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Test III- RG Question's
Terms in this set (47)
Nerve growth factor (NGF) is a water-soluble signaling molecule. Would you expect the receptor for NGF to be intracellular or in the plasma membrane? Why?
NGF is water-soluble (hydrophilic), so it cannot pass through the lipid membrane to reach intracellular receptors, as steroid hormones can. therefore, you'd expect the NGF receptor to be in the plasma membrane- which is, in fact the case.
Lipid-soluble signaling molecules, such as aldosterone, ross the membranes of all cells but affect only target cells because
Intracellular receptors are present only in target cells.
How many chromosomes are drawn in each part of Figure 12.5 (Ignore the micrograph in part 2.)
1; 1; 2
A chicken has 78 chromosomes in its somatic cells. How many chromosomes did the chicken inherit from each parent? How many chromosomes are in each of the chicken's gametes? How many chromosomes will be in each somatic cell of the chicken's offspring?
39; 39; 78
How many chromosomes are drawn in Figure 12.8? Are they duplicated? How many chromatids are shown?
6 chromosomes, duplicated; 12 chromatids.
Compare cytokinesis in animal cells and plant cells.
Following mitosis, cytokinesis results in two genetically identical daughter cells in both plant cells and animal cells. However, the mechanism of dividing the cytoplasm is different in animals and plants. In an animal cell, cytokinesis occurs by cleavage, which divides the parent cell in two with a contractile ring of actin filaments. In a plant cell, a cell plate forms in the middle of the cell and grows until its membrane fuses with the plasma membrane of the parent cell. A new cell wall grows inside the cell plate.
During which stages of the cell cycle does a chromosomes consist of two identical chromatids?
From the end of S phase in interphase through the end of metaphase in mitosis.
How does MPF allow a cell to pass the G2 phase checkpoint and enter mitosis? (See Figure 12.16)
A sufficient amount of MPF has to exist for a cell to pass G2 checkpoint; this occurs through the accumulation of cyclin proteins, which combine with Cdk to from (active) MPF.
Through a microscope, you can see a cell plate beginning to develop across the middle of a cell and nuclei forming on either side of the cell plate.This cell is most likely
A plant cell in the process of cytokinesis.
Vinblaste is a standard chemotherapeutic drug used to treat cancer. Because it interferes with the assembly of microtubules, its effectiveness must be related to
Disruption of mitotic spindle formation.
One difference between cancer cells and normal cells is that cancer cells
Continue to divide even when they are tightly packed together.
The decline of MPF activity at the end of mitosis is due to
The degradation of cyclin.
In the cells of some organisms, mitosis occurs without cytokinesis. This will result in
cells with more than one nucleus.
A particular cell has half as much DNA as some other cells in a mitotically active tissue. The cell in question is most likely in
In the light micrograph below of dividing cells near the tip of an onion root, identify a cell in each of the following stages: prophase, pro metaphase, metaphase, anaphase, and telophase.Describe the major events occurring at each stage. (Page 250)
Draw on eukaryotic chromosome as it would appear during interphase, during each of the stages of mitosis, and during cytokinesis. Also draw and label the nuclear envelope and microtubules attached to the chromosome(s).
How do asexually reproducing eukaryotic organisms produce offspring that are genetically identical to each other and to their parents?
Such organisms reproduce by mitosis, which generates offspring whose genomes are exact copies of the parent's genome (in the absence of mutation).
In Figure 13.4, how many DNA molecules (double helices) are present (see Figure 12.5)? What is the haploid number of this cell? Is a set of chromosomes haploid or diploid?
Each of the six chromosomes is duplicated, so each contains two DNA double helices. Therefore, there are 12 DNA molecules in the ell. The haploid number, n, is 3. One set is always haploid.
Compare the chromosomes in a cell at metaphase of mitosis with those in a cell at metaphase II. (See Figures 12.7 and 13.8) Draw too! Good quiz question!
13.3 CC #1 A-12.
The diploid number for fruit flies is 8, and the diploid number for grasshoppers is 46. If no crossing over took place, would the genetic variation among offspring from a given pair of parents be greater in fruit flies or grasshoppers? Explain.
13.4 #2 CC A-12.
If maternal and paternal chromatids have the same two alleles for every gene, will crossing over lead to genetic variation?
If the segments of the maternal and paternal chromatids that undergo crossing over are genetically identical and thus have the same two alleles for every gene, then the recombinant chromosomes will be genetically equivalent to the parental chromosomes. Crossing over contributes to genetic variation only it involves the rearrangement of different alleles.
A human cell containing 22 autosomes and a Y chromosome is
Homologous chromosomes move toward opposite poles of a dividing cell during
Meiosis II is similar to mitosis in that
Sister chromatids separate during anaphase.
If the DNA content of a diploid cell in the G1 phase of the cell cycle is x, the the DNA content of the same cell at metaphase of meiosis I would be
If we continued to follow the cell lineage from question 4, then the DNA content of a single cell at metaphase of meiosis II would be
How can you tell that the cell in question 6 is undergoing meiosis, not mitosis?
The cell must be undergoing meiosis because homologous chromosomes are associated with each other at the metaphase plate; this does not occur in mitosis.
