Lecture 20 Review

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What is the significance of Hox genes in Drosophila development?

Hox genes consist of proteins that initiate cellular respiration.
Hox genes determine the segmentation along the A-P axis. (correct)
Hox genes only play a role in embryonic fertilization.
Hox genes are unique to Drosophila and not found in other organisms.

What is the approximate time from fertilization to sexual maturity in Drosophila?

3 days
14 days
1 day
9 days (correct)

Who were the laureates that won the Nobel Prize in Physiology in 1995 for their work on Drosophila?

Barbara McClintock and Sydney Brenner
Craig Venter and J. Craig Venter
James Watson and Francis Crick
Ed Lewis, Christine Nusslein-Volhard, and Eric Wieschaus (correct)

Which process is responsible for the initial segmentation of the Drosophila embryo?

Gastrulation (D) Signup and view all the answers

Which of the following best describes an aspect of segmentation in Drosophila?

Segment identity is influenced by genetic control mechanisms. (D) Signup and view all the answers

What is the primary role of egg-polarity genes during early embryonic development?

They organize the A-P axis of the early embryo. (A) Signup and view all the answers

Which types of genes are expressed in the syncytial blastoderm stage?

Gap genes and pair-rule genes (A) Signup and view all the answers

What do segment-polarity genes encode for in developing organisms?

Signaling molecules and transcription regulators (C) Signup and view all the answers

What is the main function of gap genes in the early embryo?

To determine the number, spacing, size, and polarity of segments. (B) Signup and view all the answers

How do segments maintain their identity throughout development?

By a combination of gap, pair-rule, and segment-polarity genes. (A) Signup and view all the answers

What is the primary function of egg-polarity genes in Drosophila embryos?

Organize the anterior-posterior axis in the early embryo (B) Signup and view all the answers

Which gene is crucial for the formation of anterior segments in a Drosophila embryo?

Bicoid (D) Signup and view all the answers

What occurs during the syncytial blastoderm stage in Drosophila embryogenesis?

Nuclear division occurs without cell division (A) Signup and view all the answers

Which type of genes is responsible for organizing the segments in Drosophila embryos?

Egg-polarity genes (C) Signup and view all the answers

What results from defects in maternal Bicoid mRNA localization?

Lack of anterior segments (A) Signup and view all the answers

Which of the following gene classes is regulated by Bicoid in Drosophila?

Gap genes (C) Signup and view all the answers

What is a key feature of Drosophila early embryonic development?

There are 13 synchronous nuclear divisions prior to cellularization (A) Signup and view all the answers

What role do Hox genes play in Drosophila development?

Assign identity to each segment (B) Signup and view all the answers

Which statement is true regarding the gradients formed by egg-polarity gene products?

Both Bicoid and Nanos create opposing gradients in the cytoplasm (B) Signup and view all the answers

What is observed in Drosophila mutants with polarity defects?

Missing anterior or posterior segments (D) Signup and view all the answers

What characterizes the early Drosophila embryo?

It is a syncytium without individual cell boundaries. (C) Signup and view all the answers

Which class of genes is primarily responsible for regulating anterior-posterior patterning in Drosophila?

Gap Genes (C) Signup and view all the answers

How do segment polarity genes maintain their expression?

By using feedback loops and interacting with other gene classes. (B) Signup and view all the answers

What is a major difference in embryo patterning between Drosophila and vertebrates?

Drosophila has a highly polarized egg structure. (A) Signup and view all the answers

Which gene class acts after gap genes during Drosophila segmentation?

Pair-rule Genes (C) Signup and view all the answers

Which of the following is NOT a mechanism involved in early Drosophila development?

Phenotype determination (A) Signup and view all the answers

Why is Drosophila regarded as an important model organism in developmental biology?

The genetic pathways and development processes are well understood. (C) Signup and view all the answers

What defines egg-polarity genes in Drosophila?

They set up the coordinates for the embryo's axes. (A) Signup and view all the answers

What is the primary role of gap genes in the expression of gene A?

They regulate the expression of gene A in specific stripes. (D) Signup and view all the answers

Which statement is true about pair-rule genes?

They encode transcription factors and are expressed in 7 segments. (A) Signup and view all the answers

What type of mutation might display a polarity defect in segments?

Segment polarity gene mutations. (D) Signup and view all the answers

Which of the following genes is expressed at the posterior portion of each segment?

Engrailed. (B) Signup and view all the answers

What maintains the expression of segment-polarity genes throughout development?

Mutually reinforcing signals between neighboring cells. (A) Signup and view all the answers

How do pair-rule genes regulate segment-polarity genes?

