Ch.11 Meiosis/ MItosis
Adult body cells
(somatic cells) are diploid, containing 2 sets of chromosomes.
If a germ-line cell from an owl contains 8 picograms of DNA during G1 of interphase, how many pictograms pf DNA would be present in each cell during prophase I of meiosis
16
If a human check goes through mitosis how many cells and how many chromosomes per cell will be produced at the end of Cytokinesis?
2 cells with 46 chromosomes per cell
Diploid refers to this characteristic:
2 sets of homologous structures
A cell biologist examines a diploid cell form a particular species of during prometaphase of mitosis and determines that 10 centromeres are present. Based on this finding, how many chromatids should be present in a single cell form this species during anaphase II of meiosis
20
If a cell has 20 chromosomes and goes through Mitosis, how many chromosomes do the new cells have?
20
If a somatic cell from a cat contains 40 picograms of DNA during G2 of interphase, how many pictograms pf DNA would be present in each cell during metaphase II of meiosis
20
If a single cell contains 50 chromosomes and goes through Meiosis, how many chromosomes do the new cells have?
25
How many tetrads are present in a single elephant cell (2n=56) during metaphase I of meiosis
28
If a human sperm cell goes through meiosis how many cells and how many chromosomes per cell will be produced at the end of Cytokinesis 2?
4 cells with 23 chromosomes per cell
How many chromosomes in human somatic cells and gametes?
46 in somatic cells and 23 in gametes
If a germ-line cell from a salamander contains 10 picograms of DNA during G1 of interphase, how many pictograms pf DNA would be present in each gamete produced by this species
5
A cell biologist examines a diploid cell form a particular species of during metaphase of mitosis and determines that 8 centromeres are present. Based on this finding, how many centromeres should be present in a single cell form this species during anaphase II of meiosis
8
. If there were no suppression of DNA replication between meiotic divisions but cytokinesis proceeded normally, what is the most likely outcome of meiosis? A. 4 diploid cells B. 2 diploid cells C. 4 haploid cells D. 2 haploid cells E. 2 diploid cells and 2 haploid cells
A
All animal cells are diploid except A. gametes. B. muscle cells. C. nerve cells. D. germ-line cells. E. somatic cells.
A
Edouard van Beneden proposed that an egg and a sperm, each containing half the complement of chromosomes found in somatic cells, fuse to produce a single cell called a(n) ______. A. zygote B. karyotype C. embryo D. oocyte
A
In plants and animals, the zygote develops by which of the following processes? A. mitosis B. meiosis C. syngamy D. synapsis E. reduction division
A
The fusion of a male gamete with a female gamete is called A. syngamy. B. meiosis. C. mitosis. D. recombination. E. synapsis.
A
Which best describes the process of independent assortment? A. The way one pair of homologues lines up along the metaphase plate does not affect how any other pair lines up. B. Segregation of chromosomes during meiosis I is independent of their segregation during meiosis II. C. During synapsis, chromosomes pair up at random. D. Crossing over along one pair of chromosomes is independent of crossing over along the other pairs. E. During synapsis, homologues pair independently of each other.
A
Which structures indicate where crossing over has occurred. A. chiasmata B. centromeres C. kinetochores D. centrioles E. spindle fibers
A
You are comparing the events of meiosis I in cells from several different organisms. You come across one species in which you do not observe any chiasmata. The best conclusion to make is A. there is no crossing over between non-sister chromatids B. kinetochores of sister chromatids do not fuse C. the chromosome pairs will not assort independently D. chiasmata will form during meiosis II
A
karyotype
A display of the chromosome pairs of a cell arranged by size and shape. Chromosome pairs 1-22 are autsomes with similar appearance between homologues.
Synaptonemal
A lattice of protein holds two replicated chromosomes in precise register with one another (zipper like structure)
alternation of generations
A life cycle in which there is both a multicellular diploid form, the sporophyte, and a multicellular haploid form, the gametophyte; characteristic of plants and some algae. The multicellular diploid stage is called sporophyte. Meiosis in the sporophyte produces haploid cells called spores. Unlike a gamete, haploid spore doesn't fuse with another cell but divides mitotically, generating a multicellular haploid stage called the gametophyte.Cells of the gametophyte create gametes by mitosis. Fusion of two haploid gametes at fertilization results in a diploid zygote, which develops into the next sporophyte generation. Therefore, the sporophyte generation produces a gametophyte as its offspring, and the gametophyte generation produces the next sporophyte generation
A fungus
A life form that had a life cycle involving haploid cells, gametes, and a zygote would most likely be looking at
Meiosis
A process of nuclear division in which the number of chromosomes in certain cells is halved during gamete formation
Mitosis
After fertilization, the resulting zygote develops by which of the following processes
gametic
All of the following animal cells are diploid except
Zygote
An egg & sperm each containing half the complement of chromosomes found in somatic cells, fuse to produce a single cell called
This stage/phase is characterized by the movement of homologous chromosomes away from each other to the opposite ends (poles) of the cell:
Anaphase I
This stage/phase is characterized by the movement of sister chromatids away from each other to the opposite ends (poles) of the cell:
Anaphase II
One full set of chromosomes, each a single chromatid
At the end of telophase II of meiosis, each of the four resulting cells contains
one full set of chromosomes, each a single chromatid
At the end of telophase II of meiosis, each of the four resulting cells contains
. In animals, the cells that will eventually undergo meiosis to produce gametes are set aside early in development. These are called A. somatic cells. B. germ-line cells. C. sex cells. D. gametophytes. E. reproductive cells.
