Chapter 12

In ___, a single individual is the sole parent and passes copies of all its genes on to its offspring. Many single-celled organisms and some multicellular ones reproduce __. For example, a hydra can reproduce by budding and produce a genetically identical individual.

A type of reproduction involving only one parent that produces genetically identical offspring by budding or by the division of a single cell or the entire organism into two or more parts.

__ makes it possible for organisms to reproduce asexually, by producing cells that carry the same __as the parent cells. Note that all the __ of the parent cell are replicated and passed on to the offspring cells. An __ is literally a "chip off the old block" since its cells are genetically identical to those of the parent.

A process of nuclear division in eukaryotic cells conventionally divided into five stages: __, __, __, __, __. It conserves chromosome number by equally allocating replicated chromosomes to each of the daughter nuclei.

A discrete unit of hereditary information consisting of a specific nucleotide sequence in DNA (or RNA, in some viruses).

A threadlike, gene-carrying structure found in the nucleus. Each one consists of one very long DNA molecule and associated proteins. See chromatin.

A type of reproduction in which two parents give rise to offspring that have unique combinations of genes inherited from the gametes of the two parents.

A type of reproduction involving only one parent that produces genetically identical offspring by budding or by the division of a single cell or the entire organism into two or more parts.

___ produces greater genetic variation than ___. Each offspring inherits a particular combination of genes from two parents; so many combinations are possible that each offspring is essentially unique, differing from its siblings and both parents.

Human __(most body cells) are __. Each somatic cell has two sets of __ chromosomes, making a total of __.

A special kind of cell division called __ occurs in the ovaries and testes, producing __-- eggs and sperm-- that carry only one set of __ chromosomes each.

Fertilization of an egg by a sperm combines two sets of chromosomes, producing a __ with __ chromosomes. The life cycle is completed as the __ develops into a sexually mature __ adult who begins producing __.

Note that all sexual life cycles involve an alternation of diploid and haploid stages. __ produces haploid gametes, and __ produces diploid organisms.

Any cell in a multicellular organism except a sperm or egg cell.

A cell containing two sets of chromosomes (2n), one set inherited from each parent.

A two-stage type of cell division in sexually reproducing organisms that results in cells with half the chromosome number of the original cell.

In animals, the structure that produces female gametes and reproductive hormones.

The male reproductive organ, or gonad, in which sperm and reproductive hormones are produced.

A haploid cell, such as an egg or sperm. They unite during sexual reproduction to produce a diploid zygote.

The union of haploid gametes to produce a diploid zygote.

The diploid product of the union of haploid gametes in conception; a fertilized egg.

__ is essential to sex, because it enables each parent to contribute one set of chromosomes-- half the total-- to each __offspring.

The period in the cell cycle when the cell is not dividing. During __, cellular metabolic activity is high, chromosomes and organelles are duplicated, and cell size may increase. It accounts for 90% of the cell cycle.

A process of nuclear division in eukaryotic cells conventionally divided into five stages: prophase, prometaphase, metaphase, anaphase, and telophase. It conserves chromosome number by equally allocating replicated chromosomes to each of the daughter nuclei.

Chromosome pairs of the same length, centromere position, and staining pattern that possess genes for the same characters at corresponding loci. One is inherited from the organism’s father, the other from the mother.

A cell containing only one set of chromosomes (n).

Replicated forms of a chromosome joined together by the centromere and eventually separated during mitosis or meiosis II.

During the __prior to meiosis, chromosomes replicate. Unlike mitosis, where each chromosome is on its own, in __, __pair up, and each pair separates, producing two __ cells with their sister chromatids still joined. __ is like mitosis; sister chromatids separate and four haploid cells are formed. Note that each has half the chromosomes of the parent cell. These cells differ genetically from each other and from the cells of the parents.

An ordered sequence of events in the life of a eukaryotic cell, from its origin in the division of a parent cell until its own division into two; composed of the M, G1, S, and G2 phases.

Cell division occurs during this short phase, which generally involves two discrete processes: the contents of the nucleus (mainly the duplicated chromosomes) are evenly distributed to two daughter nuclei, and the cytoplasm divides in two.

DNA synthesis (or replication) occurs during this phase. At the beginning of the phase, each chromosome is single. At the end, after DNA replication, each chromosome consists of two sister chromatids.

Typically, this phase accounts for 90% of the cell cycle. It is a time of high metabolic activity. The cell grows by producing proteins and organelles, and chromosomes are replicated.

This is when division of the nucleus occurs. The chromosomes that have been replicated are distributed to two daughter nuclei.

This third subphase of interphase is a period of metabolic activity and growth. During this phase the cell makes final preparations for division.

This is the portion of the cell cycle just after division, but before DNA synthesis. During this time the cell grows by producing proteins and organelles.

This is the step in the cell cycle when the cytoplasm divides in two.

Cell division consists of two processes: __ and __. __— division of the nucleus and its chromosomes— is divided into five phases: __,__,__,__, and __. Mitosis is followed by __, when the cytoplasm splits to form two separate daughter cells.

The division of the cytoplasm to form two separate daughter cells immediately after mitosis.

The first stage of mitosis, in which the chromatin is condensing and the mitotic spindle begins to form, but the nucleolus and nucleus are still intact.

