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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

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
gene therapy
an experimental technique where a defective gene is replaced by a healthy gene in an organism's cells
geneticist
Scientist who studies genetics
genetic modification
using technology to alter the genetic makeup of an organism
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
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