Question 1

Epigenetic changes in development are important in that the gene expression of cells that make up a particular organ or tissue type is often defined by epigenetic markers. Which of the following epigenetic regulations is known to cause more long-term gene silencing during the course of development?
A) chromatin remodeling
B) DNA methylation
C) histone modifications
D) DNA ubiquitination

Accepted Answer

DNA methylation is known to cause long-term gene silencing by adding methyl groups to DNA, typically at CpG sites, which can stably repress gene expression over time.

Question 2

Activin is a protein that normally exists in a gradient within certain tissues in developing embryos. Certain undifferentiated cells cultured without activin produce epidermal cells. However, activin induces these same cells to adopt other fates (e.g., blood, muscle, heart), depending on the concentration of activin. Based on these observations, activin acts as a(n):
A) transcription factor.
B) cell-surface receptor.
C) morphogen.
D) second messenger.
E) activator.

Accepted Answer

Activin acts as a morphogen, which is a substance that establishes a gradient and influences cell fate decisions based on its concentration.

Question 3

Which of the following groups of genes is directly regulated by egg-polarity genes?
A) homeotic genes
B) gap genes
C) Hox genes
D) pair-rule genes
E) segment-polarity genes

Accepted Answer

Egg-polarity genes regulate gap genes, which are involved in the early segmentation of the embryo.

Question 4

The proteins Dorsal and Bicoid both act as morphogens in Drosophila embryogenesis. However, the establishment of the concentration gradients of each protein differs. Which of the following statements CORRECTLY describes this difference?
A) The dorsal gene is transcribed maternally while the bicoid gene is transcribed in the developing embryo.
B) The dorsal gene is transcribed in the developing embryo whereas the bicoid gene is transcribed maternally.
C) The concentration gradient of Dorsal is established through asymmetric subcellular localization whereas the concentration gradient of Bicoid is established through selective degradation.
D) The concentration gradient of Dorsal is established through asymmetric subcellular localization whereas the concentration gradient of Bicoid is established through asymmetric localization of the bicoid mRNA and thus protein.
E) The concentration gradient of Dorsal is established through differential rates of translation whereas as the concentration gradient of Bicoid is established through a transport system.

Accepted Answer

The concentration gradient of Dorsal is established through asymmetric subcellular localization, while the concentration gradient of Bicoid is established through asymmetric localization of the bicoid mRNA and thus protein.

Question 5

Which of the following statements about homeotic genes is INCORRECT?
A) Homeotic genes were first identified in invertebrates, but their homologs were found in almost all organisms.
B) All homeotic genes contain consensus sequences that result in a specific DNA-binding motif.
C) In vertebrates, homeotic genes are organized into two distinct clusters.
D) All homeotic genes encode transcription factors that direct further gene expression.
E) Homeotic genes exhibit a relationship between their order on the chromosome and the timing of their expression.

Accepted Answer

In vertebrates, homeotic genes are organized into four distinct clusters, not two.

Question 6

Which specific group of genes specifies the identities of individual body segments?
A) segmentation genes
B) gap genes
C) homeotic genes
D) pair-rule genes
E) segment-polarity genes

Accepted Answer

Homeotic genes are responsible for determining the identity and proper placement of body segments in an organism.

Question 7

When animals like Dolly the sheep are cloned using techniques that transfer a nucleus from a donor animal into the egg of a recipient animal, is the resultant clone genetically identical to the nuclear donor animal?

Accepted Answer

The answer of When animals like Dolly the sheep are...

Question 8

Use the following to answer questions 
In the late 1940s Edward Lewis discovered mutations in the Antennapedia gene that lead to legs developing on the head of a fly instead of antenna. These mutations are dominant and lead to ectopic expression of the Antennapedia gene.
-Certain mutations in the Antennapedia gene can lead to antenna developing in a mesothoracic segment where legs should have developed. What characteristics would you expect from this class of mutations? (Select all that apply.)
A) They are loss-of-function.
B) They are recessive.
C) They are gain-of-function.
D) They are dominant.
E) They result in ectopic Antennapedia expression.

Accepted Answer

These mutations result in the loss of normal function, leading to antenna development where legs should be, and are typically recessive, as they require both alleles to be affected to show the phenotype.

Question 9

Use the following to answer questions 
In the late 1940s Edward Lewis discovered mutations in the Antennapedia gene that lead to legs developing on the head of a fly instead of antenna. These mutations are dominant and lead to ectopic expression of the Antennapedia gene.
-Based on these data, how would you expect the gene to be expressed in the mutant? (Select all that apply.)
A) in every segment
B) in a more anterior segment
C) in a more posterior segment
D) earlier
E) later

Accepted Answer

The mutations lead to ectopic expression of the Antennapedia gene, which means that the gene is expressed in a different location than it normally is. In this case, the gene is expressed in the head instead of the antenna. This suggests that the gene is expressed in a more anterior segment (the head) and earlier (before the antenna develops).

Question 10

Which of the following statements about Hox genes is INCORRECT?
A) All Hox genes found in organisms other than Drosophila have a conserved pattern of identical clustered arrangements.
B) When a vertebrate Hox gene is moved to a new location within the Hox gene complex, the timing of its expression is altered.
C) The Hox genes encode transcription factors that help to determine the identity of the body region.
D) They are usually organized as clusters and the order on the chromosome is important for their expression pattern.
E) The recent studies suggest the role of miRNA in controlling the expression of some Hox genes.

