Web of Bio on the Web

The biological concept is that DNA is made up of nucleic acid. But we all know the iconic scene when Frankenstein comes to life through a surge of electricity, so there is humor there in the battery vs. nucleic acid reference.

The platypus (Ornithorhynchus anatinus) is native to Australia and has often been viewed as an odd conglomeration of reptilian and mammalian elements. The platypus is semi-aquatic, possesses venomous spurs as well as a duck bill, is a mammal, lays eggs, and nurses its young. As baffling as the animal is, a draft sequence of the platypus genome has provided more evidence as to where it belongs in animal evolution.

Although they lack nipples, the platypus produces real milk that is full of proteins, fats, and sugars. The young then suck the milk through a glandular patch on the mother’s skin. This points out that the genetic innovations that led to the development of milk occurred more than 166 million years ago, and after mammals first split from the lizard-like sauropsids. Sauropids gave rise to modern reptiles and birds.

With concern to eggs, the embryos develop for 21 days inside the uterus before expulsion. The eggs are small, about the size of a thumbnail, and leathery. After incubating for 11 days the eggs hatch and, like marsupials, the organs of the hatchlings finish developing while nursing. The platypus shares a gene for its egg-yolk type with the chicken, though the chicken possesses 3 of the gene. It also shares 2 ZPAX gene matches with amphibians and fish, as well as 4 genes found in mammals for zona pellucida which facilitates egg fertilization.

There is a set 10 chromosomes that determine sex in the platypus. This peculiarity sets it apart from all other mammals as well as from birds. During meiosis, the chromosomes link to form a chain, ensuring that every sperm gets a set of all X or all Y chromosomes.

Source: http://www.nature.com/news/2008/080507/full/453138a.html

click picture to go to source

It’s often been said that the tendency for baldness, a hereditary condition known as androgenic alopecia, comes from the mother’s side of the family. But in reality male pattern baldness is caused by a genetic predisposition inherited from either parent. This is because the genes controlling the trait do not reside on the sex chromosomes, but rather on the autosomes. Although baldness can sometimes be seen in women, the amount of testosterone is the deciding influence and men typically have more. In baldness, the enzyme 5-alpha reductase convert the androgen testosterone into dihydrotestosterone, or DHT. It then slows down hair production by acting on a hormone receptor. In some cases the hair growth will stop completely. Given that adults lose about 10,000 scalp hairs a day, if the scalp cannot replenish then it remains bald. The degree, pattern, speed, and time of onset of balding are all influenced by genetics

http://menshealth.about.com/cs/hairhairloss/a/baldness.htm

http://www.askmen.com/sports/health/21b_mens_health.html

http://www.medem.com/MedLB/article_detaillb.cfm?article_ID=ZZZ6Q72SWAC&sub_cat=300

The most important metabolic pathway: photosynthesis

One of my many houseplants, this plant is able to feed itself via the sun. Its specialized pigment molecules harnesses the solar energy and then converts it into chemical energy to build glucose from carbon dioxide molecules. Oxygen gas is then released. Such organisms underlie every ecosystem on Earth.

source: Biology: Concepts and Investigtions by Marielle Hoefnagels

This is my new blog created for Biology class, fall 2008