B
. The most common form of gene therapy involves inserting a normal gene into cells that contain a defective version of the gene. In order to use gene therapy to prevent a man from passing a defective gene on to future generations, you should try to insert normal copies of the gene into A. blood cells B. germ-line cells C. somatic cells in the testes D. bone marrow cells
B
. You are studying meiosis in an organism where 2n= 28. How many chromosomes will be present in each cell after meiosis I is complete but before meiosis II begins? A. 7 B. 14 C. 28 D. 56
B
A cell in G2 before meiosis begins, compared with one of the four cells produced at the end of meiosis II, has A. twice as much DNA and twice as many chromosomes B. four times as much DNA and twice as many chromosomes C. twice as much DNA but the same number of chromosomes D. four times as much DNA and four times as many chromosomes E. twice as much DNA and half as many chromosomes
B
A life cycle that regularly alternates between haploid and diploid stages is found in all of the following EXCEPT A. dogs B. the bacterium E. coli C. alfalfa plants D. the mold N. crassa
B
Compared to asexual reproduction, the main advantage of sexual reproduction is that it A. requires less energy B. increases the genetic diversity of the offspring C. can produce more complex offspring D. can produce a greater number of offspring
B
Crossing over between homologous chromosomes takes place during A. prophase II. B. prophase I. C. interphase II. D. interphase I. E. metaphase II.
B
Diploid organisms use meiosis to produce haploid cells. Meiosis consists of how many rounds of nuclear division? A. one B. two C. three D. four E. none of these
B
In life cycles that alternate between haploid and diploid stages, fertilization doubles the number of chromosomes per cell while ______ reduces it in half. A. mitosis B. meiosis C. binary fission D. syngamy
B
One of a pair of chromosomes with similar genetic information and from different sources like the sperm and egg. A. chiasma B. homologue C. kinetochore D. synapsis E. synaptonemal
B
The Rec8 protein holds sister chromatids together during meiosis. If an individual has a mutation that prevents degradation of Rec8, this would most likely prevent A. normal segregation during meiosis I B. normal segregation during meiosis II C. synapsis of homologous chromosomes D. crossing over during prophase I
B
The pairing of chromosomes along their lengths, which is essential for crossing over, is referred to as A. syngamy. B. synapsis. C. prophase. D. recombination. E. centromere.
B
The pairing of homologous chromosomes is called A. syngamy. B. synapsis. C. alignment. D. independent assortment. E. crossing over.
B
What immediately follows meiosis I? A. DNA replication B. prophase II C. metaphase II D. synapsis of homologues E. crossing over of homologues
B
Which best explains the process of meiosis? A. The cells that result from meiosis I are haploid, and each chromosome consists of 1 chromatid. B. The cells that result from meiosis I are haploid, and each chromosome consists of 2 chromatids. C. The cells that result from meiosis II are haploid, and each chromosome consists of 2 chromatids. D. The cells that result from meiosis I are diploid, and each chromosome consists of 2 chromatids. E. The cells that result from meiosis I are diploid, and each chromosome consists of 1 chromatid.
B
Which of the following produces new cells that are genetically identical to the original cell? A. meiosis B. mitosis C. crossing over D. independent assortment E. fertilization
B
Which of the following statements about crossing over is false? A. Crossing over takes place between non-sister chromatids. B. Crossing over takes place between sister chromatids. C. Crossing over occurs during prophase I. D. Sites of crossing over are called chiasmata. E. Crossing over is also called genetic recombination.
B
Which statement about the reductive division of meiosis is false? A. During the reductive division, homologues migrate to opposite poles of the cell. B. During the reductive division, sister chromatids migrate to opposite poles of the cell. C. During the reductive division, centromeres do not divide. D. At the end of the reductive division, each daughter nucleus has one-half as many centromeres as the parental nucleus.
B
You are studying meiosis in an organism where 2n=24. How many chromosomes will each nucleus have after meiosis II is complete? A. 24 B. 12 C. 6 D. 48
B
______ is a process of nuclear division which reduces the number of chromosomes per cell from 2 sets to 1 set. A. Mitosis B. Meiosis C. Binary fission D. Syngamy
B
Meiosis I segregation defects
Based on what you know about Rec8, you most likely would expect to observe
No S phase
Between the two division of meiosis there is
no S phase
Between the two divisions of meiosis there is
anaphase 1
Breakdown of proteins responsible for sister chromatid cohesion along chromatid arms allows homologs to separate The homologs move toward opposite pole, guided by the spindle apparatus. Sister chromatid cohesion persists at the centromere, causing chromatids to move as a unit toward the same pole.
. At the end of meiosis II, each of the four resulting cells contains A. one full set of chromosomes, each with 2 molecules of DNA. B. two full sets of chromosomes, each with 2 molecules of DNA. C. one full set of chromosomes, each with 1 molecule of DNA. D. two full sets of chromosomes, each with 1 molecule of DNA.
C
. The point of connection between two sister chromatids, before anaphase II of meiosis separates them, is called the A. centriole B. kinetochore. C. centromere. D. spindle apparatus. E. centrosome.
C
Evidence of crossing over can often be seen under the light microscope as a structure called a _______. A. kinetochore B. centromere C. chiasma D. centriole
C
In 95% of cases of Down's syndrome, there is one extra chromosome (number 21) in every cell. This aneuploid condition is most likely the result of A. failure to suppress DNA replication between meiosis I and meiosis II B. failure of the chromosomes to assort independently during meiosis C. failure of 1 homologous pair to segregate during meiosis. D. failure of 2 homologous pairs to segregate during meiosis E. failure of the cytoplasm to divide at the end of meiosis II
C
prophase 1 (early prophase)
Chromosomes begin to condense and homologs loosely pair up. Paired homologs become physically connected to each other through synapsis.Crossing over occurs between homologues and the nonsister chromatids swap alleles. Now chromosome contain a mix of parental genes.
