Please explain why chromosomal inversions are less detrimental to the organism than a duplication event.

Because of the relatively high frequency of meiotic errors that lead to developmental abnormalities in humans, many research efforts have focused on identifying correlations between error frequency and chromosome morphology and behavior. Tease et al. (2002) studied human fetal oocytes of chromosomes 21, 18, and 13 using an immunocytological approach that allowed a direct estimate of the frequency and position of meiotic recombination. Below is a summary of information [modified from Tease et al. (2002)] that compares recombination frequency with the frequency of trisomy for chromosomes 21, 18, and 13. (Note: You may want to read appropriate portions of Chapter 8 for descriptions of these trisomic conditions.) Trisomic Mean Recombination Frequency Live-born Frequency Chromosome 21 1.23 1/700 Chromosome 18 2.36 1/3000–1/8000 Chromosome 13 2.50 1/5000–1/19,000 (a) What conclusions can be drawn from these data in terms of recombination and nondisjunction frequencies? How might…

The image below shows a standard human karyotype, from a metaphase cell. Note that the positioning of the chromosomes in the image is to aid visualization; they are not lined up this way in the cell. Вох 1 Вох 2 3 88 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 © 2012 Pearson Education, Inc. If the image represents a meiotic cell, what will happen to the DNA represented in Box 1 after meiosis is complete? а. It will be split equally between the four daughter cells. Ob. It will be split between two of the four daughter cells, with different amounts of DNA in each cell. O c. It will be split between two of the four daughter cells, with the same amounts of DNA in each cell. d It will all end up in one daughter cell.

Discuss the mechanisms that lead to erroneous chromosome duplication, mention how they effect the development of Down’s syndrome.

Topic 2 Living things in their environment Find the food chains e1 Draw three different food chains for each habitat. Habitat A – a tropical sea humans birds large fish orca humpback whale small fish crabs turtles algae plankton seagrass Habit -a freshwater pond

A. Please explain the key differences between each of the following pairs of terms.      (i) Haploid vs. monoploid      (ii) Pericentric inversion vs. paracentric inversion (Please include a simple diagram, along with your written explanation.)      (iii) Homologous chromosomes vs. homeologous chromosomes:

Which type(s) of chromosomal aberrations result from chromosomal breaks on different chromosomes? Assume that a heterozygote for the aberration is viable. Select all correct answers. A.)Robertsonian translocation B.)reciprocal translocation C.)tandem duplication D.)paracentric inversion E.)pericentric inversion F.)large deletion