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If you're seeing this message, it means we're having trouble loading external resources on our website. If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked. Identify whether each process below occurs during mitosis_ meiosis (remember meiosis has both PMAT and PMAT IIl; or both: Sister chromatids separate Haploid cells are formed Homologous chromosomes pair_ haploid cells are the final result _ Crossing over occurs f.2 diploid cells are the final result _ Fill in the blanks based on your knowledge of mitosis and meiosis human has 46 chromosomes In each body cell; How many chromosomes would be found In its daughter cells after mitosis? fruit fly' $ gametes have chromosomes, because its body cells have chromosomes; kangaroo'$ somatic body cells) cells have 12 chromosomes, so that means its sex cells have chromosomes 10. Melosls: What Important event occurs during Prophase 1? Why E Important? Question 19. In simple Mendelian genetics, alleles typically occur in two forms (one dominant and one recessive). For example, there are two alleles (one pair of alleles) for seed coat in garden peas: The dominant allele for round (R) and the recessive allele for wrinkled (r). In real life, there may be more than two alleles to choose from, and they are not always dominant and recessive. In human blood types there are 3 alleles, A, B and O. They all occur at the same loci on homologous chromosome pair #9 (autosome #9). Since you must inherit a pair of these alleles, there are six different possible genotypes: AA, AO, BB, BO, AB and OO. Since there are more than two alleles to choose from, this type of inheritance is called "multiple allele inheritance." Multiple allele inheritance always involves alleles that occur at the same loci on homologous chromosomes. This is illustrated at the A-B-O Blood typing page at: Question 20. Sometimes a number of genes are involved in the inheritance of a trait. This may involve several pairs of alleles from several different loci on homologous chromosomes. Since different loci are involved, you can't use the term multiple allele inheritance. So geneticists have devised the term "multiple gene" or "polygenic inheritance." Many human traits are attributed to polygenic inheritance, including height, weight, skin color and eye color. Because there are different genes on different loci involved, numerous genotypes and phenotypes (appearances) are possible. The Rh factor is a good example of polygenic inheritance. It is illustrated at the following link: Question 21. The disease sickle-cell anemia is a good example of a genetic mutation in which the gene for the vital protein hemoglobin has mutated. The sickle-cell gene has an altered DNA base pattern so that it codes for the amino acid valine instead of glutamic acid at a precise location in the hemoglobin molecule. This results in a change in the structure of the molecule resulting in sickle-shaped rather than normal disk-shaped red blood cells. These abnormal cells do not flow as well through minute capillaries, forming painful "log jams" that impede blood circulation. In order to appreciate the answer to this question, please refer to the following hyperlink about proteins: Questions 24 - 26. See the following table showing chromosomal sex determination in four different types of animals:
Question 27. A human male and female each have 23 pairs of homologous chromosomes per cell, a total of 46 chromosomes. A male or female with Down's syndrome has the 21st chromosome (autosome) in triplicate. Instead of the normal homologous pair, there are three #21 chromosomes. In Klinefelter's syndrome, there are three #23 chromosomes (X-Y chromosomes) rather than the normal pair. In this case the individual has two X chromosomes and one Y chromosome. Because the Y chromosome carries the male-determining factor, the individual is a phenotypic male with a penis, although there may be some breast enlargement. In both of these syndromes, the total number of chromosomes per cell is raised by one compared with normal somatic cells. Question 28. See the following table: The Rh factor is an interesting example of polygenic inheritance. Unlike the A-B-O blood types where all the alleles occur on one pair of loci on chromosome pair #9, the Rh factor involves three different pairs of alleles located on three different loci on chromosome pair #1. In the following diagram, 3 pairs of Rh alleles (C & c, D & d, E & e) occur at 3 different loci on homologous chromosome pair #1. Possible genotypes will have one C or c, one D or d, and one E or e from each chromosome. For example: CDE/cde; CdE/cDe; cde/cde; CDe/CdE; etc. In order to determine how many different genotypes are possible, you must first determine how many different gametes are possible for each parent, then match all the gametes in a genetic checkerboard. Although the three pairs of genes are linked to one homologous pair of chromosomes, there are a total of eight different possible gametes for each parent: CDE, CDe, CdE, Cde, cDE, cDe, cdE, and cde. This number of gametes is based on all the total possible ways these genes can be inherited on each chromosome of homologous pair #1. [It is not based on the independent assortment of these genes during meiosis in the parents because all three genes are closely linked together on the same chromosome; therefore, all three genes tend to appear together in the same two gametes: CDE and cde.] The possible different genotypes are shown in the following table:
You can also plug into this neat little formula for calculating the number of different genotypes based on the number of alleles per locus and the number of loci per chromosome. The formula was actually devised by several of my general biology students. It may occur somewhere in a textbook, but the students came up with it independently. Question 29. See the following diagram showing one pair of homologous chromosomes, each with a single locus. Only one allele can occur at each locus, but there are 4 possible alleles per locus. Since the A1, A2, B and O alleles are located on one pair of loci on homologous chromosome pair number nine, the following genotypes are possible: A1A1, A1A2, A2A2, A1O, A2O, BB, BO, A1B, A2B and OO. Questions 32 - 33. See the following table showing the number of different gametes due to independent assortment of chromosomes during meiosis and random combination of gametes.
