BSC 120 Chapter 15
Place the steps of mitotic division in the correct order Anaphase Prophase Interphases Prometaphase Metaphase Telophase
1. 2. 3. 4. 5. 6. .
Consider a cell that has three pairs of chromosomes. What fraction of the gametes produced from this cell will contain only maternal chromosomes?
1/12 1/8 1/4 1/2 1/6
Consider a cell that has a diploid chromosome number of 10 (2n=10). How many possible genetically distinct gametes can this cell produce?
100 32 1024 16 10
Which of the following causes an extra copy of a chromosomal region to occur?
100 32 1024 16 10
Which of the following describes meiosis II in humans?
1N -> 1N 4N -> 2N 2N -> 1N 1N -> 2N 2N -> 2N
If sister chromatids failed to separate during meiosis II, what would the resulting gametes look like?
2 gametes will have 2 of the affected chromosomes and 2 gametes will have 0 of the affected chromosomes. 2 gametes will be normal, 1 gamete will have 2 of the affected chromosomes, and 1 gamete will have 0 of the affected chromosomes. None of the gametes will have any of the affected chromosomes. 2 gametes will be normal and 2 gametes will have 0 of the affected chromosomes chromosomes. 2 gametes will be normal and 2 gametes will have 2 of the affected chromosomes chromosomes.
Arrange the following events in the proper order in which they occur during meiosis I. 1 = Separation of homologous chromosomes 2 = Synapsis 3 = Crossing-over 4 = Random assortment of chromosomes on metaphase plate
2, 3, 1, 4 1, 3, 2, 4 1, 2, 3, 4 2, 4, 3, 1 2, 3, 4, 1
An organism possesses an inversion in only one homologue of a chromosomal pair. When this organism's germ cells undergo meiosis, how many of its gametes will also possess the inversion (assume crossing over does NOT occur)?
3/4 of its gametes none of its gametes 1/2 of its gametes 1/4 of its gametes all of its gametes
Consider a cell that has four pairs of chromosomes. How many orientations of all chromosomes are possible during meiosis I in that cell?
32 16 8 24 4
How many bivalents are formed in a cell with 20 chromosomes at the beginning of meiosis I?
40 5 10 1 20
A plant has a reciprocal translocation between two chromosomes. It is heterozygous for this translocation, i.e. one set of chromosomes is normal, without the translocation. What effect can you be sure that this translocation has on the health and fertility of the plant?
All of the plant's gametes will be viable due to proofreading enzymes that will fix translocations in the chromosomes before DNA replication occurs. The plant will make some normal gametes (with the full complement of DNA) and some abnormal gametes (without the full complement of DNA). The plant will not be able to compete with other plants that do not have the translocation, and so it probably die due to lack of resources. The plant will not be able to make any normal gametes (i.e. no gametes will have a full complement of DNA). The plant will die before it can reproduce.
Which type of chromosomal mutation will usually have the MOST detrimental effect on organsimal function and why?
An inversion, because genes will run in the 3' to 5' direction instead of the 5' to 3' direction. A duplication, because there will be twice as much protein produced for genes in the affected region. A deletion, because there will be no protein product produced for genes in the affected region. A reciprocal translocation, because two chromosomes are disrupted. A simple translocation, because genes lie on a different chromosome than they should.
Which of the following is NOT a true difference between mitosis and meiosis?
As a result of mitosis, daughter cells are identical to each other; as a result of meiosis, daughter cells are genetically different from each other. During prophase of mitosis, chromosomes are condensing; during prophase II of meiosis, chromosomes are already condensed from meiosis I. During cytokinesis associated with meiosis II, four daughter cells are produced; during cytokinesis associated with mitosis, two daughter cells are produced. During anaphase I of meiosis, homologous chromosomes are separated; during anaphase of mitosis, sister chromatids are separated from each other. During telophase of meiosis I, daughter nuclei are haploid; during telophase of mitosis, daughter nuclei are diploid.
