds were crossed with those producing wrinkled seeds. The result was the production of 5474 round seeds and 1850 wrinkled seeds. a) What is the original parental cross? b) Indicate the gamete types c) F1 progeny? d) What result do you expect when F1 is selfed? e) Indicate F1 selfed ga

Understanding chromosome mapping techniques.

(a) By using the map function, calculate how many real map units are indicated by a recombinant frequency of 20 percent. Remember that a mean of 1 equals 50 real map units. (b) If you obtain an RF value of 45 percent in one experiment, what can you say about linkage? (The actual figures are 58, 52, 47, and 43 out of 200 pro

Understanding the DNA structure.

In the harlequin-chromosome technique, you allow THREE rounds of replication in bromodeoxyuridine and then stain the chromosomes. What result do you expect to obtain?

Understanding the DNA structure is achieved.

If you extract the DNA of the coliphate thetaX174, you will find that its composition is 25 percent A, 33 percent T, 24 percent G, and 18 percent C. Does this make sense in terms of Chargaff's rules? How would you interpret this result? How might such a phage replicate its DNA? Ideas are expressed.

Mendelian heredity is summarized.

Consider two-child families in which the parents have been identified as carriers of an autosomal recessive gene by virtue of having at least one child with the phenotype. When the children of many such two-child families are totaled, what proportion of children in these families will show the phenotype? (Hint: The answer is N

Understanding Mendelian genetic heredity.

When a pea plant of genotype Aa Bb produces gametes, what proportion will be Ab? (Assume that the two genes are independent) (a) 3/4 (b) 1/2 (c) 9/16 (d) none (e) 1/4

Understanding Mendelian heredity.

Maple syrup urine disease is a rare inborn error of metabolism. It derives its name from the odor of the urine of affected individuals. If untreated, affected children die soon after birth. The disease tends to recur in the same family, but the parents of the affected individuals are always normal. What does this information

Understanding Mendelian analysis and heredity.

Holstein cattle are normally black and white. A superb black and white bull, Nick, was purchased by a farmer for $100 000. The progeny sired by Nick were all normal in appearance. However, certain pairs of his progeny, when interbred, produced red and white progeny at a frequency of about 25 percent. Nick was soon removed fr

Some characteristics of mRNA.

Name 5 features of mRNA that can regulate its stability or translation. Indicate whether the feature regulates stability or translation.