Crossing over
Chromosomes exchange genetic info by
crossing over
Chromosomes exchange genetic information by
A common centromere and the synaptonemal complex
Crossing over occurs during prophase I of meiosis I. The two sister chromatids of each homologous pair of chromosomes remain attached by
Prophase I
Crossing over of chromosomes takes place in
prophase I
Crossing over of chromosomes takes place in
. ______ cells contain one set of chromosomes. A. Germ-line B. Somatic C. Diploid D. Haploid
D
All of the following increase genetic variation EXCEPT A. crossing over. B. random fertilization. C. independent assortment. D. mitosis. E. mutation.
D
During meiosis, sister chromatids are held together by A. a common centromere and kinetochore microtubules. B. a common centromere and chiasmata. C. a common centromere and polar microtubules. D. a common centromere and a protein called cohesion. E. the kinetochores and a protein called cohesion.
D
Homologous chromosomes pair along their length during prophase I of meiosis. While two homologues are paired, genetic exchange may occur between them in a process called ________. A. syngamy B. synapsis C. independent assortment D. crossing over
D
Meiosis results in a reassortment of maternal chromosomes (inherited from the mother) and paternal chromosomes (inherited from the father.) If n=4 for a given species, and ignoring the effects of crossing over, what is the probability that a gamete will receive only paternal chromosomes? A. 1/2 B. 1/4 C. 1/8 D. 1/16
D
Which of the following events occurs first during meiosis? A. homologous chromosomes separate and are pulled to opposite poles of the cell B. sister chromatids separate and are pulled to opposite poles of the cell C. chromosomes decondense D. synapsis of homologous chromosomes E. pairs of homologous chromosomes align along the equatorial plate
D
Which of the following is likely to occur if you were to prevent cyclin B from associating with its cyclin-dependent kinase near the end of meiosis I? A. failure to maintain sister chromatid cohesion at the centromere B. failure to form initiation complexes necessary for DNA replication to proceed C. suppression of DNA replication D. activation of DNA replication
D
mitosis vs meiosis
DNA replication occurs during interphase in both divisions. Mitosis divides once, meiosis divides twice. synapsis does not occur in mitosis, but occurs udring porphase 1 along with crossing over in meiosis. Mitosis gets two daughter cells, each diploid (2n) and genetically identical to the parent cell. Meiosis gives four daughter cells, each haploid (n), containing half as many chromosomes as the parent cell and genetically different from the parent cell and from each other.
Two
Diploid organisms use meiosis for the development of gametes. Meiosis consists of how many rounds of nuclear division?
two
Diploid organisms use meiosis for the development of gametes. Meiosis consists of how many rounds of nuclear division?
Capital& capital to one pole; lower cases to the other pole
During Anaphase I which will move to opposite poles
synaptonemal complex
During meiosis I, homologous chromosomes (homologues) become closely associated with each other. This is synapsis. Proteins between the homologues hold them in a
Chromosomes exchange genetic information by A. fertilization. B. mitosis. C. syngamy. D. DNA replication. E. crossing over.
E
The zygote has A. one copy of each chromosome. B. one full haploid complement of chromosomes. C. chromosomes identical to those of a sperm cell. D. chromosomes identical to those of an egg cell. E. two copies of each chromosome.
E
Which structure holds two homologous chromosomes together? A. centromere B. kinetochore C. polar microtubules D. spindle apparatus E. synaptonemal complex
E
recombinant chromosomes
Each chromosome contains alleles from each parent
Chiasma
Evidence of crossing over can often be seen under the light microscope as a structure known as
chiasma
Evidence of crossing over can often be seen under the light microscope as a structure known as a ________.
random fertilization
Fusion of gametes from two individuals further increase possible 2n combination because each gamete is one of 2^23 possible arrangements
crossing over -random alignment of homologues in metaphase I (independent assortment)
Genetic differences in these cells arise from:
metaphase 1
Homologous pairs (tetrads) line up at the metaphase plate held together by the chiasmata, with one chromosome in each pair facing each pole. Both chromatids of one homolog are attached to kintechore microtubules from one pole; those of the other homolog are attached to microtubules from the opposite pole.
Capital; lower case;5 capital; lower case
If there was a single crossing over event between the second & third chromosomes from the top, the resulting chromosomes in order would be
Enzymes necessary to break & rejoin homologous chromosomes
If you could examine closely a recombination model, you may find
Independent assortment
In 95% of cases Downs syndrome, there is an entire extra chromosome in every cell. This aneuploid condition is the result of
Germline cells
In animals, the cells that will eventually undergo meiosis to produce gametes are set aside early in the development which are
germline cells
In animals, the cells that will eventually undergo meiosis to produce gametes are set aside early in the development. These are
Homologous pairs of chromosomes pair up along their length
In on the first steps in meiosis, the
homologous pairs of chromosomes pair up along their length
In one of the first steps in meiosis, the
The correct sequence of events that occurs during the production of haploid sex cell is:
Interphase I, Prophase I, Metaphase I, Anaphase I, Telophase I, Cytokinesis, Prophase II, Metaphase II, Anaphase II, Telophase II, Cytokinesis
meiosis
Making germ cells that allows two cells to fuse into a new unicellular organism (zygote)...that will become multicellular (through mitosis)
Mitosis is nuclear division, which ultimately leads to diploid somatic cells. Meiosis is nuclear division, which ultimately leads to haploid somatic cells.
