Bio Ch.8

Mitosis and cytokinesis result in the formation of ___: meiosis and cytokinesis result in the formation of___

2 diploid cells, 4 haploid cells

At the end of telophase I and cytokinesis, there are ____ haploid cells with chromosomes that consist of ___ sister chromatids each

2, 2

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

Prophase, it's the first phase of mitosis, when the centrosomes moving toward opposite poles and the nuclear envelope breaks up

The success of cell therapy to treat cancer relies on which type of cells?

T-cells

DNA replication occurs in...

The S phase of interphase *S stands for synthesis (of DNA)

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 (except occurrence of rare mutations)

Which of the following represents a chromosomally normal human female? X XXX XX XXY

XX

Crossing over is important because it...

allows the exchange of different versions of genes between homologous chromosomes

During ___sister chromatids separate

anaphase II

In the 2 cell divisions of meiosis, I and II, produce 4 haploid daughter cells... which are OR are not genetically identical to the diploid parent cell?

are not

Bacteria divide by...

binary fission

During anapase I, sister chromatids remain attached to their ____, and homologous chromosomes move to ____

centrosomes, opposite poles

What happens in metaphase?

chromosomes line up along an imaginary midline, which is equidistant between the two poles of the spindle

"The exchange of homologous portions of nonsister chromatids" this is...

crossing over

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

cytokinesis. the division of the cytoplasm that occurs in conjunction with telophase, the last phase in mitosis

During prophase, the chromatin fibers become...

discrete chromosomes

In bacterial cells, binary fission involves ___

distribution of a copy of the single parental chromosome to each daughter cell

During asexual reproduction, yeast cells can produce ___

genetically identical offspring

Haploid gamete cells contain ____ as many chromosomes as diploid somatic cells

half

During anaphase I ____ separate and migrate toward opposite poles

homologous chromosomes

Chromatids are...

identical copies of each other if they are part of the same chromosome

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

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

Which of the following damages cells and causes cell aging?

inflammation

A cell preparing to undergo meiosis duplicates its chromosome during

interphase

Nucleoli are present during...

interphase

In some organisms such as certain fungi and algae, cells undergo mitosis repeatedly without subsequently undergoing cytokinesis. What would be the consequence of this?

large cells containing many nuclei

If it werent for _____, chromosomes number would double with every generation of sexual reproduction

meiosis

Variation occurs when chromosomes are shuffled in ____

meiosis

Only during ____ do the homologous chromosomes pair up and then cross over

meiosis I

Gametes are produced by..

meisosis

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

telophase, the final phase of mitosis, when the chromosomes have arrived at the poles and nuclear envelopes of the two new cells form

Centromeres divide and sister chromatids become full-fledged chromosomes during

anaphase

The stage of mitosis during which the chromosomes move toward separate poles of the cell is

anaphase

Homologus chromosomes migrate to opposite poles during _____.

anaphase I

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

anaphase, sister chromatids separate and start their migration toward opposite poles

A cell replicates its entire chromosomal DNA only ___

before it is about to divide

The ____ _____ divides the cytoplasm in two, forms during telophase of mitosis in a plant cell

cell plate

Meisosis II typically produces ____ cells, each of which is _____

four, haploid

Anaphase II is essentially the same as mitotic anaphase, except that the cell is ...

haploid

Meiosis produces _____ ______ from a diploid parental cell

haploid gametes

Fertilization joins ____ to produce a ____

haploid gametes, diploid zygote

Research indicates that the best estimate of your age is from___

markers in your cells

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

metaphase II

After fertilization, the resulting zygote begins to divide by ___

mitosis

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

nondisjunction

The term binary fission is best applied to ____

prokaryotes

Spindle fibers attach to kinetochores during_____

prometaphase

Chromosomes become visible during ___

prophase

Segments of nonsister chromatids trade places during ____, resulting in recombination

prophase I

Synapsis occurs during____

prophase I

Order of events during meiosis is

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

During ____ a spindle forms in a haploid cell

prophase II

The exchange of parts between nonhomologous chromosomes is called

reciprocal translocation

During anaphase II, ______ separate and migrate toward opposite poles

sister chromatids

Mitosis ensures that all ____ cells receive copies of the parental chromosomes

somatic

An example of a cell that is 2n is a___

somatic cell

Mitosis occurs in ___; meiosis occurs in___

somatic or body cells, germ cell in the testes or ovaries

During prophase I of meiosis, homologous chromosomes...

stick together in pairs

What is a key difference between meiosis and mitosis?

synapsis occurs

Cytokinesis often, but not always, accompanies____

telophase

What must happen before a cell can begin mitosis?

the chromosomes must be duplicated, which occurs during interphase

What would be the immediate consequence of destroying a cell's centrosomes?

the mitotic spindle would not form

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 in MEIOSIS

Meiosis I produces ___ cells, each of which is ___

two, haploid

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

16

Diploid cells have ___ homologous copies of each chromosome

2

During prophase a homologous pair of chromosomes consists of_____

2 chromosomes 4 chromatids

Normal human gametes carry ___ chromosomes

23

The function of meiosis is to make____

4 cells with a haploid number of chromosomes

Meiosis starts with a single diploid cell and produces____

4 haploid cells

What is the typical result when a diploid cell undergoes meiosis?

4 haploid cells

Each somatic cell in an individual with down syndrome contains ___ chromosomes

47 (a result of having 3 copies of chromosomes 21)

What checkpoint does not occur late in G1?

A check that chromosome replication has been successfully completed

What is IGF-II

A chemical that stimulates growth in pancreatic tumors?

The first step of bacterial replication is ___

DNA replication

When examining cells in the laboratory, you notice that a particular cell has half as much DNA as the surrounding cells. This observation can be explained if this cell's cell cycle halted at checkpoint_____

G1

What is the correct cell cycle sequence of events for reactivated cells?

G1, S1, G2, M

A fragment of chromosome 21 reattaches to chromosome 21, but in the reverse direction. What is the name given to this change?

Inversion

An _____ occurs when a fragment reattaches to the original chromosome but in the reverse direction

Inversion

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

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

Mitosis takes place during the ___ phase

M

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

Metaphase, occurs in the middle of mitosis, when the chromosomes line up in the middle of the cell

DNA is synthesized in the ____ phase of interphase

S

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