Via indirect regulatory mechanisms. (D) Signup and view all the answers

Which gene product normally represses gene A in stripe Y?

Gap gene Z. (B) Signup and view all the answers

What is the primary characteristic of mutations in pair-rule genes?

They disrupt expression in every segment. (C) Signup and view all the answers

Which of the following describes the expression patterns of segment polarity genes?

Expressed in 14 stripes. (D) Signup and view all the answers

What is the function of the Wingless and Hedgehog proteins?

They serve as paracrine signaling molecules. (D) Signup and view all the answers

What primary role do Hox genes play in development?

Providing identity to each body segment (A) Signup and view all the answers

Which of the following genes assists in organizing the anterior-posterior (A-P) axis in the early embryo?

Gap genes (B) Signup and view all the answers

How do Hox proteins function at the molecular level?

As transcription regulators that bind DNA (A) Signup and view all the answers

What mechanism is involved in maintaining Hox gene expression during development?

Epigenetic inheritance of histone modifications (D) Signup and view all the answers

Which of the following best exemplifies the conservation of Hox genes across species?

Similar expression patterns in both flies and mammals (B) Signup and view all the answers

What occurs if Hox 10 is ectopically expressed in the thoracic region?

It represses thoracic character (B) Signup and view all the answers

Who was awarded the Nobel Prize for the discovery of Hox genes?

Ed Lewis (A) Signup and view all the answers

Which type of genetic alteration is indicated by the term 'paralogs' in relation to Hox genes?

Gene duplication (B) Signup and view all the answers

What is the effect of Hox10 expression in the lumbar region of mice?

It confers and maintains segment identity (A) Signup and view all the answers

Which genes control segmentation along the A-P axis?

Gap genes (C) Signup and view all the answers

What type of inheritance allows Hox gene expression to be maintained?

Epigenetic inheritance (C) Signup and view all the answers

What is the primary function of segmentation genes in embryonic development?

To regulate body segment placement (A) Signup and view all the answers

Which Hox gene is specifically mentioned as being involved in limb development?

Hox 10 (D) Signup and view all the answers

What type of genes are responsible for controlling segmentation along the anterior-posterior axis?

Pair-rule genes (B) Signup and view all the answers

Which of the following is TRUE about segment-polarity genes?

They encode signaling molecules and transcription regulators. (A) Signup and view all the answers

What is the main role of the gap genes during early embryonic development?

To define the identity of each segment. (B) Signup and view all the answers

What do egg-polarity genes primarily function to organize in the Drosophila embryo?

The anterior-posterior axis (A) Signup and view all the answers

Which of the following best describes gap genes?

They regulate segmentation by defining the size and spacing of segments. (C) Signup and view all the answers

What is the significance of the segmentation patterns in Drosophila development?

They establish the basic body plan by organizing the embryo along the A-P axis. (D) Signup and view all the answers

Which of the following statements accurately describes a feature of Hox genes?

Hox genes have conserved functions across different species, including humans. (C) Signup and view all the answers

Which statement accurately reflects the organization of an early Drosophila embryo?

The early Drosophila embryo is structured as a syncytium. (A) Signup and view all the answers

How does the segmented pattern in Drosophila embryos initially form?

By the interaction of egg-polarity genes and maternal factors. (B) Signup and view all the answers

What is the key role of genetic and molecular biology tools in Drosophila research?

They enable the investigation of genetic control mechanisms governing development. (C) Signup and view all the answers

What is the primary function of Hox genes in Drosophila development?

They define the anterior-posterior axis and segment identity. (D) Signup and view all the answers

Which class of genes plays a role in establishing the boundaries of segments in Drosophila?

Segment polarity genes (C) Signup and view all the answers

What concept explains why each segment in Drosophila embryos knows its identity?

The establishment of precise molecular gradients and genetic regulation. (C) Signup and view all the answers

How do segment polarity genes maintain their expression throughout development?

They rely on feedback mechanisms from surrounding cells. (A) Signup and view all the answers

What is the role of gap genes in the development of Drosophila?

They define broad areas along the A-P axis. (C) Signup and view all the answers

Why is Drosophila considered an effective model organism for studying developmental processes?

It shares key developmental mechanisms with vertebrates. (B) Signup and view all the answers

What are the primary signals that define egg polarity in a Drosophila embryo?

Localized maternal mRNAs and their protein products. (A) Signup and view all the answers

What is the role of gap gene 'Z' in relation to gene A's expression in Drosophila?

It activates gene A in stripe X and represses it in stripe Y. (D) Signup and view all the answers

Which statement describes the expression patterns of pair-rule genes?

