19.3 Body plans Flashcards
Define morphogenesis.
The regulation of anatomical development
Define homeobox genes / Hox genes.
Genes responsible for development of body plans
What do all homeobox genes contain?
A homeobox
What is a homeobox?
Section of DNA 180 base pairs long
Define homeodomain.
A motif of 60 amino acids found in all homeobox proteins.
It’s the part of the protein that binds to DNA, allowing the protein to act as a transcriptional regulator.
So Hox genes are regulatory genes
What type of organism are Hox genes present in?
Animals
What are Hox genes responsible for?
Correct positioning of body parts
In what way are Hox genes organised in animals?
Found in gene clusters
How many Hox gene clusters are found in mammals?
4 on different chromosomes
What determines the effect of genes on an organism?
The order in which genes appear on the chromosome
How many Hox genes do humans have?
39
What are ‘diploblastic’ animals?
Animals with 2 primary tissue layers
What are ‘triploblastic’ animals?
Animals with 3 primary tissue layers
