Week 11 - Development Flashcards
(19 cards)
Zygote
A fertilized egg cell formed when a sperm and egg fuse. It is the first cell of a new organism and is totipotent (can develop into any cell type, including extra-embryonic tissues).
Gametes
The reproductive cells (sperm in males, eggs in females) that carry half the genetic material (haploid) and combine during fertilization to form a zygote.
Inner Cell Mass (ICM)
A group of cells inside the early-stage embryo (blastocyst) that will develop into the embryo proper (the body of the organism). The cells here are pluripotent.
Embryo
The developing organism from the time of fertilization until significant structures have formed. In humans, it’s called an embryo from fertilization to about 8 weeks.
Extra-Embryonic Tissues
Tissues that support the embryo but do not form part of the organism itself. Examples: placenta, amniotic sac.
Totipotent
Describes cells (like the zygote) that can differentiate into any cell type, including both embryonic and extra-embryonic tissues.
Pluripotent
Cells (like those in the inner cell mass) that can give rise to any cell type in the body, but not extra-embryonic tissues.
Multipotent
Cells that can differentiate into multiple related cell types within a certain tissue or organ system (e.g., blood stem cells forming different types of blood cells).
Waddington’s Landscape
A metaphor for cell differentiation. Imagine a ball rolling down a hill with valleys representing different cell fates. As the ball rolls, it gets channeled into different valleys (cell types), showing how developmental decisions become increasingly restricted.
Embryonic Stem Cells (ESCs)
Pluripotent stem cells derived from the inner cell mass of the blastocyst. They can become any cell type in the body.
iPS Cells (Induced Pluripotent Stem Cells)
Adult somatic cells that have been reprogrammed back into a pluripotent state (similar to ESCs) using specific transcription factors. This allows for stem cell research without embryos.
Clone (Dolly, Copy Cat)
An organism genetically identical to another. Dolly the sheep was the first mammal cloned from an adult somatic cell using somatic cell nuclear transfer (SCNT). Copy Cat was the first cloned pet (a cat!).
Regulatory Transcription in Development
The process where transcription factors control when and where genes are expressed during development, shaping the organism’s structure and function.
Transcription Factor Hierarchy
A system where master transcription factors activate downstream transcription factors, creating a cascade of gene regulation. This hierarchy ensures proper timing and order of gene expression.
Master Transcription Factor
A key regulator that can control entire gene networks, often responsible for specifying major cell fates. Example: MyoD for muscle development.
Combinatorial Activity of Transcription Factors
The idea that multiple transcription factors work together to regulate a gene, allowing for complex control of gene expression depending on the combination present.
Signaling in Development
The use of chemical signals (like growth factors, hormones) between cells to coordinate development. Signals tell cells where to go, when to divide, and what to become.
EGF and Vulva Development (in C. elegans)
In the nematode worm C. elegans, Epidermal Growth Factor (EGF) signaling guides the formation of the vulva by activating specific genes in target cells, a model for how cell signaling shapes organ development.
The Role of the Environment in Plant Development
Plants are highly responsive to environmental cues like light, gravity, and water. These factors influence growth direction (tropisms), flowering time, and developmental pathways.
