Biology I- chapter 16

Cell ________, the reproduction of cells, is essential for:

-Replacing ____ cells (approx. 50 million cells die per second), growth of an organism, and wound _______.

-The _______ adult person (weight of 160 lbs.) is made up of approx. 30-35 _______ cells, give or take a few trillion.

Four events must occur for cell reproduction:

-____________ signal (Chapter 9).

-DNA __________ (Chapter 11).

-_____________ or segregation of DNA.

-Physical division of cell (called ___________).

division, dead, healing, average, trillion, Reproductive, replication, Distribution, cytokinesis

Every eukaryotic species has a characteristic number of chromosomes found within the _______.

-Humans have __  chromosomes in most cells; we inherit one set of 23 different chromosomes from each _______.

-Thus, most cells contain 23 pairs of chromosomes.

-Most pairs of chromosomes are called __________ chromosomes, and they contain _____ that control the same inherited traits.

One can visualize the number, shapes, and sizes of the chromosomes in a cell by performing a __________.

Chromosomes will differ from one another in size and ___________.

nucleus, 46, parent, homologous, genes, karyotype, appearance

The ______ cells, sperm and egg cells, have only ___ set of chromosomes; 22 __________ (chromosomes that are not the sex chromosomes) and ___ sex chromosome, an X or a Y.

-The term used to describe a cell that contains one set of chromosomes is _______ (1n).

-For humans, the haploid number of chromosomes in a gamete cell is __ (1n = 23).

-By means of sexual reproduction, a haploid sperm fuses with a haploid egg via ____________.

gamete, one, autosomes, one, haploid, 23, fertilization

The fertilized egg will have ___ haploid sets of chromosomes; one set from the ______ (1n = 23) and one set from the ______ (1n = 23).

The fertilized egg and most cells that make up the body with two sets of chromosomes are called _______ cells (2n).

-For humans, the diploid number of chromosomes in a cell is __ (2n = 46).

two, mother, father, diploid, 46

Cell division is part of a larger process called the cell _____; a series of events that leads to cell division.

Cell division requires the distribution of _______ genetic material (i.e. the DNA) from the initial ______ cell into two daughter cells.

-A dividing cell duplicates its ___, allocates the two copies to opposite ends of the nucleus, and then splits into two ________ cells.

-When this process occurs in the cells that make up the body (somatic cells; _______), it’s called _______.

-When this process occurs in the cells that produce the gametes (the sperm and egg cells; _______), it’s called _______.

cycle, identical, parent, DNA, daughter, diploid, mitosis, haploid, meiosis

The cell cycle is divided up into two main phases, each consisting of several subphases.

-__________: cells are engaged in their metabolic activities such as _______ respiration, _______________, muscle cell contraction, etc.

-Consists of subphases in which the cell is also making preparations for the cell ________ phase (such as replication of the genetic material, DNA).

-Mitosis or _______: the division phase.

-Consists of subphases involved in the ___________ of the DNA and the physical process of the cell producing two or four daughter cells.

-Cytokinesis: the division of the cell to form ________ cells.

Interphase, cellular, photosynthesis, division, meiosis, distribution, daughter

Interphase is the _______ part of the cell cycle.

-The cell _____ and increases in mass because the number of cytoplasmic components (organelles) _______ and the DNA is replicated.

Comprised of _ subphases:

-_1 (first gap): ___ molecules, proteins, and enzymes are being made; cell is _______.

-_ (synthesis of DNA): DNA ___________ occurs; chromosomes are now comprised of two sister chromatids.

-G_ (second gap): _____ preparations for cell division occur.

-At the end of interphase/G2, the chromosomes condense.

longest, grows, doubles, 3, G, RNA, growing, S, replication, 2, final,

__ phase: cells may exit the cell cycle and remain for long periods of time.

-The cells are ___ in the cell cycle and considered nondividing.

-Cells are still performing their normal _________.

-At any given time, most of our cells are in this phase.

Some cells remain in the G0 phase (adult muscle and nerve cells) and others can get back into the cell cycle (G1, S, and G2; ex. liver cells).

G0, not, functions

After the S phase, the DNA of each chromosome has been completely replicated.

-The chromosome is now comprised of the two copies, called sister __________, attached to one another.

-Each contain _______ copies of the chromosome’s DNA.

-The region where the sister chromatids are connected to one another is called the ____________.

-Later on in the process of division, the sister chromatids are pulled apart and repackaged into two new _____ at opposite ends of the parent cell.

chromatids, identical, centromere, nuclei,

Prior to DNA replication, the DNA of each eukaryotic chromosome consists of a linear DNA double helix that is found in the nucleus and is somewhat in an unravelled structure.

-After DNA replication, each chromosome is now comprised of the ___ sister chromatids.

