Basic Principles of Heredity

FLASHCARD DATA FOR BASIC PRINCIPLES OF GENETICS

Topic 1: Mendel’s Genetics

| 1. |Offspring that are the result of mating between two genetically different kinds of parents--the opposite of purebred. |hybrid |
| 2. |The study of gene structure and action and the patterns of inheritance of traits from parent to offspring. This is the branch |genetics |
| |of science that deals with the inheritance of biological characteristics. | |
| 3. |A 19th century central European monk scientist who published his ideas about genetics in 1866 but largely went unrecognized |Gregor Mendel |
| |until 1900, which was long after his death. He acquired his understanding of genetics mostly through pea plant breeding | |
| |experiments. | |
| 4. |A theory that inherited traits blend from generation to generation. Most of the leading scientists in the 19th century |blending theory |
| |accepted it. However, Gregor Mendel proved that it was not correct. | |
| 5. |Offspring that are the result of mating between genetically similar kinds of parents--the opposite of hybrid. |purebred |
| 6. |Units of inheritance usually occurring at specific locations, or loci, on a chromosome. These units are responsible for |genes |
| |hereditary characteristics in plants and animals. | |
| 7. |Alternate forms of the same gene. Because they are different, their action may result in different expressions of a trait. |alleles |
| 8. |The genetic makeup of an individual for a trait or for all of his/her inherited traits—not the observable or detectable |genotype |
| |characteristics. | |
| 9. |A genotype consisting of two identical alleles of a gene for a particular trait. |homozygous genotype |
|10. |A genotype consisting of two different alleles of a gene for a particular trait. |heterozygous genotype |
|11. |The observable or detectable characteristics of an individual organism; the detectable expression of a genotype. |phenotype |
|12. |The general term for an allele that masks the presence of another allele in the phenotype. |dominant allele |
|13. |The general term for an allele that is masked in the phenotype by the presence of another allele. |recessive allele |
|14. |Gregor Mendel's principle of genetic inheritance stating that, for any particular trait, the pair of genes of each parent |principle of segregation |
| |separate (during the formation of sex cells) and only one gene from each parent passes on to an offspring. | |
|15. |Gregor Mendel's principle of genetic inheritance stating that different pairs of genes are passed to offspring independently so|principle of independent |
| |that new combinations of genes, present in neither parent, are possible. In other words, the distribution of one pair of |assortment |
| |alleles does not influence the distribution of another pair--the genes controlling different traits are inherited independently| |
| |of one another. | |

Topic 2: Probability of Inheritance

| 1. |A simple graphical method of showing all of the potential combinations of offspring genotypes that can occur and their |Punnett square |
| |probability given the parent genotypes. This system involves the use of a tic-tac-toe square. It was named after pioneer | |
| |British geneticist. | |
| 2. |The term for a genotype in which there are two dominant alleles. |homozygous dominant |
| 3. |The term for a genotype in which there is a dominant allele and a recessive one. |heterozygous |
| 4. |The term for a genotype in which there are two recessive alleles. |homozygous recessive |
| 5. |The genotype that normally results in the expression of a recessive allele in the phenotype. |homozygous recessive |
| 6. |The only genotype that normally will not result in the expression of a dominant allele in the phenotype. |homozygous recessive |
| 7. |The genotype of an individual who is a carrier for a recessive allele that is not expressed in his/her phenotype. |heterozygous |

Part 3: Exceptions to Simple Inheritance

| 1. |The general term for inheritance patterns which can be explained by simple rules of dominance and recessiveness of genes. |Mendelian genetics |
| 2. |A trait that is determined by the combined effect of more than one gene. Human skin and hair color are examples. The |polygenic trait |
| |result of this kind of inheritance is the perception of gradation in the expression of such traits. | |
| 3. |The inheritance pattern in which a trait is expressed in the phenotype of heterozygous individuals as an apparent blend or |incomplete dominance |
| |an intermediate expression. For instance, in primroses white flowers are homozygous recessive, red ones are homozygous | |
| |dominant, and pink ones are heterozygous. | |
| 4. |The inheritance pattern in which two different alleles for a trait are expressed unblended in the phenotype of heterozygous|codominance |
| |individuals. Type AB human blood is an example. | |
| 5. |An inheritance pattern in which a gene has more than two alleles. The human ABO blood type system is an example. It is |multiple-allele series |
| |controlled by at least 3 alleles. | |
| 6. |Genes that can alter how certain other genes are expressed in the phenotype. Genes causing some kinds of cataracts can be |modifying genes |
| |affected by such accompanying genes. | |
| 7. |Genes that can either initiate or block the expression of other genes. They control the production of a variety of |regulator genes |
| |chemicals in plants and animals. Shortly after conception, some of these genes work as master switches orchestrating the | |
| |timely development of our body parts. They are also responsible for changes that occur in our bodies as we grow older. | |
| 8. |Genes whose effect does not normally occur unless certain environmental factors are present. For example, you may inherit |incompletely penetrant genes |
| |a gene for type II diabetes but never get the disease unless you become overweight, persistently stressed psychologically, | |
| |or do not get enough sleep on a regular basis. | |
| 9. |Genes that are inherited by both men and women but are normally only expressed in the phenotype of one of them. The heavy |sex-limited genes |
| |male beard is an example. While women have facial hair it is most often very fine and comparatively sparse. | |
|10. |Genes that are expressed in both men and women but differently. An example of this is gout, a disease that causes |sex-controlled genes |
| |painfully inflamed joints. If the gene is present, men are nearly eight times more likely than women to have severe | |
| |symptoms. | |
|11. |An inheritance pattern in which a gene will have a different effect depending on the gender of the parent from whom it is |genome imprinting |
| |inherited. Diabetes and psoriasis can follow this inheritance pattern. | |
|12. |The inheritance pattern in which a single allele is responsible for a variety of traits. The collective groups of symptoms|pleiotropy |
| |known as sickle-cell trait is an example. | |
|13. |Defective alleles that have segments which are doubled in their transmission from generation to generation. In the case of|stuttering alleles or unstable |
| |genetically inherited diseases, the result is increasingly severe symptoms each generation. |alleles |
|14. |Twins that come from the same fertilized egg and are, subsequently, genetically the same. They are also known as identical|monozygotic twins |
| |twins. | |
|15. |The international research effort designed to discover all human genes and to determine their functions. |Human Genome Project |

Copyright © 2004 by Dennis O'Neil. All rights reserved.