Chapter 8: The cellular Basis of Reproduction and Inheritance.

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

anaphase

Homologous chromosomes migrate to opposite poles during _____.

anaphase I

During _____ sister chromatids separate.

anaphase II

In many organisms, including humans, chromosomes are found in homologous pairs. Homologous chromosomes _____.

are identical in the arrangement of their genes, but some versions of the genes may differ between the chromosomes

Baker's yeast is an organism with 32 chromosomes that can perform asexual or sexual reproduction and exist as both a diploid and haploid cell. After meiosis, how many chromosomes will be present in each cell?

16

A certain species of animal has six pairs of chromosomes. How many DNA molecules are present in the nuclei of these animals during G2 phase?

24

In a cell containing 10 chromosomes, meiosis results in the formation of daughter cells containing _____ chromosomes.

5

A human bone marrow cell, in prophase of mitosis, contains 46 chromosomes. There are _____ chromatids.

92. Mitosis follows the S phase, during which the cell's DNA is duplicated.

Imagine that a human skin cell went through mitosis but did not undergo cytokinesis. How many chromosomes would be in the cell?

92. When the cell prepared to divide, the chromosomes were replicated, and the chromosome number went from 46 to 92. Because these were not separated into daughter cells during cytokinesis, the cell still has 92 chromosomes.

Which of the following checkpoints does not occur late in G1?

A check that chromosome replication has been successfully completed

Asexual reproduction requires ________ individual(s).

1

what are the different types of asexual reproduction

Binary fission (Bacteria); budding; fragmentation (starfish).

Crossing over occurs during _____.

Prophase I

The chromosomes arrive at the poles and nuclear envelopes form during which phase of mitosis?

Telophase

What must happen before a cell can begin mitosis?

The chromosomes must be duplicated.

The M phase of mitosis and M phase of meiosis both occur after interphase. However, the two processes differ in the arrangement and behavior of their chromosomes. How?

The pairing up of homologous chromosomes and crossing over only occur during meiosis.

Within one chromosome, what is the relationship between the sequence of bases in DNA of one sister chromatid compared to the other?

The sequences are identical.

Strictly speaking, the phrase "like begets like" refers to

asexual reproduction only.

The creation of genetically identical offspring by a single parent, without the participation of sperm and egg, is called

asexual reproduction.

A cell replicates its entire chromosomal DNA only _____.

before it is about to divide

A ___________is a lump of abnormal cells that, although growing out of control, remains at its original site.

benign tumor

Bacteria divide by:

binary fission

An individual with a malignant tumor is said to have__________

cancer.

The most common type of cancer is a ______________; this type always originates in tissues that line organs.

carcinoma

Which of the following occurs during interphase?

cell growth and duplication of the chromosomes

At the end of the mitotic (M) phase, the cytoplasm divides in a process called _________________.

cytokinesis

The process by which the cytoplasm of a eukaryotic cell divides to produce two cells is called

cytokinesis.

Meiosis starts with _____ cells and produces _____ gametes.

diploid ... haploid

The diploid phase of the human life cycle begins with _____.

fertilization

Cytokinesis _____.

finishes mitosis by dividing the cytoplasm and organelles of the original parent cell into two separate daughter cells.

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

four ... haploid

The function of meiosis is to make _____.

four cells with a haploid number of chromosomes

Meiosis starts with a single diploid cell and produces

four haploid cells.

Without crossing over

genetic recombination could not occur.

At the conclusion of meiosis I, the daughter cells are _____.

haploid and the sister chromatids are joined

Fertilization joins _____ to produce a _____.

haploid gametes ... diploid zygote

The _____ separate in meiosis I; the _____ separate in meiosis II.

homologous chromosomes ... sister chromatids

In anaphase I, _____.

homologous chromosomes move toward opposite poles

During prophase I of meiosis,

homologous chromosomes stick together in pairs.

Two chromosomes in a nucleus that carry genes controlling the same inherited characteristics are

homologous chromosomes.

Both mitosis and meiosis are preceded by

interphase

Eukaryotic cells spend most of their cell cycle in which phase?

interphase

Nucleoli are present during _____.

interphase

A cell preparing to undergo meiosis duplicates its chromosomes during

interphase.

