Ch. 8 Bio Hons pt. 2
How many pairs of autosomes do humans have?
22
A human somatic cell contains __________ chromosomes.
46
Which of these gametes contains one or more recombinant chromosomes?
B and C
During meiosis I, homologous chromosomes form a tetrad and crossing over occurs. What is the outcome of crossing over?
Crossing over creates new combinations of genes present on a single chromosome.
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.
In the picture below, the chromosomal region where the nonsister chromatids are crossing over is called a(n) _____.
chiasma
Meiosis differs from mitosis in that _____ only occurs in meiosis.
crossing over
Meiosis II typically produces _____ cells, each of which is _____.
four ... haploid
What is formed at the end of meiosis?
four genetically different cells
Meiosis starts with a single diploid cell and produces
four haploid cells.
Collectively, reproductive cells are referred to as
gametes
Unlike mitosis, meiosis results in the formation of
haploid cells
In anaphase I, __________.
homologous chromosomes move toward opposite poles
During prophase I of meiosis,
homologous chromosomes stick together in pairs.
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
Variation occurs when chromosomes are shuffled in _____.
meiosis
During _____ chromosomes align single file along the equator of a haploid cell.
metaphase II
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
A karyotype is most like
photographs of every couple at a high school prom.
In a cell containing 10 chromosomes, meiosis results in the formation of daughter cells containing __________ chromosomes.
5
Homologous chromosomes pair and cross over in
Prophase I
Synapsis occurs during _____.
Prophase I
Which of the following is a key difference between meiosis and mitosis?
Synapsis occurs.
The correct order of events during meiosis is
prophase I, metaphase I, anaphase I, telophase I, cytokinesis, meiosis II.
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.
During _____ a spindle forms in a haploid cell.
prophase II
Which processes lead to most genetic variation in sexually reproducing organisms?
random fertilization, independent orientation of chromosomes in meiosis, crossing over
The exchange of parts between nonhomologous chromosomes is called _____.
reciprocal translocation
In meiosis II, _____.
sister chromatids are separated
An example of a cell that is 2n is a __________.
somatic cell
At the end of _____ and cytokinesis, haploid cells contain chromosomes that each consist of two sister chromatids.
telophase 1
At the end of _____ and cytokinesis there are four haploid cells.
telophase II
Meiosis I produces _____ cells, each of which is _____.
two ... haploid
A cell preparing to undergo meiosis duplicates its chromosomes during
interphase
Mitosis and cytokinesis result in the formation of __________; meiosis and cytokinesis result in the formation of __________.
two diploid cells : four haploid cells
Homologous chromosomes possess the same genes arranged in the same order but may possess different __________ of some of these genes.
versions
In meiosis, the chromosomes are replicated during
Interphase
Which of the following statements regarding mitosis and meiosis is false?
Meiosis provides for asexual reproduction.
Mitosis and Meiosis Key Differences: Mitosis: - Somatic Cells - Diploid - 2 daughter cells - identical - single division - asexual reproduction - no crossing over
Meiosis: - Gametes - Haploid Cells - 4 daughter cells - genetically varied - 2 divisions - sexual reproduction - crossing over
Which of the following statements regarding mitosis and meiosis is false?
Mitosis produces daughter cells with half the number of chromosomes as the parent cell.
Which of the following variations of the sentence "Where is the cat?" is most like a chromosomal inversion?
Where the is cat?
Crossing over is important because it __________.
allows the exchange of different versions of genes between homologous chromosomes
Homologous chromosomes migrate to opposite poles during _____.
anaphase 1
During _____ sister chromatids separate.
anaphase II