Question 34. Go to the following hyperlink for an explanation: Part III. Matching Questions 35 - 60: Question 35. The following illustration shows a highly magnified cell membrane containing two kinds of embedded proteins, a carrier protein and a cell recognition protein. The cell recognition protein contains a carbohydrate "antenna" composed of polysaccharide subunits. Go to the following hyperlink for more explanation: Part IV, Multiple Choice Questions 61 - 134: Questions 61 - 62. Remember that the gene (allele) for taster (T) is dominant over the gene (allele) for nontaster (t): Questions 63 - 66. Remember that the X-linked gene (allele) for normal vision (+) is dominant over the recessive gene (allele) for color blindness (o): Questions 67 - 68. Human skin color is a good example of polygenic inheritance in people. The following table shows a cross between two mulatto parents (AaBbCc x AaBbCc). The offspring contain seven different shades of skin color based on the number of capital letters in each genotype.
Assume that three "dominant" capital letter genes (A, B and C) control dark pigmentation because more melanin is produced. The "recessive"alleles of these three genes (a, b & c) control light pigmentation because lower amounts of melanin are produced. The words dominant and recessive are placed in quotation marks because these pairs of alleles are not truly dominant and recessive as in some of the garden pea traits that Gregor Mendel studied. A genotype with all "dominant" capital genes (AABBCC) has the maximum amount of melanin and very dark skin. A genotype with all "recessive" small case genes (aabbcc) has the lowest amount of melanin and very light skin. Each "dominant" capital gene produces one unit of color, so that a wide range of intermediate skin colors are produced, depending on the number of "dominant" capital genes in the genotype. For example, a genotype with three "dominant" capital genes and three small case "recessive" genes (AaBbCc) has a medium amount of melanin and an intermediate skin color. This latter genotype would be characteristic of a mulatto. In the above cross between two mulatto genotypes (AaBbCc x AaBbCc), each parent produces eight different types of gametes and these gametes combine with each other in 64 different ways resulting in a total of seven skin colors. The skin colors can be represented by the number of capital letters, ranging from zero (no capital letters) to six (all capital letters). The approximate shades of skin color corresponding to each genotype are shown in the above table. Note: Skin color may involve at least four pairs of alleles with nine (or more) shades of skin color. The above cross between two mulattos can also be shown with the binomial expansion (a + b)6 where the letter a = number of capital letters and the letter b = number of small case letters. Each term in the expression represents the number of offspring with a specific skin color phenotype based on the number of capital letters in the genotype. For example, 20 offspring have three capital letters in their genotype and have a skin color that is intermediate between very dark with all caps (AABBCC) and very light with no caps (aabbcc). + 15 a4b2 + 20 a3b3 + 15 a2b4 + 6 ab5 + b6 6 Caps 5 Caps 4 Caps 3 Caps 2 Caps 1 Cap 0 Caps How many chromosomes are present in daughter cells after meiosis in a fruit fly?Fruit flies have 16 chromatids during the metaphase stage of mitosis. At the end of mitosis, how many chromosomes does each daughter cell have? There are 32 chromosomes in each daughter cell.
How many chromosomes does a fruit fly gamete have?Male gametes of fruit flies have a half set of chromosomes; they have 4 chromosomes. Out of these 4 chromosomes; only one chromosome constitutes sex-linked genes.
Which of the following describes the number of chromosomes in the daughter cells after mitosis?At the end of mitosis, the two daughter cells will be exact copies of the original cell. Each daughter cell will have 30 chromosomes. At the end of meiosis II, each cell (i.e., gamete) would have half the original number of chromosomes, that is, 15 chromosomes. 2.
Which of the following correctly describes meiosis choose 1 answer?The statement that best describes meiosis is C. separation of sister chromatids. During meiosis, the sister chromatids are pulled away from each other and eventually end up in separate haploid cells.
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