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The domestic dog has a diploid number (2n) of 78; 76 of the chromosomes are autosomes and 2 are sex chromosomes (X and Y). A karyotype taken from a dog's mature egg cell would have how many chromosomes?

39

If a diploid cell undergoes meiosis and produces two gametes with n + 1 chromosomes and two gametes with n - 1 chromosomes, what type of error occurred,

A nondisjuction error occurred in meiosis I, in which both members of a homologous pair migrated to the same pole of the cell.

If a diploid cell undergoes meiosis and produces two gametes that are normal, and one with n − 1 chromosomes, and one with n + 1 chromosomes, what type of error occurred?

A nondisjunction error occurred in meiosis II, in which both sister chromatids of a chromosome migrated to the same pole of the cell.

What is the difference between a chromatid and a chromosome?

A chromatid is one half of a replicated chromosome, whereas a chromosome consists of DNA wrapped around proteins in a highly organized manner.

What kind of cell results when a diploid and a haploid gamete fuse during fertilization?

A triploid cell which has three sets of chromosomes: the two from the diploid gamete and the one from the haploid gamete.

Which event does not take place before the start of mitosis? A. Organelles proliferate B. The parent cell grows C. DNA is replicated D. The nuclear envelope disintergrates

D

Independent assortment of chromosomes occurs during ______.

Meiosis I only

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

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

What is a major difference between meiosis II and mitosis in a diploid animal?

Meiosis II occurs in a haploid cell, while mitosis occurs in diploid cells.

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

four ... haploid

After telophase I of meiosis, the chromosomal makeup of each daughter cell is

haploid, and the chromosomes are each composed of 2 chromatids

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

kinetochore

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

2n. An organism that has two sets of chromosomes has a ploidy of 2n.

In human gamete production there is an average of _____ crossover events per chromosome pair.

2-3 These crossover events increase the genetic variation among gametes.

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

12. Meiosis is a reduction division that reduces the number of chromosomes passed on to daughter cells by one-half.

A group of cells is assayed for DNA content immediately following mitosis and is found to have an average of 8 picograms of DNA per nucleus. How many picograms would be found at the end of S and the end of G2?

16; 16

A cell has 6 unreplicated chromosomes. How many replicated chromosomes does the cell have after chromosome replication?

6

The chromosome number of hexaploid wheat, Triticum aestivum, can be represented as

6n

What is nondisjunction?

An error in cell division that causes homologous chromosomes or sister chromatids to move to the same side of the dividing cell

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

Anaphase

Homologous chromosomes migrate to opposite poles during ________.

Anaphase I

In meiosis, homologous chromosomes are separated during _____.

Anaphase I

Centromeres divide and sister chromatids become full-fledged chromosomes during _____.

Anaphase: anaphase sister chromatids separate and daughter chromosomes migrate to opposite poles.

The microtubule-organizing center found in animal cells is an identifiable structure present during all phases of the cell cycle. Specifically, it is know as the ________.

Centrosome

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

Chiasma. The chiasma is an X-shaped structure formed from the crossing over of homologous chromosomes, which can then exchange segments at the crossover sites.

What is occurring during the S phase of the cell cycle?

DNA is synthesized

T/F: A haploid organism has one pair of homologous chromosomes.

False. A haploid organism only has one set of chromosomes, so it has no homologous chromosomes.

T/F: Mitosis takes place during M phase, which is the longest phase of the cell cycle.

False; actually shortest

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. All maternal chromosomes would go to one daughter cell and all paternal chromosomes to the other, so different combinations would not be produced in gametes.

Which statement about the difference between homologous chromosomes and sister chromatids is correct?

Homologous chromosomes contain the same genes, but may contain different alleles. Sister chromatids contain the same genes and the same alleles.

A key difference between mitosis and meiosis is

Homologs pair up and crossing over happens during meiosis I but does not happen in mitosis .

When can nondisjunction occur?

