MG : Cell Division

DNA condenses in all or part of what two sub-phases?

1) Beginning of M (prophase - early anaphase) 2) End of M (late anaphase - telophase)

What are the six stages of mitosis and cytokinesis.

1) Prophase 2) Pro-metaphase 3) Metaphase 4) Anaphase 5) Telophase 6) Cytokinesis

Sister chromatids are present in all or part of what three sub-phases?

1) S 2) G2 3) Beginning of M (prophase - early anaphase)

DNA content per cell is doubled in all or part of what four sub-phases?

1) S 2) G2 3) Beginning of M (prophase - early anaphase) 4) End of M (late anaphase - telophase)

4 Mechanisms that contribute to genetic variation include?

1) the production of recombinant chromosomes due to crossing over 2) the independent assortment of homologous chromosomes in meiosis I 3) the separation of sister chromatids (which are no longer identical due to crossing over) in meiosis II 4) the random fusion of male and female gametes during fertilization

Female gametes are ________ times larger than sperm.

400

How many stages of meiosis exist?

8

A cell has 16 chromosomes. How many chromosomes would its daughter cells have after meiosis?

8 Meiosis reduces the number of chromosomes passed on to daughter cells by one-half.

Separation of sister chromatids occurs _______.

At anaphase in mitosis and anaphase II in meiosis.

Phases of the cell cycle : G1 Checkpoint

At this point, cell commits to go through the cycle.

Which structure is not found in all mitotic cells? A) Spindle fibers B) Centriole C) Sister chromatids D) Kinetochore

B) Centriole

Deciphering the stages in of Real Cells requires:

Carefully observation of the 1) Completeness of the mitotic spindle 2) The location of the chromosomes 3) How condensed the chromosomes are

Phases of the cell cycle : After the M Checkpoint

Cell divides, forming two daughter cells.

After chromosomes condense, the _________ is the region where the identical DNA molecules are most tightly attached to each other.

Centromere(s)

Phases of the cell cycle : G2

Centrosome replicates

The ___________ are the organizing centers for microtubules involved in separating chromosomes during mitosis.

Centrosome(s)

During interphase, most of the nucleus is filled with a complex of DNA and protein in a dispersed form called __________.

Chromatin

Haploid -

Containing only a single chromosome set

Diploid -

Containing two chromosome sets, one maternal and one paternal

Without crossing over, sister chromatids remain identical and thus, pairs of daughter cells would be identical. With crossing over, however, all four daughter cells are genetically unique.

Crossing Over: After Metaphase 1: 2 unique Sister cells are produced. After Metaphase 2: 4 unique daughter cells are produced. No Crossing Over: After Metaphase 1: 2 unique Sister cells are produced. After Metaphase 2: 4 like daughter cells are produced. (2 and 2 are identical)

In most eukaryotes, division of the nucleus is followed by __________, when the rest of the cell divides.

Cytokinesis

Each of the following events occurs during mitosis except _______. A) chromosomes condense B) microtubules assemble between centrioles C) nuclear membrane breaks down D) polar microtubules contract, pulling attached chromosomes toward the poles

D) polar microtubules contract, pulling attached chromosomes toward the poles

Phases of the cell cycle : S

DNA Replicates

During telophase, the nonkinetochore microtubules ______________ . Choices: Shorten Lengthen Disassemble

Disassemble

Cytokinesis -

Division of the Cytoplasm

Mitosis -

Division of the Nucleus

When is DNA duplicated for cell division?

During the S period of interphase.

A dyad is composed of two homologous chromosomes joined at a common centromere. True or False

False - A dyad is composed of two SISTER CHROMATIDS joined at a common centromere.

Haploid cells do not undergo mitosis. True or False

False : Both haploid and diploid cells can undergo mitosis.

In animal cells, the two types of mitotic spindles function the same in the stages of Mitosis. True or False

False : the two types function differently in the mitotic stages / stages of mitosis.

The parent cell that enters meiosis is diploid, whereas the ________ daughter cells that result are haploid.

Four

List the of steps in the eukaryotic cell cycle in the correct order?

G1 S G2 M G1 The S phase is both preceded and followed by a period of growth (G1 and G2)

Once a cell passes the ______ _________, it usually completes the cell cycle..... that is, IT DIVIDES.

G1 Checkpoint

Crossing over refers to _________.

Genetic exchange between nonsister chromatids during meiosis

In dividing cell, most of the cell's growth occurs during ______.

Interphase

Phases of the cell cycle : The 3 sub-phases (G1, S, & G2) make up what cell phase?

