An individual who is homozygous at a particular locus

Epistasis c. Polygenic inheritance d. Complete dominance e. Genes that tend to be inherited together are said to be: a. The principle of independent assortment is violated by: a. X-linked genes. What are the predicted phenotypes of the children from the union of a woman who is heterozygous for hemophilia and a man who is normal blood clotting characteristics?

Use the Punnett square to verify your answer. All normal. In a two-point test cross, 36 of the offspring were recombinant types. The remaining 64 offspring were parental types. How many map units separate the two loci? Alleles b. Loci c. Homozygotes d. Coupled traits e. The genotype for a pea plant that is homozygous recessive for both height and pea color would be: a.

Mendel's principle of segregation states that: a. Using standard conventions for naming alleles, which of the following pairs is correct? Tt - recessive phenotype b. TT - heterozygous c. Mating an individual expressing a dominant phenotype, but whose genotype is unknown, with an individual expressing the corresponding recessive phenotype is an example of: a. In humans, brown eyes are dominant and blue eyes are recessive. If two brown-eyed individuals have a child with blue eyes, that means: a.

Which of the following represents the possible genotype s resulting from a cross between an individual homozygous for black hair BB and a heterozygous Bb individual? What are the possible phenotypes of the children if the mother has Type A blood and the father has type AB blood? A brown-eyed couple already has a child with blue eyes. What is the probability that their next child will have blue eyes? The term dominant" means that: a.

When pink-flowered plants were crossed they produced offspring with red, pink, and white flowers in a ratio of This is an example of: a. A Barr body in a mammalian female cell represents: a. Back to Top - T - Tay-Sachs Disease a genetically inherited condition caused by the inability to produce the enzyme hexosaminidase A. This results in progressively increased fluid pressure on the brain and the subsequent degeneration of the brain and nervous system beginning about 6 months of age and inevitably resulting in death usually by age The gene responsible for Tay-Sachs Disease is recessive.

Back to Top - U - unit inheritance Gregor Mendel's idea that the characteristics of parents are passed on to descendants unchanged as units. In other words, the hereditary material of any organism is made up of discrete units now called genes. Back to Top - V - virus a category of extremely small microscopic parasites of plants, animals, and bacteria. Since viruses cannot reproduce without a host cell, they are not strictly speaking living organisms.

More precisely, this is a cell that is formed when a sperm and an ovum combine their chromosomes at conception.

A zygote contains the full complement of chromosomes in humans 46 and has the potential of developing into an entire organism. All rights reserved.

Return to Last Page Return to Menu. An individual with these traits is an "albino. This is a pleiotropic trait. The alleles for a trait occupy the same locus or position on homologous chromosomes and thus govern the same trait.

However, because they are different, their action may result in different expressions of that trait. There are 20 different kinds of amino acids in living things. Proteins are composed of different combinations of amino acids assembled in chain-like molecules.

Amino acids are primarily composed of carbon, oxygen, hydrogen, and nitrogen. The inheritance of this syndrome is subject to genome imprinting. Children with Angleman syndrome typically also have small heads, experience seizures, have pronounced speech impairment, are hyperactive, and have balance disorders.

It proposed that inherited traits blend from generation to generation. Through his plant cross-breeding experiments, Gregor Mendel proved that this was wrong. Carriers often do not show any signs of the trait but can pass it on to their offspring. This is the case with hemophilia. Cataracts are common in elderly people. They may be inherited or caused by diabetes and environmental factors. In contrast, an acute disease is one with a rapid onset and a short but usually severe course.

Chromosomes are composed primarily of DNA and protein. They are visible only under magnification during certain stages of cell division.

Humans have 46 chromosomes in each somatic cell and 23 in each sex cell. Neither allele is dominant or recessive, so that both appear in the phenotype or influence it. Type AB blood is an example. Such traits are said to be codominant. Usually, the term is used in reference to the crossing of two pure breeding homozygous plants.

This disease also prevents normal absorption of fats and other nutrients from food. Cystic fibrosis occurs as a result of inheriting a recessive allele for it from both parents. About 30, people have cystic fibrosis in the U. In advanced stages, this often results in blindness from cataracts , nerve damage, gangrene in the feet and legs leading to amputation, heart disease, and kidney failure. Type 1 diabetes melitis juvenile onset diabetes is due to decreased production of insulin by the pancreas.

Type 2 diabetes melitis is due to increased resistance of cells in the body to insulin. The gene or genes for diabetes are incompletely penetrant. Dominant alleles for a trait are usually expressed if an individual is homozygous dominant or heterozygous. DNA is composed of sugars, phosphates and bases arranged in a double helix shaped molecular structure.

Segments of DNA in chromosomes correspond to specific genes. The term is also frequently used to refer to the appearance of a new species. The next and subsequent generations are referred to as f2, f3, etc. Since it is an X-linked trait, males more often have it expressed in their phenotypes. Most fragile-X males have large testes, big ears, narrow faces, and sensory integration dysfunctions that result in learning disabilities. It is likely to occur 1 in births.

Approximately 1 in females are carriers of the gene for this trait. The loss or addition of individuals can easily change the gene pool frequencies of both the recipient and donor populations--that is, they can evolve.

More precisely, it is the collective genotype of a population. Physically, a gene is a sequence of DNA bases that specify the order of amino acids in an entire protein or, in some cases, a portion of a protein.

A gene may be made up of hundreds of thousands of DNA bases. True breeding organisms are homozygous since the trait in question can be held constant as they produce the same phenotypic result. In this tutorial, find out more about certain types of inheritance that does not follow the Mendelian inheritance patterns. Examples are incomplete dominance and complete dominance Read More. Genes are expressed through the process of protein synthesis.

This elaborate tutorial provides an in-depth review of the different steps of the biological production of protein starting from the gene up to the process of secretion. Also included are topics on DNA replication during interphase of the cell cycle, DNA mutation and repair mechanisms, gene pool, modification, and diseases