Homologous chromosomes contain the same gene loci but may have different alleles of a particular gene. Sister chromatids are identical copies of each other produced during DNA replication.
One homologous chromosome comes from the father, and the other comes from the mother. Sister chromatids are identical copies of each other.
How are sister chromatids and homologous chromosomes different from each other?
two … haploid
At the end of meiosis I there are two haploid cells.
Meiosis I produces _____ cells, each of which is _____.
four … haploid
At the end of meiosis II there are typically 4 haploid cells.
Meiosis II typically produces _____ cells, each of which is _____.
anaphase II
Anaphase II is essentially the same as mitotic anaphase except that the cell is haploid.
During _____ sister chromatids separate.
telophase I
At the end of telophase I and cytokinesis, there are two haploid cells with chromosomes that consist of two sister chromatids each.
At the end of _____ and cytokinesis, haploid cells contain chromosomes that each consist of two sister chromatids.
prophase I
Synapsis occurs during _____.
the pairing of homologous chromosomes
occurs in prophase I
occurs in prophase I
What is synapsis?
anaphase I
During anaphase I sister chromatids remain attached at their centromeres, and homologous chromosomes move to opposite poles.
Homologous chromosomes migrate to opposite poles during _____.
metaphase II
Metaphase II is essentially the same as mitotic metaphase except that the cell is haploid.
During _____ chromosomes align single file along the equator of a haploid cell.
telophase II
At the end of _____ and cytokinesis there are four haploid cells.
prophase II
During _____ a spindle forms in a haploid cell.
evolution
Heritable variation is required for which of the following?
Barring mutation, the two sister chromatids must be identical.
Two sister chromatids are joined at the centromere prior to meiosis. Which statement is correct?
The two chromatids were formed by duplication of a chromosome.
This chromosome has two chromatids, joined at the centromere. What process led to the formation of the two chromatids?
The cell is diploid because it contains two sets of chromosomes.
This cell contains two copies of each chromosome, one from the male parent and the other from the female parent, making it diploid.
This cell contains two copies of each chromosome, one from the male parent and the other from the female parent, making it diploid.
What is the best evidence telling you whether this cell is diploid or haploid?
Gametes (sperm and eggs) and Spores
In most animal life cycles, the products of meiosis are gametes. However, in plants, the products of meiosis are spores.
Identify all possible products of meiosis in plant and animal life cycles.
sister chromatids separate during anaphase.
Meiosis II is similar to mitosis in that
2x.
If the DNA content of a diploid cell in the G1 phase of the cell cycle is x, then the DNA content of the same cell at metaphase of meiosis I would be
x.
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
meiosis
Meiosis produces haploid gametes from a diploid parental cell.
Human gametes are produced by _____.
23
This is the number of chromosomes in a single set of human chromosomes.
Normal human gametes carry _____ chromosomes.
16
A diploid organism whose somatic (nonsex) cells each contain 32 chromosomes produces gametes containing _____ chromosomes.
two diploid cells … four haploid cells
In mitosis a cell that has doubled its genetic material divides to produce two diploid daughter cells. In meiosis a cell that has doubled its genetic material undergoes two rounds of division, producing four haploid cells.
Mitosis results in the formation of how many cells; meiosis results in the formation of how many cells?
the exchange of homologous portions of nonsister chromatids
The result is new combinations of genetic material (genetic recombination).
What is crossing over?
tens of thousands
How many genes are present in the human genome?
the precise location of a gene on a chromosome
What is a locus?
they can both occur in multicellular organisms
Sexual and asexual reproduction are alike in that __________.
asexual reproduction and mitosis
A clone is the product of __________.
a photograph of all the chromosomes in a single cell from an individual
A karyotype is __________.
a diploid zygote
Fertilization produces __________.
mitosis, meiosis, and fertilization
The sexual cycle of the diploid, multicellular algal genus Fucus involves __________.
fungi
A life cycle in which the only multicellular form is haploid is most typical of __________.
meiosis … fertilization
In sexually reproducing species, the chromosome number remains stable over time because __________ and __________ always alternate.
44
The egg (ovum) of a rabbit contains 22 chromosomes. How many chromosomes are in the somatic (body) cells of a rabbit?
5
In a diploid cell containing 10 chromosomes, meiosis results in the formation of daughter cells containing __________ chromosomes.