Meiosis & mitosis are both processes that involve nuclear division. What is the difference between the two
There is a reduction in the chromosome number during two separate nuclear and cell division to produce somatic cells
Meiosis also has been called reduction division because
Mitosis is nuclear division, which ultimately leads to diploid somatic cells. Meiosis is nuclear division, which ultimately leads to haploid gametes.
Meiosis and mitosis are both processes that involve nuclear division. What is the difference between the two?
The alignment of sister chromatids at the middle of the cell occurs during this phase:
Metaphase II
Homologue
One of a pair of chromosomes with similar genetic info & from different sources like sperm & egg
DNA replication errors could be corrected by recombination
One of the most likely explanation for the evolutionary origin of sexual reproduction is that
DNA replication errors could be corrected by recombination
One of the most likely explanations for the evolutionary origin of sexual reproduction is that
Meiosis
Organisms that undertake sexual reproduction alternate between ... & fertilization
meiosis
Organisms that undertake sexual reproduction alternate between ______ and fertilization.
zygote
P. J. van Beneden proposed that an egg and a sperm, each containing half the complement of chromosomes found in somatic cells, fuse to produce a single cell called a(n) _______.
meiosis
Produces haploid gametes; cells have half the number of chromosome sets as the original cell each gamete receives one member of each pair of homologous chromosomes meiosis consists of one round of DNA replication, followed by two rounds of nuclear division. produces 4 daughter cells
Crossing over during Meiosis occurs during this phase:
Prophase I
The alignment of homologous chromosomes at the middle of the cell occurs during this phase:
Prophase I
When does DNA synthesis occur during the cell cycle of sex cells?
S-phase of Interphase
chromosomal
Sexual reproduction and the close association between homologous chromosomes that occurs during meiosis probably evolved as a mechanism to repair _________ damage.
Mitosis
Sexual reproduction increases genetic variability through all of the following EXCEPT
mitosis
Sexual reproduction increases genetic variability through all of the following except
Diversity
Sexual reproduction is significant in increasing genetic
diversity
Sexual reproduction is significant in increasing genetic ______.
Chiasma
Structures that may be visible under the microscope and indicate where crossing over has occurre
prophase 1 (mid prophase)
Synapsis ends with the disassembly of the synaptonemal complex and thechromosomes in each pair move apart slightly. Each homologous pair has a chiasmata. Spindles form, centrosomes move, nuclear encelope breaks down.
The completion of movement of homologous chromosomes to the opposite end of the cell, nuclear redevelopment and the beginning of cytokinesis occurs during this phase of Meiosis:
Telophase I
The completion of movement of sister chromosomes to the opposite ends of the cell, nuclear redevelopment and the beginning of cytokinesis occurs during this phase of Meiosis:
Telophase II
Zygote
The cell produced by the fusion of an egg & sperm is the
zygote
The cell produced by the fusion of an egg and a sperm is the
Animals
The four haploid cells resulting from meiosis may father divide by mitosis in all of the following organisms except
animals
The four haploid cells resulting from meiosis may further divide by mitosis in all of the following organisms except?
Syngamy
The fusion of male gamete cells with female gamete cells
syngamy
The fusion of male gamete cells with female gamete cells is called
Synapsis
The homologous chromosomes pair up side by side during meiosis I. Each homologue pairs along its entire length. This process is called
synapsis
The pairing and physical connection of duplicated homologous chromosomes mediated by synaptonemal protein complex.
Synapsis
The pairing of chromosomes along their lengths which is essential for crossing over is referred to as
synapsis
The pairing of chromosomes along their lengths which is essential for crossing over is referred to as
Centromere
The point of connection between the two sister chromatids before anaphase of mitosis separates them is called the
centromere
The point of connection between the two sister chromatids before anaphase of mitosis separates them is called the
Meiosis
The reduction division that separates two haploid complements from each other is called
meiosis
The reduction division that separates two haploid complements from each other is called.... Organisms that undertake sexual reproduction alternate between ______ and fertilization.
a lattice of proteins that holds homologues together
The synaptonemal complex develops early in meiosis. It is
recombination
The two homologous chromosomes pair along their length early in the first nuclear division. During this physical joining genetic exchange occurs between them in a process called _________.
Recombination
The two homologous chromosomes pair along their length early in the first nuclear division. During this physical joining genetic exchange occurs between them in the process of
Two copies of each chromosome
The zygote has
two copies of each chromosome
The zygote has
Haploid
These type of cells such as gametes contain one set of chromosomes
DNA
Unlike meiosis I, there is no doubling of ______ before the start of meiosis II.
DNA
Unline meiosis I, there is no doubling of ____ before the start of meiosis II
Prophase II
What immediately follows meiosis I
In anaphase I, where one pair separates does not affect how any other part separates
Which is an explanation for independent assortment, a factor in producing genetic variability
In anaphase I, where how one pair separates does not affect how any other pair separates
Which of the following is an explanation for independent assortment, a factor in producing genetic variability?
mitosis
Which of the following produces identical cells
Mitosis
Which produces identical cells
The number of chromosomes is reduced by half
Why does sexual reproduction require both meiosis & syngamy
14
You are studying meiosis in an organism that has 28 chromosomes diploid. How many chromosomes will each nucleus have after meiosis I, but before cytokinesis
Haploid
______ cells such as gametes contain one set of chromosomes.
Meiosis
_______ is a process of nuclear division in which the number of chromosomes in certain cells is halved during gamete formation.
