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