Which statement about mitosis and cytokinesis is TRUE?
At the end of cytokinesis there are two daughter cells with half the number of chromosomes as the parent cell. At the end of cytokinesis there are two daughter cells with a normal complement of diploid genetic material. At the end of mitosis the DNA is replicated, but sister chromatids have not yet separated. At the end of mitosis there are two daughter cells with half the number of chromosomes as the parent cell. At the end of mitosis there are two daughter cells with a normal complement of diploid genetic material.
Enter your answer in the provided box. A research scientist is observing cell division in cells derived from a diploid organism. She traps the cell at the end of mitotic prophase and counts a total of 128 chromatids.
Based on this count, how many chromosomes would be contained in a normal gamete for this organism? _______________________ chromosomes
Which of the following statements about microtubules during anaphase is TRUE?
Both attached and unattached microtubules elongate. Both attached and unattached microtubules shorten. Those attached to chromosomes elongate, while those that are unattached shorten. Those attached to chromosomes shorten, while those that are unattached elongate. Both attached and unattached microtubules elongate at first and then shorten.
During the G2 phase, the cell is preparing for mitosis. Using the knowledge of cellular organelles and molecules, which molecule is produced in the highest quantity during the G2 phase?
Ca2+ pump proteins rRNA DNA Polymerase tubulin, the microtubule protein DNA
Normally, crossing over occurs between homologous regions of homologous chromosomes. Sometimes mistakes happen, and crossing over occurs between non-homologous regions of homologous chromosomes, resulting in duplications and deletions. What characteristic of a chromosome would make non-homologous recombination more likely?
Chromosomes that have a large amount of heterochromatin Chromosomes that have a large number of restriction sites Chromosomes that have duplicated regions within them Chromosomes that are very long Chromosomes that are very short
In germline cells, when does DNA replicate?
During the G1 phase Immediately proceeding prophase I During prophase I During the interkinesis, between telophase I and prophase II During the S phase
The cell cycle consists of several checkpoints at which the cycle can be stopped before continuing to the next phase. Which of the following is not a function of these checkpoints?
Ensuring that conditions are favorable for DNA replication and cell division Limiting the amount of daughter cells that might contain genetic abnormalities Supplying energy for the replication of chromosomes into pairs of sister chromatids Making sure chromosomes are correctly replicated before nuclear division is complete Preventing the start of mitosis until all chromosomes are fully replicated
Which of the following represents the correct order of the phases of the cell cycle?
G1 -> S -> G2 -> M G1 -> G2 -> M -> S G1 -> G2 -> S -> M G1 -> M -> G2 -> S G1 -> S -> M -> G2
During which stage of meiosis would you find a cell with a diploid chromosome number and recombinant chromosomes?
G2 metaphase I prophase II anaphase II at the completion of meiosis I
A research lab is working with a particular species of insect that is known to be diploid with 14 chromosomes. While sorting through a colony of these insects, the researchers happen upon an unusual phenotype in one particular individual. It is determined that this organism is aneuploid, with a total of 15 chromosomes. What number of chromosomes must have been present in the two gametes that united to form the zygote?
Gamete 1 (normal): ___________ chromosomes Gamete 2 (resulting from nondisjunction): __________ chromosomes
Consider a normal chromosome with the following gene sequence along its length F G H I J K L. Which of the following sequence represents an inversion?
H I J K L F G H K L J K L F G H I F G H I J K J K L F G K J I H L
Polyploidy in wheat is common. The tetraploid species (2n=4x=28) Triticum dicoccoides and Triticum araraticum are the wild ancestors of most domestic tetraploid varieties. There are no wild hexaploid species. Triticum aestivum is the common, hexaploid (2n=6x=42) wheat that is used to make bread and other baked goods. It is the result of a cross between a domestic tetraploid wheat (such as Triticum durum, the wheat used to make pasta) and a wild diploid goat grass Aegilops tauschii. Which of the following statements about wheat is TRUE?
