BIOL&160 - SmartBook Assignment Chapter 10 part 2:Non-Mendelian Inheritance

A gene that has two codominant alleles and one recessive allele, such as the gene conferring human blood type, has ______ possible genotypes and ______ possible phenotypes.

6; 4

In Morgan's crosses of true-breeding red-eyed females and true-breeding white-eye males, all F1 flies had red eyes. Select all of the following that Morgan observed in the F2 flies when the F1 flies were mated.

About 25% of the F2 flies had white eyes. All the white-eyed F2 flies were male.

What is a consequence of multiple proteins being involved in one biochemical pathway?

An altered phenotype can be due to mutations in different possible genes.

An inactivated X chromosome in a female cell is called a(n) ______ body and is turned off early in embryonic development to prevent the use of genes on one of the X chromosomes.

Barr

Two different alleles of a heterozygous genotype are both fully expressed to produce the phenotype in a type of expression called ________.

Blank 1: codominance

True or false: For some of the traits Mendel studied, alleles were incompletely dominant or codominant.

False Reason: For the seven traits Mendel studied, heterozygous individuals shared a phenotype with homozygous dominant individuals.

What describes X inactivation in humans?

One X chromosome in each cell is turned off in XX females.

What type of gene expression was present in the seven traits Mendel studied?

One allele was completely dominant over the other.

What describes an inheritance pattern called epistasis?

One gene affects the expression of another gene.

A woman who is heterozygous for the X-linked, recessive hemophilia allele mates with a man who does not have hemophilia. Which of the possible offspring will have hemophilia?

Son: one X chromosome carrying the recessive hemophilia allele and one Y chromosome

What describes the basis of gene linkage maps, as proposed by Sturtevant in 1911?

The farther apart two genes are, the more likely crossing over is to separate them.

Select the true statement about genes and chromosomes.

The number of genes in a cell exceeds the number of chromosomes.

Who discovered X-linked traits while studying eye color of fruit flies?

Thomas Hunt Morgan

What type of inheritance is depicted in this pedigree?

autosomal recessive

Match each element of a pedigree to its correct description.

circle shapes --> females square shapes --> males half-filled shapes --> carriers horizontal lines --> connect parents

In a type of gene expression called ______, two different alleles are both expressed fully in the phenotype of the offspring.

codominance

The picture shows human ABO blood types. AB blood type is an example of

codominance.

Siamese cats and Himilayan rabbits have light-colored bodies but darker-colored paws, ears, and tail due to an enzyme whose activity varies with temperature. This is an example of

environmental effects.

The effect of diet and lifestyle choices on phenotypes in humans is an example of

environmental effects.

The pink snapdragon flowers in the picture are an example of

incomplete dominance. Reason: In codominance, two different alleles are fully expressed, while in incomplete dominance, the phenotype of the heterozygote is intermediate between that of the two homozygotes.

What parent passed the disorder to individual 5 in the second generation?

male parent Reason: The female was not a carrier of the disorder and was not affected by the disorder.

Blood clotting is an example of how

many genes and proteins affect the same phenotype.

In a gene expression pattern called ________ dominance, the heterozygote has an intermediate phenotype between the homozygotes.

Blank 1: incomplete

Genes that are located on the same chromosome and inherited together are called ________ genes.

Blank 1: linked, linkage, or LINKED

True or false: X-linked genetic disorders can only occur in female humans and Y-linked genetic disorders can only occur in male humans.

False Reason: It is true that Y-linked genetic disorders only occur in male humans because female humans lack a Y chromosome; however, X-linked genetic disorders can occur in male and female humans because both genders have at least one X chromosome.

True or false: In the inheritance of X-linked disorders, males can be carriers of the disorder.

False Reason: Males will always either express the disorder or be unaffected because they only have copy of the allele carried on the X chromosome.

Select all of the following that are true about autosomal recessive inheritance of a human disorder.

Heterozygous individuals are called carriers. Both parents of an affected individual carry at least one copy of the disease-causing allele.

What genotype produces the phenotype of type AB blood?

IAIB

In Morgan's studies, why did males display the white-eye trait more often than females?

The white-eye allele is on the X chromosome, and males do not have another X to mask the white-eye allele.

What occurs early in embryonic development of female mammals to prevent "double dosing" of proteins from X chromosomes?

X inactivation

What pattern of inheritance is shown if only males are affected by a disorder over several generations, but no females are?

X-linked recessive

Referring to Morgan's experiments with red-eyed and white-eyed fruit flies, match each genotype to its correct phenotype.

XRY --> red-eyed male XRXR --> red-eyed female XrY --> white-eyed male XrXr --> white-eyed female

Typically, the sex chromosomes of a human female are

XX.

