chapter 8 meiosis study guide
Drag the labels onto the grid to indicate the phases of mitosis and meiosis. Use only pink labels for pink targets.
a - mitosis b-prophase c-metaphase d-anaphase,telophase,cytokinesis e-meiosis f-propase i g-metaphase i h-anaphase i, telophase i, cytokinesis i - meiosis ii
Drag the terms to complete the concept map below.
a-diploid organisms b-haploid gametes c-meiosis II d-maternal chromosomes e-crossing over occurs f-sister chromatids separate
If a fragment of a chromosome breaks off and then reattaches to the original chromosome at the same place but in the reverse direction, the resulting chromosomal abnormality is called _____.
an inversion
Click on the diagram to view an animation. This animation illustrates the events of _____.
anaphase I
Homologous chromosomes migrate to opposite poles during _____.
anaphase I
Click on the diagram to view an animation. This animation illustrates the events of _____.
anaphase II
During _____ sister chromatids separate.
anaphase II
The diploid phase of the human life cycle begins with _____.
fertilization
Drag each image to the phase of meiosis II it depicts.
first image - prophase ii second image - metaphase ii third image - anaphase ii fourth image - telophase ii / cytokinesis
Meiosis II typically produces _____ cells, each of which is _____.
four ... haploid
The function of meiosis is to make _____.
four cells with a haploid number of chromosomes
Meiosis starts with a single diploid cell and produces
four haploid cells
What is the typical result when a diploid cell undergoes meiosis?
four haploid cells
The _____ separate in meiosis I; the _____ separate in meiosis II.
homologous chromosomes ... sister chromatids
In anaphase I, _____.
homologous chromosomes move toward opposite poles
During prophase I of meiosis,
homologous chromosomes stick together in pairs.
A cell preparing to undergo meiosis duplicates its chromosomes during
interphase
Click on the diagram to view an animation. This animation illustrates _____.
interphase
A fragment of chromosome 21 reattaches to chromosome 21, but in the reverse direction. What is the name given to this change?
inversion
When we say that an organism is haploid, we mean that _____.
its cells each have one set of chromosomes
The function(s) of meiosis is/are _____.
reproduction (production of gametes)
In meiosis II, _____.
sister chromatids are separated
During anaphase II, _____.
sister chromatids separate and migrate toward opposite poles
An example of a cell that is 2n is a(n) _____.
somatic cell
Mitosis occurs in _____; meiosis occurs in _____.
somatic or body cells ... germ cells in the testes or ovaries
At the end of _____ and cytokinesis, haploid cells contain chromosomes that each consist of two sister chromatids.
telophase I
Click on the diagram to view an animation. This animation illustrates the events of _____.
telophase I and cytokinesis
At a critical point in meiosis, the chromosomes do not replicate. This occurs between _____.
telophase I and prophase II
At the end of _____ and cytokinesis there are four haploid cells.
telophase II
Click on the diagram to view an animation. This animation illustrates the events of _____.
telophase II and cytokinesis
Fertilization joins _____ to produce a _____.
haploid gametes ... diploid zygote
Meiosis is typically accomplished in _____.
three steps. All of the chromosomes are duplicated in a diploid cell, and then there are two cell divisions to produce a total of four haploid gametes.
A diploid organism whose somatic (nonsex) cells each contain 32 chromosomes produces gametes containing _____ chromosomes.
16
Normal human gametes carry _____ chromosomes.
23
An organism has a haploid chromosome number n = 4. How many tetrads will form during meiosis?
4
In a cell containing 10 chromosomes, meiosis results in the formation of daughter cells containing _____ chromosomes
5
Trisomy for most autosomes is fatal, yet trisomy or even tetrasomy (four copies) of the X chromosome is not. What is the explanation for this difference?
Only one copy of the X chromosome is active, regardless of the total number of X chromosomes.
Drag each image to the phase of meiosis I it depicts.