The second stage of mitosis, in which discrete chromosomes consisting of identical sister chromatids appear, the nuclear envelope fragments, and the spindle microtubules attach to the kinetochores of the chromosomes.

The third stage of mitosis, in which the spindle is complete and the chromosomes, attached to microtubules at their kinetochores, are all aligned at the metaphase plate.

The fourth stage of mitosis, in which the chromatids of each chromosome have separated and the daughter chromosomes are moving to the poles of the cell.

The fifth and final stage of mitosis, in which daughter nuclei are forming and cytokinesis has typically begun.

The cytoplasm of a cell in late __ contains two __, each of which may contain a pair of __. In the nucleus, the chromosomes have been replicated during __ phase, but are still dispersed in the form of __. One or more nucleoli are present.

Material present in the cytoplasm of all eukaryotic cells, important during cell division; the microtubule-organizing center

A structure in an animal cell composed of cylinders of microtubule triplets arranged in a 9 + 0 pattern. An animal cell usually has a pair of centrioles involved in cell division.

The complex of DNA and proteins that makes up a eukaryotic chromosome. When the cell is not dividing, itexists as a mass of very long, thin fibers that are not visible with a light microscope.

During __, the nucleoli disappear and chromatin fibers coil up to become discrete chromosomes. Each chromosome consists of two identical sister chromatids, joined at the __. __ grow out from the centrosomes, initiating formation of the __.

Replicated forms of a chromosome joined together by the centromere and eventually separated during mitosis or meiosis II.

The centralized region joining two sister chromatids.

During __, the nuclear envelope breaks into fragments. Some of the spindle fibers reach the chromosomes and attach to __, structures made of proteins and specific sections of DNA at the __. __ overlap with those coming from the opposite pole.

A specialized region on the centromere that links each sister chromatid to the mitotic spindle.

At __, the __ is fully formed, and the microtubules attached to __ move the chromosomes to the __, an imaginary plane equidistant from the poles.

An assemblage of microtubules and associated proteins that is involved in the movements of chromosomes during mitosis.

__ begins when the two __ of each chromosome come apart, separating the sister __. Once separate, each sister chromatid is considered a full-fledged daughter chromosome. Motor proteins of the __ "walk" the daughter chromosomes along the spindle microtubules toward opposite poles, and the microtubules __. At the same time, the spindle microtubules not attached to chromosomes lengthen, pushing the two poles farther apart and elongating the cell.

During __, __ form around the identical sets of chromosomes at the two poles of the cell. The chromosomes uncoil and nucleoli appear in the two new nuclei. Meanwhile, __begins, splitting the cytoplasm and separating the two daughter cells.

In animal cells, __begins with the formation of a __. At the site of the furrow, a ring of __contracts, much like the pulling of drawstrings. The cell is pinched in two, creating two identical daughter cells.

The first sign of cleavage in an animal cell; a shallow groove in the cell surface near the old metaphase plate.

In plant cells, __begins when __containing __ material collect in the middle of the cell. The vesicles fuse, forming a large sac called the __. The __ grows outward until its membrane fuses with the plasma membrane, separating the two daughter cells. The __ contents join the __ cell wall. The result is two daughter cells, each bounded by its own continuous plasma membrane and cell wall.

A double membrane across the midline of a dividing plant cell, between which the new cell wall forms during cytokinesis.

Cell division functions in __ and in the growth and repair of organisms. Cell division consists of two processes. __, the division of the nucleus, is usually followed immediately by __, the division of the cytoplasm.

In __, the first stage of mitosis. In the nucleus, the nucleoli have already disappeared. Chromosomes have condensed and become clearly visible, contained within the nuclear envelope. In the cytoplasm, the __ begins to form during __.

During __, the nuclear envelope breaks up. The chromosomes become even shorter and thicker. The microtubules of the __ attach to the chromosomes and move them toward the __of the cell.

In __ of mitosis, the chromosomes convene at the __, an imaginary plane equidistant from the spindle poles. Each chromosome consists of two sister __, joined at a __.

__ begins when the paired __of each chromosome separate and the __-- now full-fledged chromosomes-- are moved to the poles. At the same time, the poles of the cell are moved apart, stretching the cell.

During __, two daughter nuclei form at the poles of the cell. Nuclear envelopes form around the gathered chromosomes, and the chromosomes become less tightly coiled. In the nuclei nucleoli appear, and in the cytoplasm the __breaks up,

__ begins during __. In animal cells, a __forms, pinching the cell in two and separating the two identical daughter cells.

Cancer can be caused by many different agents, called __. Some __ are linked with cancers in specific parts of the body. Your personal lifestyle can greatly affect your exposure to __ and therefore certain kinds of cancers.

While the cause of uterine cancer is not known, the hormone __ seems to be associated with this type of cancer. A high fat diet and cigarette smoke may also contain __linked with uterine cancer.

A chemical agent that causes cancer.

While the cause of prostate cancer is not known, the hormone __ appears to be involved in the development of prostate cancer. A high fat diet may also induce or speed up progression of this cancer.

Several chemicals in cigarette smoke are carcinogenic. Some of these chemicals are also found in marijuana smoke. There is overwhelming scientific evidence that these __ cause lung cancer.

Certain viruses are capable of causing cancer of lymphatic cells (__).

Cancers of the tissues that form white blood cells.