Many species can reproduce either asexually or sexually. What might be the evolutionary significance of the switch from asexual to sexual reproduction that occurs in some organisms when the environment becomes unfavorable?
Pea plants heterozygous for flower position and stem length (AaTt) are allowed to self-pollinate, and 400 of the resulting seeds are planted. Draw a Punnett square for this cross. How many offspring would be predicted to have terminal flowers and be dwarf? (See Table 14.1)
CC 14.1 #1
List all gametes that could be made by a pea plant heterozygous for seed color, seed shape, and pod shape (YyRrIi; see Table 14.1). How large a Punnet square would you need to draw to predict the offspring of a self-pollination of this "trihybrid"?
The plant could make eight different gametes (YRI, YRi, YrI, Yri, yRI, yRi, yrI, and yri). To fit all the possible gametes in a self-pollination, a Punnett square would need 8 rows and 8 columns. It would have spaces for the 64 possible unions of gametes in the offspring.
If a man with type AB blood marries a woman with type O, what blood types would you expect in their children? What fraction would you expect of each type?
Half of the children would be expected to have type A blood and half type B blood.
A rooster with gray feathers and a hen of the sam phenotype produce 15 gray, 6 black, and 8 white chicks. What is the simplest explanation for the inheritance of these colors in chickens? What phenotypes would you expect in the offspring of a cross between a gray rooster and a black hen?
The black and white alleles are incompletely dominant, with heterozygotes being gray in color. A cross between a gray rooster and a black hen should yield approximately equal numbers of gray and black offspring.
Beth and Tom each have a sibling with cystic fibrosis, but neither Beth nor Tom nor any of their parents have the disease. Calculate the probability that if this couple has a chid, the child will have cystic fibrosis. What would be the probability if a test revealed the Tom is a carrier but Beth is not? Explain your answers.
1/9 (Since cystic fibrosis is caused by a recessive allele, Beth and Tom's siblings who have CF must be homozygous recessive. Therefore, each parent must be a carrier of the recessive allele. Since neither Beth nor Tom has CF, this mean they have a 2.3 chance of being a carrier. If they are both carriers, there is a 1/4 chance that they will have a child with CF. 2/3 X 2/3 X 1/4= 1/9); 0 (Both Beth and Tom would have to be carriers to produce a child with the disease.)
Joan was born with six toes on each foot, a dominant trait called polydactyl. Two of her five siblings and her mother, but not her father, also have extra digits. What is Joan's genotype of the number-of-digits character? Explain your answer. Use D and d to symbolize the alleles for this character.
Draw it- Two pea plants heterozygous for the characters of pod color and pod shape are crossed. Draw the Punnett square to determine the phenotypic ratios of the offspring.
TYU 1- 14
A man has six fingers on each hand and six toes on each foot. His wife and their daughter have the normal number of digits. Remember that extra digits is a dominant trait. What fraction of this couple's children would be expected to have extra digits?
Propose a possible reason that the first naturally occurring mutant fruit fly Morgan saw involved a gene on a sex chromosome.
To show the mutant phenotype, a male needs to possess only one mutant allele. If this gene had been on a pair of autosomes, two mutant alleles would have had to be present for an individual to show the recessive mutant phenotype, a much less probable situation.
A white-eyed female Drosophila is mated with a red-eyed (wild-type) male, the reciprocal cross of the one shown in 15.4. What phenotypes and genotypes do you predict for the offspring?
CC 15.2 #1
Neither Tim nor Rhoda has Duchenne muscular dystrophy, but their firstborn son does. What is the probability that a second child will have the disease? What is the probability if the second child is a boy? A girl?
Genes A, B, and C are located on the same chromosome. Testcrosses show that the recombination frequency between A and B is 28%and between A and C is 12%. Can you determine the linear order of these genes? Explain.
The ABO blood type locus has been mapped on chromosome 9. A father who has type AB blood and a mother who has type O blood have a child with trisomy 9 and type A blood. Using this information, can you tell in which parent the nondisjunction occurred? Explain your answer. (See Figure 14.11.)
No. The child can be either IAIAi or IAii. A sperm of genotype IAIA could result from nondisjunctionin the father during meiosis II, while an egg with the genotype ii could result from nondisjunction in the mother during either meiosis I or meiosis II.
The gene that is activated on the Philadelphia chromosome codes for an intracellular tyrosine kinase. Review the discussion of cell cycle control in Concept 12.3, and explain how the activation of this gene could contribute to the development of cancer.
A wild-type fruit fly (heterozygous for gray body color and normal wings) is mated with a black fly with vestigial wings. The offspring have the following phenotypic distribution: wild-type, 778; black vestigial, 785; black-normal, 158; gray-vestigial, 162. What is the recombination frequency between these genes for body color and wing size? Is this consistent with the results of the experiment in Figure 15.9?
Page 311 #4
Between T and A, 12%; between A and S, 5%.
Page 311 #5
Between nT and S, 18%; sequence of genes is T-A-S.
Page 311 #12
As you learned in Chapter 12, mitosis gives rise to two daughter cells that are genetically identical to the parent cell. Yet you, the product of many mitotic divisions, are not composed of identical cells. Why?
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