In Mendel's experiments, offspring always looked like one of their two parents due to the ________ dominance of one allele over the other.
Some genes display ________ dominance; that is, individuals with heterozygous alleles exhibit a phenotype intermediate between those with homozygous alleles
In a third type of dominance, _________, both alleles are expressed in the phenotype of individuals that have heterozygous alleles. (The human blood groups designated M, N, and MN are examples of this)
The human ABO blood groups are an example of multiple ________, (ii, IAIA, IAi, IBIB,IBi,IAIB)
it is more common that one gene can have multiple effects; this is called ___________ (ie. albino + crossed eyes)
Sometimes a gene at one location on a chromosome can affect the expression of a gene at a second location; this is called ____________ (ie. recessive horse pigment code overrides horse brown color dominance)
skin color in humans is a quantitative character. Quantitative characters usually indicate that the character is controlled by more than one gene. This is termed ____________ inheritance
Human __________ describe the interrelationships between parents and children, over generations, regarding a specific trait.
People that are heterozygotic but do not express the recessive trait. They are ____________ of the recessive trait.
one of the most common genetic diseases that affects people of Caucasian ancestry. This disease encodes for a protein that is involved in chloride ion transport; individuals with homozygous alleles for this gene have extreme problems with salt balance in cells (lungs & intestine)
This disease is only observed in individuals that are homozygous for the recessive allele, and the main symptom of is mental retardation. The best prevention for the affected is a life-long diet restricting proteins
Individuals that carry homozygous alleles for _______ disease suffer from a number of problems including anemia, pain, fever, and fatigue. The trait affects the hemoglobin molecule found in red blood cells
___________ disease is a hereditary disease that causes progressive damage to the nervous system. It is characterized by difficulties in three areas: uncontrollable movements, dementia, and psychiatric disturbances. It is caused by a dominant allele.
the normal, prevalent phenotype (studied in fruit flies: red eyes) represented by w+ is the ___________
the X and Y chromosomes are called ______ chromosomes because they determine the sex of an individual.
Genes that are located on sex chromosomes are called sex-linked genes. All other chromosomes in a cell (i.e., other than the sex chromosomes) are referred to as ______________
By convention, males are said to be _________ for sex-linked genes because they have half as many alleles as a female.
In some insects sex is determined by the ____ system, in which females have two copies of the X chromosome and males only one. Therefore, the sex of the offspring will be determined by whether or not an X chromosome is present in the sperm that fertilizes the ovum
The ____ system occurs in some birds, insects, and fish. In this system the chromosomes found in the ovum are variable and sperm always contribute a Z chromosome. Here, it is the female (not the male) that determines the sex of the offspring
Bees and ants display a type of sex determination, called the ___________ system. Females develop from fertilized eggs and are diploid, whereas males develop from unfertilized eggs and are haploid.
The ______ body is an inactivated X chromosome that stays condensed throughout the cell cycle. By inactivated, it is meant that most of the genes on the chromosome are not expressed and cannot be used to make proteins. Therefore, like the cells in males, females have only one functioning X chromosome and they contribute only one dose (copy) of the genes on that chromosome
The gene for the inactivation of the X chromosome, called the _____ gene, is located on the X chromosome. This gene does not appear to code for a protein. It is one of the few genes expressed on the inactivated X chromosome.