12. Meiosis

Meiosis I

It has half the amount of DNA as the parent cell.

It has half the chromosomes but twice the DNA of the parent cell.

It has one-fourth the DNA and one-half the chromosomes as the parent cell.

It is genetically identical to the parent cell.

A daughter cell is created by meiosis I and the first round of cytokinesis. This daughter cell is just beginning meiosis II. Which of the following is an appropriate description of this daughter cell’s genetic contents?a) It has half the amount of DNA as the parent cell.b) It has half the chromosomes but twice the DNA of the parent cell.c) It has one-fourth the DNA and one-half the chromosomes as the parent cell.d) It is genetically identical to the parent cell.

Phases of meiosis I | Cells | MCAT | Khan Academy

DRAW IT The diagram shows a cell in meiosis. <img src="https://lightcat-files.s3.amazonaws.com/problem_images/b84eaf0f1d29ce0a-Ques.jpg" alt="" /> c. Identify the stage of meiosis shown.

If the DNA content of a diploid cell in the G1 phase of the cell cycle is x, then the DNA content of the same cell at metaphase of meiosis I will be
a. 0.25x.
b. 0.5x.
c. x.
d. 2x.

 Sister chromatids separate and migrate toward opposite poles. 

 No. This may occur during telophase I and does occur during telophase II. 

 No. This happens on the metaphase plate during metaphase I and II. 

 No. The cell is diploid until the end of meiosis I and cytokinesis. 

 Homologs separate and migrate toward opposite poles. 

Review the events of meiosis I and what separates to achieve chromosome reduction in the dividing cells.

Which of the following occurs during anaphase I?

After telophase I of meiosis, each daughter cell is                   .
a. diploid, and the chromosomes are composed of one double-stranded DNA molecule;
b. diploid, and the chromosomes are composed of two sister chromatids;
c. haploid, and the chromosomes are composed of one double-stranded DNA molecule;
d. haploid, and the chromosomes are composed of two sister chromatids

Short Video: Meiosis Sperm

DRAW IT The diagram shows a cell in meiosis.  a. Label the appropriate structures with these terms: chromosome (label as duplicated or unduplicated), centromere, kinetochore, sister chromatids, nonsister chromatids, homologous pair (use a bracket when labeling), homolog (label each one), chiasma, sister chromatid cohesion, and gene loci, labeling the alleles of the F and H genes.

 No. Four haploid cells are present at the end of telophase II and cytokinesis. 

 No. Two diploid cells are the result of the completion of the mitotic cell cycle. 

 No. Neither the mitotic cell cycle nor meiosis and cytokinesis directly produce four diploid cells. 

 one haploid ovum and three polar bodies 

 No. This is a final result of oogenesis (egg production) in mammals. 

Consider the events of meiosis I. How many cell divisions occur in meiosis?

At the end of telophase I of meiosis and the first cytokinesis, there are __________.

 No. During anaphase I, homologous chromosomes separate and migrate toward opposite poles. 

 No. Cytokinesis is the division of the cytoplasm to form two cells. 

 No. Synapsis does not occur during prophase II. 

 No. During metaphase I, tetrads align along the metaphase plate. 

Review the events of meiosis.

Synapsis occurs during __________.

The two homologs of a pair move toward opposite poles of dividing cell during
a. mitosis.
b. meiosis I.
c. meiosis II.
d. fertilization.

 physically connects homologous chromosomes during mitosis 

 No. Synapsis does not occur during mitosis. 

 is broken down by enzymes during anaphase II 

 No. The synaptonemal complex is broken down late in prophase I. 

 No. Chiasmata persist after the synaptonemal complex has been broken down. 

 No. Cohesins hold the sister chromatids together along their lengths and at the centromeres. 

 physically connects homologous chromosomes during prophase I 

How do homologous chromosomes maintain their precise alignment during synapsis?

The synaptonemal complex __________.

Which diagram represents anaphase I of meiosis?<img src="https://static.studychannel.pearsonprd.tech/courses/biology/thumbnails/a67738a9" class="fr-fic fr-dii">a) Ib) IIc) IIId) IVe) Vf) VI

 Homologous chromosomes line up at the center of the cell. 

 No. Pairs of homologous chromosomes line up during metaphase I, not prophase I. 

 No. This also occurs during prophase II. 

 No. A spindle of microtubules forms during both prophase I and prophase II. 

Crossing over occurs during this phase.

Which event occurs only during prophase I of the first meiotic division?

DRAW IT The diagram shows a cell in meiosis.  b. Describe the makeup of a haploid set and a diploid set.

Meiosis (Updated)

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