Heredity and Genetics Vocabulary
Trait – A characteristic caused by genetics or the environment
Chromosomes – Long strands of DNA that contain many genes
Genes – Part of chromosome that controls a trait(30,000 in humans)
Allele – Different forms of genes
Recessive allele – Only see this trait if two are present
Dominant Allele – Always shows its trait
Hybrid – Has two different alleles for same trait
Purebred – Has two identical alleles for same trait
Probability – The likelihood that an event will occur
Punnett Square – A chart that shows all possible combinations of
alleles between two organisms
Phenotype – The visibly expressed trait (ie. blue eyes)
Genotype – The allele combination for a trait (ie. Bb or bb.)
Homozygous – Two identical alleles (Purebred)
Heterozygous – Two different alleles (Hybrid)
Codominant Alleles – Neither allele is dominant(ie. Blood types or
spotted dog)
Incomplete Dominance – The dominant alleles mix – (Green flower
from blue and yellow alleles)
Meiosis – Process that creates sex cells with one copy of each gene or
half the number of chromosomes
Cross-Fertilization – A gamete(sex cell) from each parent gives one
allele for each trait to make a new organism(humans)
# of human chromosomes – 23 pairs or 46 chromosomes
X and Y – Human chromosomes that determine gender
Mutation – When a chromosome is not copied correctly
Carrier – Someone who has one recessive allele for a trait but doesn’t
show it.
Pedigree – A chart that tracts a particular trait in a family
Karyotype - A picture of all the chromosomes of a cell
Genome – All the DNA in one cell of an organism
Gene therapy – The insertion of a corrected gene into a person to try
and correct a problem.
Genetic Engineering – Transferring a gene from one organism to
another to produce a new trait. (ie. Glowing Frog)
Selective breeding – Only mating organisms with desirable traits.
Clone – An organism that is genetically identical to the parent
organism
DNA – Deoxyribonucleic acid – The molecule that is the base of all
chromosomes
Four bases of DNA – Adenine and Thymine; Guanine and Cytosine
Heredity – The passing of traits from parent to offspring
Sex-linked Disorders – A malfunctioning gene that is on the X
chromosome(hemophilia or color blindness) Why are males more
likely to have them?
Gregor Mendel – A monk in the 1850’s that studied how plants
inherit traits
Genetic Disorders – Illnesses or disorders caused by an abnormal
gene (Examples: Downs and Turner Syndrome -wrong number of
chromosomes, Recessive traits - Sickle Cell Anemia, Cystic Fibrosis)
Inherited Trait – A trait totally controlled by your genes (ie. Eye
color)
Environmental Trait – A trait that is expressed as a combination of
your genes and the environment. (ie. Skin color)
Epigenetics – How genes are turned on or off by their environment
GM Foods – Organisms that have been genetically modified for
farmers. (rice that produces more grain)
Skills to have for test: Explain the scientific method that Mendel used
to perform his investigations, Create/analyze a pedigree chart.
Determine the probability that offspring will have certain traits using a
punnett square, explain Hardy-Weinburg principles that affect
evolution of species(five fingers), explain the affects that a change in
one organism can have on other species within an environment.
Explain the process of cloning and why it is not being used with
humans, explain how identical twins are formed. Explain the
advantages and disadvantages to Genetically Modified/Engineered
foods. Explain the difference between environmental and inherited
traits, Explain meiosis. Contrast asexual and sexual reproduction.