lec 7 genetics imprinting

1. What is imprinting primarily known as in the context of genetics?

a. A random mutation process in chromosomes
b. An epigenetic phenomenon leading to functional differences between parental genes
c. A process occurring only in haploid organisms
d. A phenomenon causing changes in DNA sequencing

b

2. Where does imprinting primarily occur in flowering plants?

a. Xylem and phloem tissues
b. Haploid generation germ cells resulting from meiosis
c. Roots and stems
d. Pollen and ovules

b

In mammals, what is the result of deficiencies in gene expression from the paternal chromosome region 15q11-13?

a. Angelman Syndrome
b. Androgenetic zygotes
c. Hydatidiform moles
d. Prader-Willi Syndrome

a and d

Which statement best describes the chromosomal phenomenon of imprinting?

a. It affects only a few genes in a specific chromosomal region
b. Imprinting causes changes in chromatin structure and gene expression
c. Imprinted genes are randomly dispersed across chromosomes
d. It impacts gene expression equally from both parental chromosomes

b

What is the role of DNA methylation in the process of imprinting?

a. It silences the active allele
b. It disrupts the imprinting process
c. Both parental alleles have identical methylation patterns
d. Loss of methylation can lead to significant phenotypic effects

d

6. Why is diploidy considered advantageous in genetics?

a. It allows for the expression of both parental alleles equally
b. Deleterious mutations can be masked by a normal allele on the homologous chromosome
c. Diploid organisms have higher mutation rates
d. It prevents gene expression variation

b

In imprinting, which genome undergoes demethylation shortly after fertilization?

a. Paternal genome
b. Maternal genome
c. Both genomes demethylate simultaneously
d. None of the above

a

How many imprinted genes have been identified in mouse and humans combined?

a. 10-20 genes
b. 50 genes
c. Over 200 genes
d. Less than 5 genes

b

Which organism does NOT show imprinting according to the provided text?

a. Mammals
b. Insects
c. Plants
d. Birds

d

What mechanism is responsible for the failure of endosperm growth in plants with incorrect genome ratios?

a. Heterochromatinization
b. Endosperm pigment synthesis
c. DNA demethylation
d. Somatic cell division

a

Which phenomenon indicates that imprinting is a stable change during development?

a. Differential gene expression between parental alleles
b. Chromosomal translocation
c. Random mutation occurrence
d. Chromatin rearrangement

a

What are Dnmt 1 responsible for in the eight-cell embryo?

a. Paternal DNA replication
b. Elimination of DNA methylation
c. Methylation of imprinted genes
d. Chromosomal recombination

c

How is gene expression affected in Prader-Willi Syndrome (PWS)?

a. Deficiencies in gene expression from the paternal chromosome region
b. Overexpression of genes on chromosome 15q11-13
c. Abnormal methylation in the imprinted region
d. Loss of DNA methylation

a

In imprinting, what does methylation of the silent allele generally indicate?

a. Activation of gene expression
b. Chromatin compaction
c. Inhibition of gene transcription
d. Enhanced replication rates

c

Which statement best describes the timing of DNA replication in imprinted genes?

a. Active alleles replicate earlier than inactive ones
b. Inactive alleles replicate before active ones
c. DNA replication timing remains the same for all alleles
d. Replication timing varies randomly

a

What is a characteristic feature of active alleles in imprinted regions?

a. Compact chromatin structure
b. Hypersensitivity to nuclease digestion
c. Late replication timing
d. Replication inhibition

b

How do gynogenetic zygotes differ from androgenetic zygotes in terms of development?

a. They form ovarian teratomas
b. They show excessive placental growth
c. The embryos die with excessive placental growth
d. They develop without any abnormalities

a

What is the function of imprinting gametic in organisms?

a. Ensuring equal gene expression from parental regions
b. Creating functional differences between paternal and maternal genes
c. Preventing functional differences in offspring
d. Stabilizing chromosomal inheritance

b

Which phenomenon has been proposed to explain the presence of imprinting in various organisms?

a. Pathological states
b. De novo methylation
c. Somatic cell pairing
d. Duplication of parental chromosomes

c

What is the significance of a sex-specific pattern of methylation in the context of imprinting?

a. It preserves gene patterns between maternal and paternal alleles
b. It disrupts gene expression during embryonic development
c. It ensures proper replication timing
d. It leads to a loss of DNA methylation

a

How does imprinting affect sex determination and differentiation in scale insects?

a. It leads to the preferential inactivation of the maternal X chromosome
b. It causes the loss of maternally derived chromosomes
c. It results in the heterochromatinization and loss of paternally derived chromosomes
d. It triggers abnormal growth patterns in embryonic tissues

c

Which phenomenon demonstrates the potential for gametic imprinting in Drosophila?

a. Maternal chromosome set loss in zygotes
b. Loss of paternal chromosome set in zygotes
c. Expression level variation of eye color gene based on parental inheritance
d. Normal gene expression patterns in both maternal and paternal alleles

c

In mammals, what distinguishes the development of androgenetic and gynogenetic zygotes?

a. Normal development with no abnormalities
b. Differences in embryonic growth patterns
c. Formation of hydatidiform moles in both cases
d. Balanced placental growth rates

b

Which genetic diseases are associated with alterations to imprinted genes in humans?

a. Hemophilia and Sickle Cell Anemia
b. Prader-Willi Syndrome and Angelman Syndrome
c. Cystic Fibrosis and Huntington's Disease
d. Alzheimer's and Parkinson's Disease

b

How does imprinting contribute to gene expression differences in marsupials?

a. It leads to preferential inactivation of the maternal X chromosome
b. It causes abnormal growth in embryonic tissues
c. It results in the loss of paternally derived chromosomes
d. It triggers differential gene expression based on parental origin

a

What is the primary reason for the abnormal growth patterns seen in androgenetic zygotes in humans?

a. Excessive placental growth
b. Poor embryonic differentiation
c. Loss of maternal chromosomes
d. Hydatidiform moles formation

d

How is the expression level of the white eye color gene affected in Drosophila based on parental inheritance?

a. It remains constant regardless of parental origin
b. It is higher when inherited maternally
c. It is higher when inherited paternally
d. It is completely suppressed in both cases

c

In flowering plants, what is the consequence of endosperm with an incorrect ratio of paternally and maternally derived genomes?

a. Proper embryo development
b. Growth failure leading to embryo death
c. Enhanced seed development
d. Increased endosperm pigment synthesis

b

What is the impact of imprinting on gene clusters in mouse and human chromosomes?

a. Random dispersion of imprinted genes
b. Differential methylation patterns in active alleles
c. Clustering of imprinted genes in specific chromosomal regions
d. Equal expression of imprinted genes from both parental chromosomes

c

How does imprinting in mammals differ from imprinting in plants and insects?

a. It is limited to haploid organisms
b. It primarily occurs in germ cells resulting from meiosis
c. It leads to loss of chromosomes in offspring
d. It involves differential gene expression according to parental origin

d

How does imprinting primarily impact sex determination and differentiation in mammals?

a. It leads to the loss of paternally derived chromosomes
b. It results in the preferential inactivation of the maternal X chromosome
c. It causes abnormal growth patterns in embryonic tissues
d. It triggers gene expression differences based on parental origin

b

What distinguishes the development of androgenetic and gynogenetic zygotes in mammals?

a. Normal development with no abnormalities
b. Differences in placental growth rates
c. Formation of hydatidiform moles in both cases
d. Varied embryonic growth patterns

b