Common structural elements in proteins such as α-helices or β-sheets are characterized by uniformly repeating, energetically favorable main chain conformations which additionally exhibit a completely saturated hydrogen-bonding network of the main chain NH and CO groups. Although polyproline or polyglycine type II helices (PPII or PGII ) are frequently found in proteins, they are not considered as equivalent secondary structure elements. Which of the following statements are correct about PP and PGs.

A. PGII -like helices form hexagonal bundles which appear to fulfill the criterion of a (largely) saturated hydrogen-bonding network of the main-chain groups

B. main chain NH and CO groups of the central PGII -helix are saturated by either intra- or intermolecular hydrogen-bonds, resulting in a self-contained hydrogen-bonding network

C. The formation of the right-handed PPI helix is possible only with proline residues because of the required cis conformation. 

D. PPII helices seem to be stabilized by main chain-water hydrogen bonds (in the absence of main chain- main chain H-bonds), and tend to have a regular pattern of hydrogen bonds with water. After this, it is not surprising, that PPII helices are found mostly on the protein surface.

#Question id: 4888

#Unit 8. Inheritance Biology

The A locus and the D locus are link with 50 % chance of crossing over observed between them. If Ad/Ad is crossed to aD/aD, and the F1 is test cross, which of the following phenotype is statement is correct?

A) Frequency of recombinant progeny is equal to parental frequency

B) Frequency of recombinant progeny is less than parental frequency

C) Distance between Locus A and B is 50 map unit

D) Distance between Locus A and B is 25 map unit

#Question id: 4889

#Unit 8. Inheritance Biology

A three point test cross was carried out in Drosophila melanogaster involving three adjacent incomplete link genes A, C and B arranged in the same order. The distance between A to C is 20 map units (mu) and that between B to C is 10 map. If pure line Drosophila AAbbCC crosses with aaBBcc to produce F1 offspring were allowed to cross with aabbcc result in 1000 offspring, which of the following genotype combination with number is correct?

#Question id: 4890

#Unit 8. Inheritance Biology

A strain of Neurospora crassa, unable to synthesize the vitamin thiamine (t), is crossed with a strain that cannot synthesize the amino acid arginine (a). What information can be obtained from the resultant frequencies of ascospore patterns?

 A) The two loci (a) and (t) are independent assortment of each other

B) Both genes are closely linked to their respective centromeres.

C) no crossovers occurred between either gene and its centromere.

D) These two gene may reside on different chromosomes.

#Question id: 4891

#Unit 8. Inheritance Biology

plantlike organism on the planet Pandora can have three recessive genetic traits: bluish leaves, due to an allele (a) of gene A; a feathered stem, due to an allele (b) of gene B; and hollow roots due to an allele (c) of gene C. The three genes are linked and recombine. A geneticist performed a testcross with an organism that had been found to be heterozygous for the three recessive traits, and she was able to identify progeny of the following phenotypic distribution (+ = wild type):

 A) Genes are in the order: a-c-b

B) Genes are in the order: a-b-c.

C) Genes are in the order: b-a-c

D) Interference is one

E) Greatest distance between gene a and b

#Question id: 4892

#Unit 8. Inheritance Biology

The RFLP pattern for this locus, obtained by hybridization using a probe internal sites, from family is shown below: Based on the above profile, what is the nature of the genetic disorder?

#Question id: 4893

#Unit 8. Inheritance Biology

In tomatoes, tall (D) is dominant over dwarf (d) and smooth fruit (P) is dominant over pubescent fruit (p), which is covered with fine hairs. A farmer has two tall andsmooth tomato plants, which we will call plant A and plant B. The farmer crosses plants A and B with the same dwarf and pubescent plant and obtains the following numbers of progeny

a. The genotypes of both plant A and plant B are DdPp

b. In plant A, Gene D and Gene P link as cis configuration

c. In plant B, Gene D and Gene P link as cis configuration

d. In plant A, Gene D and Gene P link as trans configuration

e. In plant B, Gene D and Gene P link as trans configuration

Which of the following above statement are not correct?