A&P II Lesson 11

The phenotypes that would result from the cross of H1H2 and H1H2 (H1 represents the normal gene for hemoglobin and H2 represents the incomplete dominant allele that causes the formation of abnormal hemoglobin) are

25% normal, 50% sickle cell trait, 25% sickle cell anemia.

In a simple dominant-recessive inheritance pattern, what percentage of the offspring would be expected to exhibit the dominant trait if the parents were heterozygous and homozygous-recessive?

50%

An example of a homozygous gene pair is

AA.

An individual who is homozygous dominant for a trait can be symbolized

AA.

If the blood type gene IO is present in the genotype, the person cannot have blood of type

AB.

Nondisjunction in which homologous autosomes do not separate, therefore a cell receives an extra chromosome, results in

All of these are correct.

A normal male has the sex chromosome combination XX.

False

T/F: If one parent has sickle cell anemia and the other parent is normal, the chance of a child with sickle cell anemia is 50%.

False

The total number of chromosomes found within a human zygote is 23.

False

A person with type A blood could have the genotype

IAIA or IAIO.

The phenotypes that would result from the cross of H1H1 and H1H2 (H1 represents the normal gene for hemoglobin and H2 represents the incomplete dominant allele that causes the formation of abnormal hemoglobin) are

None of these is correct.

Which of the following would not be a possible blood type for the baby of a mother with type AB and a father with type B blood?

O

The genotypes and phenotypes that would result from the cross of Aa and Aa (A = normal pigmentation and a = albinism) are

Phenotypes: 3/4 normal and 1/4 albino; Genotypes: 1/4 homozygous dominant, 1/2 heterozygous, and /4 homozygous recessive

Which of the following is true in regard to the determination of the gender of a baby?

The sex chromosome in the sperm determines the gender of the baby.

Which of the following is true regarding egg cells?

They always contain an X chromosome.

A color-blind male child always receives the gene for color blindness from his mother.

True

The particular combination of genes present within a zygote constitutes its genotype.

True

If an egg cell without an X chromosome is fertilized by an X-bearing sperm cell, then this will result in

Turner's syndrome.

_______ inheritance is due to recessive genes located on X chromosomes.

X-linked

If the parent genotypes are AA and aa, the offspring are expected to be

all Aa.

The phenotypes expected from the cross of a color-blind female and a normal male are

all females have normal color vision and all males are color blind.

The phenotypes expected from the cross of a color-blind male and a normal (homozygous dominant) female are

all males and females have normal color vision.

If a color-blind male is married to a homozygous dominant (normal) female, the possible offspring are

all offspring normal.

A procedure used to obtain enough fetal tissue to test for genetic disorders by culturing cells is called

amniocentesis.

Within a set of human chromosomes, 22 pairs are called________.

autosomes

An example of a sex-influenced trait is

baldness.

Dominant genes in a genotype are designated by

being capitalized.

Hemophilia is

characterized by a defect in the clotting mechanism

Homologous pairs of chromosomes are

chromosomes from the mother and father that contain similar genetic information.

When is the chromosome number reduced by one-half during gametogenisis

during the first meiotic division

In meiosis, crossing over occurs during the

first meiotic prophase.

The portion of a DNA molecule that contains the information for producing one kind of protein is called a(n)______.

gene

Incomplete dominance is defined as

gene pairs occurring in two forms that are expressed differently and neither is dominant to the other.

The origin of the 46 chromosomes in a human zygote is

half from the sperm and half from the egg.

When the alleles of a gene pair are different they are said to be

heterozygous.

Genetic transmission of genes located within a portion of the Y chromosome for which there is no homologous region in the X chromosome is called

holandric inheritance.

The chromosomes of a set that contain similar genetic material comprise a(n) ________.

homologous pair

When the alleles of a gene pair are identical they are said to be

homozygous.

When the alleles of a gene pair are expressed differently but neither is dominant to the other, they are called __________.

incompletely dominant

Genetics is the study of

inherited variation.

During which stage in mitosis are genes and chromosomes duplicated

interphase

The significance of synapsis during meiosis is that

intertwined chromosomes may break and exchange parts.

If a Y-bearing sperm cell fertilizes a normal egg cell, the zygote will be a ______.

male

Down syndrome is caused by

nondisjunction.

The genotypes and phenotypes that would result from a cross of AA and Aa (A = normal pigmentation and a = albinism) are

phenotypes-all normal; genotypes-50% homozygous dominant and 50% heterozygous.

The phenotypes and genotypes that would result from a cross of Aa and aa (A = normal pigmentation and a = albinism) are

phenotypes-half normal and half albine; genotypes-half heterozygous and half homozygous recessive.

A gene is defined as a

portion of a DNA molecule that contains the information for producing one kind of protein molecule.

A gene that is not expressed in the heterozygous condition is called

recessive.

X-linked genes are always expressed more frequently in males than in females due to the fact that

there is no allele on Y chromosomes.

If the parent genotypes are Aa and Aa, the offspring are expected to be

¼ AA, ½ Aa, ¼ aa.