In meiosis, when homologous chromosomes fail to separate In mitosis, when sister chromatids fail to separate In meiosis, when sister chromatids fail to separate

Nucleoli are present during what part of mitosis?

Interphase

Which if the following would enable you to detect aneuploidy?

Karyotyping

Crossing over normally takes place during which of the following processes?

Meiosis I

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

Metaphase

Homologous pairs of chromosomes are lined up independently of other such pairs during ______.

Metaphase I

During _____ chromosomes align single file along the equator of a haploid cell.

Metaphase II

What is the composition of a tetrad at the beginning of prophase I?

One pair of homologous chromosomes. One chromosome in a tetrad is paternally inherited, while the other is maternally inherited. Each chromosome consists of two chromatids.

How is plant cell cytokinesis different from animal cell cytokinesis?

Plant cells deposit vesicles containing cell-wall building blocks on the metaphase plate; animal cells form a cleavage furrow.

Spindle fibers attach to kinetochores during _____.

Prometaphase: attachment of spindle fibers to kinetochores is one of the events of prometaphase

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

Prophase

Synapsis occurs during _____.

Prophase I

During ______ a spindle forms in a haploid cell.

Prophase II which is essentially the same as mitotic prophase except that the cells are haploid.

Chromosomes become visible during _____.

Prophase: During prophase, the chromatin fibers become discrete chromosomes.

Which molecule types are present in chromosomes?

Proteins and nucleic acids

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

Sister chromatids

What is a major difference between mitosis and meiosis I in a diploid organism?

Sister chromatids separate in mitosis, while homologous pairs of chromosomes separate in meiosis I.

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

Telophase

At the end of _____ and cytokinesis, haploid cells contain chromosomes that each consist of two sister chromatids.

Telophase I

At the end of _____ and cytokinesis there are four haploid cells.

Telophase II

If a diploid cell containing a large number of chromosomes skipped crossing over but completed the other steps of meiosis cell division to produce gametes, what would be the outcome?

The cell can still create new combinations of maternal and paternal alleles in anaphase I.

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

The sequence of bases of a particular gene

Which major events occur during anaphase of mitosis?

The sister chromatids on replicated chromosomes separate, and the spindle poles are pushed father apart.

Which statement about the daughter cells following mitosis and cytokinesis is correct?

They are genetically identical with each other and with the parent cell.

Which syndrome is characterized by the XO chromosome abnormality?

Turner syndrome

After S phase, what makes up a single chromosome?

Two sister chromatids

A radiation accident leads to a damaged gene in yeast Saccharomyces cerevisiae which leads to improper function of that gene. If this species reproduces asexually, which offspring will inherit a copy of the damaged gene?

all offspring

During _____ sister chromatids separate.

anaphase II

An advantage of asexual reproduction is that

asexual reproduction enables the species to rapidly colonize habitats that are favorable to that species.

In the cells of some organisms, mitosis occurs without cytokinesis. This results in _______.

cells with more than one nucleus

What are homologous chromosomes?

chromosomes that are similar in their size, shape, and gene content

In a human karyotype, chromosomes are arranged in 23 pairs. If we choose one of these pairs, such as pair 14, which of the following do the two chromosomes of the pair have in common?

length, centromere position, staining pattern, and traits coded for by their genes

Nondisjuntion that leads to problems in offspring occur in:

meiosis I and II

Crossing over, resulting in an increase in genetic variation, occurs between ________.

nonsister chromatids of homologous chromosomes

When does DNA replication take place regarding meiosis? DNA replication ________.

occurs before meiosis I begins

Which of the following does NOT occur during mitosis?

replication of DNA

Cytokinesis often, but not always, accompanies _____.

telophase

In human and many other eukaryotic species' cells, the nuclear membrane has to disappear to permit _____.

the attachment of microtubules to kinetochores

Of the following chromosomal abnormalities, which type is most likely to be viable in humans?

trisomy

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

two ... haploid