BMS240 CH3 Basic Principals of Heredity – Flashcards

A genetic factor (region of DNA) that helps determine a characteristic

One of two or more alternate forms of a gene.

A specific place on chromosome occupied by an allele.

A set of alleles possessed by an individual

An individual organism possessing two of the same alleles at the locus.

An individual organism possessing two different alleles at the locus

The physical appearance of a characteristic.

The mating between individuals who have different alleles at one genetic locus of interest. The characteristics being studied are governed by 2 alleles for a single locus.

Refers to an organism that exhibits a particular trait and all progeny also exhibit that trait. It is possible in humans through selfing or brother/sister crossing.

To self pollinate or self fertilize. Not a good idea in humans as it leads to a higher rate of genetic diseases.

The first generation of a cross.

The offspring from the parents in the P generation.

A pair of crosses between a male of one strain and a female of another, and vice versa.

The generation produced by interbreeding individuals of an F1 generation and consisting of individuals that exhibit the result of recombination and segregation of genes controlling traits for which stocks of the P generation.

The form of a gene that overpowers the recessive part of a gene.

An in heritable masked characteristic which is only expressed in offspring when inherited by both parents.

One factor in a pair of traits dominates the other in inhertance, unless both factors of the pair are recessive.

Each individual diploid organism possesses 2 alleles for each trait and these alleles separate when gametes are formed, 1 allele going to each gamete.

The theory that chromosomes are linear sequences of genes. The unifying theory stating that inheritance patterns may be generally explained by assuming that genes are located in specific sites on chromosomes.

When you cross (a hybrid) with one of its parents or an organism with the same genetic characteristics as one of the parents.

The Punnett square is a diagram that is used to predict an outcome of a particular cross or breeding experiment. The diagram is used by biologists to determine the probability of an offspring having a particular genotype.

A genetic cross between a homozygous recessive individual and a corresponding suspected heterozygote to determine the genotype of the latter.

A gene or characteristic which prevails among individuals in natural conditions, as distinct from an atypical mutant type.

The mating between two organisms that are identically hybrid for two traits.

The law of chance governs which particular characteristics of the parental pair will occur in each offspring.

Mendel was successful for several reasons. He chose to work with a plant, Pisum sativum, that was easy to cultivate, grew relatively rapidly compared with other plants, and produced many offspring whose phenotypes were easy to determine, which allowed Mendel to detect mathematical ratios of progeny phenotypes. The seven characteristics that he chose to study exhibited only a few distinct phenotypes and did not show a range of variation. Finally, by looking at each trait separately and counting the numbers of the different phenotypes, Mendel adopted a reductionist experimental approach and applied the scientific method. From his observations, he proposed hypotheses that he was then able to test empirically.

Genotype: The set of genes possessed by an individual organism. Phenotype: Appearance or manifestation of a characteristic.

Each individual diploid organism possesses 2 alleles for each trait and these alleles separate when gametes are formed, 1 allele going to each gamete. ......

Mendel's principles assert that the genetic factors or alleles are discrete units that remain separate in an individual organism with a trait encoded by the dominant allele being the only one observed if two different alleles are present. According to Mendel's principles, if an individual contains two different alleles, then the individual's gametes could contain either of these two alleles(but not both) Blending inheritance proposes that offspring are the result of blended genetic material from the parent and the genetic factors are not discrete units. once blended, the combined genetic material could not be separated from each other in future genetations

One factor in a pair of traits dominates the other in inhertance, unless both factors of the pair are recessive.

Walter Sutton's chromosome theory of heredity states that genes are located on chromosomes. The independent segregation of pairs of homologous chromosomes in meiosis provides the biological basis for Mendel's two principles of heredity.

The principle of independent assortment states that alleles at different loci segregate independently of one another. The principle of independent assortment is an extension of the principle of segregation: the principle of segregation states that the two alleles at a locus separate; according to the principle of independent assortment, when these two alleles separate, their separation is independent of the separation of alleles at other loci.

In anaphase I of meiosis, each pair of homologous chromosomes segregate independently of all other pairs of homologous chromosomes. The assortment is dependent on how the homlogs line up during metaphase I. This assortment of homologs explains how genes located on different pairs of chromosomes will separate independently of one another. Anaphase II results in the separation of sister chromatids and subsequent production of gametes carrying single alleles for each gene locus as predicted by Mendel's principle of segregation

Law of dominance: mendle crossed a homozygous wrinked seed with a homozygous round pea and his results showed that all of the offspring had round seeds. He concluded that round seeds must be dominant over wrinked seeds. Therefore his law of dominance states that one factor in a pair of traits dominates the other in inhertance, unless both factors of the pair are recessive. Law of Segregatoion: Mendle then crossed the results of the F1 generation and found that the wrinked phenotype appeared again in a 3:1 ratio (round:wrinkled). He concluded through the law of segregation that although f1 plants show the phenotype of one parent, both traits are passed on to the F2 generation in a 3:1 ratio. Therefore one characteristic from one parent is inherited. The law of Independent Assortment: Mendle then focused on one trait at the same time using dihybrid crosses: shape round, wrinkled and colour yellow, green. When he performed the cross from the F1 generation to the F2 generation the alleles for each locus separate with one allele going to each gamete. He noticed the alleles can separate in 2 ways: 1.R with Y and r with y RY and ry 2.R with y and r with Y Ry and rY Both ways are equally possible. Therefore mendles law of independent assortment states that the law of chance govern which particular characteristics of the parental pair will occur in each offspring.