Biology 181: Chapter 11
Gametes are haploid. Haploid means that the cells contain how many sets of chromosomes?
1
Meiosis has how many rounds of DNA replication?
1
How many rounds of cell division are required for meiosis?
2
A human gamete contains ________ chromosomes.
23
A human gamete contains how many chromosomes?
23
After crossing over is complete, the homologous chromosomes remain attached at the chiasmata. How many chromatids are attached at this point?
4
At the end of anaphase I in meiosis, each pole of the cell contains which of the following?
A haploid set of duplicated chromosomes
When meiosis occurs without recombination, which of the following has occurred?
Achiasmate segregation
When meiosis proceeds without recombination, this is referred to as ____________ segregation.
Achiasmate segregation
The events of metaphase II include which of the following?
Alignment of individual chromosomes along the metaphase plate
DNA replication should occur (choose all that apply)?
Before meiosis I Before mitosis
In meiosis, when does DNA replication occur?
Before meiosis I only
Gametes produced by meiosis contain which of the following?
Both paternal and maternal chromosomes which have been subject to crossing over
How can the maintenance of low levels of cyclin B between meiosis I and II potentially suppress DNA replication?
By preventing the formation of replication initiation complexes
What is the name for the sites of crossing over in a chromosome?
Chiasmata
When used to characterize the first meiotic division, the term "reductive division" refers to the reduction of which of the following?
Chromosomes
Shugoshin proteins are involved with which of the following?
Cohesion protection during anaphase I
The sister chromatids found in the daughter nuclei at the end of telophase I are not identical to each other due to which of the following?
Crossing over
Meiosis produces cells that are not identical to each other because of which of the following events (choose all that apply)?
Crossing over Random orientation of chromosomes in metaphase I
DNA replication is suppressed between meiosis I and II by which of the following?
Cyclin B
Select the true statements about the life cycle of sexually reproducing organisms.
Depending on the organism, either the haploid or the diploid stage can be dominant. In all sexually reproducing organisms, meiosis is required for the production of haploid cells. The life cycle of sexually reproducing organisms involves alternation between the haploid and diploid stage.
Which of the statements below are true for chromosomes in eukaryotic cells?
Diploid cells have a maternal homologue and a paternal homologue. Diploid cells have two versions of each chromosome.
The reason for the monopolar arrangement of sister chromatids in meiosis I is that it allows for which of the following?
Each joined pair of homologues to align on the metaphase plate
When are germ line cells set aside from somatic cells?
Early in development
Four daughter cells that are haploid
Formation of new spindle fibers Break down of each nuclear envelope
After meiosis is complete which of the following are produced?
Four daughter cells that are haploid
The number of chromosomes in the parent cell
Four daughter cells that are haploid
A zygote is created when two haploid cells, called _________, fuse.
Gametes
Sperm and egg cells are known as which of the following?
Gametes
Which of the following are true statements regarding sexual reproduction?
Haploid cells are produced through meiosis. The offspring receives genetic material from two parents.
Which is not a characteristic of meiosis II?
Homologous chromosome pairs are separated
During anaphase I which of the following occurs?
Homologues are pulled apart
Which of the following is one of the significant results of meiosis?
It creates haploid gametes for sexual reproduction.
Synapsis (or pairing) of homologous chromosomes occurs during which process?
Meiosis
Which type(s) of cellular division produce(s) cells that are not genetically identical to the mother cell?
Meiosis
Sister chromatid cohesion is maintained during which process?
Meiosis I
Which of the following is sometimes referred to as a reductive division?
Meiosis I
DNA replication is suppressed prior to which cellular event?
Meiosis II
Which of the following is a distinctive feature of meiosis?
Meiosis includes a cell division that is not preceded by DNA duplication.
Which of the following must occur during anaphase I?
Meiosis specific cohesins must be removed from chromosome arms, but not from sister centromeres.
Which process is responsible for the production of the adult body of an animal from a zygote?
Mitosis
Aneuploid gametes are produced by which of the following?
Nondisjunction during meiosis
During which stage of meiosis do synapsis and crossing over occur?
Prophase I
One reason that it is likely that no two human gametes will have the same combination of homologous chromosomes is due to which of the following?
Random assortment of chromosomes
Which of the following is a meiosis specific cohesin protein in yeast?
Rec8
When the alleles of genes that were formerly on separate homologues can be found on the same homologue which of the following has occurred?
Recombination has occurred
The destruction of the Rec8 protein on chromosome arms allows for which of the following to occur?
Separation of homologues in anaphase I
Meiosis II resembles mitosis because it involves the movement of which of the following?
Single chromatids towards the poles of the cell
The process that brings all four chromatids in a pair of homologues together in close association is called which of the following?
Sister chromatid cohesion
Which of the following accurately pairs animal somatic and germline cells with the number of chromosomes in them.
Somatic cells:diploid; Germline cells:diploid
The association of homologous pairs guided by heterochromatin sequences is called which of the following?
Synapsis
The structure consisting of paired homologues along a lattice of proteins between them is called what?
