Ch 12 & 13 HW

Mitosis is responsible for what key process in multicellular eukaryotes?

All of the responses are correct.

Prometaphase

Microtubules attach to kinetochore

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

centrosome(s)

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

cytokinesis

The division of the cytoplasm following mitosis is called _____.

cytokinesis

During mitosis, microtubules attach to chromosomes at the ______________.

kinetochore(s)

During _____ sister chromatids separate.

anaphase II

This image depicts a view of _____ during meiosis.

prophase II

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

sister chromatid(s)

What is the ploidy of this cell model?

diploid

During which substage of mitosis do sister chromatids break apart and start moving to opposite poles of the cell?

Anaphase

Which answer correctly associates a phase of mitosis with what happens to chromosomes during that phase?

Anaphase: Sister chromatids separate.

During which stage of mitosis are chromosomes lined up in the center of the cell?

Metaphase

For the male Drosophila shown in Figure 13.1, what are the (1) haploid number, (2) ploidy, and (3) total number of chromosomes?

(1) 4, (2) 2n, and (3) 8

What proportion (percent) of chromosomes in a human skin cell are paternal chromosomes?

50%

What is the ploidy of this cell model? (Figure #1)

triploid

Which processes lead to most genetic variation in sexually reproducing organisms?

-crossing over -random fertilization -independent assortment of chromosomes in meiosis

Mitosis

-prophase -prometaphase -metaphase -anaphase -telophase

Suppose a diploid cell with three pairs of homologous chromosomes (2n = 6) enters meiosis. How many chromosomes will the resulting gametes have in each of the following cases? 1. meiosis occurs normally 2. nondisjunction of 1 chromosome pair in meiosis I 3. nondisjunction of all 3 chromosome pairs in meiosis I 4. nondisjunction on 1 chromosome in 1 daughter cell in meiosis II 5. nondisjunction of all 3 chromosomes in 1 daughter cell in meiosis II

1. 3 only 2. 2 or 4 3. 0 or 6 4. 2, 3, or 4 5. 0, 3, or 6

Normal human gametes carry _____ chromosomes.

23

What is the ploidy of organisms that have two sets of chromosomes?

2n

The karyotype of a trisomic individual is symbolized as ____.

2n+1

Which of these gametes contains one or more recombinant chromosomes?

B and C

Which structure is directly correlated with the production of genetic variability in the daughter cells produced during meiosis?

Chiasma

The chromosomes are replicated.

False

True or false? A haploid organism has one pair of homologous chromosomes.

False

True or false? Mitosis takes place during M phase, which is the longest phase of the cell cycle.

False

Two important checkpoints that regulate the cell's progression through the cell cycle occur in the _____ and _____ phases of the cell cycle.

G1, G2

To which part of the centromere do mitotic spindle fibers attach during prometaphase?

Kinetochore

Metaphase

Kinetochores are motionless in relation to poles of cell.

Anaphase

Kinetochores move toward poles of cell.

Which of the following statements about meiosis and mitosis is true?

Meiosis II is similar to mitosis in that sister chromatids of each chromosome separate.

During what phase of the cell cycle does the DNA become replicated?

S

Which term describes two recently replicated DNA strands that are joined together just before cell division?

Sister chromatids

Telophase

Spindle microtubules disassemble.

For the experiment shown in Figure 12.6, which answer best describes what the prediction would be if chromosome movement were based on microtubule shortening at the spindle pole?

The darkened section will move toward the spindle pole but the distance between chromosomes and the darkened section will remain constant.

Which event does not take place before the start of mitosis?

The nuclear envelope disintegrates.

What information can not be obtained from an individual's karyotype?

The sequence of bases of a particular gene

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

centromere(s)

Each chromosome contains one long molecule of double-stranded DNA and proteins.

True

The bands on the chromosomes represent certain genes.

True

There are five different lengths of chromosomes in this cell.

True

This cell is 2n = 10.

True

This cell is diploid.

True

Prophase

Tubulins assemble into spindle microtubules.

Meiosis typically produces _____ cells, each of which is _____.

four ... haploid

The statement, "It is a matter of chance which homolog goes to which daughter cell" best describes _____.

independent assortment

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

interphase

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

mitotic spindle(s)

In which mitotic phase do the chromosomes condense and does the mitotic spindle begin to form?

prophase

A diploid species has ten distinct types of chromosomes. A haploid cell of this species contains how many chromosomes?

10

If a cell has 24 chromosomes, how many chromosomes would each of its four daughter cells have after meiosis?

12

A diploid organism whose somatic (nonsex) cells each contain 32 chromosomes produces gametes containing _____ chromosomes.

16

Which answer correctly identifies a cell-cycle checkpoint with a criterion for passing it?

G2 checkpoint: Chromosomes have replicated successfully.

How would genetic variation be affected if, during meiosis I, maternal chromosomes always lined up together on one side of the metaphase plate and paternal chromosomes always lined up on the other side (ignoring the effects of crossing over)?

Gametes would contain either maternal chromosomes only or paternal chromosomes only.

What would be the outcome of meiosis I if none of the homologous chromosomes separate at anaphase?

One daughter cell would be 2n; the other would have no chromosomes.

Which stage of mitosis is characterized by the disintegration of mitotic spindles and the formation of two new nuclear membranes?

Telophase