3. body plans Flashcards
What is morphogenesis?
the regulation of the pattern of anatomical development
its the same small group of genes that control the growth and development of vastly different living forms
How was morphogenesis discovered?
mutations observed in fruit flies- EG. extra pair of wings
these flies feed and reproduce on rotting fruit, they are easy to keep and have a short life cycle so are popular for genetic studies
What are homeobox genes and how do they work?
they are regulatory genes
group of genes which all contain a homeobox
a homeobox is a section of DNA 180 base pairs long, coding for a part of a protein 60 amino acids long, similar in animals, plants and fungi. This part of the protein (a homeodomain) binds to DNA, switching other genes on and off
Mice and humans still share some of these genes, even though their common ancestor was about 60 million years ago
Pax 6 is one of the homeobox genes, what can it cause when mutated?
form of blindness, due to underdevelopment of the retinas, affecting humans, fruit flies and mice
suggesting that its involved in the development of eyes in all 3 species
What are hox genes and how do they work?
group of homeobox genes that are only present in animals, involved in the correct positioning of body parts, and are found in clusters on chromosomes.
their order on the chromosome is the order in which their effects are expressed in the organism- humans have 39 in total
What are body plans?
cross-section through the organism, showing the arrangement of tissue layers
when and how do individual ve3rtibrae and associated structures develop?
from segments in the embryo called somits, directed by hox genes to develop in a particular way depending on their position in the sequence
State the 3 types of symmetry in animals and provide examples
radial- jellyfish have no right or left side, only top and bottom
bilateral- most animals have left and right side as well as head and tail, instead of just a top and bottom
asymmetry- sponges have no lines of symmetry
Which 2 processes are essential in shaping organisms?
mitosis- in cell division or proliferation
apoptosis- programmed cell death
what’s the role of mitosis in shaping organisms?
increase the number of cells- leading to growth
What’s the role of apoptosis in shaping organisms?
by removing unwanted cells and tissues
cells undergoing apoptosis can release chemical signals , stimulating mitosis and cell proliferation- leading to the remodelling of tissues
which factors effect the expression of regulatory genes?
stress is a condition where the homeostatic balance within an organism is upset,
external factors- light intensity or temperature
internal- change in hormone release or psychological stress
Drugs- thalidomide given to pregnant women in the 1950’s and 60’s, to treat morning sickness, late found prevented the normal expression of the particular hox gene, resulting in the birth of babies with shortened limbs.
this drug currently exploited as cancer treatment, thought to stop growth of capillary networks, needed for tumours to grow.
these have greater impact, during the growth and development of an organism.
What’s ontology?
the development of an organism