Synaptonemal complex
At this stage of meiosis I, the sister chromatids have reached their respective poles, and they then decondense.
Telophase
Identify the difference between metaphase of mitosis and metaphase of meiosis I.
The chromosomes align singly in mitosis and in pairs in meiosis I.
Of the following choices, which is a similarity between mitosis and meiosis?
The number of chromosomes in the parent cell
Choose the reasons why the two homologous chromosomes do not separate from each other during the first meiotic division.
They are held together by cohesin proteins. They held together via sites of crossing over.
During anaphase I of meiosis I, which of the following describes the homologues?
They are segregated.
In yeast, the Rec8 protein replaces the Scc1 protein in the cohesin complex during meiosis. Why is this important?
This allows the sister chromatids to stay together during meiosis I
Typically, how many cells contribute genetic material during sexual reproduction?
Two
An organism is diploid when its cells carry which of the following?
Two sets of chromosomes
During meiosis I, the kinetochores of sister chromatids act as _______.
a unit, to which polar microtubules attach.
During ________ I of meiosis, the homologues are pulled toward opposite poles of the cell.
anaphase I
Errors in meiosis can lead to gametes with the wrong number of chromosomes which are referred to as ________ gametes.
aneuploid
Errors in meiosis can lead to gametes with the wrong number of chromosomes which are referred to as __________ gametes.
aneuploid
The process of recombination begins with the introduction of a double strand break into one of the homologs. This has led scientists to believe that the enzymatic machinery responsible for recombination first evolved
as a mechanism for the repair of dsDNA breaks
The points where chromatids are held together following crossing over are called _________.
chiasmata or chiasma
he sites of crossing over are called
chiasmata or chiasma
Recombination nodules are structures that contain the enzymes needed for ___________.
crossing over
In most animals, the ______ state of the life cycle is much larger than the ______ state of the life cycle.
diploid; haploid
In animals, the cells that will eventually perform meiosis to produce gametes are called _________ _________ cells.
germ line
Meiosis includes a cell division that is not preceded by DNA duplication.
haploid
When a cell undergoes meiosis, 4 daughter cells are produced. In terms of the number of chromosomes, each daughter cell contains a ___________ nucleus.
haploid
A unique event in meiosis I is
homologous pairing
In meiosis, the random orientation of homologous chromosomes on the metaphase plate leads to
independent assortment of maternal and paternal chromosomes in the gametes
During meiosis I, the ____________ of sister chromatids function as a unit, attaching to the same microtubule.
kinetochores or centromeres
The _____ of sister chromatids are attached to the same pole during meiosis I and to opposite poles during meiosis II.
kinetochores or centromeres
The importance of the recombination machinery for proper disjunction of chromosomes is supported by the observation that
loss of recombination function leads to higher levels of meiotic nondisjunction
In sexually reproducing organisms, which type(s) of cell division requires two sequential rounds of division?
meiosis
The pulling apart of homologues occurs during anaphase of
meiosis I
What type of division (meiosis or mitosis) does the diploid zygote of an animal have to go through (usually many times) in order to give rise to all of the cells in the adult body?
mitosis, mitotic, or mitotic division
A recombination ___________ contains the enzymatic machinery necessary to break and rejoin chromatids of the homologous chromosomes.
nodule
When chromosomes do not sort properly during cell division this is referred to as
nondisjunction
The term __________ refers to an event in which the chromosomes do not sort properly during cell division.
nondisjunction, non-disjunction, or non disjunction
The four daughter cells produced by meiosis are
not genetically identical to each other
In sexual reproduction in eukaryotes, each parent contributes
one set of chromosomes to the offspring.
In ____________ I of meiosis, the replicated chromosomes condense, the homologous chromosomes form bivalents, and crossing over occurs.
prophase I
In anaphase I a pole may receive either the maternal or paternal homologue from each chromosome pair. This means that the genes on different chromosomes assort ________.
randomly
A result of crossing over is genetic _______; this leads to increased genetic variation in the offspring.
recombination
Eukaryotes that reproduce through Blank 1Blank 1 sexual , Correct Unavailable reproduction require two cells to contribute genetic material for the production of the next generation.
sexual
When reproduction is achieved through meiosis and subsequent fertilization, it is called ________ reproduction.
sexual
Anaphase of mitosis separates ______ while anaphase I of meiosis separates ______.
sister chromatids; homologues
Both somatic and germline cells are diploid. However,
somatic cells undergo mitosis, while germline cells can undergo meiosis.
The two types of gametes typically produced by multicellular eukaryotic organisms are
sperm cells egg cells
During meiosis, homologous chromosomes become closely associated in the process of pairing, or
synapsis
During prophase I, all four chromatids of the two homologues become closely associated as a result of pairing, also known as ____________.
synapsis
The process of _______ (or pairing) is the association of homologous pairs which leads to crossing over.
synapsis
During meiosis I the sister kinetochores are attached to
the same pole
When two haploid gametes unite, they create a diploid cell called a(n)
zygote