Science test Flashcards-study guide
cytosine
a compound found in living tissue as a constituent base of nucleic acids. It is paired with guanine in double-stranded DNA.
adenine
a compound which is one of the four constituent bases of nucleic acids. A purine derivative, it is paired with thymine in double-stranded DNA.
guanine
a compound that occurs in guano and fish scales, and is one of the four constituent bases of nucleic acids. A purine derivative, it is paired with cytosine in double-stranded DNA.
thymine
a compound which is one of the four constituent bases of nucleic acids. A pyrimidine derivative, it is paired with adenine in double-stranded DNA.
deoxyribose
a sugar derived from ribose by replacing a hydroxyl group with hydrogen.
phosphate
a salt or ester of phosphoric acid, containing PO43− or a related anion or a group such as —OPO(OH)2.
hydrogen bond
Hydrogen bonding is a special type of dipole-dipole attraction between molecules, not a covalent bond to a hydrogen atom.
nitrogenous base
Nitrogenous base: A molecule that contains nitrogen and has the chemical properties of a base.
nucleotide
A nucleotide is the basic building block of nucleic acids (RNA and DNA). A nucleotide consists of a sugar molecule (either ribose in RNA or deoxyribose in DNA) attached to a phosphate group and a nitrogen-containing base.
pedigree
A diagram of family history that uses standardized symbols.
heredity
the passing on of physical or mental characteristics genetically from one generation to another.
trait
a distinguishing quality or characteristic, typically one belonging to a person.
genetics
Genetics is the scientific study of genes and heredity—of how certain qualities or traits are passed from parents to offspring as a result of changes in DNA sequence.
fertilization
fertilization
purebred
(of an animal) bred from parents of the same breed or variety.
gene
(in informal use) a unit of heredity which is transferred from a parent to offspring and is held to determine some characteristic of the offspring.
alleles
one of two or more alternative forms of a gene that arise by mutation and are found at the same place on a chromosome.
dominant allele
A dominant allele is a variation of a gene that will produce a certain phenotype, even in the presence of other alleles.
recessive allele
Recessive refers to a type of allele which will not be manifested in an individual unless both of the individual’s copies of that gene have that particular genotype.
hybrid
the offspring of two plants or animals of different species or varieties, such as a mule (a hybrid of a donkey and a horse).
probability
the extent to which something is probable; the likelihood of something happening or being the case.
Punnett square
The Punnett square is a square diagram that is used to predict the genotypes of a particular cross or breeding experiment.
phenotype
the set of observable characteristics of an individual resulting from the interaction of its genotype with the environment.
genotype
the genetic constitution of an individual organism.
homozygous
having two identical alleles of a particular gene or genes.
heterozygous
having two different alleles of a particular gene or genes.
