What is the term used to describe the process of maturation that a cell goes through from an undifferentiated state to a postmitotic differentiated cell type?

Commitment

When is a cell considered specified toward a given fate?

When it maintains its developmental maturation toward that cell type even in isolation.

What is the term used to describe a cell that is committed or determined to a given fate?

Committed cell

How many modes of cell specification are there?

Three

What is autonomous specification?

Cells that possess cytoplasmic determinants and mature into their determined cell types even when isolated.

Who first observed the yellow crescent in the tunicate embryo and showed that cells with this yellow crescent give rise to muscle?

Conklin

What is conditional specification?

The acquisition of a given cell identity based on its position or interactions with other cells and molecules.

Do most species have cells that develop via autonomous specification or conditional specification?

Both autonomous specification and conditional specification.

What is syncytial specification?

The process of specifying cell fate in a syncytium of nuclei.

What maintains the positioning of nuclei in a syncytium, enabling specification of these nuclei by opposing morphogen gradients?

Cytoskeletal arrangements

What genetic technique allows scientists to follow the developmental history of individual cells?

Brainbow

What is responsible for the sorting out of one cell type from another?

Inductive interactions

Which membrane structures are often involved in cell sorting out?

Cadherin proteins

How can cadherins cause cells to sort out?

By changing the surface tension properties of the cells

What determines the specific response to an inducer in inductive interactions?

The competence of the responding cells

What type of interactions occur when a cell or tissue secretes proteins that induce changes in neighboring cells?

Paracrine interactions

What are paracrine factors and how do they affect competent responding cells?

Secreted proteins that bind to cell membrane receptors and activate signal transduction pathways

What are morphogens and how do they affect gene expression?

Secreted signaling molecules that affect gene expression differently at different concentrations

How do signal transduction pathways begin?

With a conformational change in the cell membrane receptor caused by a paracrine or juxtacrine factor

How can the differentiated state of cells be maintained?

Through positive feedback loops involving transcription factors, autocrine factors, or paracrine factors

What is the role of the extracellular matrix in cell differentiation and migration?

It serves as a source of signals and modifies how signals are secreted across cells

11. What is the epithelial-mesenchymal transition (EMT) and when does it occur?

A series of transformations involved in wound healing and cancer metastasis

How is the cell surface involved in cell signaling?

All of the choices are correct

What are juxtacrine signaling interactions?

Local protein interactions between receptors on adjacent cells or between a cell membrane and an extracellular matrix

Which signaling pathway influences organ size?

Hippo signaling

In mammals, primary sex determination is a function of:

The sex chromosomes

Which combination of sex chromosomes is typically associated with females in mammals?

What role does the mammalian Y chromosome play in male sex determination?

It plays a key role in the development of the male gonads

In XY animals, which cells differentiate and enclose the germ cells within testis cords?

Sertoli cells

In XX mammals, the germ cells become surrounded by:

Granulosa cells

In humans, the SRY gene encodes:

The testis-determining factor

7. What is the function of the SOX9 gene in testis formation?

It initiates testis formation

Which proteins have a positive feedback loop that activates testicular development and suppresses ovarian development?

Fgf9 and Sox9 proteins

What proteins are involved in mammalian ovary formation?

Wnt4 and Rspo1 proteins

What transcription factor is required for ovary formation in mammals?

Foxl2

What happens to the Müllerian duct in male mammals?

It is destroyed by anti-Müllerian hormone (AMH) produced by the Sertoli cells

What enables the differentiation of the penis, scrotum, and prostate gland in mammals?

Conversion of testosterone to dihydrotestosterone

In Drosophila, sex is determined by:

The number of X chromosomes in the cell

What role does the Drosophila Sex-lethal gene play in sex determination?

It activates the expression of the transformer gene in females

What is the function of the Sxl protein in Drosophila sex determination?

It splices an inhibitory exon from the transformer (tra) transcript

The Tra protein acts as an RNA splicing factor to splice exons from the doublesex (dsx) transcript. The dsx gene is transcribed in both XX and XY cells, but its pre-mRNA is processed to form different mRNAs, depending on whether the Tra protein is present. What is the role of the proteins translated from both dsx messages?

They activate or inhibit transcription of sexually dimorphic genes.

In Drosophila, Tra proteins also activate the fruitless gene in males (but not in females). What is the role of the fruitless gene?

It activates brain sexual differentiation.

In turtles and alligators, sex is often determined by the temperature experienced by the embryo during the time of gonad determination. What enzyme is involved in distinguishing male from female patterns of gonadal differentiation?