autosome
a chromosome that is not directly involved in determining sex; not a sex chromosome
A cell biologist examines a skin cell from a lizard during metaphase of mitosis and determines that 20 chromatids are present. The role of meiosis in this species is to a. produce 4 daughter cells that are genetically different from each other b. produce 4 daughter cells that are genetically different form the original parental cell c. reduce the number of chromosomes per cell from 10-5 d. reduce the number of chromosomes from 20 to 10
a, b ,c
A cell biologist examines a leaf cell from an alfafa plant during metaphase of mitosis and determines that 32 chromatids are present. The role of fertilization in this species id to a. produce a new cell that has a combination of chromosomes from 2 different parents b. increase the number of chromosomes per cell form 16 to 32 c. increase the number of chromosomes form 8 to 16 d. combine the chromosomes form 2 haploid cells into a single diploid cell
a,c,d
Mitosis is considered to be this type of reproductive process ________ because it provides this advantage to the cell, ________:
a-sexual, takes less energy to form
If there were no suppression of DNA replication between meiotic divisions but cytokinesis proceeded normally, what is the most likely outcome of meiosis a. 4 diploid cells b. 2 diploid cells c. 4 haploid cells d. 2 haploid cells e. 2 diploid cells and 2 haploid cells
a. 4 diploid cells
During anaphase I, which best represents segregation of the chromatids that make up one pair of homologues? ( M represents a maternal chromotid and P represents a paternal chromatid. Assume no crossing over occurs) a. M and M to one pole and P and P to the other pole b. M and P to one pole and P and M to the pole c. M to one pole; P to the other pole d. half of M and half of P to each pole e. the segregation of these chromatids is completely random
a. M and M to one pole; and P and P to the other pole
Which structures indicate where crossing over has occurred a. chiasmata b. centromeres c. kinetochores d. centrioles e. spindle fibers
a. chiasmata
All animal cells are diploid except a. gametes b. muscle cells c. nerve cells d. germ line cells e. somatic cells
a. gametes
Which cells never divide by meiosis a. haploid cells b. diploid cells c. somatic cells d. germ line cells e. zygotes
a. haploid b. somatic e. zygotes germ line cells will eventually go through meiosis so it will divide
In plants and animals, the zygote develops by which of the following processes? a. mitosis b. meiosis c. syngamy d. synapsis e. reduction division
a. mitosis
In meiosis, sister kinetochores are attached to the same pole of the cell during meiosis I and sister chromatid cohesion is released during anaphase II. What would be the likely result if sister kinetochores were attached to different poles of the cell during meiosis I and sister chromatid cohesion was released during anaphase I a. sister chromatids would migrate to the opposite poles during anaphase I b. sister chromatids would migrate to the opposite poles during anaphase II c.sister chromatids would migrate to the same pole during anaphase I d. sister chromatids would migrate to the same pole during anaphase II
a. sister chromatids would migrate to the opposite poles during anaphase I
The fusion of a male gamete with a female gamete is called a. syngamy b. meiosis c. mitosis d. recombination e. synapsis
a. syngamy
Which best describes the process of independent assortment a. the way one pair of homologous lines up along the metaphase plate does not affect how how any other lines up b. segregation of chromosomes during meiosis I is independent of their segregation during meiosis II c. During synapsis, chromosomes pair up at random d. Crossing over along one pair of chromosomes is independent of crossing over along the other pairs e. During synapsis, homologous pair independently of each other.
a. the way one pair of homologous lines up along the metaphase plate does not affect how how any other lines up
You are comparing the events of meiosis I in cells form several different organisms. You come across one species in which you do not observe any chiasmata. The best conclusion to make is a. there is no crossing over between non-sister chromatids b. kinetochores of sister chromatids do not fuse c. the chromosome pairs will not assort independently d. chiasmata will form during meiosis II
a. there is no crossing over between non-sister chromatids
Edouard van Beneden proposed that an egg and a sperm each containing half the complement of chromosomes found in somatic cells, fuse to produce in single cell called a. zygote b. karyotype c. embryo d. oocyte
a. zygote
Tetrad formation refers to this process:
alignment of homologous chromosomes on top of each other during Prophase I
When a male sperm cell unites/fuses with a female egg cell what is produced?
an embryonic stem cell
somatic cell
any cell in a multicellular proganism except a sperm or egg or their precursors
Gametes
are haploid, containing only 1 set of chromosomes
telophase 1 and cytokinesis
at the beginning of telophase 1, each half of the cell has a complete haploid set of duplicated chromosomes. Each chromosome is composed of two sister chromatids; one or both chromatids include regions of nonsister chromatid DNA. Cytokinesis usually occurs simultaneously with telophase 1, forming two haploid daughter cells.