Hexaploid wheat is more desirable than tetraploid wheat Wheat species that are tetraploid are more closely related to hexaploid species than to other tetraploid wheat species Wheat species that are hexaploid have a higher level of diversity within their genomes than do wheat species that are tetraploid of diploid Hexaploid wheat have smaller, abnormally shaped cells compared to its tetraploid or diploid relatives Hexaploid wheat is, for the most part, sterile
Choose the correct terms that apply to the following statements about Prophase I of meiosis bivalent eight one crossing over two cytokinesis synapsis chaisma centromere four
Homologous chromosomes pair together to form a ____________ . The process of pairing of homologous chromosomes is called ____________ . In each bivalent, there would be a total of ____________ centromere(s). In a bivalent, you should be able to see ____________ total sister chromatids. A physical exchange of material between two homologous chromosomes is called ____________ . The visible evidence that exchange of genetic material has occurred is called a ____________ .
Insert the correct terms to complete the following statements about changes in chromosome number. down syndrome patau syndrome klinefleter syndrome aneuploid edward syndrome euploid as less more haploid turner syndrome
In ____________ , an extra chromosome 21 is present in body cells. In ____________ , there is only a single X chromosome present (and no Y chromosome). In ____________ , there is trisomy for chromosome 13. An abnormality in chromosome number is called a/an ____________ state. Individuals with ____________ develop as sterile males, although they have an extra X chromosome (XXY). In general, abnormalities involving autosomes are ____________ severe (i.e. include mental impairment) than those involving the sex chromosomes.
How is the formation of the spindle during mitosis and meiosis I different?
In mitosis spindle fibers shorten to separate sister chromatids. In meiosis spindle fibers elongate to push homologous chromosomes to opposite ends of the cell. In mitosis the spindle arises from two centrosomes. In meiosis I it arises from a single centrosome. In mitosis the spindle fibers from only one centrosome attach to a chromosome's centromere. In meiosis I spindle fibers from both centrosomes attach to each chromosome's centromere. In mitosis the spindle arises from a single centrosome. In meiosis I it arises from two centrosomes. In mitosis spindle fibers from both centrosomes attach to each chromosome's centromere. In meiosis I the spindle fibers from only one centrosome attach to a chromosome's centromere.
Why are two phases of meiosis necessary?
In order to produce 4 gametes In order to both reduce the chromosome number and separate sister chromatids All of these In order to produce two daughter cells In order to maximize variation in the next generation
Which of the following statements about crossing over is TRUE?
It occurs only between genes that are heterozygous. None of these statements are true regarding crossing over. It results in reduced genetic variation among gametes. It occurs only in males. It occurs only in some chromosomes.
How long does crossing over increase variation in a population?
It produces differences in the frequency of alleles between two generations. It produces point mutations in alleles that could act as novel variation. It produces offspring with alleles that neither parents carried. All of these are ways that crossing over effects variation in a population. It produces offspring with combinations of alleles that neither parent carried.
Docetaxel is a drug that is used in the treatment of cancer. It interferes with cell division by inhibiting microtubule depolymerization. Specifically, what effect will this have on mitosis?
It will prevent chromosomes from fully condensing during prophase. It will prevent sister chromatids from separating during anaphase. It will prevent cytokinesis from completing. It will prevent chromosomes from lining up on the metaphase plate. All of these choices will occur
Crossing over often occurs during prophase. How could scientists use an easy to measure trait that is linked to the gene responsible for a certain genetic condition to locate the disease causing gene?
Linked traits are controlled by the same genes, so they are not separated by crossing over. Linked traits are on different chromosomes, so they do not experience crossing over. Linked traits occur very close together on a chromosome, so they are not usually separated by crossing over. Linked traits occur very far away on a chromosome, so they are not usually separated by crossing over. Linked traits are only controlled by a single parent (usually the mother), so they are not separated by crossing over.
