Genetics vocabulary
Mendel-discovered principals of inheritance by studying peas. He focused on
contrasting characteristics. Tall/dwarf, purple flower/white flower.
Gene---A trait found in an organism. Eye color, height, blood type.
Locus/Loci—the place on a chromosome where the gene is placed.
Allele—the different forms a gene has—eye color has 3 alleles [brown, green,
blue, hazel, black and grey]
Homozygous-when both alleles are the same. AA, TT, gg.
Heterozygous-when the two alleles differ. Aa, Bb. Gg.
Dominant—when one allele can hide another. Purple hides white flowers in
peas.
Recessive—a trait that can be hidden by a dominant allele. Blue eyes are
hidden by brown eye color.
Co-dominant—when both alleles are made. Both the A and B protein in an
AB individual cover blood cells. A does not hide B or visa versa.
Incomplete Dominant—When the alleles create a middle result. Red and
white flowers produce pink flowers in snapdragons.
X-Linked The gene is found on the X chromosome. Males have only one X so
recessive traits only need one allele.
Multiple alleles—some traits have several genes that combine to make a
trait. Height and skin color are created by multiple alleles so a range of
heights and skin colors are produced.
Linked traits—when two traits are on the same chromosome. They are
passed together.
Karyotype—a picture taken of a cells chromosomes allowing analysis of a
persons chromosomes. Extra/missing/damaged chromosomes can be seen.
Monohybrid cross—crossing two individuals for a single trait. Round
seed/wrinkled seed.
Dihybrid cross—crossing two individuals for two traits. Round
seed/wrinkled and Tall/short seed.
P Generation—the original parents in an experiment.
F1 Generation—the possible children from a cross.
F2 Generation—the possible grandchildren from the first cross.
Genotype—the genetic makeup of an organism for a trait. AA/Aa/aa
In a dihybrid cross AABB, AaBB, aaBB, AABb, etc.
Phenotype—the effect produced by the genotype. TT = tall, Tt=tall, tt=short
In a dihybrid cross RrYy=round and yellow rryy=wrinkled and green.
Environment-the surroundings that can effect gene expression. Cells are
surrounded by testosterone make the baldness allele dominant in men. The
SAME allele is recessive in women who have much less testosterone.
Probability-the likelihood that something will happen. Use fraction in
genetics usually.
Genetics vocabulary
Pedigree-a visual representation of traits passed from generation to
generation.
Principal of Segregation-when creating gametes [meiosis] the paired alleles
are separated. Tt would separate so half the ova carry tall the other half carry
short.
Principal of Independent Assortment-Different alleles are placed in
gametes in all possible combinations. AaTt gametes would be AT or At or
aT or at.
Punnett square-visual model that display the possible offspring from a
defined cross.