You are studying meiosis in an organism where 2n= 24. How many chromosomes will each nucleus have after meiosis II is complete a. 24 b. 12 c. 6 d. 48
b. 12
You are studying meiosis in an organism where 2n=28. How many chromosomes will be present in each cell after meiosis I is complete but before meiosis II begins a. 7 b. 14 c. 28 d. 56
b. 14
Which statement about the reductive division of meiosis is false? a. During the reductive division, homologues migrate to opposite poles of the cell b. During the reductive division, sister chromatids migrate to opposite poles of the cell c. during the reductive division, centromeres do not divide d. at the end of the reductive division, each daughter nucleus has one half as many centromeres as the parental nucleus
b. During the reductive division, sister chromatids migrate to opposite poles of the cell
Which best explains the process of meiosis a. The cells that result from meiosis I are haploid and each chromosomes consists of 1 chromatids b. The cells that result from meiosis I are haploid and each chromosomes consists of 2 chromatids c. The cells that result from meiosis II are haploid and each chromosomes consists of 2 chromatids d. The cells that result from meiosis I are diploid and each chromosomes consists of 2 chromatids e. The cells that result from meiosis I are diploid and each chromosomes consists of 1 chromatids
b. The cells that result from meiosis I are haploid and each chromosomes consists of 2 chromatids
A life cycle that regularly alternates between haploid and diploid stages is found in all of the following except a. dogs b. bacterium E. coli c. alfafa plants d. the mold N. crassa
b. bacterium E.coli
Which of the following statements about crossing over is false? a. crossing over takes place between non-sister chromatids b. crossing over takes place between sister chromatids c. crossing over occurs during prophase I d. sites of crossing over are called chiasmata e. crossing over is also called genetic recombination
b. crossing over takes place between sister chromatids
A cell in G2 before meiosis begins, compared with one of the four cells produced at the end of meiosis II has a. twice as much DNA and twice as many chromosomes b. four times as much DNA and twice as many chromosomes c. twice as much DNA but the same number of chromosomes d. four times as much DNA and four times as many chromosomes e. twice as much DNA and half as many chromosomes
b. four times as much DNA and twice as many chromosomes
In animals, the cells that will eventually undergo meiosis to produce gametes are set aside early in development. These are called a. somatic cells b. germ-line cells c. sex cells d. gametophytes e. reproductive cells
b. germ-line cells
the most common form of gene therapy involves inserting a normal gene into cells that contain a defective version of the gene. In order to use the gene therapy to prevent a man from passing a defective gene on to the future generations, you should try to insert normal copies of the gene into a. blood cells b. germ-line cells c. somatic cells in the testes d. bone marrow cells
b. germ-line cells to produce new healthy sperm and eggs (gamete)
One of a pair of chromosomes with similar genetic information and from different sources like the sperm and egg a. chiasma b. homologue c. kinetochore d. synapsis e. synaptonemal
b. homologue
Compare to asexual reproduction, the main advantage of sexual reproduction is that it a. requires less energy b. increases the genetic diversity of the offspring c. can produce more complex offspring d. can produce a greater number of offspring
b. increases the genetic diversity of the offspring.
In life cycles that alternate between haploid and diploid stages, fertilization doubles the number of chromosomes per cell while_____ reduces it in half a. mitosis b. meiosis c. binary fission d. syngamy
b. meiosis
______ is a process of nuclear division which reduces the number of chromosomes per cell from sets to 1 set a. mitosis b. meiosis c. binary fission d. syngamy
b. meiosis
Which of the following produces new cells that are genetically identical to the original cell? a. meiosis b. mitosis c. crossing over d. independent assortment e. fertilization
b. mitosis
The Rec8 protein holds sister chromatids together during meiosis. If an individual has a mutation that prevents degradation of Rec8, this would most likely prevent a. normal segregation during meiosis I b. normal segregation during meiosis II c. synapsis of homologous chromosomes d. crossing over during prophase I
b. normal segregation during meiosis II destruction of Rec8 protein on the chromosome arms appears to be what allows homologous to be pulled apart at anaphase I.
Crossing over between homologous chromosomes takes place during a. prophase II b. prophase I c. interphase II d. interphase I e. metaphase II
b. prophase I
What immediately follows meiosis I a. DNA replication b. prophase II c. metaphase II d. synapsis of homologous e. crossing over of homologous
b. prophase II
The pairing of chromosomes along their lengths , which is essential for crossing over is referred to as a. syngamy b. synapsis c. prophase d. recombination d. centromere
b. synapsis
The pairing of homologous chromosomes is called a. syngamy b. synapsis c. alignment d. independent assortment e. crossing over
b. synapsis
Why does sexual reproduction require both meiosis and syngamy (fusion of gametes to form a new cell) a. The process of meiosis results in the production of gametes fuse to form a new cell, and the number of chromosomes is restored to the full amount. Therefore, by coupling meiosis and syngamy, the organism ensures that the number of chromosomes will be maintained b. the process of meiosis results in the production of gametes in which the number of chromosomes is reduced by half. During syngamy, two gametes fuse to form a new cell, and the number of chromosomes is restored to the full amount. Therefore, by coupling meiosis and syngamy, the organism ensures that the proper number of chromosomes will be maintained. c. the process of meiosis results in the production of gametes in which the number of chromosomes is doubled. During syngamy, gametes are reduced by half , and the number of chromosomes is restored to the full amount. Therefore, by coupling meiosis and syngamy, the organism ensures that the proper number of chromosomes will be maintained.
b. the process of meiosis results in the production of gametes in which the number of chromosomes is reduced by half. During syngamy, two gametes fuse to form a new cell, and the number of chromosomes is restored to the full amount. Therefore, by coupling meiosis and syngamy, the organism ensures that the proper number of chromosomes will be maintained.
Diploid organisms use meiosis to produce haploid cells. Meiosis consists of how many rounds of nuclear division a. one b. two c. three d. four e. none of these
b. two
How many chromosomes in the beginning and end of mitosis, meiosis 1, meiosis 2
beginning of mitosis: 46; end of mitosis: 46 beginning of meiosis 1: 46; end of meiosis 1: 23 beginning of meiosis 2: 23; end of meiosis 2: 23
How many sister chromatids in the beginning and ned of mitosis, meiosis 1, meiosis 2?
beginning of mitosis: 92; end of mitosis: 46 beginning of meiosis 1: 92; end of meiosis 1: 46 beginning of meiosis 2: 46; en of meiosis 2: 23
How many homologues in the beginning and end of mitosis, meiosis 1, meiosis 2
beginning of mitosis:0; end of mitosis: 0 beginning of meiosis 1: 23; end of meiosis 1:0 beginning of meiosis 1: 0; end of meisis 2: 0
anaphase 2
breakdown of proteins holding the sister chromatids together at the centromere allows the chromatids to separate. The chromatids move toward opposite poles as individual chromosomes.
