BIO 105: Ch.6 Reproduction at the Cellular Level

The ________________________ describes cells that are not actively preparing to divide after interphase.

G0 phase

The are three different checkpoints:

G1 checkpoint, G2 checkpoint, and M checkpoint

There are three stages of interphase:

G1 phase, S phase, and G2 phase

Homologous chromosomes

are matched chromosome pairs of a diploid organism; at particular nucleotide segments, we find genes

Proto-oncogenes

are normal genes that can become cancerous oncogenes if mutated

Prokaryotes such as _______________________ propagate by binary fission.

bacteria

The common mechanism of _______________ ( a term used for a diverse array of diseases) is uncontrolled cell division.

cancer

Single-celled organisms use ________________________ as their method of reproduction.

cell division

The cell cycle consists of what?

cell growth and cell replication

G2 checkpoint

chromosome duplication is assessed

In unicellular organisms, _____________________ cells are individuals.

daughter

Matched chromosomes are known as _______________, while cells that contain only one set of chromosomes are known as ________________.

diploid/haploid

The first stage of interphase is the G1 phase...

during this phase, little change is visible as the cell is accumulating energy reserves and the chemical building blocks of DNA

All multicellular organisms use cell division for what purposes?

growth, and in most cases, the maintenance and repair of cells and tissues

Each eukaryote has a unique number of chromosomes located in the nucleus of the cell...

humans have 46, fruit flies have 8, spinach has 12, and so on

The ____________________ sexually reproducing organism -- including humans -- begins as a fertilized egg, or zygote.

individual

There are two distinct phases of the cell cycle:

interphase, where the cell growth and DND replication occur; miotic phase, where the contents of the cell are separated and the cell undergoes division

Metaphase

involves the arrangement of chromosomes along the metaphase plate and the attachment of spindle fibers (from each "pole") to each sister chromatid

Prophase

involves the breakdown of the nuclear envelope, condensing of chromosomes, emergence of spindle fibers form the centrosomes, and migration of centrosomes to the "poles" of the cell

Prometaphase

is characterized by the appearance of kinetochores at the centromeres and the attachment of spindle microtubules to those kinetochores

The G2 phase...

is characterized by the cell replenishing energy and protein stores that are needed in the next step of the cell cycle

one a human individual is fully grown, cell reproduction...

is still necessary to repair or regenerate tissues; for example, new blood and skin cells are constantly being produced.

Telophase

is the last step before the official division of the cell and involves the surrounding of the chromosomes (formally sister chromatids) by a nuclear envelope at each pole; additionally, the mitotic spindle breaks down and the spindle fibers push the poles further apart

Cytokinesis

is the second and final step of the miotic phase; it is the process that leads to two separate daughter cells

Anaphase

is the step where the centromeres split and the resulting sister chromatids are pulled toward each pole; also certain spindle fibers begin to elongate

M checkpoint

it is determined if all sister chromatids are attached to spindle microtubules

G1 checkpoint

it's determined whether conditions are favorable for cell division to proceed, and DNA integrity is assessed

During the S phase, DNA replication...

leads to the formation of sister chromatids that remain firmly attached to the centromere

For unicellular organisms, cell division is the _________ method to produce new individuals; in both prokaryotic and eukaryotic cells, the outcome of cell reproduction is a pair of daughter cells that are genetically identical to the parent cell.

only

Replication of the circular piece of DNA in prokaryotes begins at an ______________ and proceeds in both directions; from there, the cell elongates and the duplicated chromosomes move to each pole of the cell.

origin

Cytokinesis differs quite drastically among eukaryotes:

plant cells are effectively separated by a cell plate; animal cells are separated by a cleavage furrow

Trillions of cell divisions subsequently occur in a controlled manner to _________________ a complex, multicellular human; that original cell was the ancestor of every other cell in the body.

produce

The first step of the miotic phase is mitosis, which is divided into five stages:

prophase, prometaphase, metaphase, anaphase, and telophase

Cell cycle checkpoints

provide a way for the cell cycle to be stopped until favorable conditions arise; this is an important mechanism for preventing mutated cells from continuing to divide

It can be described as a ______________________________ and is commonly found in mature cells that have no need to divide; for example, the cardiac muscle cells of an adult human.

resting phase

FtsZ proteins begin to form a _________________ in the middle of the cell that will eventually divide into two identical cells.

septum

In bacterial cells, the genome consists of a ____________________________________________________; therefore, the process of cell division is simplified.

single, circular DNA chromosome

To achieve the outcome of identical daughter cells, some steps are essential:

the genomic DNA must be replicated and then allocated into the daughter cells; the cytoplasmic contents must also be divided to give both new cell the machinery to sustain life

Binary fission

the prokaryotic equivalent to the eukaryote's cell division; however, because of the relative size and cellular organization of prokaryotes, it is a much simpler process

Genome

the total DNA content of a given cell; in prokaryotes, it is a simple, circular strand of DNA; in eukaryotes, it takes on a more complex double-helical structure

Certain genes can code for negative-regulator proteins such as p53, a common _____________________________________________ that effectively halts the cell cycle process until certain actions are completed; cells with mutated p53 proteins can become cancerous.

tumor suppressor gene

Mitosis is ___________________________ because there is no nucleus or multiple chromosomes. This type of cell division is called binary fission.

unnecessary