Which of the following statements about the mitotic spindle is TRUE?
Microtubules in the mitotic spindle attach directly to the DNA in the centromere Kinetochore microtubules in the mitotic spindle attempt to connect to kinetochore proteins in the centromeres of the condensed chromosomes. Centrioles are necessary for the proper separation of sister chromatids Kinetochore proteins make up kinetochore microtubules, which connect to the centromeres of the condensed chromosomes Astral microtubules extend toward the opposite centrosome and overlap with polar microtubules to properly position the spindle
If a homologous pair of chromosomes fails to separate during meiosis I, what will be the result?
None of the gametes will have the affected chromosomes. 2 gametes will be normal and 2 gametes will have 2 of the affected chromosomes. 2 gametes will have 2 of the affected chromosomes and 2 gametes will have 0 of the affected chromosomes. 2 gametes will be normal, 1 gamete will have 2 of the affected chromosomes and 1 gamete will have 0 of the affected chromosomes. 2 gametes will be normal and 2 gametes will have 0 of the affected chromosomes.
Meiosis II separates sister chromatids. What might make sister chromatids differ from each other?
None of these, sister chromatids will always be identical If sister chromatids were recombined during crossing over If sister chromatids come from different homologous chromosomes If sister chromatids were randomly assorted during meiosis I If sister chromatids were heterozygous
Part of a chromosome is duplicated. Why might this be a positive evolutionary force?
Organisms that are able to survive chromosomal mutations, like duplications, must already be highly fit. If an organism make twice as much protein, it will be better suited to its environment. Organisms with bigger genomes are better able to cope with environmental change. If there are two genes, one is free to mutate and take on a different function. It won't -- all mutations are detrimental to an organism.
Using the chart at the beginning of the animation and your knowledge of cells, in what stage of the cell cycle do most cells spend the majority of their lives?
S C G1 M G2
Why do chromosomes condense during prophase?
So that sister chromatids will stay together All of these are TRUE So that they will not be damaged when they are moved around the cell So we can see them So that a centromere will form
Chromosome duplication occurs prior to both mitosis and meiosis.
TRUE FALSE
Why must chromosomes form a loop in order to pair during meiosis if not of the homologues has an inversion?
The chromosome with the inversion is missing a section that the normal chromosome possesses, this causes the normal chromosome to form a loop in that region. Chromosomes with an inversion must form a loop when they pair with their homologue so that they don't pair with nonhomologous chromosomes that have the same inversion. In order for homologous regions of the normal and inverted chromosomes to align, a loop must form. The inversion causes a kink in the DNA that take on a looped structure when chromosomes condense. All of these are reasons why chromosomes must form a loop in order to pair during meiosis if one of the homologues has an inversion.
How can you compare the complement of DNA in an interphase (G1) diploid cell and a cell that has just completed meiosis 1?
The meiotic cell has twice as much DNA and twice as many chromosomes. They have the same number of chromosomes, but the meiotic cell has half as much DNA. They have the same amount of DNA, but the meiotic cell has twice as many chromosomes. The meiotic cell has half as much DNA and half as many chromosomes. They have the same amount of DNA, but the meiotic cell has half as many chromosomes.
In a translocation, the absolute amount and content of the genome remains the same. Why might some translocations still make an organism inviable?
Translocations will cause some segments of the chromosome to be deleted, so there will be no protein produced from genes in those regions. Translocations are mutations, and all translations are detrimental to an organism. Translocations may cause problems during gamete formation when homologous chromosomes are pairing. Translocations may have break points in the middle of a gene, causing it to become nonfunctional. Trasnlocations move genes to a chromosome that they are not supposed to be on.
Random orientation of chromosomes during meiosis increases the amount of variation in the next generation. What other process during meiosis leads to an increase in variation in the next generation?