Aromatase

In most species, the precursors of the gametes are the primordial germ cells (PGCs). Where do the PGCs form in most species?

Outside the gonads

The cytoplasm of the PGCs in many species contains inhibitors of transcription and translation, making them translationally and transcriptionally silent. What is the purpose of this inhibition?

To prevent the activation of sexually dimorphic genes

In most organisms studied, the coordination of germline sex (sperm/egg) is coordinated to somatic sex (male/female) by signals coming from the gonad. What is the role of these signals?

To coordinate the development of germline and somatic sex

In humans and mice, germ cells entering ovaries initiate meiosis while in the embryo, while germ cells entering testes do not initiate meiosis until puberty. What is the significance of this difference?

It determines the timing of meiosis initiation in germ cells

What is the purpose of the first division of meiosis?

To separate the homologous chromosomes

What is the purpose of the second division of meiosis?

To separate the chromatids

Which type of meiosis is characterized by the production of four gametes per meiosis and the absence of meiotic arrest?

Spermatogenic meiosis in male mammals

Which type of meiosis is characterized by the production of one gamete per meiosis and a prolonged first meiotic prophase?

Oogenic meiosis in female mammals

In male mammals, what do the primordial germ cells (PGCs) generate?

Stem cells that last for the life of the organism

In female mammals, what do the germ cells do during the first meiotic prophase (dictyate stage)?

Synthesize mRNAs and proteins

In some species, what is modified in meiosis to form a diploid egg?

The first division of meiosis

What is the purpose of the prolonged first meiotic prophase in female mammals?

To allow the egg to grow

In which stage of meiosis are germ cells retained until ovulation in female mammals?

First meiotic prophase

What do germ cells in the dictyate stage synthesize in female mammals?

mRNAs and proteins

In which type of meiosis do PGCs become germ stem cells in the ovaries?

Spermatogenic meiosis in female mammals

What is the purpose of the signals coming from the gonad in coordinating germline and somatic sex in most organisms?

To coordinate the development of germline and somatic sex

What is the significance of the difference in meiosis initiation timing in germ cells in male and female mammals?

It determines the timing of meiosis initiation in germ cells

In which stage of meiosis are germ cells translationally and transcriptionally silent?

First meiotic prophase

What is the term used to describe the process of producing a new generation without fertilization?

Parthenogenesis

What are the two separate activities accomplished by fertilization?

Sex and reproduction

2. Which of the following is NOT an event of fertilization?

Activation of egg metabolism to start development

What is the function of the acrosome in the sperm head?

Contains enzymes needed to digest extracellular coats surrounding the egg

4. What is the female gamete called in an earlier stage of development?

Oocyte

What is the extracellular layer surrounding the egg cell membrane called in mammals?

Zona pellucida

Which of the following statements is true about the activation of the egg and sperm?

Both activations involve calcium ions and membrane fusions

What do eggs secrete to attract and activate sperm in many organisms?

Diffusible molecules

What are the chemotactic molecules secreted by the egg called?

Resact and speract

What initiates the acrosome reaction in sea urchin sperm?

Egg jelly compounds

How is fusion between sperm and egg likely mediated?

By protein molecules with hydrophobic groups

What is the process by which the sperm penetrates the egg called?

Acrosome reaction

What is the term for the early stage of development when the zygote undergoes rapid cell division?

Cleavage

What is the name of the solid ball of cells that forms during early embryonic development?

Morula

What is the process by which the blastocyst attaches to the uterine wall?

Implantation

What is the outer layer of cells in the blastocyst called?

Trophoblast

What is the term for the process by which cells become specialized and take on specific functions?

Differentiation

What is the name of the structure that forms from the inner cell mass during embryonic development?

Embryo

What is the term for the process by which the three germ layers form during embryonic development?

Gastrulation

What are the three germ layers that form during gastrulation?

Ectoderm, mesoderm, endoderm

What is the outermost germ layer that gives rise to the skin and nervous system?

Ectoderm

What is the middle germ layer that gives rise to muscles, bones, and blood vessels?

Mesoderm

What is the innermost germ layer that gives rise to the digestive system and respiratory system?

Endoderm

Polyspermy occurs when:

Two or more sperm fertilize an egg.

The fast block to polyspermy is mediated by the influx of:

Sodium ions

The slow block to polyspermy is mediated by the release of:

Calcium ions

100

The cortical granule reaction causes the:

Hardening of the vitelline envelope into the fertilization envelope.