Unit 2 Concept 3🧬✅

Science

Zygote

A fertilized egg that undergoes repeated cell division after a sperm fertilizes an egg.

Differentiation

A process that creates special structures and functions, allowing specialized cells to become tissues, organs, and organ systems.

Stem Cells

Undifferentiated cells that can become differentiated into one or more types of specialized cells.

Embryonic Stem Cells

Cells that have never differentiated and retain the ability to become any cell type.

Adult Stem Cells

Partially differentiated cells found in adult bone marrow that can only become certain types of cells.

Organism

One individual member of a species.

Organ System

A set of organs working together for a common function, such as the digestive system.

Organ

A set of tissues working together for a common function, such as the stomach.

Tissue

A group of cells working together for a common function, such as muscle tissue.

Cell

The most basic unit of life that possesses all the characteristics of life.

Cell Cycle

A repeated pattern of growth, DNA duplication, and cell division occurring in eukaryotic cells for growth and repair.

Interphase

The growth phase of the cell cycle comprising G1, S, and G2 phases, resulting in $2$ full sets of chromosomes by its end.

G1 Phase

The Gap 1 phase of interphase in which the cell grows and synthesizes proteins.

S Phase

The Synthesis phase of interphase during which DNA replication occurs, doubling the number of chromosomes.

G2 Phase

The Gap 2 phase of interphase involving additional cell growth and protein synthesis.

Chromosome

One long continuous thread of DNA containing thousands of genes and regulatory information.

Gene

A specific section of DNA containing instructions for making a protein.

Homologous Chromosomes

Matching pairs of chromosomes in normal body cells, with half inherited from the biological mother and half from the biological father.

Chromatid

One half of a duplicated chromosome.

Sister Chromatids

Two identical chromatids attached to each other.

Centromere

The pinched region of condensed chromosomes that holds sister chromatids together.

Telomere

The protective ends of a DNA molecule.

Mitosis

The division phase of the cell cycle where $1$ cell divides into $2$ identical daughter cells.

Prophase

The phase of mitosis where chromosomes condense into visible sister chromatids (X's), the nuclear membrane disappears, and spindle fibers form out of centrioles.

Metaphase

The phase of mitosis where spindle fibers attach to centromeres and chromosomes align along the middle of the cell.

Anaphase

The phase of mitosis where sister chromatids separate to opposite poles of the cell, becoming individual chromosomes.

Telophase

The phase of mitosis where chromosomes decondense into threadlike chromatin, nuclear membranes re-form at each pole, spindle fibers break down, and cytokinesis begins.

Cytokinesis

The process of cytoplasm division into $2$ individual cells, beginning at the end of mitosis.

Cleavage Furrow

A structure formed in animal cells during cytokinesis that pinches the cell into $2$ equal parts.

Cell Plate

A structure formed midway between divided nuclei in plant cells during cytokinesis that gradually develops into a cell membrane.

External Signals

Regulatory signals originating outside the cell, such as hormones and nutrients.

Internal Signals

Regulatory signals originating from inside the cell's nucleus, such as DNA.

Checkpoint

A critical point in the cell cycle where 'stop' and 'go' signals regulate progression through phases such as G1, S, G2, and M.

Apoptosis

Programmed cell death triggered by internal or external signals that activate self-destructive enzymes.

Cancer

Uncontrolled cell division occurring when normal cell cycle regulation breaks down.

Tumor

A clump of cells dividing uncontrollably.

Benign

Describing abnormal cells that remain clustered together, typically being harmless and easily removable.

Malignant

Describing cancer cells that break away from a primary tumor and spread to other parts of the body.

Metastasize

The spreading of disease or cancer cells from one organ to other parts of the body.

Carcinogens

Cancer-causing agents and chemicals that mutate DNA, such as tobacco smoke and asbestos.