genetics 5

Select all of these that are true of genes that follow a Mendelian inheritance pattern.

1. Expression of genes in the offspring directly influences their traits. 2. The genes are transmissible from generation to generation. 3. The genes segregate during gamete formation. 4The genes segregate independently.

Which of these are examples of extranuclear genes?

1. Genes located on a chromosome in a mitochondrion 2. Genes located on a chromosome in a chloroplast

Select characteristics of mitochondrial DNA mutations.

1. Mitochondrial DNA mutations are transmitted from a mother to all of her offspring. 2. Mitochondrial DNA mutations may occur in somatic cells and accumulate as a person ages

Select all of these that are true of mitochondrial genes.

1. Most mitochondrial proteins are encoded by nuclear genes. 2. Human mtDNA carries relatively few genes. 3. Mitochondrial DNA contains both coding and noncoding regions.

What information do you need to predict an offspring's phenotype when considering imprinted genes?

1.If the offspring expresses the allele that is inherited from the mother or the father 2. Which allele was inherited from which parent

In the snail Lymnaea peregra, shell coiling is regulated by a maternal effect gene, and dextral is dominant to sinistral. What is the expected genotype of the offspring for the cross shown in the image?

100% Dd

What is genomic imprinting?

A form of epigenetic inheritance in which a segment of DNA is marked in a way that it alters gene expression

In the experiment carried out by Davidson, Nitowsky, and Childs, which outcome would support the Lyon hypothesis?

All nine clones expressed either the fast or slow G-6-PD protein but not both.

The inactivated X chromosome in somatic cells of mammals, like the one shown by the arrow in this image, is called a

Barr body

What determines the snail coiling pattern in Lymnaea peregra?

Gene products provided by maternal nurse cells to the oocyte

Which phases of X chromosome inactivation occur only during embryonic development?

Initiation Spreading

Within the two-to four-cell snail embryo, which factor is responsible for the origin of dextral and sinistral shell coiling?

Orientation of the mitotic spindle

Which genes on the X chromosome are able to escape the effects of X chromosome inactivation in female mammalian cells?

Pseudoautosomal genes

True or false: The genes located in mitochondria and chloroplasts do not exhibit Mendelian patterns of inheritance.

TRUe

The genome located in the nucleoid of a mitochondrion or chloroplast consists of a ______ chromosome.

circular, double-stranded DNA

Population of cells that are all derived from a single cell are called .

clone

Chloroplasts evolved from an endosymbiotic relationship between ______.

cyanobacteria and eukaryotic cells

Extranuclear genes are not segregated into gametes the same way the nuclear chromosomes are. As such, extranuclear genes ______ exhibit Mendelian patterns of inheritance.

do not

The theory that explains the evolution of some eukaryotic organelles such as chloroplasts and mitochondria is called the

endosymbiosis theory

The genome of a chloroplast is _____ than the genome of a mitochondrion.

larger

The size of a human mitochondrial chromosome is ______ the size of a typical bacterial chromosome.

less than 1%

Based on the information in the figure,will the paternal or maternal chromosome be active in the resulting zygote?

maternal

In an inheritance pattern called , the genotype of the mother directly determines the phenotype of her offspring for a given gene.

maternal effect

Chloroplasts and mitochondria are inherited through the cytoplasm of the egg. This type of extranuclear inheritance is called ______.

maternal inheritance

Snail shell coiling is due to a maternal effect gene with two alleles. The dominant allele D causes dextral (right-handed) shell coiling while the recessive allele d leads to sinistral (left-handed) coiling. The gene product is transferred from nurse cells into the egg as shown in the diagram for a homozygous (dd) mother. Suppose this egg is fertilized by a gamete from a dextral (DD) male. What are the expected phenotypes of the offspring?

sinistral

Patterns of imprinting are maintained in what type of cells throughout development?

somatic

Select all of these that are true of chloroplast DNA.

1. A typical chloroplast genome is about 100,000 - 200,000 bp in length. 2. Many chloroplast proteins are encoded by nuclear genes.

Which chromosome 15 genes are lost in the deletion causing Prader-Willi syndrome?

1. NDN 2. snoRNA genes 3. SNRPN

Which statements regarding nucleoid structure of mitochondria and chloroplasts are true?

