Caity Rowe's Biology 111 Wikispace
Homework Post #1 ~ Anton van Leeuwenhoek

 Born in Delft, Holland in 1632 to family of tradesmen, no fortune and having no higher education, Anton van Leeuwenhoek was an unlikely scientist. It was his curiosity, open mind and diligence that made him the great scientist he was known as.

Leuwenhoek used homemade microscopes to observe microscopic organisms. In the mid 1660's, Anton van Leeuwenhoek learned to grind lenses and made simple microscopes. His microscopes were able to enhance organisms to 200 times their original size. The compound microscope however, was created nearly forty years before his birth. Therefore, Leeuwenhoek was falsely credited with the invention of the microscope, and should not have been.

Over the years, Leeuwenhoek used his microscope to study many things too small to be seen with the naked eye. Leeuwenhoek stated in his letter June 12, 1716 "... And therewithal, whenever I found out anything remarkable, I have thought it my duty to put down my discovery on paper, so that all ingenious people might be informed thereof". In order to inform others of his discoveries, he wrote detailed descriptions and hired an artist to draw the organisms he found. He then sent them to the Royal Society along with letters to document his discoveries.

Leeuwenhoek made many discoveries over the years. He discovered Spirogyra, Vorticella, microscopic foraminifera, blood cells, sperm cells, numerous microscopic animals and many more. He also studied bee stingers, plaque from teeth, animal and plant tissues, mineral crystals and fossils.

Anton van Leeuwenhoek was a very influential scientist who continued his observations until the last of his days. Leeuwenhoek passed away on August 30, 1723 and is famous to this day for his influence and scientific discoveries.


Ford, B. J. 1991. The Leeuwenhoek Legacy. Biopress, Bristol, and Farrand Press, London.

Homework Post #2 ~ Apoptosis


Apoptosis, also known as cell suicide, is when a cell is programmed to die as a reaction to certain stimuli. When a cell dies through apoptosis it does so in a controlled way. Apoptosis is sometimes referred to as cell suicide because the cell plays a role in its own death.

The apoptosis process begins with the cell beginning to shrink itself. The chromatin breaks down, which causes nuclear condensation and the cell take a “horse-shoe” like shape. The cell continues to shrink and in the final stages of apoptosis the cell appears to develop blisters.

Some of the most common stimuli that cause apoptosis include ionizing radiation, viral infection and cell stress.

Dash, P. (n.d.). Apoptosis. Retrieved March 2, 2011, from
Individual Post #1 ~ Trisomy 21

Also known as Down Syndrome, Trisomy 21 is a genetic condition when there is an extra copy of chromosome 21. Down Syndrome is the most common birth defect in humans, occuring in 1 of 800 births. People tipically inherit 23 chromosomes from both their mother and their father. People with Down Syndrome however, often receive one chromosome 21 from their father and two chromosome 21 from their mother. It is possible for them to receive only a portion of the third chromosome 21, but most often receive an entire extra chromosome 21.

The genetic condition affects both brain and body development. There are many different symptoms of trisomy 21 however, the affects it has on one’s appearance are easily recognized. Some of these physical traits include decreased muscle tone at birth, small mouth and ears, short fingers, slanted eyes, and extra skin on the nape of their neck. Some other affects it has on Downs children are poor judgement, short attention span, impulsive behaviour and delayed learning.

There are many other medical conditions that can be seen in children that live with Down Syndrome. Some of these medical conditions include eye problems, hearing problems, sleep apnea, hip problems and thyroid problems.

Unfortunately, there are no known cures for Down Syndrome and families must learn to adjust to their child’s needs. Although they suffer from both physical and mental limitations, they are fully capable of living an independent life and even having children of their own.


Down Syndrome. (2010). Retrieved March 3, 2011, from

Heyn, S. (n.d.). Down Syndrome. Retrieved March 3, 2011, from


Individual Post #2 ~ Giraffes


Being that my nickname is giraffe, I only found it fitting to post about them. The largest mammal on earth, the giraffe stands at eighteen feet tall and weighs roughly two thousand pounds. Giraffes have a maximum galloping speed of 37 mph. Giraffes are found south of the Sahara desert in Africa and live in scattered herds with other giraffes.
The herbivores diet consists of shoots and leaves of African shrubs and trees. Their 18 inch black tongue enables them to gather bunches of leaves into their mouth.
Giraffes have the ability to rest while standing, although the do rest folding their legs under themselves for short periods of time. They also sleep for small bursts of five minutes at a time, holding their necks vertical for this period.
A giraffe’s colour varies from a dark brown to a chestnut brown. The colour is dispersed in a pattern of blotches in various shapes and sizes.
Typically calm creatures, a giraffe’s strength should not be underestimated. They use their hooves as offensive weapons, usually to defend their calves. A giraffe’s kick has enough power to kill lions, their only naturel predator.
Females conceive for the first time at the age of five. They carry the calf in the womb for fifteen months, giving birth to a calf every twenty months on average. The typical female giraffe has about twelve babies over their life span.
Interesting facts.

