Terminology

HOW TO USE THIS SHEET
Cover the 'Simple Meaning' column and try to define each term aloud. Then check the memory cue. The most easily confused pairs are highlighted in the comparison sections.

Term

Simple Meaning

What to Remember

Memory Cue

Atrophy

Decrease in cell size.

Often occurs with disuse, reduced blood supply, reduced hormonal/neural stimulation, or aging.

A = Away / smaller

Hypertrophy

Increase in cell size.

Cells become bigger because of increased workload or hormonal stimulation.

H = Huge cells

Hyperplasia

Increase in the number of cells.

Occurs because the rate of cell division increases; hormones or growth factors can stimulate it.

Hyperplasia = more cells

Metaplasia

Reversible replacement of one mature cell type by another mature cell type.

Usually develops in response to chronic stress; the replacement cell may tolerate the environment better.

Meta = change cell type

Dysplasia

Abnormal changes in cell size, shape, and organization.

Your chapter states dysplasia is not a true cellular adaptation; it is atypical hyperplasia.

Dys = disorganized

DO NOT MIX THESE UP
Hypertrophy = bigger cells.  Hyperplasia = more cells.  Metaplasia = different mature cell type.  Dysplasia = abnormal/disorganized cells.

Term

Simple Meaning

What to Remember

Memory Cue

Necrosis

Cell death caused by severe injury.

Cells swell, plasma membrane breaks, contents may leak out, and inflammation is frequent. Usually pathologic.

SWELL + SPILL + INFLAMMATION

Apoptosis

Regulated/programmed cell death.

Cells shrink, fragment into apoptotic bodies, the membrane stays largely intact, and significant inflammation does not occur.

SHRINK + PACKAGE + NO inflammation

NECROSIS vs APOPTOSIS
Necrosis: enlarged/swollen cell + disrupted membrane + leakage + inflammation.
Apoptosis: reduced/shrunken cell + intact membrane + apoptotic bodies + no adjacent inflammation.

Term

Simple Meaning

What to Remember

Memory Cue

Genotype

The composition of genes/alleles at a given locus.

It is the genetic makeup at that locus.

GENO = genes

Phenotype

The outward or observable result of genotype plus environment.

Environment can change the phenotype even when the genotype stays the same.

PHENO = physical/observable

Multifactorial inheritance

A trait or disease influenced by multiple genes AND environmental factors.

Common diseases can result from the combined effects of genetic susceptibility and environment/lifestyle.

MULTI = many genes + environment

Polygenic risk

Genetic risk estimated by combining the effects of many disease-associated DNA variants.

Most individual variants have small effects; combining them can identify higher genetic susceptibility. It is a risk estimate, not certainty.

POLY = many genetic variants

GENOTYPE vs PHENOTYPE
Genotype = what genes you have.  Phenotype = what is expressed/observed after genes interact with the environment.

Term

Simple Meaning

What to Remember

Memory Cue

DNA methylation

Addition of a methyl group to DNA, usually to cytosine at CpG sites.

Dense methylation of a region is generally associated with decreased transcription or gene silencing.

Methyl = usually OFF

Histone modification

Chemical changes to histone proteins around which DNA is wrapped.

Changes how tightly DNA is packaged and therefore how accessible genes are to transcription factors.

Open chromatin = ON; closed = OFF

EPIGENETIC KEY
DNA methylation and histone modification change GENE EXPRESSION without changing the underlying DNA sequence itself.

Term

Simple Meaning

What to Remember

Memory Cue

Proto-oncogene

A normal gene that helps regulate normal cell growth and differentiation.

When altered or overexpressed, it can become an oncogene.

Proto = normal growth gene

Oncogene

An altered/activated growth-promoting gene that drives uncontrolled proliferation.

Can result from point mutation, gene amplification, or chromosomal translocation.

ONCO = accelerator stuck ON

Tumor suppressor gene

A protective gene that normally restrains cell proliferation or helps protect against cancer.

Cancer risk rises when suppressor function is lost; your chapters describe loss of both copies as important for many tumor-suppressor genes.

Tumor suppressor = BRAKE

Metastasis

Spread of cancer cells from the original tumor to distant tissues or organs.

Major steps described: invasion → intravasation → circulation → extravasation → colonization.

MetaSTASIS = spread to distant site

Tumor grade

How abnormal/differentiated the tumor cells look microscopically.

Lower grade is more differentiated; higher grade is less differentiated/anaplastic and more abnormal-looking.

GRADE = what cells LOOK like

Tumor stage

How far the cancer has spread anatomically.

Based on tumor extent/local invasion, lymph nodes, and distant metastasis; TNM = Tumor, Nodes, Metastasis.

STAGE = where/how far it SPREAD

ONCOGENE vs TUMOR SUPPRESSOR
Oncogene = growth accelerator stuck ON.  Tumor-suppressor gene = protective brake that is lost or disabled.

GRADE vs STAGE
GRADE = microscopic appearance/differentiation.  STAGE = anatomic extent/spread.  If the question asks 'what do the cells look like?' think GRADE. If it asks 'how far has it spread?' think STAGE.