The cell produced by the fusion of an egg and a sperm is the A. gamete. B. oocyte. C. zygote. D. germ line cell. E. somatic cell.
c
The synaptonemal complex is A. a cluster of microtubules at each pole of the cell. B. a network of microtubules that forms the spindle apparatus. C. a network of proteins that holds homologues together. D. the area where microtubules attach to the centromere of each chromosome. E. a region of highly coiled DNA.
c
Sister chromatids move to opposite poles of the cell during a. anaphase I of meiosis b. metaphase I of meiosis c. anaphase II of meiosis d. anaphase of mitosis
c, d
Nondisjunction is the failure of homologous chromosomes to separate during meiosis I, or the failure of sister chromatids to separate during meiosis II or mitosis. As a result, both homologous chromosomes or both sister chromatids migrate to the same pole of the cell. This produces daughter cells with a imbalance of chromosomes. If 18 pairs of sister chromatids segregate normally during meiosis II in cats (n=19) but we have nondisjunction of 1 pair, then at the end of meiosis II we will have a. 3 cells of 20 chromosomes and 1 cell with 18 b. 2 cells of 20 chromosomes and 2 cells of 18 c. 2 cells with 19 chromosomes, 1 with 20 and 1 with 18 d. 3 cells with 18 chromosomes and 1 cell with 20
c. 2 cells with 19 chromosomes, 1 with 20 and 1 with 18
Nondisjunction is the failure of homologous chromosomes to separate during meiosis I, or the failure of sister chromatids to separate during meiosis II or mitosis. As a result, both homologous chromosomes or both sister chromatids migrate to the same pole of the cell. This produces daughter cells with a imbalance of chromosomes. A cell biologist examines the final products of meiosis in an earthworm (2n=36) and finds 2 cells with 20 chromosomes and 2 cells with 16 chromosomes . Most likely this was because a. 2 pairs of sister chromatids failed to separate during meiosis II b. 1 pairs of sister chromatids failed to separate during meiosis II c. 2 pairs of homologous chromosomes failed to separate during meiosis I d. 1 pairs of homologous chromosomes failed to separate during meiosis I
c. 2 pairs of homologous chromosomes failed to separate during meiosis I
The synaptonemal complex is a. a cluster of microtubules at each pole of the cell b. a network of microtubules that forms the spindle apparatus c. a networks of proteins that holds homologous chromosomes together d. the area where microtubules attach to the centromere of each chromosome e. a region of highly coiled DNA
c. a network of proteins that holds homologous chromosomes together
Which of the following is likely to occur if you were to prevent cyclin B from associating with its cyclin-dependent kinase near the end of meiosis I a. failure to maintain sister chromatid cohesion at the centromere b. failure to form initiation complexes necessary for DNA replication to proceed c. suppression of DNA replication c. activation of DNA replication
c. activation of DNA replication
The point of connection between two sister chromatids before anaphase II of meiosis separates them, is called the a. centriole b. kinetochore c. centromere d. spindle apparatus e. centrosome
c. centromere
Evidence of crossing over can often be seen under the light microscope as a structure called a a. kinetochore b. centromere c. chiasma d. centriole
c. chiasma
In 95% cases of Down's syndrome, there is one extra chromosome (number 21) in every cell. This aneuploid condition is most likely the result of a. failure to suppress DNA replication between meiosis I and meiosis II b. failure of the chromosomes to assort independently during meiosis c. failure of 1 homologous pair to segregate during meiosis d. failure of 2 homologous pair to segregate during meiosis II e. failure of the cytoplasm to divide at the end of meiosis II
c. failure of 1 homologous pair to segregate during meiosis aneuploid= gametes with improper number of chromosomes
At the end of meiosis II, each of the four resulting cells contains a. one full set of chromosomes, each with 2 molecules of DNA b. two full set of chromosomes, each with 2 molecules of DNA c. one full set of chromosomes, each with 1 molecules of DNA d. two full set of chromosomes, each with 1 molecules of DNA
c. one full set of chromosomes, each with 1 molecules of DNA
The cell produced by the fusion of an egg and a sperm is the a. gamete b. oocyte c. zygote d. germ line cells e. somatic cell
c. zygote
What happens to the chromosome number during meiosis?
chromosome number is reduced by half
DNA is divided up into these operational units, i.e. the strucutres that are actually separated during meiosis and mitosis.
chromosomes
Meiosis I.... Prophase I
chromosomes coil tighter -nuclear envelope dissolves -homologues become closely associated in synapsis -crossing over occurs between non-sister chromatids
What is shown in Figure 11-4?
