BSC 101 Unit 1: How does inheritance work?
dominant allele
-An allele whose trait always shows up in the organism when the allele is present. -an allele that is fully expressed in the phenotype of a heterozygote -ex) widow's peak
gene
-a unit of heredity that is transferred from a parent to offspring and is held to determine some characteristic of the offspring. -A segment of DNA on a chromosome that codes for a specific trait
methyl group
A chemical group consisting of a carbon bonded to three hydrogen atoms. The methyl group may be attached to a carbon or to a different atom.
unreplicated chromosome
A chromosome that consists of a single copy (in eukaryotes, a single "thread")
replicated chromosome
A chromosome that has been copied; consists of two identical chromatids, each containing one double-helical DNA molecule
codominance
A condition in which neither of two alleles of a gene is dominant or recessive.
Pleiotropy
A single gene having multiple effects on an individuals phenotype
recessive allele
An allele that is masked when a dominant allele is present
heterozygous
An organism that has two different alleles for a trait -Aa
homozygous
An organism that has two identical alleles for a trait -AA or aa
genotype
An organism's genetic makeup, or allele combinations.
phenotype
An organism's physical appearance, or visible traits.
homologus chromosomes
Chromosomes that have the same sequence of genes and the same structure
allele
Different forms of a gene
blending inheritance
Early concept of heredity proposing that offspring possess a mixture of the traits from both parents
law of independent assortment
Mendel's second law, stating that allele pairs separate from one another during gamete formation
law of segregation
Mendelian law stating that two alleles for each trait separate during meiosis
incomplete dominance
Situation in which one allele is not completely dominant over another allele
epigentic inheritance
patterns of inheritance that are due to something other than differences in DNA sequences
locus (loci - plural)
the physical location of a gene on a chromosome
discrete traits
traits that are clearly different from each other
polygenetic inheritance
two or more genes contribute to the phenotypic expression of a single characteristic