32 terms

Life Science: Genetics 2019

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Heredity
the passing of traits from parent to offspring
Genetics
The scientific study of heredity
Gregor Mendel
The father of genetics (1860s); monk &
scientist; first to analyze patterns of inheritance; figured out the fundamental principles of genetics by studying pea plants
Trait
a characteristic; Examples - hair color, eye color, height
Allele
"options" or different "versions" of a gene that code for a specific trait; Example: hair color = brown or blond
Symbol
a letter
Dominant
allele that will always show if present. Symbol: Capital Letter
Recessive
allele that will be hidden by a dominant allele. Symbol: lower-case letter
Genotype
Genetic make-up; Consists of 2 alleles
Examples - BB, Bb or bb
Phenotype
the physical appearance from the genes. Examples - purple or white
Homozygous
a genotype with the SAME alleles; Example: BB or bb
Homozygous Dominant
a genotype with two DOMINANT alleles
Example - BB
Homozygous Recessive
a genotype with two RECESSIVE alleles
Example - bb
Purebred
Individuals with homozygous genotypes
Heterozygous
a genotype with DIFFERENT alleles. Example: Bb
Hybrids
Individuals with heterozygous genotypes
Classic Dominance/Complete Dominance
ONE allele is dominant; Example: red + white = red
Incomplete Dominance
Neither allele is dominant = BLENDED phenotype; Example: red + white = pink
Multiple Allele Traits
More than 2 alleles are possible; Examples: Eye Color (Brown, Blue, Green), blood type (A, B, AB, O)
Co-dominance
Two alleles are dominant = MIXED phenotype; Example: red + white = spotted
Sex-Linked Traits
genes located on one of the X chromosome (affects males more than females)
X-Linked Disorders
gene causing the trait or the disorder is located on the X chromosome; Affects males (XY) more than females (XX); Examples: Colorblindness, Hemophilia,
Law of Segregation
alleles will separate when making egg or sperm (only 1 gets passed on).
Law of Independent Assortment
random separation; each gene or chromosome is inherited independently of the other
Punnett Squares
a table used to calculate the probability (chance) of passing a trait on to offspring
Test cross
crossing the individual with an unknown genotype with a homozygous recessive individual; the offspring can reveal the unknown allele
Pedigree
A family tree diagram that shows how a trait is inherited over several generations.
Recessive trait
skips generations; affects both males and females; homozygous recessive has the trait/disorder
Carrier
a person who carries the gene for the the disorder, but does NOT have the disorder (heterozygous genotype)
Dominant trait
does NOT skip generations; affects both males and females; both homozygous dominant and heterozygous have the trait/disorder.
sex chromosomes
X and Y chromosomes; determines gender (male or female)
Autosome
Any chromosome that is not a sex chromosome
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