  • Their elongated neck has seven vertebrae, the same amount as most mammals
  • The giraffe has an elastic blood vessel and valves in the venous system in their
neck to aid in regulating blood pressure when bent over
  • Young males partake in “necking” to determine dominance.
  • At birth the calf is six feet tall
  • They eat seventy-five pounds of food a day
  • They have the longest tail of any mammal ( eight feet long)
  • They have never been observed bathing
  • Their heart pumps sixteen gallons of blood a minute
  • They spend sixteen to twenty hours a day eating
  • They can live to be twenty-five years old
  • TheVy regurgitate food and chew it as cud
  • They stand while giving birth and the calf drops six feet to the ground.
  • They have no tear ducts
Video Of Giraffes Necking~

ContentGiraffe. Retrieved March 3, 2011, from Facts. Retrieved March 3, 2011, from Retrieved March 3, 2011, from and Video

Individual Post #3 ~ Twins Part 1Identical Twins

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Identical twins, the closest nature can get to human cloning, is often the description we use for twins that share a similar appearance. Identical twins however refer to how the twins are formed, not their appearance. Monozygotic twins (identical twins) are formed of a single zygote that was divided into two parts after conception. This causes the formation of two individual embryos that share the same DNA. There are no known reasons for the zygote split. It is also not hereditary.
At birth, the obstetrician may not be able to confirm whether or not the twins are identical. However, often the ultrasound technician has the ability to find whether or not the twins share a single placenta, which is the strongest indication of identical twins.
Identical twins interact in the womb, touching and even appearing to kiss.
Recent studies show that even though the twins came from the same fertilized egg and should share the same DNA, differences develop overtime. According to Shiva Singh, a molecular geneticist at the University of Western Ontario, “The genetic genome is dynamic, not static. What you got from your parents is not what you have in the end”. It is said that identical twins will have more differences at sixty than at three years old. More studies are being done to discover why one of the twins may suffer from a genetic disease, when the other does not.

Although identical twins grow into unique individuals, even those separated at birth have been reunited only to discover that they have similar personalities, interests, and carriers.

Content Fierro, Pamela. (n.d.). Identical twins. Retrieved from iype, mark. (2011, march 31). Identical twins not actually identical, shocking canadian research finds. Retrieved from Identical twins. (n.d.). Retrieved from Images And Videos

Individual Post #4 ~ Twins Part 2Fraternal Twins


Fraternal twins are much different from the identical twins I spoke of before. Unlike identical twins, two separate eggs are fertilized by two separate sperm. Fraternal twins have no more in common than siblings born at different times. They have 50% of the same DNA like any other siblings. They can be the same sex or opposite sex. They can have the same blood type but may not. They can have similarities in appearance just as any other siblings. However, some sets of fraternal twins are nearly identical, the olsen twins for example.There are two ways for this to occur, either through superfecundation or superfetation. Superfecundation is hyper ovulation, when two eggs are released and two sperm fertilize them. Superfetation is when the mother becomes pregnant, but as much as 24 days later ovulates again and releases another egg which is then fertilized. In vitro fertilization is another form of superfetation.

Interesting Facts:· Fraternal twins are most often seen in African women, and least often seen in Asian women· You can have boy/boy, girl/girl, and boy/girl sets
ContentIdentical twins or fraternal twins. (n.d.). Retrieved from Facts about fraternal twins. (n.d.). Retrieved from Images/Videos
Individual Post #5 ~ Twins Part 3
Parasitic Twins

Also known as asymetrical conjoined twins, the cause of parasitic twins is still somewhat unknown. They are believed to be from two embryos formed in the uterus; one of which stopped developing and takes on a vestigial state.

Parasitic twins can be attached to any part of the body and has no set appearance. They also depend on the fully developed twin as their host.

There are many different types of parasitic twins. A few examples are craniopagus parasiticus, epigatric, dipygus, and fetus in fetu. Craniopagus parasiticus is where a parasitic head is attached to the head of the fully developed twin. Epigatric parasitic twins are where the underdeveloped twin is attached to the other twin at the abdomen. Dipygus is when the developed twin has two sets of lower extremities. The form of parasitic twin that is most feared is fetus in fetu. This is when the parasitic twin resides inside the other twin. This form of parasitic twin sometimes goes unnoticed until after death and an autopsy is performed.
ContentParasitic twins. (n.d.). Retrieved from Images
Individual Post #6 ~ AIDS


AIDS can be traced back 100 years. Old African medical documents show that AIDS first crossed from chimps to humans in 1908. The virus mutates over time. Scientists studied the differences between a sample from 1959 and more recent ones to establish that HIV most likely began spreading in humans in 1930. It is though that AIDS has been transmitted from monkeys to humans for hundreds of years, however it has only been spread from human to human after the development of humans. Education, test, and prevention will likely reduce the spread of HIV in humans. “High-risk sexual behaviours in cities are necessary to allow one of the viral jumps from chimps to get a toehold in humans. The good news is that this suggests HIV lives right on the edge of extinction.” ~ Worobey
ContentMacKenzie, Debora. "First cities in central africa triggered AIDS." NewScientist. 04 Oct 2008: 10. Print. Images

Individual Post #7 ~ Scorpion Venom Treating Cancer?


