9/16 Developmental Biology - Commitment and Specification

These flashcards cover key concepts from Chapter 1 and parts of Chapter 2-7 of the lecture notes on developmental commitment and specification, including definitions, mechanisms, and historical experiments.

Commitment can be divided into three steps: specification, determination, and __.

differentiation

The process on a cell basis where a cell becomes instructive during development to turn into a certain kind of cell is called __.

specification

Specification operates through autonomous, conditional, and, in some embryos, __ mechanisms.

sensational

Once a cell's fate is set, it reaches the state called __.

determination

To truly understand specification or determination, one must __ the cells, not just watch them.

experimentally challenge

If we remove a red cell from an embryo, grow it in isolation, and it turns into a muscle cell, we can say it is __ to make a muscle cell.

specified

To make assumptions about cell fate and conduct experiments, we need a __ to understand what cells normally turn into.

fate map

The process of specification is __, meaning it is not fixed and can be challenged experimentally.

labile

When a cell adapts to its environment, for example, by responding to signals from neighboring cells, it demonstrates __ specification.

conditional

Historically, the step of determination was thought to be __.

irreversible

Auguste Weissman hypothesized that different __ segregated into daughter cells making them different from one another, a concept known as mosaic development.

chromosomes

Oscar Hertwig proposed that __ among cells must also be important for development.

interactions

In almost all embryos, both autonomous (mosaic) and __ (interactions or signaling) processes are happening.

conditional

Wilhelm Ruh's experiment of killing one cell of a 2-cell amphibian embryo resulted in __.

half an embryo

When a 2-cell amphibian embryo is separated, rather than one cell being killed, the result is __.

twins

A __ describes the pattern of cell divisions and how cytoplasm is divided into different cells in an embryo.

cell lineage

A __ is a summation of all the different cell lineages, summarizing what all cells will become, often overlaid on an early embryo.

fate map

The animal pole typically contains the male and female pronuclei, while the __ pole tends to have more yolk.

vegetal

In autonomous specification, early cell types can be specified by __ determinants such as proteins or RNAs encoding regulatory molecules.

internal

Transcription factors and __ molecules are the meat of the molecular mechanisms for early development.

signaling

We use __ to determine where specific genes are being expressed within an embryo.

in situ hybridization

mRNA detection tells us if a gene is being __, but not necessarily if it's being translated into a protein.

transcribed

In ascidian embryos, the MACHO1 mRNA acts as a __ determinant, a transcription factor that specifies muscle cell fate.

maternal

Hilde Mangold's experiments showed that most transplanted amphibian cells adopt the fate of their new location, indicating __ specification.

conditional

The Spemann-Mangold organizer region, when transplanted, is able to __ a complete second embryonic axis.

organize

A __ is a single cell membrane enclosing multiple nuclei that share a common cytoplasm.

syncytium

In Drosophila, maternal determinants like caudal and bicoid form __ that influence nuclear fates during syncytial specification, before cellularization occurs.

gradients