Biological Sciences - Animal Development

What is a zygote?

A zygote is the initial cell formed when a sperm cell fertilizes an egg cell, marking the beginning of a new organism's development.

How are zygotes produced?

Zygotes are produced through the process of fertilization, where a sperm cell successfully penetrates and fertilizes an egg cell.

What is cellular differentiation?

Cellular differentiation is the process by which a less specialized cell becomes a more specialized cell type, allowing for the development of distinct cell functions and structures in an organism.

What is a triloblast?

A type of organism that has three primary germ layers: ectoderm, mesoderm, and endoderm, contributing to the development of various tissues and organs.

What is metamorphosis?

Metamorphosis is a biological process by which an organism undergoes a profound change in form and structure, typically involving distinct life stages such as larva, pupa, and adult.

What are the five stages a trophoblast must go through to become a multicellular organism?

The five stages are fertilization, cleavage, gastrulation, neurulation, and organogenesis

When does metamorphosis occur?

Metamorphosis occurs after organogenesis, marking the transition from larval to adult form.

What is the acrosomal reaction?

The acrosomal reaction is a process during fertilization where the sperm's acrosome releases hydrolytic enzymes that help penetrate the egg's protective layers, facilitating sperm-egg fusion.

What are cortical granules?

Cortical granules are specialized secretory vesicles found in the egg that release enzymes during fertilization to prevent polyspermy and assist in forming the fertilization envelope.

What does it mean when an egg depolarizes?

When an egg depolarizes, it refers to the change in the electrical charge across the egg membrane, which is crucial for initiating the block to polyspermy and activating the egg for development.

What is a blockage when referring to fertilization?

A mechanism that prevents multiple sperm from fertilizing the same egg, ensuring that only one sperm can successfully penetrate and fuse with the egg.

What is polyspermy?

The fertilization of an egg by multiple sperm, which can lead to abnormal development and is typically prevented by mechanisms such as cortical granule release.

What happens after a sperm binds to an egg?

After a sperm binds to an egg, the egg undergoes depolarization, initiating the block to polyspermy and activating the egg's developmental processes.

What does the release of Ca2+ cause?

The release of Ca2+ causes a series of intracellular changes that lead to egg activation, including cortical granule exocytosis and the establishment of the fertilization envelope.

What is a gamete?

A reproductive cell that fuses with another gamete during fertilization to form a zygote, typically sperm in males and eggs in females.

What is cell proliferation?

The process by which cells divide and reproduce, leading to an increase in cell numbers, crucial for growth and development.

What is cell specialization?

The process by which generic cells develop into distinct cell types with specific functions, essential for the formation of tissues and organs.

What is cell interaction?

The communication and signaling between cells that influences their behavior, growth, and function, playing a vital role in tissue development and homeostasis.

What is cell movement?

The process by which cells migrate and change position, playing a vital role in tissue formation, wound healing, and development.

What is the name for the three germ layers?

Ectoderm, mesoderm, and endoderm.

What is the key aspect of nerulatiopn?

The formation of the neural tube from the ectoderm, which ultimately develops into the central nervous system.

What is the importance of organogenesis?

Results in tissues becoming organized functional organs composed of differentiated cells.

What is the cortical reaction in fertilization?

The cortical reaction is a process that occurs after sperm penetration, leading to the release of cortical granules from the egg, which prevents polyspermy and initiates changes in the egg's membrane.

What does the acrosome do? after the sperm has made contact with the egg?

The acrosome releases hydrolytic enzymes that dissolve the jelly coat.

After the acrosome dissolves the jelly coat, what happens?

The sperm binds to the egg's plasma membrane, allowing for fusion and entry into the egg. This process facilitates fertilization by enabling the sperm to penetrate the egg.

after the sperm binds to the eggs plasma membrane, what happens?

The sperm and egg plasma membranes fuse allowing the sperm to enter the nucleus of the egg, leading to the formation of a zygote.

What does the egg do in response to the fusion of the sperm and egg plasma membranes?

Depolarization of the egg, which blocks other sperm from entering and triggers cortical granule release. This process prevents polyspermy and is a fast block to it.

Depolarization is considered…

A fast block to polyspermy and a change in membrane potential.

Calcium ions are released from the ER to trigger what reaction?

Cortical reactions, which lead to a wave of calcium ions that sweep across the egg.

The release of calcium ions does three things…

It triggers cortical granule exocytosis, activates egg metabolism, and initiates embryonic development.

What is the vitelline layer responsible for?

The vitelline layer is responsible for providing structural support to the egg and facilitating sperm binding during fertilization.

How does the vitelline layer harden?

It hardens through the cortical reaction, which involves the release of enzymes that modify its structure, creating a protective barrier.

What do cortical granules do?

Cortical granules release enzymes that modify the vitelline layer, preventing additional sperm from fertilizing the egg and forming a protective barrier. Considered the slow block to polyspermy.

When the nucleus of the sperm fuses with the egg, what is produced?

A diploid zygote is produced.

What is cleavage?

Cleavage is the series of rapid cell divisions that occur after fertilization, leading to the formation of a multicellular embryo with no significant growth.

What does cleavage lack?

G1 and G2 phases of the cell cycle, resulting in a rapid increase in cell number without growth.

What type of growth does cleavage consist of?

S phase and M phaseof the cell cycle, allowing for rapid cell division without increasing the overall size of the embryo.

What is a blastula?

A hollow ball of cells formed during early embryonic development, following cleavage.

What is a blastoderm?

A layer of cells that forms during the early stages of embryonic development, lying above the yolk in a developing embryo.

What is a blastocyst?

A structure formed in the early development of mammals, consisting of an inner cell mass and an outer trophoblast layer, which eventually implants into the uterine wall.

Are the cells in each division of the cleavage stage becoming smaller or bigger?

The cells in each division of the cleavage stage become smaller, as they divide without significant growth in overall size.

What is yolk?

A nutrient-rich substance found in the egg of many animals, providing essential materials for the developing embryo.

What is a vegetal pole?

The region of an egg that is rich in yolk and typically opposite the animal pole, influencing early embryonic development.

What is the animal pole?

The region of an egg that is relatively low in yolk and typically opposite the vegetal pole, where the embryo's development is initiated.

What is meroblastic cleavage?

A type of cleavage in which only a portion of the egg is divided into smaller cells, typically seen in eggs with a large amount of yolk. Incomplete type of cell cleavage, occurring in birds and some fishes.

What is holoblastic cleavage?

A type of cleavage in which the entire egg is divided into smaller cells, typically seen in eggs with moderate to low yolk content, resulting in complete cell division. Occurs in amphibians and mammals. A complete type of cleavage.