Biology H Chapter 11 Vocabulary - Genetics & Meiosis

genetics

the study of heredity and inherited characteristics

trait

an inherited characteristic

purebred

organism receives the same genetic trait from both parents

hybrid

organism receives different traits from parents

genes

a unit of heredity which is transferred from a parent to offspring and is held to determine some characteristic of the offspring

allele

different forms of a gene on the same location of a chromosome

genotype

genetic makeup of an organism, determined by the combination of genes inherited from both parents

phenotype

physical characteristic of an organism, as determined by its genotype

Punnett square

a method of determining hybrid crosses

principle of independent assortment

principle which states that different genes have no effect on each other (ie. blue eyes =/= blue hair)

principle of segregation

only one of the two genes from a parent is passed down to each offspring

principle of dominance

dominant alleles are expressed over recessive alleles

multiple alleles

multiple alleles that correspond to one gene

polygenic traits

many genes contribute to one phenotype/trait

homologous chromosomes

two chromosomes that correspond to the same thing (ie. two chromosome 18s)

diploid

cells with two sets of chromosomes, one from each parent

haploid

cells with one set of chromosomes (ie. gametes)

meiosis

the division of gametes (one diploid cell into four unidentical, haploid sister cells)

tetrad

structure where two homologous chromosomes are connected (only prophase I)

crossing over

cellular process that happens during meiosis when chromosomes of the same type are lined up and exchange genetic materials

codominance

a type of inheritance in which two versions (alleles) of the same gene are expressed separately to yield different traits in an individual (ie. blood type)