Two distinct phases, meiosis I and meiosis II. Attachment of the spindle fibers to homologous chromosomes. Crossing over between homologous chromosomes. All of these lead to increased variation in the next generation. The formation of 4 haploid daughter cells.
Mitosis results in the formation of two genetically identical daughter cells. This is because
after replication, the material is compared and corrected to be identical. the chromosomes pair up (synapse) in prophase as a counting mechanism. all the genetic material is duplicated then segregated equally to the daughter cells. daughter cells are initially haploid, but they duplicate their chromosomes to become diploid again. the number of chromosomes needs to be reduced before cytokinesis.
The spindle apparatus is fully formed by the end of
anaphase II. metaphase II. prometaphase II. telophase II. prophase II.
The four daughter cells produced in meiosis
are diploid just like the parent cell. have one of each pair of chromosomes found in the parent cell. have double the number of chromosomes as the parent cell. have identical chromosomes. have one-fourth the number of chromosomes of the parent cell.
In meiosis, a chromosome carrying an inversion
cannot pair with a normal homologous chromosome. can pair with any non-homologous chromosome. can pair with a normal homologous chromosome by forming an internal loop. can only pair with a chromosome carrying the same inversion. can only pair with a chromosome carrying a different inversion.
Which of the following is unique to meiosis?
chromosomes align along the central plate of the cell nuclear membrane breaks down crossing-over none of these choices. DNA organizes into chromosomes
Which of the following events do NOT occur in prophase of mitosis?
chromosomes are replicated nucleolus breaks down mitotic spindle begins to form nuclear membrane breaks down DNA condenses to form chromosomes
The number of cells produced in meiosis is
equal to the number of cells produced in mitosis. one-fourth the number of cells produced in mitosis. twice the number of cells produced in mitosis. half the number of cells produced in mitosis. four times the number of cells produced in mitosis.
Daughter cells produced in meiosis have
half the number of chromosomes as daughter cells produced in mitosis. twice the number of chromosomes as daughter cells produced in mitosis. one-fourth the number of chromosomes as daughter cells produced in mitosis. four times the number of chromosomes as daughter cells produced in mitosis. the same number of chromosomes as daughter cells produced in mitosis.
At the end of meiosis I, each daughter cell is
haploid, and each chromosome consists of a single chromatid. haploid, containing a mixture of single- and double-chromatid chromosomes. diploid, and each chromosome consists of two chromatids. haploid, and each chromosome consists of two chromatids. diploid, and each chromosome consists of a single chromatid.
Separation of _________________ occurs in anaphase II of meiosis
homologous chromosomes sister chromatids the two nuclei non-sister chromatids non-homologous chromosomes
During anaphase I of meiosis, _____________ move towards opposite cell poles, whereas during anaphase II of meiosis, __________ are separated.
homologous chromosomes ; non-sister chromatids homologous chromosomes ; sister chromatids homologous chromosomes ; non-homologous chromosomes sister chromatids ; homologous chromosomes sister chromatids ; non-sister chromatids
Which of the following occurs when a piece of one chromosome breaks off and is attached to another chromosome?
inversion duplication deletion reciprocal translocation simple translocation
When a chromosome is broken in two pieces and reconnected so that a region is flipped from the normal order, this is called...
inversion duplication reciprocal translocation deletion simple translocation
a 2n=6 germline cell completes meiosis I. Each daughter cell
is 2n = 3. is a haploid gamete. contains six chromosome, each composed of two sister chromatids. contains three chromosomes, each composed of two sister chromatids. is n = 6.
The mitotic spindle fibers attach to chromosomes via special structures termed
keratins. centrioles. asters. kinetochores. centrosomes.