22
How many pairs of autosomes do humans have?
are identical copies of each other formed through DNA synthesis
Sister chromatids __________.
its cells have a single set of chromosomes
When we say that an organism is haploid, we mean that __________.
two … diploid
Somatic cells in humans contain __________ set(s) of chromosomes and are therefore termed __________.
at fertilization, when gametes fuse
Nearly all life cycles have both haploid and diploid phases. Usually, the transition from haploid to diploid takes place __________.
gametes can fuse to form a zygote, but spores can develop into independent organisms without first forming a zygote
Spores and gametes are different in that __________.
liver cells
Humans have 46 chromosomes. This number of chromosomes will be found in __________.
meiosis
What results in cells that contain half the parental chromosome number?
two haploid cells
At the end of telophase I of meiosis and the first cytokinesis, there are __________.
four haploid cells
What is the typical result when a diploid cell has completed meiosis?
prophase I
Synapsis occurs during __________.
Sister chromatids separate and migrate toward opposite poles.
What occurs during anaphase II?
Homologs separate and migrate toward opposite poles.
What occurs during anaphase I?
division of the cytoplasm to create two cells
Cytokinesis is the __________.
to make cells with a haploid (half that of the parents) number of chromosomes
What is the function of meiosis?
prophase I
Crossing over occurs during __________.
chiasmata
Regions of chromosomes where nonsister chromatids cross over are called __________.
physically connects homologous chromosomes during prophase I
The synaptonemal complex __________.
4
An organism has a haploid chromosome number n = 4. How many tetrads will form during meiosis?
Synapsis of homologous pairs occurs.
Which event occurs only during prophase I of the first meiotic division?
Homologous chromosomes separate.
Which of the following occurs in meiosis, but NOT mitosis?
decreasing the chromosome number to haploid introducing genetic variation among the daughter cells ensuring that each daughter cell gets a single, complete set of chromosomes undergoing two rounds of cytokinesis
Which function makes meiosis lengthier and more complex than mitosis?
16
Ignoring crossover events, how many kinds of gametes can be produced by an organism with a diploid number of 8?
random fertilization, independent assortment, crossing over
Which of the following contributes to genetic variation in sexually reproducing species?
223
In humans, the haploid number of chromosomes is 23. Independent assortment has the possibility of producing __________ different types of gametes
They align and assort independently to form any of 16 different combinations.
The diploid number of chromosomes in a certain animal is 8 (2n = 8). How do the four pairs of homologous chromosomes align and separate during meiosis?
1/8
In a diploid set of chromosomes, one member of each pair of homologous chromosomes is derived from the father (paternal), and the other comes from the mother (maternal). If 2n = 6, what is the probability that a particular gamete will contain only paternal chromosomes?
it provides a method to increase genetic variation
The major contribution of sex to evolution is that __________.
Although energetically more costly than asexual reproduction, sexual reproduction leads to different combinations of alleles that could provide adaptability in a changing environment.
Which of the following statements reflects an advantage that sexual reproduction likely provides over asexual reproduction?
sexual reproduction … reproduce asexually but can increase genetic variation present in a population by means of the uptake of DNA from other rotifers
Although __________ is nearly universal among animals, bdelloid rotifers __________.
a sperm.
A human cell containing 22 autosomes and a Y chromosome is
meiosis I.
Homologous chromosomes move toward opposite poles of a dividing cell during
sister chromatids separate during anaphase
Meiosis II is similar to mitosis in that
2x.
If the DNA content of a diploid cell in the G1 phase of the cell cycle is x, then the DNA content of the same cell at metaphase of meiosis I would be
x.
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
part of a chromosome turned around
Unless the chromosomes were stained to show band patterns, a karyotype would be LEAST likely to show which of the following?
Diploid cells can divide by mitosis.
Diploid cells can divide by meiosis.
Haploid cells can divide by mitosis.
Haploid cells cannot divide by meiosis.
Diploid cells can divide by meiosis.
Haploid cells can divide by mitosis.
Haploid cells cannot divide by meiosis.
Which, if any, of the following statements is true?
multicellular haploid stage (gametophyte)
multicellular diploid stage (sporophyte)
zygote
spores
multicellular diploid stage (sporophyte)
zygote
spores
Which of the following is part of the life cycle called alternation of generations?
They have genes for the same traits at the same loci.
Which of the following statements about homologous chromosomes is correct?
multiplication of body cells
Which of the following is a function of mitosis in humans?
the random alignment of homologous pairs of chromosomes at metaphase I
Which of the following answers is NEITHER involved with crossing over NOR an outcome of crossing over?
