Heredity: Glossary

A

allele

a form or version of a gene; an individual inherits two alleles for each gene, one from each parent

C

cells

the very small units that make up all living things, specialized to do different jobs

characteristic

a feature such as eye color, hair color, nose shape, or special skills that describe an organism

chromosome

structures inside each cell nucleus made up of DNA; humans have 23 pairs in each cell, half from each parent

clone

to produce an exact genetic copy of an individual organism

conserve

protect or save

D

DNA

deoxyribonucleic acid: a long, twisted molecule within each cell that contains instructions for cell growth and development

dominant

the version (allele) of a trait that is stronger; when an organism received a dominant and a recessive allele from its two parents, the dominant version will be expressed

double helix

the shape of a DNA molecule; looks like a twisted ladder

E

endangered

rare, in danger of becoming extinct

F

forensic

using science to solve crimes

G

gene therapy

an experimental technique where a defective gene is replaced by a healthy gene in an organism's cells

generation

a single step in the line of descent within a family; Grandparents, parents, and children make up three generations

genes

units of heredity contained in chromosomes; sections of DNA that carry instructions for making proteins and information that determine specific traits

genetic modification

using technology to alter the genetic makeup of an organism

geneticist

Scientist who studies genetics

genetics

the science that studies how traits are passed from one generation to another

genome

all the DNA in a cell, including all the genes

genotype

the genetic sequence that is expressed as a specific trait

H

heredity

the passing down of traits from parent to child

heterozygous

inheriting different forms of a particular gene from each of two parents

homozygous

inheriting identical forms of a particular gene from each of two parents

I

inherited trait

a trait passed on from the parent organism to offspring

instinct

a behavior that an organism is born with and does not have to be learned

M

monk

A member of a special religious group who lives with other monks and devotes his life to service or learning

mutation

a change in the lineup of DNA instructions, causing the instructions to the cell to change

N

nucleotides

four kinds of molecules (building blocks)that when joined together make up DNA

nucleus

a structure inside a cell that acts as the boss of the cell and tells it what to do. Contains chromosomes and genes.

O

offspring

the children of the parent organism

organism

any living thing made of cells

P

phenotype

an observable expression of a trait, such as blue eyes, red hair, or blood type

population

all organisms of the same species living in a particular environment or area

proteins

structure made inside cells according to instructions in DNA, that do most of the work of the body

R

recessive

The version (allele) of a trait that is weaker; two recessive alleles must be present for the trait to be expressed

S

side effects

unintended results from a scientific experiment

T

traits

features or characteristics of a species or organism

U

unique

one of a kind, exactly like nothing else

V

variation

diversity in gene expression or frequencies; differences between individuals or populations