Interphase

Pro-metaphase -

Is marked by fragmentation of the nuclear envelope, expansion of the spindle into the nuclear region, and attachment of some spindle fibers to the chromosomes via the kinetochores.

During mitosis, microtubules attach to chromosomes at the _______________.

Kinetochore(s)

During prophase, the microtubules of the mitotic spindle _____________. Choices: Shorten Lengthen Disassemble

Lengthen

During anaphase, the nonkinetochore microtubules ______________ and move past each other, and the kinetochore microtubules _____________. Choices: Shorten Lengthen Disassemble

Lengthen Shorten

Metaphase -

Marked by the alignment of chromsomes along the metaphase plate, is brought about by kinetochores aligning and then remaining motionless relative to the poles of the cell.

What are the 8 stages of meiosis

Meiosis I: 1) Prophase I 2) Metaphase I 3) Anaphase I 4) Telophase I (followed by cytokinesis) Meiosis II: 5) Prophase II 6) Metaphase II 7) Anaphase II 8) Telophase II (followed by cytokinesis)

Chromosomes condense, microtubules assemble between centrioles, and the nuclear membrane breaks down during ___________.

Mitosis

Phases of the cell cycle : The M phase includes _______ and ___________.

Mitosis and Cytokinesis

The _______ ________ is a cell structure consisting of microtubules, which forms during early mitosis and plays a role in cell division.

Mitotic Spindle(s)

Phases of the cell cycle : After the G2 Checkpoint

Mitotic spindle begins to form

Phases of the cell cycle : G1

Non-dividng cells exist cell cycle.

Novel combinations of genes can arise from _______.

Reciprocal exchange of DNA between homologs during prophase I

DNA replication produces two identical DNA molecules, called ___________ __________ , which separate during mitosis.

Sister Chromatid(s)

What is the arrangement of chromosomes during metaphase?

Sister chromatids are aligned along the equatorial plane of the cell. (Line Down the Middle)

Anaphase -

The cohesin proteins are cleaved, and the kinetochores move toward the poles of the cell, separating the sister chromatids.

Crossing over contributes significantly to the genetic variation seen in gametes. Why?

The exchange of maternal and paternal genes between the nonsister chromatids of a homologous chromosome pair creates recombinant chromosomes with unique combinations of alleles.

Telophase -

The kinetochore microtubules of the spindle disassemble. As the chromosomes reach the poles of the cell, the nuclear envelopes of the two new daughter nuclei form.

Prophase -

The microtubules of the spindle apparatus begin to assemble from individual tubulin subunits. As the identical chromatids of each pair of sister chromatids condense during this stage, they are held together by cohesin proteins.

In humans, what is a fundamental difference between the production of female gametes and male gametes?

The production of female gametes involves an unequal division of cytoplasm. (During the production of female gametes, one daughter cell contains most of the cytoplasm and one polar body contains only a small amount of cytoplasm.)

During meiosis if crossing over did not occur, what would be the result?

There would be less genetic variation among gametes.

Motor protein in the kinetochore are responsible for the moving/pulling of chromosomes to the poles of the cell. True or False

True

The cell cycle consists of a Longer phase called interphase and a shorter phase called mitosis, during which cell division takes place. True or False

True

The end result of meiosis is four haploid daughter cells. True or False

True

The primary differences observed for plant cell mitosis relative to animal cell mitosis occur during telophase. True or False

True During telophase, plant cells synthesize a cell plate that is laid down across the region of the metaphase plate.

The second meiotic division is similar to mitosis in that the sister chromatids separate. True or False

True - The second meiotic division is also called an equational division and involves the separation of sister chromatids, similar to what occurs in mitosis.

Unlike with asexual reproduction, offspring of sexual reproduction are genetically __________ from each other and from both of their parents.

different

DNA content is _______ in both meiosis I and meiosis II. Ploidy level changes from diploid to haploid in meiosis I, and remains haploid in meiosis II.

halved

In meiosis I -

homologous chromosomes pair and then separate

Ploidy -

is the number of sets of chromosomes in the nucleus of a biological cell.

The mitotic spindle consists of two types of microtubules: ______________ microtubules and __________________ microtubules.

kinetochore nonkinetochore

In organisms that reproduce _____________, the processes of DNA replication, chromosome alignment and separation in meiosis I and II, and fertilization ensure that traits pass from one generation to the next. Crossing over, the exchange of maternal and paternal DNA segments that occurs during meiosis I, is not required to guarantee heredity.

sexually

In meiosis II -

the sister chromatids separate