1. There may be more than one nucleoid per organelle. 2. The genome consists of double-stranded DNA. 3. There may be more than one chromosome in the nucleoid. 4. The genome is a circular.

The genetic material inherited in an organelle, such as a mitochondrion or a chloroplast, exhibits _____ inheritance.

1. extranuclear 2. cytoplasmic

Which statements regarding genomic imprinting are true? Genomic imprinting ______.

1. occurs in several species including insects, mammals, and flowering plants 2. determines X-chromosome inactivation in marsupials 3. may involve a single gene, a part of a chromosome or the entire chromosome

In the snail Lymnaea peregra, shell coiling is regulated by a maternal effect gene, and dextral is dominant to sinistral. What is the expected phenotype of the offspring for the cross shown in the image?

100% sinistral

Which of these best describes a clone?

A population of cells derived from a single cell

Match each stage of genomic imprinting with the correct description.

Establishment of the imprint--- During gametogenesis either maternal or paternal allele is silenced and the other is expressed Maintenance of the imprint--- The imprint pattern is continued throughout development in somatic cells Erasure and reestablishment of the imprint--- The imprint is removed in germline cells

True or false: All genes on the inactivated X chromosome remain inactivated throughout life in a somatic cell of an adult female.

FALSE

True or false: Like X chromosomes in human females, one of the Z chromosomes in female birds is randomly inactivated in somatic cells.

FALSE

True or false: Epigenetic changes to a chromosome are permanent modifications that remain over the lifetime and later generations of the organism.

False

Match the phases of X chromosome inactivation with the correct description.

Initiation--- One of the two X chromosomes is targeted for inactivation Spreading--- Inactivation begins at the Xic region and continues in both directions along the X chromosome. Maintenance--- The inactivated X chromosome is replicated as a Barr body and compaction is continued from embryonic development through adulthood.

If the expression of genes in the offspring directly influences their traits, the genes are transmissible from generation to generation, the genes segregate during gamete formation, and the genes of the trait segregate independently, then the genes follow ______ inheritance patterns.

Mendelian

Even though offspring receive two alleles, one maternal and one paternal, during genomic imprinting only one allele is expressed. What is this phenomenon called?

Monoallelic expression

The mice in the figure are heterozygous, Igf2 Igf2-, yet they have different phenotypes due to genomic imprinting. What is this phenomenon called?

Monoallelic expression

Which human mitochondrial disease is caused by a mutation in a gene required for ATP synthesis?

Neurogenic muscle weakness

Which human diseases are caused by mutations in mitochondrial DNA?

Neurogenic muscle weakness Leber hereditary optic neuropathy

What are the three phases of X chromosome inactivation?

Nucleation, spreading, and maintenance

A male with Klinefelter syndrome (XXY) would have how many Barr bodies in his cells?

ONE

Which statement best describes how X chromosomes are inactivated in female mammals?

One X is randomly inactivated in each cell at an early stage of embryonic development.

Select all of these that are human diseases caused by genomic imprinting.

Prader-Willi syndrome Angelman syndrome

Prader-Willi syndrome is associated with the imprinting of a gene encoding a splicing factor called ______.

SNRPN

What happens to the inactivated X chromosome in female mammals when cells divide?

The inactivated X chromosome is passed along to all future somatic cells.

Which of these statements are true for human mitochondrial diseases?

They often exhibit varying degrees of severity within families They are usually chronic degenerative disorders They usually affect cells that require high levels of ATP

A deletion of a region of chromosome 15 that includes the gene has been shown to cause Angelman syndrome.

UBE3A

For Angelman syndrome, which gene is lacking in expression?

UBE3A

In somatic cells of human females one of the two X chromosomes is randomly turned off. What is this mechanism called?

X-chromosome inactivation

What is the primary role of the X-inactivation center (Xic)?

X-chromosome inactivation

A person who has somatic cells with two Barr bodies could have which of the following genotypes?

XXX XXXY

The short region on the X chromosome that plays an important role in X chromosome inactivation is the

Xic

In birds males are ZZ and females are ZW. Studies have shown that male birds express twice as much gene product of some Z-linked genes. What does this suggest?

Z-linked genes are not dosage compensated in birds.