Which of the following represents the correct order of the phases of mitosis?
metaphase -> prophase -> telophase -> anaphase prophase -> metaphase -> telophase -> anaphase prophase -> metaphase -> anaphase -> telophase metaphase -> prophase -> anaphase -> telophase prophase -> anaphase -> metaphase -> telophase
Random orientation of homologous chromosomes occurs in __________ of meiosis.
metaphase I metaphase II prophase II anaphase I prophase I
During which state of meiosis would you find haploid cells with 1/4 as much DNA as its mother cell when it began meiosis I?
metaphase I telophase I telophase II prophase II prophase I
Sister chromatids separate in
mitosis and meiosis II. mitosis, meiosis I and meiosis II. mitosis and meiosis I. meiosis II only. meiosis I and meiosis II.
The division of the cytoplasm is called
mitosis. meiosis. synapsis. cytogenetics. cytokinesis.
Which of the following events occur during prophase I?
movement of centrosomes breakdown of nuclear envelope, condensation of chromosomes, and movement of centrosomes breakdown of nuclear envelope and condensation of chromosomes breakdown of nuclear envelope condensation of chromosomes
A crossover in meiosis is an exchange of genetic material between
non-sister chromatids of non-homologous chromosomes. non-sister chromatids of homologous chromosomes. sister chromatids of the same chromosome. sister chromatids of non-homologous chromosomes. sister chromatids of homologous chromosomes.
Crossing over is possible due to what event that occurs in meiosis I but not mitosis?
nondisjunction synapsis reduction division karyokinesis independent assortment
If crossing over occurs between two chromatids on a single pair of homologous chromosomes, how many gametes will have a recombinant chromosome?
none of them 3 of the 4 2 of the 4 all 4 1 of the 4
An inversion is best described as a
reversal of the sex of an individual. change in the DNA from an A-T base pair to a G-C base pair. change from the homozygous to the heterozygous state. change from the dominant to the recessive form of a gene. reversal in the orientation of a segment of a chromosome.
Which of the following events occur during anaphase I?
separation of homologous chromosomes, formation of synaptonemal complex, and lengthening of kinetochore microtubules separation of homologous chromosomes and formation of synaptonemal complex formation of synaptonemal complex separation of homologous chromosomes lengthening of kinetochore microtubules
In meiosis I _________________.
sister chromatids are separated, producing haploid daughter cells the cell prepares for its second round of DNA replication that will occur before meiosis II homologous chromosome pairs are separated, producing diploid daughter cells homologous chromosome pairs are separated, producing haploid daughter cells kinetochore microtubules attach to both sister chromatids of each homologous pair
A crossover in meiosis is an exchange of genetic material between
sister chromatids of the same chromosome. sister chromatids of non-homologous chromosomes. non-sister chromatids of homologous chromosomes. sister chromatids of homologous chromosomes. non-sister chromatids of non-homologous chromosomes.
Synapsis is the side-by-side alignment of
spindle fibers. homologous chromosomes. nuclei prior to the division of the cytoplasm. sister chromatids of a chromosome. non-homologous chromosomes.
The function of sexual reproduction is to increase variation within populations. Meiosis is the molecular mechanism that leads to sexual reproduction. As such, some of the features that make it unique lead to genetic diversity. Which of these unique features are responsible for increasing genetic diversity?
synapsis homologous recombination synapsis and homologous recombination homologous recombination and reduction division reduction division
Which of the following features are unique to meiosis?
synapsis, homologous recombination, and reduction division synapsis and homologous recombination reduction division synapsis homologous recombination
At the end of meiosis II, there are
two haploid cells, with each chromosome consisting of a single chromatid. four haploid cells, with each chromosome consisting of a single chromatid. two haploid cells, with each chromosome containing two sister chromatids. four diploid cells, with each chromosome consisting of a single chromatid. four haploid cells, with each chromosome containing two sister chromatids.
A tetrad is made up of
two homologous pairs of chromosomes. two homologous chromosomes, each consisting of two chromatids. four non-homologous chromatids. four non-homologous chromosomes. four homologous pairs of chromosomes.