Prophase I - blue background, smaller spindle metaphase I - blue background, larger spindle with visible chromosomes Anaphase I - yellow background with spindle Telophase/cytokinesis - yellow background with cells
The M phase of mitosis and M phase of meiosis both occur after interphase. However, the two processes differ in the arrangement and behavior of their chromosomes. How?
The pairing up of homologous chromosomes and crossing over only occur during meiosis.
During meiosis I, homologous chromosomes form a tetrad. What does this accomplish?
This brings the chromosomes into alignment so that crossing over can create new combinations of genes present on a single chromosome.
Although in humans there are 22 pairs of autosomal chromosomes, only three different chromosomal trisomies are commonly seen in newborns. Of the remaining 19 autosomes, many trisomies have not been seen in newborns. Why not?
Trisomy for the other autosomal chromosomes is often lethal, and the affected embryos are miscarried.
Click on the diagram below. Then click on the enlarged image to view an animation. Click to launch animation Which of these gametes contains one or more recombinant chromosomes?
B and C
Which of these cells is (are) haploid?
C and D
Which event occurs only during prophase I of the first meiotic division?
Synapsis of homologous pairs occurs.
What name is given to this process? To view the animation, click here. Then click on the image to start the animation.
asexual reproduction
Asexual and sexual reproduction differ in that sexual reproduction _____.
can produce great variation among the offspring
In the picture below, the chromosomal region where the nonsister chromatids are crossing over is called a(n) _____.
chiasma
Click on the diagram to view an animation. This animation illustrates the process of _____.
crossing over
Meiosis starts with _____ cells and produces _____ gametes.
diploid ... haploid
Gametes are produced by _____.
meiosis
If it weren't for _____, chromosome number would double with every generation of sexual reproduction.
meiosis
Looking through a light microscope at a cell undergoing meiosis, you see that the chromosomes have joined into XX-shaped tetrads. These tetrads are lined up along a plane that runs through the center of the cell. This cell is in _____.
meiosis I
Click on the diagram to view an animation. This animation illustrates the events of _____.
metaphase I
Click on the diagram to view an animation. This animation illustrates the events of _____.
metaphase II
During _____ chromosomes align single file along the equator of a haploid cell.
metaphase II
During meiosis, the events that occur in _____ are similar to those that occur in _____ of mitosis.
metaphase II ... metaphase
Looking through a light microscope at a cell undergoing division, you see that the condensed chromosomes have lined up along the midline of the cell. The homologous pairs are NOT joined in tetrads. Each chromosome takes its own place in line, independentof its homolog. You are witnessing _____.
metaphase of mitosis
After fertilization, the resulting zygote begins to divide by _____.
mitosis
During meiosis, homologous chromosomes sometimes "stick together" and do not separate properly. This phenomenon is known as _____.
nondisjunction
Duplication of the chromosomes to produce sister chromatids _____.
occurs in both mitosis and meiosis
Asexual reproduction _____.
produces offspring genetically identical to the parent
Click on the diagram to view an animation. This is an animation of _____.
prophase I
Crossing over occurs during _____.
prophase I
During meiosis, segments of nonsister chromatids can trade places. This recombination of maternal and paternal genetic material is a key feature of meiosis. During what phase of meiosis does recombination occur?
prophase I
Synapsis occurs during _____.
prophase I
The correct order of events during meiosis is
prophase I, metaphase I, anaphase I, telophase I, cytokinesis, meiosis II.
Click on the diagram to view an animation. This animation illustrates the events of _____.
prophase II
During _____ a spindle forms in a haploid cell.
prophase II
The exchange of parts between nonhomologous chromosomes is called _____.
reciprocal translocation
In a cell with eight chromosomes, one chiasma develops during meiosis I in only one particular pair of homologs. How many recombinant chromosomes will there be at the completion of meiosis II?
two
Meiosis I produces _____ cells, each of which is _____.
two ... haploid
In theory, when a nondisjunction for chromosome 18 occurs during meiosis I, four gametes can be produced. If these gametes are fertilized with unaffected gametes from the second parent, what observations would you make concerning the resulting embryos?
Two of the embryos will be trisomic for chromosome 18, and two will contain a single copy of chromosome 18.