11.1-11.4: sexual reproduction and meiosis

eukaryotes that reproduce through _____ reproduction require two cells to contribute genetic material for the production of the next generation.

sexual

Sperm and egg cells are known as which of the following?

• Somatic cells

• Meiotic cells

• Zygotes

• Gametes

Gametes

When two gametes fuse, they produce a single cell with twice the chromosomes of each gamete. This new cell is called a(n) _____

zygote

Which of the following statements accurately describes meiosis?

• Meiosis is a special division that produces gametes with half the normal number of chromosomes.

• Once they are produced from the germ line, gametes undergo meiosis to produce even more gametes.

• In meiosis, two gametes with half the chromosomes of normal cells fuse to produce a cell with the normal number of chromosomes.

Meiosis is a special division that produces gametes with half the normal number of chromosomes.

Gametes are haploid which means that they contain how many sets of chromosomes?

one set

Typically, how many cells contribute genetic material during sexual reproduction?

two

Which of the following are true statements regarding sexual reproduction?

• Haploid cells are produced through meiosis.

• The offspring receives genetic material from two parents.

• Specialized somatic cells fuse during fertilization.

• Gametes are always produced by mitosis.

• Haploid cells are produced through meiosis.

• The offspring receives genetic material from two parents.

The two types of gametes typically produced by multicellular eukaryotic organisms are _______

sperm cells and egg cells

When two gametes (a sperm and an egg) unite, they produce a single cell called a(n) _______

zygote

A human gamete contains _____ chromosomes

23

_________ is a reduction division which produces cells with half the normal number of chromosomes.

meiosis

in most animals, the ______ state of the life cycle is much larger than the ____ state of the life cycle

diploid; haploid

An organism is diploid when its cells carry how many sets of chromosomes?

2 sets

When reproduction is achieved through meiosis and subsequent fertilization, it is called _______ reproduction

sexual

What type of division (meiosis or mitosis) does the diploid zygote of an animal have to go through (usually many times) in order to give rise to all of the cells in the adult body?

mitosis

When are germ line cells set aside from somatic cells?

Early in development

Both somatic and germline cells are diploid. However, _______

somatic cells undergo mitosis, while germline cells can undergo meiosis

Select the true statements about the life cycle of sexually reproducing organisms.

• The haploid stage never involves mitosis.

• Depending on the organism, either the haploid or the diploid stage can be dominant.

• In all sexually reproducing organisms, meiosis is required for the production of haploid cells.

• The life cycle of sexually reproducing organisms involves alternation between the haploid and diploid stage.

• In some organisms, sexual reproducing does not involve meiosis or fertilization.

• Depending on the organism, either the haploid or the diploid stage can be dominant.

• In all sexually reproducing organisms, meiosis is required for the production of haploid cells.

• The life cycle of sexually reproducing organisms involves alternation between the haploid and diploid stage.

How many rounds of cell division are required for meiosis?

2

Synapsis (or pairing) of homologous chromosomes occurs during which process?

meiosis

Which process is responsible for the production of the adult body of an animal from a zygote?

Mitosis

During prophase I, all four chromatids of the two homologues become closely associated as a result of pairing, forming a structure known as a(n) ______

tetrad

Germ line cells are different from somatic cells in that germ line cells produce which of the following?

Haploid gametes

When the alleles of genes that were formerly on separate homologues can be found on the same homologue which of the following has occurred?

• Reductive division has occurred

• Recombination has occurred

• Cytokinesis has occurred

Recombination has occurred

Which of the following accurately pairs animal somatic and germline cells with the number of chromosomes in them.

• Somatic cells:haploid; Germline cells:haploid

• Somatic cells:diploid; Germline cells:haploid

• Somatic cells:diploid; Germline cells:diploid

• Somatic cells:haploid; Germline cells:diploid

Somatic cells:diploid; Germline cells:diploid

In sexually reproducing organisms, which type(s) of cell division requires two sequential rounds of division?

meiosis

During meiosis, homologous chromosomes become closely associated in the process of pairing, or _______

synapsis

In many species, homologues become connected during meiosis I by a complex structure called the ______

synaptonemal complex

The sites of crossing over are called _______

chiasmata

a result of crossing over is genetic ______; this leads to increased genetic variation in the offspring.

recombination

Identify the difference between metaphase of mitosis and metaphase of meiosis I.

The chromosomes align singly in mitosis and in pairs in meiosis I.

