bruhhh what the Gell

Cancer

A disease where cells accumulate mutations that cause uncontrolled division, loss of identity, inability to die, and ability to spread

Tumor

A mass of cancerous cells that takes up space, wastes resources, contributes nothing, and can travel to other locations

Metastasis

When cancer cells lose their anchors, break away from the original tumor, and start new tumors elsewhere in the body

Dedifferentiation

When cancer cells lose their specialized identity and stop performing their original job

Apoptosis

Programmed cell death; the normal process by which damaged or worn out cells tidy up and destroy themselves

Sporadic cancer

Cancer caused by random mutations that accumulate over a lifetime, NOT inherited; accounts for 90

Inherited cancer risk

When someone is born with one already

Tumor heterogeneity

The fact that even within the same tumor, different cells have different mutations, making cancer hard to treat

Cell Cycle

Mitosis is separate but G1, synthesis, and G2 are a part of interphase

G1 phase

The first gap phase where the cell grows and performs its daily functions

S phase

Synthesis phase where the cell makes a complete copy of its DNA

G2 phase

The second gap phase where the cell grows more and prepares for division

M phase

Mitosis; the phase where the cell actually divides into two daughter cells

G0 phase

A resting state where most normal cells spend their time, not dividing

Mitosis

Cell division that produces two genetically identical daughter cells; cancer cells do this uncontrollably

Cell cycle checkpoint

A quality control gate that prevents the cell from advancing unless strict conditions are met

G1 checkpoint

Checks whether there is DNA damage before the cell starts copying its DNA

G2 checkpoint

Checks whether the new DNA copy is correct and whether the cell is large enough to divide

Metaphase checkpoint

Checks whether all chromosomes are properly lined up and attached to spindle fibers before the cell splits

Tumor suppressor protein

A protein at each checkpoint that stops the cell cycle when something is wrong; if broken, cells divide even with damage

Loss of contact inhibition

Normal cells only divide when connected to neighbors; cancer cells lose this requirement and divide regardless

Unregulated cell division

Cancer cells bypass checkpoints and divide continuously without proper signals

Disabled apoptosis

Cancer cells have broken death mechanisms so the body cannot get rid of them normally

Checkpoint failure consequence

When checkpoints are broken, damaged DNA gets copied and passed to daughter cells, accelerating mutation accumulation

Nondisjunction

When chromosomes are missorted during division because the metaphase checkpoint failed, resulting in cells with wrong chromosome numbers

Mutagen

Anything that damages DNA and increases cancer risk

Natural mutagen

Sources of DNA damage that are unavoidable, including oxygen free radicals, UV radiation, and X

Avoidable mutagen

Sources of DNA damage that can be reduced, including tobacco smoke, alcohol, and industrial chemicals

Free radicals / ROS

Unstable oxygen molecules that damage DNA bases, causing point mutations anywhere in the genome

Pyrimidine dimer

Abnormal bond between two T or C bases on the same DNA strand caused by UV light exposure

DNA crosslink

Abnormal bond between two DNA strands caused by chemicals like tobacco smoke; can break the backbone when strands are separated

Double stranded break

The hardest type of DNA damage to repair because there is no intact template strand to copy from

Point mutation

A single base change in the DNA sequence caused by damage during replication

DNA repair enzymes

Proteins that constantly scan DNA and fix mismatches and damage by cutting out the bad section and rebuilding it using the other strand as a template

p53

A major tumor suppressor gene; inheriting one broken copy dramatically increases cancer risk, often appearing around age 30

BRCA1 / BRCA2

Tumor suppressor genes involved in DNA repair; inheriting one broken copy increases cancer risk, often appearing in the 50s

Rb

A tumor suppressor gene controlling cell division; inheriting one broken copy causes retinoblastoma, typically in children ages 1

Two hit model

The idea that you need both copies of a tumor suppressor gene broken for cancer to develop; inheriting one broken copy means only one more hit is needed

Chemotherapy

Cancer treatment that kills all actively dividing cells by disrupting mitosis; also kills healthy dividing cells causing side effects like hair loss

Paclitaxel / Taxol

A chemotherapy drug that disrupts spindle formation, causing anaphase to go wrong and cells to die from chromosome missortation

Side effects of chemotherapy

Caused by the drug killing healthy fast

CAR T cell therapy

A newer treatment where a patient's own T cells are genetically modified to recognize and kill cancer cells specifically

Why no single drug cures all cancers

Because every cancer has unique mutations, so a drug targeting one mutation will not work on a different cancer's mutations

Gene expression microarray

A tool that measures which genes are turned on or off in cancer cells compared to normal cells; used to diagnose cancer type and guide treatment