Biology Unit 10 Genetics

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gene
A segment of DNA on a chromosome that codes for a specific trait
allele
An alternative form of a gene
dominant
Describes a trait that covers over, or dominates, another form of that trait.
recessive
An allele that is masked when a dominant allele is present
homozygous
An organism that has two identical alleles for a trait
heterozygous
An organism that has two different alleles for a trait
Gregor Mendel
Augustinian monk and botanist whose experiments in breeding garden peas led to his eventual recognition as founder of the science of genetics (1822-1884)
Genetics
Study of heredity
heredity
Passing of traits from parents to offspring
P generation
Parental generation, the first two individuals that mate in a genetic cross
F1 generation
the first generation of offspring obtained from an experimental cross of two organisms
F2 generation
Offspring resulting from interbreeding of the hybrid F1 generation.
Principle of Dominance
Mendel’s second conclusion, which states that some alleles are dominant and others are recessive
Law of Segregration
Mendel’s first law, stating that allele pairs separate during gamete formation, and then randomly re-form as pairs during the fusion of gametes at fertilization.
phenotype
An organism’s appearance or other detectable characteristic
genotype
An organism’s genetic makeup, or allele combinations.
Punnet Square
A chart that shows all the possible combinations of alleles that can result from a genetic cross
monohybrid cross
A cross between individuals that involves one pair of contrasting traits
genotypic ratio
the ratio of the genotypes that appear in offspring
phenotypic ratio
a ratio that shows the varied outcomes that results from a genetic cross and is based on physical appearance alone
Autosomal trait/disorder
A trait coated by a gene meaning their equal copies
Autosome
…, Any chromosome that is not a sex chromosome
Sex linked trait/disorder
Allele related to the chromosomal sex of the individual
Sex chromose
determine the sex of the individual; determines if they are male or female; two sex chromosomes are X and Y
Dihybrid cross
A cross between individuals that have different alleles for the same gene
Law of Independent Assortment
Each member of a pair of homologous chromosomes separates independently of the members of other pairs so the results are random
Incomplete dominance
A pattern of inheritance in which two alleles, inherited from the parents, are neither dominant nor recessive. The resulting offspring have a phenotype that is a blending of the parental traits.
Codominance
A condition in which neither of two alleles of a gene is dominant or recessive.
Multiple alleles
three or more forms of a gene that code for a single trait
Polygenic trait
Traits controlled by two or more genes
Karyotype
A display of the chromosome pairs of a cell arranged by size and shape.
Genetic disorders
Problems caused by defects in the genes or by inherited characteristics
Pedigree
A diagram that shows traits/diseases in a family throughout history
Normal
AA
Carrier
Aa
Affected
aa
Male
XY
Female
XX
Categories: Genetics