Cell Cycle, Mitosis, and Cancer Regulation

Comprehensive review flashcards covering cell cycle regulation, checkpoints, cancer biology, chromosome structure, mitotic phases, cytokinesis, and prokaryotic binary fission.

Control points throughout the cell cycle where proteins inspect the process and provide a stop or go signal are called __________.

checkpoints

The most important cell cycle checkpoint, which checks for DNA damage before allowing entry into the S phase, is the __________ checkpoint.

$$G_1$$

If a cell detects unrepaired DNA damage at the $G_1$ checkpoint, it exits the active cycle and enters a nondividing state designated as the __________ phase.

$$G_0$$

Two examples of specialized human cell types that remain permanently in the $G_0$ phase are muscle cells and __________ cells.

nerve

The cellular process defined as programmed cell death when damaged cells cannot be repaired is __________.

apoptosis

During the $G_2$ checkpoint, the cell verifies the completion of DNA replication; if damage cannot be repaired, apoptosis occurs and the cell will not go into __________.

$$G_0$$

The $M$ (spindle) checkpoint halts the progression of the cell cycle at metaphase if there is improper attachment of chromosomes to __________.

microtubules

Checkpoint proteins that advance the cell forward into the next stage of the cell cycle are classified as __________ regulators.

positive

Proteins that halt the cell cycle or trigger apoptosis in response to cellular errors are known as __________ regulators.

negative

An abnormal mass of tissue whose cells are confined strictly to the original site and cannot spread elsewhere in the body is a __________ tumor.

benign

A mass of cancerous cells that can invade surrounding tissues and establish tumors in different areas of the body is a __________ tumor.

malignant

When cancerous cells break away from the primary tumor mass and spread to distant sites in the body, they __________.

metastasize

On average, cancer cells evade cell cycle controls by accumulating __________ or more mutations in genes that regulate cycle checkpoints.

$$60$$

In laboratory culture outside the body, normal cells divide approximately $20\text{--}50$ times, whereas cancer cells divide __________.

infinitely

A normal gene that promotes cell growth and division by functioning as an 'on switch' for the cell cycle is a(n) __________.

proto-oncogene

A mutated or permanently active form of a proto-oncogene that drives uncontrolled cell proliferation is known as a(n) __________.

oncogene

Genes that normally function to halt cell division when errors arise are called tumor suppressor genes, a prominent example of which is __________.

$$p53$$

The branch of medicine specifically dedicated to researching, identifying, and treating cancer is __________.

oncology

Unlike chemotherapy which distributes systemically through the body, the localized cancer treatment shown that uses high-energy beams to target the tumor itself is __________.

radiation

The ordered series of growth and division events through which a cell replicates itself to produce two identical daughter cells is called the __________.

cell cycle

During interphase, chromosomes duplicate their DNA to form pairs of identical sister chromatids during the __________ phase.

S

Nonsex body cells in plants and animals that reproduce via mitosis and are not sperm or egg cells are called __________ cells.

somatic

Human somatic cells are diploid ($2n$) and contain a total of $46$ chromosomes arranged into __________ homologous pairs.

$$23$$

In the diagram illustrating chromosome terminology, the constricted structural point where sister chromatids are held together is the __________.

centromere

Chromosomes that share the same length, carry genes controlling the same traits, and consist of one maternal and one paternal copy are called __________ chromosomes.

homologous

During interphase, DNA exists in a relaxed, uncoiled form called __________ to facilitate replication.

chromatin

Centrosomes synthesize microtubule polymers called __________ that attach to centromeres and move chromosomes during division.

spindle fibers

During the __________ stage of mitosis, the nuclear envelope breaks down and centrosomes migrate toward opposite poles of the cell.

prophase

In the stage of mitosis illustrated in the diagram, chromosomes align centrally along the __________.

metaphase plate

The mitotic stage shown in the diagram, where sister chromatids separate and are pulled toward opposite poles, is __________.

anaphase

The phase of mitosis in which unduplicated chromosomes arrive at the poles and a new nuclear envelope forms around each set is __________.

telophase

In plant cell cytokinesis as shown in the diagram, Golgi vesicles fuse along the center of the dividing cell to construct a(n) __________.

cell plate

Cytokinesis in animal cells occurs when a contractile ring of actin filaments pinches inward to form a(n) __________.

cleavage furrow

In eukaryotic organisms, the two main functions of mitotic cell division are growth of the organism and the __________ and repair of cells and tissues.

maintenance

Prokaryotic organisms such as bacteria lack a nucleus and divide asexually through a rapid division method depicted here called __________.

binary fission