Genes and Body Plans (5.1.1)

HideShow resource information
What are homeobox genes?
Genes that determine how an organism's body develops as it grows from a zygote into a complete organism. These genes determine the body plan, including the polarity and the positioning of organisms.
1 of 10
Why are homeobox genes highly conserved?
A mutation in a homeobox gene would not be beneficial, but would be disastrous and the organism would not be likely to survive.
2 of 10
What is the body plan of a Drosophila fly?
Head- 3 segments. Thorax- 3 segments. Abdomen- 8 segments.
3 of 10
Give an example of a homeobox mutation in a Drosophila fly?
It has a homeobox gene called Ubx which stops the formation of wings in one of the thorax segments. If the fly has a mutation in both copies of Ubx, then wings grow in the thorax segment instead of halteres.
4 of 10
What do the homeobox genes consist of?
Each gene consists of 180 base pairs, which result in a polypeptide which is 60 amino acids long.
5 of 10
How are homeobox genes arranged?
They are arranged in clusters called Hox clusters. The more evolved an organism, the more clusters it will have in order to control the development of a more complex body plan.
6 of 10
When are homeobox genes activated?
Different homeobox genes are activated and expressed at different stages of embryo development.
7 of 10
What is retinoic acid?
It's a derivative of vitamin A, which activates the homeobox genes necessary for the development of the skeleton and CNS. It is known as a morphogen.
8 of 10
What is a morphogen?
A substance that controls the pattern of tissue development.
9 of 10
What happens if too much retinoic acid is taken in?
If too much is taken in by a woman in the first month of pregnancy, it can interfere with the expression of the homeobox genes, leading to birth defects such as brain deformities.
10 of 10

Other cards in this set

Card 2

Front

Why are homeobox genes highly conserved?

Back

A mutation in a homeobox gene would not be beneficial, but would be disastrous and the organism would not be likely to survive.

Card 3

Front

What is the body plan of a Drosophila fly?

Back

Preview of the front of card 3

Card 4

Front

Give an example of a homeobox mutation in a Drosophila fly?

Back

Preview of the front of card 4

Card 5

Front

What do the homeobox genes consist of?

Back

Preview of the front of card 5
View more cards

Comments

No comments have yet been made

Similar Biology resources:

See all Biology resources »See all DNA, genetics and evolution resources »