The Leiurus Quinquestriatus scorpion, found in the Middle East, is now being tested for a possible treatment of malignant brain cancer. Among the neurotoxins in the scorpion’s venom, there is also a peptide that binds to a receptor that is found only in some tumour cells and is non-toxic to humans. According to NewScientist, the October 2008 issue, " In culture, the peptide has invaded tumours in breast, skin, brain and lung tissue, but left healthy cells untouched". When trials began in 2007, 59 people suffering from brain tumours were treated with the agent. The people that were injected with higher doses lived three months longer on average than those who received a lower dose in treatment. Other trials are currently being done to see wether the agent, when inject into the blood stream, has the ability to find secondairy tumours.

MacKenzie, Debora. "First cities in central africa triggered AIDS." NewScientist. 04 Oct 2008: 10. Print.

Individual Post #8 ~ Sea Anemone


Sea anemones are brightly coloured sea creatures from the Phylum Cnidaria. They are polyps that attach to a surface with a pedal disk (an adhesive foot) and a column shaped body. Sea anemones are small creatures, averaging between 1.8 and 3 centimeters in diameter. However, some have been recorded as small as 4 millimetres and as large as 2 meters in diameter.
A sea anemone’s mouth is surrounded by tentacles. The nematocysts in the cnidocytes release toxins on contact. This is what causes the sticky feeling. The toxins paralyze the prey which makes it easier to move into the gastrovascular cavity to be digested. It is also used for defense.
Some species have both males and females, others are hermaphrodites. For this reason, sea anomones are capable of both sexual and asexual reproduction.
Although they are generally sessile, sea anemones have been observed swimming. They do this by either flexing their bodies or by using their tentacles.

Interesting Facts:

  • Sea anemones have a lifespan of 60 to 80 years
  • Few species of anemones are toxic to humans
  • Some species of anemones are aggressive toward other species. Cnidocytes are fired on contact with the other anemone which may result in tissue damage to both anemones.
  • Although they kill most fish species, clown fish have a mucus layer thicker than that of other fish, which allows them to live in the tentacles of the anemone.

ContentSea anemone. (n.d.). Retrieved from anemone. (n.d.). Retrieved from

Individual Post #9 ~ Pregnant Without Being Pregnant?


Withall of the technological advancements; from computers to artificial lungs, toIVF treatments, technology is changing the way we think. Hung-Ching Liu’s team at the CornellUniversity’s Center for Reproductive Medicine are now working to use thesetechnologies to create an artificial womb. They have grown mouse embryos for 17 days, in the artificial womb. The mice were only two days early of beingfull term. Thus far, all of the foetuseshad some form of mutation.

The goal is to eventually give women with damaged or diseased uterus theopportunity to give birth to a child, and eventually to be used outside of thebody. For women who just don’t want togo through the stress of pregnancy, the weight gain or the stretch marks, you’llhave a long wait ahead of you.


Whelan, Jo. "Too posh to get pregnant?." NewScientist. 21 Oct 2006: 53. Print.


Individual Post #10 ~ Dystrophic Epidermolysis


Epidermolysis bullosa is agenetic condition that mildly affects 50 in a million newborns. Thiscondition causes skin to be very fragile and blister, from friction, minorinjuries or in severe cases with touch.

Thereare three main types of epidermolysisbullosa:

  • Hallopeau-Siemens:the most sever type of the condition. Infants are typically born covered in blisters. This type of the condition also causes joint deformities,fusion of the fingers and toes, and the loss of vision, fingernails andtoenails. This form of the condition caneven lead to squamous cell carcinoma, a severe form of cancer.
  • Non-Hallopeau-Siemens:this type is slightly less severe. Blistering is mainly on hands, feet, elbows and knees.
  • AutosomalDominant Type: this type is very mild. Blistering results in mild scarring. In some cases, the only signs of the condition are abnormal nails.
The severe epidermolysis bullosacases most often occur when each parent carries the gene. In milder cases, 70 percent inherited thegene from a parent, while 30 percent have developed a new mutated.


Dystrophic epidermolysis bullosa. (2008). Retrieved from