When we say that an organism is haploid, we mean that _____.

its cells each have one set of chromosomes

Sister chromatids are

joined together at a centromere.

A __________ is an abnormally growing mass of cells that is actively spreading through the body.

malignant tumor

If it weren't for _____, chromosome number would double with every generation of sexual reproduction.

meiosis

Looking through a light microscope at a cell undergoing meiosis, you see that the chromosomes have joined into XX-shaped tetrads. These tetrads are lined up along a plane that runs through the center of the cell. This cell is in _____.

meiosis I

Nondisjunction occurs when

members of a chromosome pair fail to separate.

At which stage of mitosis are chromosomes lined up in one plane in preparation for their separation to opposite poles of the cell?

metaphase

During which phase of mitosis do the chromosomes line up on a plane equidistant from the two spindle poles?

metaphase

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

metaphase II

Looking through a light microscope at a cell undergoing division, you see that the condensed chromosomes have lined up along the midline of the cell. The homologous pairs are NOT joined in tetrads. Each chromosome takes its own place in line, independent of its homolog. You are witnessing _____.

metaphase of mitosis

After fertilization, the resulting zygote begins to divide by _____.

mitosis

Consider the process by which bacterial populations grow. What process performs a similar function in humans?

mitosis. Binary fission and mitosis share some similarities in their function, which is to produce two daughter cells genetically identical to the parent cell. Both are forms of asexual reproduction.

During meiosis, homologous chromosomes sometimes "stick together" and do not separate properly. This phenomenon is known as _____.

nondisjunction

Duplication of the chromosomes to produce sister chromatids _____.

occurs in both mitosis and meiosis

In meiosis II, _____.

sister chromatids are separated

During anaphase II, _____.

sister chromatids separate and migrate toward opposite poles

Prior to mitosis, each chromosome of a eukaryotic cell consists of a pair of identical structures called

sister chromatids.

Mitosis occurs in _____; meiosis occurs in _____.

somatic or body cells ... germ cells in the testes or ovaries

Cytokinesis often, but not always, accompanies ______.

telophase

During which phase of mitosis does the nuclear envelope re-form?

telophase

Looking through a light microscope at a dividing cell, you see two separate groups of chromosomes on opposite ends of the cell. New nuclear envelopes are taking shape around each group. The chromosomes then begin to disappear as they unwind. You are witnessing _____.

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

The genetic material is duplicated during

the S phase.

What is different concerning the DNA in bacterial cells as opposed to eukaryotic cells?

the amount of DNA present, whether the DNA is housed in a nucleus or not, and whether the DNA is linear or circular.

One event occurring during prophase is _____

the beginning of the formation of the mitotic spindle

At the start of mitotic anaphase,

the centromeres of each chromosome come apart.

Cancer is not usually inherited because

the chromosomal changes in cancer are usually confined to somatic cells.

Crossing over is _____.

the exchange of homologous portions of non-sister chromatids

Meiosis is typically accomplished in _____.

three steps. All of the chromosomes are duplicated in a diploid cell, and then there are two cell divisions to produce a total of four haploid gametes.

In sexually reproducing multicellular organisms, the main functions of mitosis are _____.

tissue repair/replacement of damaged cells; growth and development

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

two ... haploid

During prophase a homologous pair of chromosomes consists of _____.

two chromosomes and four chromatids

Mitosis and cytokinesis result in the formation of _____; meiosis and cytokinesis result in the formation of _____.

two diploid cells ... four haploid cells

At the end of telophase I of meiosis, as cytokinesis occurs, there are _________

two haploid cells

Looking into your microscope, you spot an unusual cell. Instead of the typical rounded cell shape, the cell has a very narrow middle separating two bulging ends. It sort of looks like the number 8! Then you realize that this cell is

undergoing cytokinesis.

The phase of mitosis during which the mitotic spindle begins to form is

prophase.

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

random fertilization, independent orientation of chromosomes in meiosis, and crossing over.