crossing-over
Meiosis results in a reassortment of maternal chromosomes (inherited form the mother) and paternal chromosomes (inherited form the father). if n=4 for a given species and ignoring the effects of crossing over what is the probability that a gamete will receive only paternal chromosomes a. 1/2 b. 1/4 c.1/8 d.1/16
d. 1/16
A geneticist examines a somatic cell from a fly during metaphase of mitosis and determines that 16 chromatids are present. If a germ-line cell from this species divides by meiosis then at the end of meiosis I each cell will contain a. 8 chromosomes with 8 DNA molecules b. 8 chromosomes with 16 DNA molecules c. 4 chromosomes with 4 DNA molecules d. 4 chromosomes with 8 DNA molecules
d. 4 chromosomes with 8 DNA molecules
During meiosis, sister chromatids are held together by a. a common centromere and kinetochore microtubules b. a common centromere and chiasmata c. a common centromere and polar microtubules d. a common centromere and a protein called cohesion e. the kinetochores and a protein called cohesion
d. a common centromere and a protein called cohesion (also called sister chromatids cohesion)
Homologous chromosomes pair along their length during prophase I of meiosis. While two homologous are paired, genetic exchange may occur between them in a process called a. syngamy b. synapsis c. independent assortment d. crossing over
d. crossing over
____ cells contain one set of chromosomes a. germ-line b. somatic c. diploid d. haploid
d. haploid
All of the following increase genetic variation except a. crossing over b. random fertilization c. independent assortment d. mitosis e. mutation
d. mitosis
Which of the following events occurs first during meiosis a. homologous chromosomes separate and are pulled to opposite poles of the cell b. sister chromatids separate and are pulled to opposite poles of the cell c. chromosome decondense d. synapsis of homologous chromosomes e. pairs of homologous chromosomes align along the equatorial plate
d. synapsis of homologous chromosomes (which is the pairing of the chromosomes)
Female and male skin cells can be described as being:
diploid
Chromosomes exchange genetic information by a. fertilization b. mitosis c. syngamy d. replication e. crossing over
e. crossing over (which takes place during prophase I) exchanging= crossing
Which structure holds down two homologous chromosomes together a. centromere b. kinetochore c. polar microtubules d. spindle apparatus e. synaptonemal complex
e. synaptonemal complex
The zygote has a. one copy of each chromosome b. one full haploid complement of chromosomes c. chromosomes identical to those of a sperm cell d. chromosomes identical to those of an egg cell e. two copies of each chromosomes
e. two copies of each chromosomes
zygote
fertilized egg; when haploid sperm fuses with haploid egg
What is formed at the end of meiosis?
four genetically different cells
At the end of meiosis, there are
four haploid daughter cells
Another name for the four haploid daughter cells produced at the end of meiosis is:
gametes
The major advantage that Meiosis provides to a given individual is:
genetic diversity
Crossing over
genetic recombination between non-sister chromatids -Physical exchange of chromatid regions
Female egg cells and male sperm cells can be described as being:
haploid
spores
haploid cells produced by sporophytes during meiosis
unicellular
having or consisting of a single cell
This is synapsis
homologous chromosomes (homologues) become closely associated with each other
Sexual reproduction
includes the fusion of gametes (fertilization) to produce a diploid zygote.
types of genetic variations
independent assortment of chromosomes crossing over random fertilization
DNA replication
is suppressed between meiosis I and meiosis II
Gametes are produced by the process of
meiosis
porphase 1 (late prophase)
microtubules from one pole attach to the two kinetochores. The homologou pairs move toward the metaphase plate.
MeiosisI Anaphase I
microtubules of the spindle shorten -homologues are separated from each other -sister chromatids remain attached to each other at their centromeres
Meiosis I, Telophase I
nuclear envelopes form around each set of chromosomes -each new nucleus is now haploid -sister chromatids are no longer identical because of crossing over
telophase 2 and cytokinesis
nuclei form, the chromosomes begin decondensing, and cytokinesis occurs. The meiotic division of one parent cell produces foru daughter cells each iwth a hapoid set of unduplicated chromosomes. The four daughter cells are genetically distinct from one another and from the parent cell.
Life cycles
of sexually reproducing organisms involve the alternation of haploid and diploid stages.
The term "haploid" means:
one set of chromosomes
haploid
one set of chromosomes (n) gametes are haploid created by meiosis
homologous chromosomes
pair of chromosomes that have the same length, centromere position, and gen loci, but maybe have different alleles. One homologous chromosome is inherited from the organism's father, the other from mother.
tetrad
paired homologues
Mitosis
produces 2 cells identical to each other (Well Sort of, Remember Stem Cells)
Meiosis
produces haploid cells that are not identical to each other.
crossing over
produces recombinant chromosomes
Tetrad formation occurs during this phase of Meiosis:
prophase of meiosis I
Independent assortment of chromosomes
random orientation of homologous pairs in metaphase 1; each pair lines up independent of neighboring pairs. Possible combination is 2^n (n=the pairs of chromosomes)
gonads
reproductive glands-male, testes; female, ovaries
meiosis 2
same as mitosis except cells are haploid and sister chromatids are not identical
Meiosis occurs in these types of cells:
sex cells
Meiosis is considered to be this type of reproductive process ________ because it provides this advantage to the cell:
sexual, genetic diversity
Chiasmata
sites of crossing over
chiasmata
sites of crossing over
gametes
sperm and egg cells
prophase 2
spindle apparatus form. Chromosomes, which are still composed of two chromatids associated at the centromere, move toward the metaphase 2 plate.
MeiosisI Metaphase I
terminal chiasmata hold homologues together following crossing over -microtubules from opposite poles attach to each homologue, not each sister chromatid -homologues are aligned at the metaphase plate side-by-side -the orientation of each pair of homologues on the spindle is random
zygote
the cell resulting from the union of an ovum and a spermatozoon (including the organism that develops from that cell)
metaphase 2
the chromosomes are positioned at the metaphase plate. Because of crossing over in meiosis 1, the two sister chromatids of each chromosome are not genetically identical. The kinetochores of sister chromatids are attached tomicrotubules extending from opposite poles.
The process or act of "crossing over" is best described as:
the exchange of genetic material by homologous chromosomes during prophase I
diploid
two sets of chromosomes. (2n) one set from each parent. Pairs of homologous chromosomes
Meiosis involves
two successive cell divisions with no replication of genetic material between them