They are expressed in seven segments, alternating between odd and even. (B) Signup and view all the answers

What is the characteristic defect associated with segment polarity genes?

Polarity defects observed in every segment. (C) Signup and view all the answers

Which genes negatively regulate the expression of gene A?

Gap gene 'Z' in stripe Y. (A) Signup and view all the answers

What is the primary function of segment polarity genes?

To establish segment boundaries and polarity. (A) Signup and view all the answers

Which is a known characteristic feature of pair-rule genes?

Their mutations cause loss of entire segments. (A) Signup and view all the answers

What components are encoded by segment polarity genes?

Transcription factors and paracrine signaling molecules. (C) Signup and view all the answers

What is the effect of mutations in gap genes on Drosophila development?

Loss of specific segments depending on the gap gene affected. (C) Signup and view all the answers

Which pair of genes work through a signaling loop to maintain segment polarity?

Wingless and Hedgehog. (D) Signup and view all the answers

What is the general function of egg-polarity genes in Drosophila embryonic development?

To organize the anterior-posterior axis of the early embryo (C) Signup and view all the answers

Which type of genes are primarily responsible for establishing anterior-posterior patterning in Drosophila?

Egg-polarity genes (D) Signup and view all the answers

What is the outcome of a bicoid mutation in Drosophila?

Lack of anterior segments (C) Signup and view all the answers

What is the role of Hox genes during Drosophila segmentation?

To determine the identity of individual segments (A) Signup and view all the answers

What type of gradients do egg-polarity gene products create in the Drosophila embryo?

Opposing gradients (D) Signup and view all the answers

Which maternal molecule is critical for anterior patterning in Drosophila embryos?

Bicoid (A) Signup and view all the answers

During which stage do Drosophila embryos exhibit rapid nuclear divisions without cellular division?

Syncytial blastoderm stage (D) Signup and view all the answers

Which class of genes is responsible for creating the segments in Drosophila and their distinct features?

Hox genes (A) Signup and view all the answers

What is the primary function of pair-rule genes during Drosophila development?

To create alternating segments in the embryo (A) Signup and view all the answers

What does the presence of a gradient of Bicoid protein in the Drosophila embryo indicate?

Regulation of gap gene expression (C) Signup and view all the answers

What is the role of Hox genes in segment identity?

Hox genes provide identity to each segment. (C) Signup and view all the answers

Which process is essential for maintaining Hox gene expression throughout development?

Epigenetic inheritance of histone modifications. (C) Signup and view all the answers

Which type of proteins do Hox proteins primarily act as?

Transcription regulators that bind to DNA. (A) Signup and view all the answers

What outcome occurs from ectopic expression of Hox10 in the thoracic region of mice?

Repression of thoracic character. (C) Signup and view all the answers

Which genes are responsible for organizing the anterior-posterior axis of the early embryo?

Egg-polarity genes. (B) Signup and view all the answers

What significance do paralogs have in the context of Hox genes?

They are duplicated genes with potential functional redundancy. (D) Signup and view all the answers

What was a key finding regarding Hox gene expression in vertebrates and invertebrates?

Hox gene expression patterns are conserved across species. (C) Signup and view all the answers

Who is credited with the discovery of Hox genes and received a Nobel Prize for it?

Ed Lewis. (B) Signup and view all the answers

What do segment-polarity genes control in developing organisms?

Segmentation along the anterior-posterior axis. (D) Signup and view all the answers

What is a function of Hox genes in vertebrates aside from segment identity?

Influence limb development. (A) Signup and view all the answers

Which mechanism enables Hox gene expression to be maintained throughout organismal development?

Chromatin remodeling complex recruitment. (D) Signup and view all the answers

Which gene class acts as master regulators by controlling the expression of multiple downstream genes?

Hox genes. (D) Signup and view all the answers

What aspect of genetic diversity in Hox genes is indicated by the term 'gene duplication'?

Generation of paralogs with potentially redundant functions. (A) Signup and view all the answers

Embryonic Patterning

The process by which the body plan of an organism is established, including the development of segments along the anteroposterior (A-P) axis.

Fate Map

A map that shows the developmental fate of cells in an embryo, tracing their lineage and contributions to different tissues and organs.

Hox Genes

A set of genes that control the development of body segments in animals. They specify the identity of each segment along the A-P axis, influencing the formation of structures like wings, legs, or antennae.

Fruit Fly Development Stages

In fruit flies, the development of segments along the head-to-tail axis (A-P axis) starts with the egg and proceeds through a series of distinct stages - fertilization, gastrulation, segmentation and organogenesis.