Mesoderm

Inner cell mass

Ectoderm

Endoderm

Meroblastic, telolecithal

Meroblastic, mesolecithal

Hobolastic, centrolecithal

Holoblastic, isolecithal

Cells do not undergo apoptosis.

It is not useful for studies on aging, due to its short life cycle.

It cannot be used for behavioural studies.

All cell lineages have been mapped.

Segments of DNA can move around within the genome.

Messenger mRNA expression is regulated at the level of translation.

The same gene can code for several different proteins.

Several different genes can code for the same protein.

must to be within a few hundred base pairs of the gene they enhance.

will not function if they are moved experimentally.

must to be within a few base pairs of the gene they enhance.

can be tens of thousands of base pairs from the gene they enhance.

Introns encode proteins and are retained in mRNA, whereas exons are removed from mRNA.

Exons and introns are typically translated into protein.

Only exons are present in genes (DNA), while both introns and exons are present in the mRNA produced from the gene.

Exons are the protein-coding component, while introns are spliced out of RNA as it is processed into mRNA.

zygote-morula-gastrula-blastula

zygote-blastula-morula-gastrula

zygote-morula-blastula-gastrula

zygote-blastula-gastrula-morula

The size of the fertilised egg

Whether the species lays eggs or has live birth

The number of cleavage divisions that precede gastrulation

The density and distribution of yolk

Label the cells with GFP and follow them in an early chicken embryo

Knock out an essential gene required for lower jaw formation in the mouse

Add the cells to the head region of a developing C. elegans

Carry out an EMS mutagenesis screen in Drosophila