The regulation of a genomic imprint involves ______ near the imprinted gene.

an imprinting control region

Snail shell coiling is due to a maternal effect gene with two alleles. The dominant allele D causes dextral (right-handed) shell coiling while the recessive allele d leads to sinistral (left-handed) coiling. The gene product is transferred from nurse cells into the egg as shown in the diagram for a heterozygous (Dd) mother. Suppose this egg is fertilized by a gamete from a sinistral (dd) male. What is the expected phenotype of the offspring?

dextral for both the D and d genotypes in the egg

Despite the fact that human males are XY and human females are XX, they have equal expression of many genes on their sex chromosomes. This phenomenon is called .

dosage compensation

What accounts for equal expression of genes on the sex chromosomes despite the fact that males and females have an unequal complement of sex chromosomes?

dosage compensation

A pattern of inheritance in which a temporary alteration to a chromosome modifies gene expression but is not permanent over many generations is called _______inheritance.

epigenetic

An offspring receives genetic material located in the mitochondria. This is an example of

extranuclear inheritance

For the experiment testing the Lyon hypothesis at the cellular level carried out by Davidson, Nitowsky, and Childs, the individual who donated the cells must have been a ______ for the gene of interest.

female heterozygous

In humans with a typical constitution of chromosomes, X-chromosome inactivation induces dosage compensation by randomly inactivating one of the X chromosomes in the somatic cells of ______.

females

As seen in the figure, de novo methylation of a gene or chromosome occurs in ______.

gametes

In a form of epigenetic inheritance called____ _____ , a segment of nuclear DNA is marked in a non-permanent way that alters gene expression throughout the life of the individual.

genomic imprinting

The human diseases Prader-Willi syndrome and Angelman syndrome are influenced by ______.

genomic imprinting

In chloroplasts, the gene for the photosynthetic enzyme RUBISCO can be mutated. Leaf cells with chloroplasts carrying this mutation will appear white due to the absence of photosynthesis. Leaves with a mixture of mutated and non-mutated chloroplasts show heteroplasmy, with green and white variegation. The RUBISCO gene is inherited from the mother. If the mother plant has green leaves and the father plant has white leaves, which types of leaves can be seen among the offspring?

green

In chloroplasts, the gene for the photosynthetic enzyme RUBISCO can be mutated. Leaf cells with chloroplasts carrying this mutation will appear white due to the absence of photosynthesis. Leaves with a mixture of mutated and non-mutated chloroplasts show heteroplasmy, with green and white variegation. The RUBISCO gene is inherited from the mother. If the mother plant is variegated and the father plant has fully green leaves, which types of leaves can be seen among the offspring?

green, white and variegated

A species that produces two kinds of gametes, with unequal distribution of cytoplasmic organelles, is said to be a ______ species.

heterogamous

In _____. species, two kinds of gametes are made such that the distribution of cytoplasmic organelles is unequal in the two gamete types and organelles are often inherited from one parent.

heterogamous

The variegation of the leaf shown in the image can be explained by ______.

heteroplasmy

The type of inheritance that occurs because extranuclear genes are inherited through the cytoplasm of an egg is called .

maternal inheritance

Human mitochondrial diseases, such as Leber hereditary optic neuropathy, are usually ______ inherited.

maternally

A mitochondrion or chloroplast ______ nucleoid

may have more than one

At the molecular level, one way genomic imprinting is regulated is by DNA .

methylation

The endosymbiosis theory explains how eukaryotic cells developed the cellular organelles: ________and ________.

mitochondria and chorloplast

In a mitochondrion, genetic material is located in a region called the

nucleoid

Genes located on chromosomes are called nuclear genes because they are located in the cell

nucleus

The non-Mendelian inheritance pattern observed in snail coiling is most related to ______.

oogenesis

For a human offspring to express a paternal mitochondrial gene, the individual must have inherited a mitochondrion from the sperm. This is called ______.

paternal leakage

In a somatic cell, the genomic imprint is _____.

permanent

Mitochondria may have evolved from an endosymbiotic relationship between ______.

purple bacteria and eukaryotic cells

As shown in the image, X chromosomes are randomly inactivated during embryonic development. This is also called ______.

the Lyon hypothesis

The coat color of the calico cat shown in the image is best explained by ______.

the Lyon hypothesis

In the case of the Igf2 gene, which copy is expressed in the offspring?

the allele from the father