-A human cell in __ will have 46 chromosomes, whereas the same cell in G2 will still have 46 chromosomes, but now be comprised of 46 pairs of sister chromatids (92 total sister chromatids).

When a cell prepares to divide, the sister chromatids become highly compacted and readily visible under the microscope.

two, G1

The mitosis phase of the cell cycle is comprised of several subphases:

-___phase.

-Prometaphase.

-_etaphase.

-___phase.

-____phase.

-Cytokinesis: the physical division of the parent cell into two daughter cells.

Pro, M, Ana, Telo

Prophase is the _____ stage of mitosis and at this stage:

• Duplicated chromosomes are highly _________ and become visible.

-_______ envelope begins to defragment/disassemble.

-The _____________ of the spindle apparatus begin to form and attach to chromosomes.

-The two identical sister chromatids are still attached at the centromere.

-_____________ (comprised of centrioles) move to ________ poles (ends of the nuclear region).

first, compacted, Nuclear, microtubules, Centrosomes, opposite

Metaphase is the ______ stage of mitosis and at this stage:

-The nuclear envelope has completely __________ (disappears from microscopic view; the textbook refers to this property as being part of prometaphase).

-Centrosomes are at opposite poles.

-Chromosomes are attached to microtubules causing them to be lined up in a single row at the _________ plate.

-Each chromosome is still comprised of two sister chromatids.

-In human cells there are 46 chromosomes, so therefore a total of __ sister chromatids are present.

second, fragmented, metaphase, 92

Anaphase is the _____ stage of mitosis and at this stage:

-The microtubules _______, causing the centromeres to split, resulting in the sister chromatids being pulled _____.

-Each independent sister chromatid is now termed a _____________.

-Each sister chromatid being pulled to the opposite pole is an _____ copy of the other.

-They are no longer called sister chromatids at this points; each one is called a ____________.

third, shorten, apart, chromosome, exact, chromosome

Telophase is the ____ stage of mitosis and at this stage:

-Each set of chromosomes decondense/_______.

-Nuclear envelope __-____ around each of the two separate sets of chromosomes.

-Microtubules __________.

-Cytokinesis of the cell cytoplasm takes place.

-Although cytokinesis is typically discussed as a separate phase, the actual phase overlaps with the second half of telophase.

-Each of the two newly formed daughter cells can now enter G1 phase of interphase and the cell cycle _______.

-The cells may also enter the G0 phase.

last, unravel, reforms, disassemble, repeats

Cytokinesis: The ________ division of the cell into two daughter cells (division of _________).

physical, cytoplasm

For the most part, animal and plant cells go through a similar cell cycle with the same phases and subphases.

Among the few differences are:

-Plant cells do ___ have centrioles, but are still able to produce the ____________ needed for separation of the sisters chromatids.

-The process of cytokinesis is different:

-In ______ cells, cytokinesis results from the formation of a cleavage furrow (forms from the _______ of cell).

-In _____ cells, cytokinesis results from the formation of a cell plate (forms from ______ the cell).

not, microtubules, animal, outside, plant, within

The timing and rates of cell division in different parts of an animal or plant are crucial for normal growth, ___________, and maintenance.

The frequency of cell division _______ with cell type.

-Some human cells divide frequently throughout life (____ cells), others have the ability to divide, but keep it in reserve (_____ cells), and mature _____ and muscle cells do not appear to divide at all after maturity.

The events of the cell cycle are highly regulated to ensure that the nuclear ______ is intact and that the conditions are appropriate for a cell to divide.

development, varies, skin, liver, nerve, genome

As an organism develops from a ______ to a sexually mature adult, the zygote’s genes are passed on to all somatic cells by _______.

The ______ cells (sperm and egg), which develop in the ovaries and testis, are not produced by mitosis.

Instead, these cells undergo the process of _______ in which the chromosome number is divided in ____.

-Human sperm or egg cells have a _______ set of __ different chromosomes, one from each parent/homologous pair.

-Meiosis is the process by which haploid (1n) cells are ________ from a cell that was originally _______ (2n).

zygote, mitosis, gamete, meiosis, half, haploid, 23, produced, diploid

Meiosis is called a _________ division (2n → 1n).

-For this to happen, a diploid parent cell will undergo ___ consecutive rounds of divisions, ending with the formation of ____ haploid daughter cells.

-Meiosis I.

-Meiosis II.

-Each round of division consists of a P, M, A, T, and subsequent cytokinesis.

-Like mitosis, meiosis I is preceded by __________, where DNA replication occurs and each chromosome is comprised of two sister chromatids (but does ___ happen again before meiosis II)

reduction, two, four, interphase, NOT

___phase I is the first stage of meiosis I:

-Duplicated chromosomes are highly compacted and become _______.

-Nuclear envelope begins to defragment/___________.

