Cell Division, the Cell Cycle, and Cancer Vocabulary

Comprehensive practice flashcards covering cell division, phases of mitosis, cell-cycle checkpoints, and cancer-related cellular mechanisms.

What is binary fission?

A form of asexual reproduction in prokaryotes in which the cell copies its DNA and divides into two genetically similar daughter cells.

What is an origin of replication?

A specific location on a DNA molecule where DNA replication begins.

What are somatic cells?

All body cells other than reproductive cells (gametes). In humans, most somatic cells contain two sets of chromosomes.

What are gametes?

Haploid reproductive cells, such as sperm and eggs, that join during fertilization to form a diploid zygote.

What are gonads, and which organs serve as gonads in humans?

The reproductive organs that produce gametes and sex hormones; the ovaries and testes are the human gonads.

What is a genome?

The complete set of an organism's genetic material, including all of its DNA.

What is chromatin?

The material that makes up chromosomes: DNA wrapped around proteins, especially histones. It is usually less condensed between cell divisions.

What are histones?

Proteins around which DNA winds, helping package and organize DNA into chromatin.

What are nucleosomes?

The basic repeating units of chromatin, each consisting of DNA wrapped around a group of histone proteins.

What are chromosomes, and what does each replicated chromosome consist of?

Structures made of DNA and associated proteins that carry genetic information. Each replicated chromosome consists of two sister chromatids joined at a centromere.

What is a sister chromatid?

One of two identical copies of a chromosome made during DNA replication; the copies remain attached until they separate during cell division.

What is the centromere?

The chromosome region that holds sister chromatids together and where the kinetochore forms.

What is the cell cycle?

The ordered series of events in which a cell grows, copies its DNA, and divides. It includes interphase and the mitotic (M) phase.

What occurs during interphase, and what stages does it include?

The cell grows, performs normal functions, copies its DNA, and prepares to divide; it includes G1, S, and G2.

What happens during the Gap 1 phase (G1)?

The cell grows, carries out normal activities, and makes proteins and organelles needed for later stages.

What occurs during the Gap 2 phase (G2)?

The cell continues growing and prepares the materials needed for mitosis following DNA replication.

What happens during the DNA synthesis phase (S phase)?

The cell replicates its DNA, producing two identical sister chromatids for each chromosome.

What is mitosis?

Division of the nucleus in which duplicated chromosomes are separated into two nuclei. It is usually followed by cytokinesis.

What events occur during prophase?

Chromatin condenses into visible chromosomes, the nucleolus disappears, and the mitotic spindle begins to form as centrosomes move apart.

What happens during prometaphase?

The nuclear envelope breaks down and spindle microtubules attach to kinetochores on chromosomes.

What takes place during metaphase?

Chromosomes line up at the cell's equator, with sister chromatids attached to spindle fibers from opposite poles.

What is the metaphase plate?

An imaginary plane midway between the two spindle poles where chromosomes line up during metaphase.

What occurs during anaphase?

Sister chromatids separate and are pulled toward opposite poles of the cell.

What occurs during telophase?

Chromosomes arrive at opposite poles, begin to decondense, and new nuclear envelopes form around each set.

What is cytokinesis?

Division of the cytoplasm, producing two separate daughter cells after nuclear division.

What is a cleavage furrow and how does it form?

The indentation that forms in an animal cell as a contractile ring tightens and pinches the cell into two during cytokinesis.

What is a cell plate?

A membrane-bound structure that forms between the two daughter nuclei in a dividing plant cell and develops into the new cell wall separating the cells.

What is a centrosome?

The main microtubule-organizing center in animal cells. It duplicates before division and helps organize the mitotic spindle; it usually contains a pair of centrioles.

What are centrioles?

Small cylindrical structures made of microtubules, typically found in pairs within animal-cell centrosomes. They help organize centrosomes but are not present in all eukaryotic cells.

What is the mitotic spindle?

A structure made of microtubules and associated proteins that moves and separates chromosomes during mitosis.

What are asters?

Star-shaped arrangements of microtubules that extend from centrosomes toward the cell edge in many animal cells during cell division.

What are kinetochores?

Protein structures assembled at each chromosome's centromere that serve as attachment sites for spindle microtubules.

What are kinetochore microtubules and what is their role?

Spindle microtubules that attach to kinetochores and help move chromosomes, including pulling sister chromatids toward opposite poles during anaphase.

What is the function of non-kinetochore microtubules?

They do not attach to chromosomes; instead, they overlap with microtubules from the opposite pole and help push the poles apart, lengthening the cell.

What is cohesin?

A protein complex that holds sister chromatids together after DNA replication until it is cleaved at the onset of anaphase.

How do actin microfilaments function during cytokinesis in animal cells?

They are thin protein filaments forming part of the cytoskeleton that work with myosin to form a contractile ring.

What is myosin and what role does it play during cytokinesis?

A motor protein that uses energy from ATP to move along actin filaments, helping the actin ring contract and pinch an animal cell in two.

What are cell cycle control systems?

Networks of regulatory molecules that control the timing and sequence of cell-cycle events and help ensure that each stage is completed correctly before the next begins.

What conditions are monitored at the G1 checkpoint?

The cell checks its size, nutrients, growth signals, and DNA condition before committing to DNA replication; if conditions are unsuitable, the cell may pause or enter G0.

What is evaluated at the G2 checkpoint?

The cell checks that DNA has been completely and correctly replicated and that the cell is ready to enter mitosis.

What is verified at the M checkpoint (mitosis checkpoint)?

It verifies that every chromosome is properly attached to spindle microtubules before sister chromatids are allowed to separate.

What is the G0 phase?

A nondividing state in which a cell exits the active cell cycle. Some cells remain in G0 temporarily, while others stay there permanently or for long periods.

What is a cyclin?

A regulatory protein whose concentration rises and falls during the cell cycle. Cyclins bind to and help activate cyclin-dependent kinases.

What are cyclin-dependent kinases (CDKs)?

Protein kinases that become active when bound to cyclins. They regulate cell-cycle events by adding phosphate groups to target proteins.

What constitutes maturation-promoting factor (MPF) and what is its role?

A cyclin-CDK complex, commonly cyclin B bound to CDK1, that triggers a cell's entry into mitosis by phosphorylating target proteins.

What are growth factors?

External signaling proteins that stimulate cells to grow and divide by binding to receptors and activating cell-signaling pathways.

What is anchorage dependence?

The requirement of many normal animal cells to attach to a suitable surface or extracellular matrix before they can grow and divide.

What is density-dependent inhibition?

The tendency of normal animal cells to stop dividing when they become crowded and contact neighboring cells.

What is transformation in the context of cell biology?

A change in which a normal cell acquires characteristics of a cancer cell, often including loss of normal cell-cycle controls and abnormal growth.

What is a benign tumor?

An abnormal mass of cells that remains localized and does not invade nearby tissues or spread to distant parts of the body.

What is a malignant tumor?

A cancerous mass of cells that can invade surrounding tissues and may spread to other parts of the body.

What does it mean for cancer cells to metastasize?

To spread from the original tumor to other parts of the body, usually when cancer cells travel through the blood or lymph and establish new tumors.