6.1 Body Plans & apoptosis Flashcards
What is morphogenesis?
Regulation of the pattern of anatomical development
What controls development of all organisms?
The same group of genes
The genes were discovered by scientists investigating what?
Fruit flies with strange mutations e.g. Legs in the place of antennae
Why are fruit flies easy to study?
Small
Short life cycle
Easy to keep
(Homeobox genes) what is a homeobox?
Section of DNA 180bp coding for part of a protein of 60 amino acids
(Homeobox genes) what is the part of the protein called and what is it similar in?
Homeodomain
Similar in plants animals and fungi
(Homeobox genes) why are homeobox genes regulatory genes?
Responsible for switching genes on and off
(Homeobox genes) how have the homeobox genes been linked to humans and mice?
Common ancestor
Mutations led to very different organisms
Many homeobox genes present in both have same nucleotide sequence
(Homeobox genes) what happens when the pax6 homeobox gene is mutated?
It causes a form of blindness in humans, mice and fruit flies
(Hox genes) what are hox genes?
Group of homeobox genes only present in animals
(Hox genes) what are hox genes responsible for?
Ensuring correct positioning of body parts
(Hox genes) mammals have how many clusters of hox genes?
4 on different chromosomes
(Hox genes) in what order are hox genes expressed?
In the order they appear on chromosomes
(Hox genes)how many hox genes do humans have?
39
(Body plans) how are body plans represented ?
Cross sections through the organisms showing arrangement of body tissue
(Body plans) what do diploblastic animals have?
2 primary tissue layers
(Body plans) what do triploblastic animals have?
3 primary tissue layers
(Body plans) what is a body plan?
Cross section through an animal showing arrangement of tissue layers
(Body plans) what is radial symmetry?
Animals having symmetry around a central axis (diploblastic)
(Body plans) what is bilateral symmetry?
Body can be divided into 2 mirror image halves