Which of the following is sometimes referred to as a reductive division?

Meiosis I/reduction division

In meiosis, when does DNA replication occur?

Before meiosis I only

in ______ I of meiosis, the replicated chromosomes condense, the homologous chromosomes form bivalents, and crossing over occurs.

prophase

What does the term sister chromatid cohesion refer to?

The tight association of sister chromatids in a tetrad during prophase I

Anaphase of mitosis separates ______ while anaphase I of meiosis separates ______.

sister chromatids; homologues

a recombination _____ contains the enzymatic machinery necessary to break and rejoin the chromatids of homologous chromosomes.

nodule

When used to characterize the first meiotic division, the term "reductive division" refers to the reduction of which of the following?

• Number of chromosomes

• Number of daughter cells

• Cell size

Number of chromosomes

Choose the reasons why sister chromatids do not separate from each other during the first meiotic division.

• They are held together by cohesin proteins.

• They are no longer homologous.

• They are permanently attached to each other.

• They are held together via sites of crossing over.

• They are held together by cohesin proteins.

• They are held together via sites of crossing over.

Meiosis has how many rounds of DNA replication?

1

During which stage of meiosis do synapsis and crossing over occur?

Prophase I

during meiosis I, the ______ of sister chromatids function as a unit, attaching to microtubules originating from the same pole.

kinetochores

The tight association of sister chromatids in a tetrad during prophase I is known as ______

sister chromatid cohesion

Recombination nodules are structures that contain the enzymes needed for _____

crossing over

After crossing over is complete, the homologous chromosomes remain attached at the chiasmata. How many chromatids are attached at this point?

4

During meiosis I, each homologue is attached to one pole. This is called ______

monopolar attachment

Which of the following is a unique behavior of kinetochores that allows the separation of homologous chromosomes during meiosis I?

• Bipolar attachment

• Chiasmata formation

• Monopolar attachment

• Synaptonemal complex formation

monopolar attachment

During meiosis I, the kinetochores of sister chromatids act as

a unit, to which polar microtubules attach.

Construct the correct sequence of events for meiosis I, starting at the top.

1. paired homologous align at the equator, microtubules attach to kinetochores of sister chromatids

2. nuclear envelope re-forms around each daughter nucleus

3. separated homologues cluster at each pole

4. microtubules shorten, chiasmata are broken, homologous chromosomes are pulled to opposite poles

5. chromosomes condense, forming of spindle apparatus begins, homologous chromosomes pair and crossing over occurs

1. chromosomes condense, forming of spindle apparatus begins, homologous chromosomes pair and crossing over occurs

2. paired homologous align at the equator, microtubules attach to kinetochores of sister chromatids

3. microtubules shorten, chiasmata are broken, homologous chromosomes are pulled to opposite poles

4. separated homologues cluster at each pole

5. nuclear envelope re-forms around each daughter nucleus

During anaphase I of meiosis I, which of the following describes the homologues?

• They are segregated.

• They are aligned.

• They are decondensed.

• They are integrated.

They are segregated.

during meiosis I, chromosomes exhibit ______ attachment because each homologue is attached to one pole instead of sister chromatids becoming attached to opposite poles

monopolar

In meiosis, the random orientation of homologous chromosomes on the metaphase plate leads to ______

independent assortment of maternal and paternal chromosomes in the gametes

Because the kinetochores of sister chromatids during meiosis I exhibit ______ attachment, the two homologous chromosomes in a tetrad are pulled towards opposite poles of the cell as they line up at the equatorial plane.

monopolar

At which stage of meiosis I have the chromosomes reached their respective poles, where they begin to decondense.

Telophase

Some cells can undergo meiosis with _______ segregation, in which meiosis proceeds without recombination.

achiasmate

The tight association of sister chromatids in a tetrad during prophase I is known as ______

sister chromatid cohesion

during _____ I of meiosis, the homologues are pulled toward opposite poles of the cell.

anaphase

After metaphase l, a pole may receive either the maternal or the paternal homologue from each chromosome pair, so chromosomes are said to assort _____

independently

Which of the the following events is observed during metaphase II?

• Alignment of homologous pairs along the metaphase plate

• Alignment of individual chromosomes along the metaphase plate

• Cytokinesis

• Synapsis and crossing over

Alignment of individual chromosomes along the metaphase plate

The sister chromatids found in the daughter nuclei at the end of telophase I are not identical to each other due to which of the following?