-Microtubules begin to form.

-___________ move to opposite poles.

-Homologous chromosomes pair with one another (bivalents, via synapsis).*

-Crossing over occurs.*

Pro, visible, disassemble, Centrosomes

Metaphase I is the _______ stage of meiosis I:

-The nuclear envelope has completely __________.

-Synapsed pairs of chromosomes are attached to ___________ causing them to be lined up in a double row at the metaphase plate.*

-The ___________ chromosomes are each comprised of two sister chromatids (so four total) and stay ________.*

-Homologous chromosomes randomly align along the ____________ plate.*

second, fragmented, microtubules, homologous, attached, metaphase

Anaphase I is the _____ stage of meiosis I:

-Each chromosome partner of the homologous pairs move to their respective opposite _____.

-Each chromosome partner is independently attached to microtubules at the centromere.

-The sister chromatids for each chromosome are still held _________.*

-The chromosome number is reduced from diploid to _______.

third, poles, together, haploid

Telophase I is the ______ stage of meiosis I:

-Chromosomes decondense/_______.

-Nuclear envelope __-____ around each of the two sets of chromosomes.

-___________ of the cell cytoplasm occurs.

-Each daughter cell has 23 chromosomes, with each chromosome still being comprised of its two ______ chromatids.*

-Each of the two newly formed daughter cells progress directly into ________ II of meiosis II.*

fourth, unravel, reforms, Cytokinesis, sister, prophase

The two daughter cells formed in meiosis I immediately undergo a second division, called meiosis __.

-The two daughter cells are haploid and contain one chromosome of each homologous pair (__ chromosomes total).

-The events that occur in meiosis II are more similar to those in mitosis.

The principal differences in meiosis II are:

-Preceding meiosis II, there is not another __________ phase and thus no second round of chromosome ___________.*

-______ alignment occurs between the sister chromatids in Metaphase II (like that of the homologous chromosome partners in Metaphase I).*

II, 23, interphase, replication, Random

Duplicated chromosomes are highly compacted and become visible.

Nuclear envelope begins to defragment/disassemble.

Microtubules begin to form.

Centrosomes move to opposite poles.

There are 23 chromosomes with the two identical sister chromatids still attached at the centromere.

Prophase II

___________ are at opposite poles.

Chromosomes are attached to microtubules causing them to be lined up in a single row at the metaphase plate.

Each chromosome is _____ comprised of two sister chromatids.

-In human cells there are now 23 chromosomes, so therefore a total of 46 sister chromatids are present.

-Chromosomes/sister chromatids randomly align.*

Metaphase II, Centrosomes, still

The difference between anaphase I and II is that in anaphase II the __________ of each chromosome divides.

The sister chromatids (now pulled _____ and termed chromosomes) move to the opposite poles, as in mitosis.

There are no longer any ______ homologous chromosomes or ______ chromatids at this stage.

Anaphase II, centromere, apart, paired, sister

Chromosomes decondense/unravel.

Nuclear envelope re-forms around each of the two sets of chromosomes.

Cytokinesis of the cell cytoplasm occurs, dividing each of the two cells into a total of ____ daughter cells.

-Each daughter cell is _______ and contains 23 chromosomes.*

The four resultant haploid daughter cells are the sperm or ___.

Telophase II, four, haploid, egg

Mitosis and meiosis have several key differences:

-Mitosis produces daughter cells that are genetically _________ to the parent and to each other (i.e. clones).

-Mitosis is ___ division resulting in ___ genetically identical daughter cells.

-Meiosis produces daughter cells that are genetically _________ to the parent and to each other (i.e. promotes variation).

-Meiosis is ___ consecutive divisions resulting in ____ daughter cells that are not genetically identical.

-The chromosome number is reduced by half in _______ (2n → n), but not in mitosis (2n → 2n).

identical, one, two, different, two, four, meiosis

Mitosis and meiosis have several key differences:

-DNA replication occurs ____ to mitosis and meiosis I, but ___ between meiosis I and II.

-During ___phase of meiosis I, the homologous chromosomes bind to each other to form pairs (bivalents).

-This explains why crossing over commonly occurs during meiosis.

-During (pro)metaphase of mitosis and meiosis II, pairs of sister chromatids are attached to both poles.

-In contrast, during meiosis I, each pair of sister chromatids (within a homologous pair) is attached to a ______ pole.

prior, not, pro, single

Mitosis and meiosis have several key differences:

-Homologous chromosome pairs align along the metaphase plate during metaphase of meiosis I, whereas sister chromatids align along the metaphase plate during metaphase of _______ and _______ II.

-At anaphase of meiosis I, the homologous chromosomes separate, but the sister chromatids remain together.

-In contrast, sister chromatid separation occurs during anaphase of mitosis and meiosis II.

mitosis, meiosis