What chromosomes typically make up the sex chromosomes in a human male?

XY

Select all of the types of offspring that were produced when Morgan crossed white-eyed females of the genotype XrXr with red-eyed males of the genotype XRY. (Hint: construct a Punnett square.)

XrY white-eyed males XRXr red-eyed females

Select all of the following that are true about Barr bodies.

absorb stain more readily than active X chromosomes inactivated X chromosome

Epigenetic effects on gene expression involve

activating or inactivating genes without altering the DNA sequence.

For X-linked recessive disorders, males who inherit a recessive allele from the mother will be

affected by the condition.

The pedigree shown in the picture depicts the inheritance of a(n)

autosomal dominant disorder.

Alfred Sturtevant proposed that the farther apart two alleles are located on the same chromosome, the more likely ______ is to separate them.

crossing over

What process, depicted in the picture, produces nonidentical chromatids and can interrupt linkage between two genes?

crossing over

The exchange of genetic material between homologous chromosomes during prophase I of meiosis is called ______ and can explain the appearance of ______ in the offspring.

crossing over; recombinant traits

To construct linkage maps, scientists estimate the distance between genes on the same chromosome based on the ______, as indicated by the percentage of recombinant offspring.

crossover frequency

Select all of the following pairs that are examples of environmental effects on a phenotype in humans.

diet affecting severity of type II diabetes infectious agents affecting the course of cystic fibrosis

Select all of the following that describe Y-linked traits.

disorders involving defects in sperm production very few disorders

Because early in development ______ is inactivated in XX females, cells in the adult individual will express either the paternal or maternal allele in patches.

either the paternal or maternal X allele

Research in ______ explores how cells turn genes on or off without changing the DNA sequence.

epigenetics

What type of protein interaction involves the phenotype of one gene inhibiting or enhancing the expression of another gene?

epistasis

When one gene's products affect the expression of another gene, this is called

epistasis.

X inactivation occurs early in ______ embryonic development and prevents ______ of every gene on the X chromosome.

female; a double dose

Whereas the codominant IA and IB blood type alleles encode ______, the i allele encodes ______.

functional proteins; a nonfunctional protein

Match each genotype in human blood typing with its correct phenotype.

genotype IAi or IAIA --> blood cells have only A surface molecules genotype IBi or IBIB --> blood cells have only B surface molecules genotype IAIB --> blood cells have both A and B surface molecules genotype ii --> blood cells have neither A nor B surface molecules

Match each genotype in human blood typing with its correct phenotype.

genotype IAi or IAIA --> type A blood genotype IBi or IBIB --> type B blood genotype IAIB --> type AB blood genotype ii --> type O blood

Using the frequency of crossing between genes V and W, what can be created, as shown in the picture?

linkage map

Select all of the following that are true about linked genes.

located on the same chromosome do not assort independently inherited together

After Mendel's work, biologists determined that a single chromosome carries

many genes.

A type of gene expression called pleiotropy occurs when

one gene has multiple effects on the phenotype.

What diagram is shown in the picture?

pedigree

A chart showing the presence and absence of phenotypes in multiple generations of a family is called a

pedigree.

What might a human geneticist use to determine if an allele for a single human gene is dominant or recessive?

pedigrees showing family relationships over multiple generations

In ______, one gene encodes a protein that is important in many biochemical pathways or that affects many parts of the body.

pleiotropy

Human eye color is controlled by multiple enzymes encoded by multiple genes; therefore, human eye color is an ______ trait.

polygenic

If the phenotype reflects the activities of more than one gene, it is called a ______ trait.

polygenic

What produces different patches of color in female calico cats that are heterozygous for the color gene on the X chromosome?

random X inactivation early in development

Genes that are located on the X or Y chromosome are said to be ______ and often are expressed in one sex more than the other.

sex-linked

Red-green color blindness and hemophilia are examples of ______, which are controlled by alleles on the sex chromosomes.

sex-linked genes

The blood-clotting disorder hemophilia in humans is an example of a(n) ______ disorder.

sex-linked, recessive

Most sex-linked traits, such as hemophilia and red-green color blindness, are controlled by genes on

the X chromosome.

Presence of the phenotype of an autosomal recessive disorder in one generation and then absence of the phenotype in the next generation likely means

the allele is present in heterozygotes that are carrying the disorder.

The effect of temperature or nutrition on the expression of genes are examples of how ______ can alter the phenotype.

the environment

In human traits that are determined by single genes with either dominant and recessive alleles, how do researchers study the inheritance pattern of the genes and determine whether alleles are dominant or recessive?

tracking gene expression over multiple generations

Select all of the following that describe the inheritance of an autosomal dominant disorder.

typically present in every generation expressed in homozygous dominant individuals and heterozygous individuals