DNA, Mutations, the Cell Cycle & Cancer 2026

mutation

a change in the nucleotide-base sequence of a gene or DNA molecule

mutagen

something that CAUSES mutations (for example, radiation)

insertion mutation

change in DNA in which a nucleotide is added

deletion mutation

change in DNA in which a nucleotide is lost

substitution mutation

change in DNA in which a single nucleotide is replaced

Gene

A segment of DNA on a chromosome that codes for a specific trait

codon

a sequence of 3 nucleotides in DNA (or RNA), like a 'word' that is a code for a specific amino acid, Ex, ATG

carcinogen

A cancer-causing substance

cancer

A disease in which some cells grow and divide uncontrollably (due to mutations), damaging the parts of the body around them.

mitosis

cell division - one cell copies all its parts and divides into two cells

DNA

deoxyribonucleic acid, the molecule that contains the information that determines inherited characteristics- used to build molecules that make up your body

nucleotide

the building block of DNA (has 3 parts: sugar, phosphate and nitrogenous base)

adenine (A)

The nitrogenous base that pairs with Thymine (T) in DNA

thymine (T)

Nitrogenous base that pairs Adenine (A) in DNA

cytosine (C)

Nitrogenous base that pairs with guanine (G).

guanine (G)

Nitrogenous base that pairs with Cytosine (C) in DNA and RNA

mutation

a change in the nucleotide-base sequence of a gene or DNA molecule

mutagen

something that CAUSES mutations (for example, radiation)

deoxyribose

sugar molecule that makes up part of the backbone of DNA

phosphate

molecule (not sugar) that makes up part of the backbone of DNA

DNA replication

the process of making a copy of DNA, needed in order to make new cells in mitosis

Chromosomes

threadlike structures made of DNA molecules that contain the genes

Gene

A segment of DNA on a chromosome that codes for a specific trait

mitosis

cell division - when a cell pulls apart into 2

the cell cycle

series of events that cells go through as they grow and divide

apoptosis

programmed cell death

tumor suppressor genes

make proteins that stop cell division and kill cells

proto-oncogenes

code for proteins that tell normal cells to grow and divide.

oncogenes

mutated genes that cause the cell to grow and divide uncontrollably (like pressing the gas pedal in the car)

G1 phase events

Cell grows, organelles multiply

S phase events

DNA replication

G2 phase events

cell gets organized for division

M phase events

cell divides in an organized way (prophase, metaphase, anaphase, telophase, cytokinesis)

cell cycle checkpoints

'traffic stops' in the cell cycle - making sure everything is healthy and that the DNA is ok

DNA repair genes

code for proteins that correct/repair DNA mutations

p53 gene

codes for proteins that cause the cell cycle to stop, the DNA repair, or apoptosis in cells with bad DNA

melanin

A pigment that gives the skin its color

folate

vitamin needed for healthy fetal development, destroyed by too much UV

Vitamin D

vitamin needed to absorb calcium to build strong bones, made in the epidermis when skin absorbs UV-B rays

evolutionary advantages for dark skin in high UV intensity areas

protects folate but allows UV-B in enough to produce Vitamin D

evolutionary advantages for light skin in low UV intensity areas

folate is not at risk, allows UV-B in enough to produce Vitamin D

melanocyte

cell that produces brown pigment in the epidermis