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exam3 chp 12-17

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

sister Chromatid (s)

after chromosomes condense the _____ is the region where the identical DNA molecules are most tightly attached to each other.

Centromeres

the ____ is a cell structure consisting of microtubles which forms during early mitosis and play a role in cell division.

mitotic spindle (s)

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

chromatin

in most eukaryotes, division of the nucleus is followed by ______, when the rest of the cell divides.

Cytokinesis

The _______ are the organizing centers for microtubles involved in separating chromosomes during mitosis.

Centrosome s

the stages of mitosis are?

prophas,Prometaphase, Metaphase, anaphase and telophase

Will this cell elongate during mitosis? (yes or no?)
Will the sister chromatids separate from each other? (yes or no?)
Will the chromosomes move to the poles ?

yes,yes,no

true or false The cell plate consists of the plasma membrane and cell wall that will eventually separate the two daughter cells.Vesicles from the Golgi apparatus move along microtubules, coalesce at the plane of cell division, and form a cell plate.

true

In some organisms, such as certain fungi and algae, cells undergo the cell cycle repeatedly without subsequently undergoing cytokinesis. What would result from this?

large cells containing many nuclei

Nucleoli are present during _____.

interphase

Cytokinesis often, but not always, accompanies _____.

telophase

Chromosomes become visible during _____.

prophase

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

anaphase

Spindle fibers attach to kinetochores during _____.

prometaphase

During prophase a homologous pair of chromosomes consists of _____.

two chromosomes and four chromatids

Cells will usually divide if they receive the proper signal at a checkpoint in which phase of the cell cycle?

G1

Which of the following is true of benign tumors, but not malignant tumors?

They remain confined to their original site

Which of the following is a function of the S phase in the cell cycle? The synthesis of sister chromatids
The separation of sister chromatids
The synchronization of organelle division

The synthesis of sister chromatidsDNA replication occurs during S phase and results in two sister chromatids for each original chromosome.

The copying of chromosomes occurs during which of the following phases of the cell cycle? G2 phase
S phase
M phase

Chromosomes must undergo replication before mitosis can occur; this copying occurs during the S phase.

For the first several divisions of early frog embryos, cells proceed directly from the M phase to the S phase and back to M without gaps. Which of the following is likely to be true about dividing cells in early frog embryos?

The cells get smaller with each generation.

True or false? The M phase is characterized by the replication and division of a cell's chromosomes.

False

If an organism normally has 34 chromosomes, how many molecules of DNA should there be in the G1 phase of the cell cycle?

34

Which of the following events would cause the cell cycle to arrest? Synthesis of cyclins by growth factors and activation of a cyclin-Cdk complex
Complete chromosome replication
Poor nutrient conditions

Poor nutrient conditions

Which of the following does not occur during mitosis? spindle formation
separation of the spindle poles
replication of the DNA
separation of sister chromatids

replication of the DNA

ne difference between cancer cells and normal cells is that cancer cells are arrested at the S phase of the cell cycle.
are unable to synthesize DNA.
cannot function properly because they are affected by density-dependent inhibition.
are always in the M phase of the cell cycle.
continue to divide even when they are tightly packed together.

continue to divide even when they are tightly packed together.

Through a microscope, you can see a cell plate beginning to develop across the middle of a cell and nuclei forming on either side of the cell plate. This cell is most likely a plant cell in metaphase.
a bacterial cell dividing.
an animal cell in the process of cytokinesis.
an animal cell in the S phase of the cell cycle.
a plant cell in the process of cytokinesis.

a plant cell in the process of cytokinesis.

Vinblastine is a standard chemotherapeutic drug used to treat cancer. Because it interferes with the assembly of micro-tubules, its effectiveness must be related to myosin denaturation and inhibition of cleavage furrow formation.
inhibition of DNA synthesis.
suppression of cyclin production.
inhibition of regulatory protein phosphorylation.
disruption of mitotic spindle formation.

disruption of mitotic spindle formation.

In the cells of some organisms, mitosis occurs without cytoki-nesis. This will result in

cells with more than one nucleus

A particular cell has half as much DNA as some other cells in a mitotically active tissue. The cell in question is most likely in

G1.

The drug cytochalasin B blocks the function of actin. Which of the following aspects of the animal cell cycle would be most disrupted by cytochalasin B?

cleavage furrow formation and cytokinesis

What is crossing over?

the exchange of homologous portions of nonsister chromatids

Which of the following occurs during meiosis but not during mitosis?Chromosomes migrate to opposite poles.
Chromosomes align at the metaphase plate.
Synapsis occurs

Synapsis occurs

Mitosis results in the formation of how many cells; meiosis results in the formation of how many cells?

two diploid cells ... four haploid cells

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

two ... haploid

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

four ... haploid

During _____ sister chromatids separate.

anaphase II

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

telophase I

Synapsis occurs during _____.

prophase I

Homologous chromosomes migrate to opposite poles during _____.

anaphase I

Heritable variation is required for which of the following?mitosis
evolution
asexual reproduction

evolution

Meiosis II is similar to mitosis in that

sister chromatids separate during anaphase.

Which life cycle stage is found in plants but not animals?multicellular haploid
multicellular diploid
gamete
zygote

multicellular haploid

Consider pea plants with the genotypes GgTt and ggtt . These plants can each produce how many type(s) of gametes?

four ... one

Two organisms with genotype AaBbCcDdEE mate. These loci are all independent. What fraction of the offspring will have the same genotype as the parents?

1/16

Which of the following is true of an X-linked gene, but not of a Y-linked gene? It does not segregate like other genes.
The gene is present in both males and females.
It is only expressed in female offspring.

The gene is present in both males and females

In general, the frequency with which crossing over occurs between two linked genes depends on what?

how far apart they are on the chromosome

What is a nondisjunction?

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

When can nondisjunction occur? Choose the best answer. In mitosis, when sister chromatids fail to separate
In meiosis, when sister chromatids fail to separate
All three answers are correct.

All three answers are correct.

Which syndrome is characterized by the XO chromosome abnormality?

Turner syndrome

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

A triploid cell

Humans are diploid and have 46 chromosomes (or two sets). How many sets of chromosomes are found in each human gamete?Humans are diploid and have 46 chromosomes. How many chromosomes are found in each human gamete?

1,23

_____ is the process by which haploid gametes form a diploid zygote.

Fertilization

How are human mitochondria inherited?

from the mother only

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