Accepted Answer

Hox genes in organisms other than Drosophila do not always have an identical clustered arrangement, as there can be variations in the number and arrangement of Hox genes across different species.

Question 11

List the five major classes of developmental genes in Drosophila in the order (earliest to latest) that they regulate development.

Accepted Answer

The answer of List the five major classes of developmental...

Question 12

Which of the following choices lists the CORRECT sequence of gene expression during Drosophila development? 1. Segmentation genes
2) Egg-polarity genes
3) Homeotic genes
A) 1, 2, 3
B) 2, 3, 1
C) 2, 1, 3
D) 3, 2, 1
E) 3, 1, 2

Accepted Answer

Egg-polarity genes are expressed first to establish the axes, followed by segmentation genes that define the segments, and finally homeotic genes that determine the identity of each segment.

Question 13

What have the cloning experiments in plants and animals confirmed with regard to developmental processes?

Accepted Answer

The answer of What have the cloning experiments in plants...

Question 14

Briefly describe when and how Dolly the sheep was cloned.

Accepted Answer

The answer of Briefly describe when and how Dolly the...

Question 15

What are Hox genes?

Accepted Answer

The answer of What are Hox genes?...

Question 16

Which of the following pairing of genes and developmental processes is INCORRECT?
A) bicoid and nanos-anterior posterior axis
B) antennapedia complex-head and anterior thoracic segment
C) cactus and toll-dorsal development
D) hunchback-ventral development
E) bithorax complex-posterior thoracic and abdominal segment

Accepted Answer

Hunchback is involved in anterior-posterior axis development, not ventral development.

Question 17

Which of the following is the CORRECT order of gene groups expressed in normal Drosophila development? 1. Gap genes
2) Homeotic genes
3) Pair-rule genes
4) Segment-polarity genes
5) Egg-polarity genes
A) 1, 2, 3, 4, 5
B) 4, 2, 5, 1, 3
C) 3, 1, 2, 5, 4
D) 5, 2, 4, 3, 1
E) 5, 1, 3, 4, 2

Accepted Answer

The correct order is egg-polarity genes, gap genes, pair-rule genes, segment-polarity genes, and then homeotic genes.

Question 18

The Bicoid protein in fruit flies specifies anterior development. In the absence of Bicoid protein in an egg, the embryo will develop two tails. The bcd^- mutation is recessive and exhibits a maternal effect. Which of the following CORRECTLY describes the embryos produced from a cross between a bcd⁺/ bcd^- male and a bcd^-/bcd^- female? A) All embryos will be normal. B) All embryos will have two tails. C) Three-fourths of the embryos will have two tails. D) One-half of the embryos will have two tails. E) One-fourth of the embryos will have two tails.

Accepted Answer

The bcd^- mutation exhibits a maternal effect, meaning the phenotype of the offspring is determined by the genotype of the mother. Since the mother is bcd^-/bcd^-, she cannot provide Bicoid protein, resulting in all embryos developing with two tails, regardless of their genotype.

Question 19

The product of the bicoid gene is critical for the establishment of _____ structures in the Drosophila embryo.
A) anterior
B) posterior
C) dorsal
D) ventral
E) segment

Accepted Answer

The bicoid gene product is a morphogen that is essential for the development of anterior structures in the Drosophila embryo. It establishes a gradient that helps determine the anterior-posterior axis.

Question 20

Which of the following genes determines the identity of individual segments during development?
A) bicoid
B) nanos
C) cactus
D) disheveled
E) dorsal

Accepted Answer

The answer of Which of the following genes determines the...

Quiz 22: Developmental Genetics and Immunogenetics

Epigenetic changes in development are important in that the gene expression of cells that make up a particular organ or tissue type is often defined by epigenetic markers. Which of the following epigenetic regulations is known to cause more long-term gene silencing during the course of development?

Which of the following groups of genes is directly regulated by egg-polarity genes?

The proteins Dorsal and Bicoid both act as morphogens in Drosophila embryogenesis. However, the establishment of the concentration gradients of each protein differs. Which of the following statements CORRECTLY describes this difference?

Which of the following statements about homeotic genes is INCORRECT?

Which specific group of genes specifies the identities of individual body segments?

When animals like Dolly the sheep are cloned using techniques that transfer a nucleus from a donor animal into the egg of a recipient animal, is the resultant clone genetically identical to the nuclear donor animal?

Which of the following statements about Hox genes is INCORRECT?

List the five major classes of developmental genes in Drosophila in the order (earliest to latest) that they regulate development.

Which of the following choices lists the CORRECT sequence of gene expression during Drosophila development? 1. Segmentation genes 2) Egg-polarity genes 3) Homeotic genes

What have the cloning experiments in plants and animals confirmed with regard to developmental processes?

Briefly describe when and how Dolly the sheep was cloned.

What are Hox genes?

Which of the following pairing of genes and developmental processes is INCORRECT?

Which of the following is the CORRECT order of gene groups expressed in normal Drosophila development? 1. Gap genes 2) Homeotic genes 3) Pair-rule genes 4) Segment-polarity genes 5) Egg-polarity genes

The product of the bicoid gene is critical for the establishment of _____ structures in the Drosophila embryo.

Which of the following genes determines the identity of individual segments during development?