• Segregation

• Synapsis

• Crossing over

• Independent assortment

Segregation

After meiosis is complete which of the following are produced?

• Two daughter cells that are diploid

• Four daughter cells that are haploid

• Four daughter cells that are diploid

• Two daughter cells that are haploid

Four daughter cells that are haploid

When meiosis occurs without recombination, which of the following has occurred?

• Non-independent assortment

• Achiasmate segregation

• Aneuploidy

Achiasmate segregation

the term _____ refers to an event in which the chromosomes do not segregate properly during cell division.

nondisjunction

Errors in meiosis can lead to gametes with the wrong number of chromosomes which are referred to as _____ gametes

aneuploid

At the end of anaphase I in meiosis, each pole of the cell contains which of the following?

• A diploid set of duplicated chromosomes

• A set of homologous pairs

• A haploid set of non-duplicated chromosomes

• A haploid set of duplicated chromosomes

A haploid set of duplicated chromosomes

Of the following choices, which is a similarity between mitosis and meiosis?

• The diversity of the daughter cells

• The number of daughter cells

• The number of chromosomes in the parent cell

• The number of chromosomes in daughter cells

The number of chromosomes in the parent cell

Which of the following is characteristic of meiosis II?

• Sister chromatids are separated.

• Four diploid cells are produced.

• Chromosome pairs form.

• Homologous chromosomes are separated.

Sister chromatids are separated.

Which of the following is a meiosis-specific cohesin protein in yeast?

Rec8

When a cell undergoes meiosis, 4 daughter cells are produced. In terms of the number of chromosomes, each daughter cell contains a ________ nucleus

haploid

The process of recombination begins with the introduction of a double strand break into one of the homologs. This has led scientists to believe that the enzymatic machinery responsible for recombination first evolved ______

as a mechanism for the repair of dsDNA breaks

Which of the following must occur during anaphase I?

• Meiosis specific cohesins must be removed from sister centromeres, but not from chromosome arms.

• Meiosis specific cohesins must be removed both from chromosome arms and sister centromeres.

• Meiosis specific cohesins must be removed from chromosome arms, but not from sister centromeres.

Meiosis specific cohesins must be removed from chromosome arms, but not from sister centromeres.

Aneuploid gametes are produced by what?

nondisjunction during meiosis

The destruction of the Rec8 protein on chromosome arms allows for which of the following to occur?

• Separation of homologues in anaphase I

• Separation of sister chromatids during anaphase II

• Crossing over during prophase I

Separation of homologues in anaphase I

Which of the following is a distinctive feature of meiosis?

• Sister chromatids stay together throughout both meiosis divisions.

• Meiosis results in the production of both diploid and haploid cells.

• Meiosis includes a cell division that is not preceded by DNA duplication.

Meiosis includes a cell division that is not preceded by DNA duplication.

Match the type of sister kinetochore attachment to the appropriate type of alignment of chromosomes.

miotic →

meiotic →

miotic → bipolar

meiotic → monopolar

In yeast, what happens to sister chromatid cohesion during meiosis?

The Scc1 protein is replaced by Rec8 in the cohesin complex.

The importance of the recombination machinery for proper disjunction of chromosomes is supported by the observation that ______

loss of recombination function leads to higher levels of meiotic nondisjunction

How can the maintenance of low levels of cyclin B between meiosis I and II potentially suppress DNA replication?

According to one hypothesis, DNA replication is suppressed between meiosis I and II by which of the following?

• Shugoshin proteins

• Cyclin B

• Rec8

Cyclin B

Sister chromatid cohesion is maintained during which process?

Meiosis I

Shugoshin proteins are involved in ______

cohesion protection during anaphase I

The four daughter cells produced by meiosis are ______

not genetically identical to each other

During meiosis I the sister kinetochores are attached to ____

the same pole

Gametes produced by meiosis contain which of the following?

• Both paternal and maternal chromosomes which have been subject to crossing over

• Only paternal chromosomes

• Only maternal chromosomes

• Exact copies of both paternal and maternal chromosomes

Both paternal and maternal chromosomes which have been subject to crossing over

How can the maintenance of low levels of cyclin B between meiosis I and II potentially suppress DNA replication?

By preventing the formation of replication initiation complexes

Which type(s) of cellular division produce(s) cells that are not genetically identical to the mother cell?

meiosis