The exchange of parts between non-homologous chromosomes is called _____.

reciprocal translocation

Benign tumors differ from malignant tumors in that the cells of a benign tumor _____.

remain confined to their original site

The function(s) of meiosis is/are _____.

reproduction (production of gametes)

____________ reproduction, in contrast, generates genetically unique offspring. To accomplish this, an organism must produce ____________-- sperm and egg -- through the process of __________. The cells produced this way will be ___________, meaning that they contain a single set of chromosomes. Such cells are produced only in the __________.

sexual; gametes; meiosis; haploid; gonads

The sister chromatids separate and begin moving toward opposite poles of the cell during which phase of mitosis?

Anaphase

___________ reproduction, in contrast, generates genetically unique offspring. To accomplish this, an organism must produce ______________ -- sperm and egg -- through the process of ___________

Asexual; gametes; meiosis

____________ reproduction is a means of creating new individuals solely by __________, the form of cell division that creates genetically identical daughter cells.

Asexual; mitosis

________________ reproduction is a means of creating new individuals solely by __________ the form of cell division that creates genetically identical daughter cells.

Asexual; mitosis

Which of the following occurs during mitosis?

Chromatids separate.

Which events occur during prophase?

Chromosomes condense and are attached to spindle fibers; The nuclear envelope breaks down.

Which of the following statements regarding the differences between mitosis and meiosis is false?

Crossing over is a phenomenon that creates genetic diversity during mitosis.

Which of the following statements correctly describes the timing of DNA synthesis?

DNA is synthesized in the S phase of interphase.

The centrosomes move away from each other and the nuclear envelope breaks up during which phase of mitosis?

Prophase

The first step of bacterial replication is _____.

DNA replication

Which of the following statements regarding Down syndrome is false?

Down syndrome is least likely to be seen in the infants of mothers over 40.

True or false. Mitosis takes place during M phase of the cell cycle, which is longer than interphase.

False

Consider the cell cycle shown below. Cells will usually divide if they receive the proper signal at a checkpoint in the _____ phase of the cell cycle.

G1

Immune system cells enter a resting phase after undergoing mitosis. When activated - for example, by an infection - they can reenter the sequence of events in the cell cycle that leads to cell division. What would be the correct sequence of events?

G1, S, G2, M

Which of the following statements regarding genetic diversity is false?

Genetic diversity is enhanced by mitosis.

During _____, the cell carries out its normal functions and the chromosomes are thinly spread out throughout the nucleus.

Interphase

During binary fission, one copy of the duplicating chromosome moves to the opposite end of the cell. What does this achieve?

It ensures that each daughter cell receives one copy of the chromosome.

The chromosomes line up in the center of the cell during which phase of mitosis?

Metaphase

_________________is the spread of cancer cells from their site of origin to other sites in the body.

Metastasis

Which of the following statements regarding the function of mitosis is false?

Mitosis allows organisms to generate genetic diversity.

Which of the following statements regarding mitosis and meiosis is false?

Mitosis produces daughter cells with half the number of chromosomes as the parent cell; Meiosis provides for asexual reproduction.

Which of the following features likely accounts for the difference between plant and animal cell cytokinesis?

Plant cells have cell walls.

Which of the following statements regarding prokaryotes is false?

Prokaryotic chromosomes are more complex than those of eukaryotes.

If the diploid number of chromosomes in a certain animal is 6 (2n = 6), there are three sets of two homologous chromosomes each, or three pairs. How do these three pairs align and separate in meiosis?

They align and assort independently to form any of eight different combinations.

Crossing over is important because it _____

allows the exchange of genes between homologous chromosomes

Spindle fibers attach to kinetochores during _____.

pro-metaphase

Asexual reproduction _____.

produces offspring genetically identical to the parent

Chromosomes become visible during _____.

prophase

During which stage of meiosis do synapsis and crossing over occur?

prophase I

Synapsis occurs during _____.

prophase I

The correct order of events during meiosis is

prophase I, metaphase I, anaphase I, telophase I, cytokinesis, meiosis II.

During meiosis, segments of non-sister chromatids can trade places. This recombination of maternal and paternal genetic material is a key feature of meiosis. During what phase of meiosis does recombination occur?

prophase I.

During _____ a spindle forms in a haploid cell.

prophase II