Genetics Quiz Class Notes

Supermodels of Science Quiz Class Notes

Scientists use many different organisms to study diseases in humans.

They do this because organisms like worms, mice and yeast have many of the same genes as humans, and scientists can make changes in an organism's genes similar to changes in humans with specific diseases.

These "model organisms" can teach us important information that can help us learn about and find treatments for human diseases. Select a model organism to begin.

C. elegans

C. elegans is a tiny worm that lives in dirt.

Because the worm is transparent, it is easy to observe individual cells and watch how internal organs develop. The adult C. elegans worm consists of only 959 cells.

A scientist had the bright idea of using a glowing protein, called green fluorescent protein (GFP), to identify specific cells in developing C. elegans.

He discovered that brain cells glowed green when he put GFP in them.

The scientist was able to use GFP to make a map of cells in the brain, allowing him to understand how animal brains are organized.

GFP is now used by thousands of researchers in dozens of organisms to identify specific types of cells and to show where specific genes are turned on.

Fruit fly

The tiny fly that is attracted to overripe bananas on your kitchen counter is called D. melanogaster, commonly known as the fruit fly.

Scientists have been raising fruit flies in the laboratory for about 100 years, studying how their genes affect development, appearance, behavior, lifespan, and many other traits.

One way scientists use fruit flies is to figure out how daily, or circadian, rhythms work.

They have found that mutations in several genes affect the time of day or night that flies walk around, eat, and sleep.

In humans, a mutation in one of these genes causes a form of familial advanced sleep-phase syndrome (FASPS). People with this mutation fall asleep very early in the evening and wake up in the middle of the night.

Scientists have also discovered that different forms of another gene determine whether a person is severely affected by sleep deprivation.


Laboratory mice are the most commonly used animal in research.

There are many different types of laboratory mice. These model organisms are easy to house and handle and they reproduce quickly, so scientists can compare grandparents, parents, and children at the same time.

Some scientists use mice to study gene changes in Huntington's disease.

Huntington's disease causes affected people to have unusual movements, emotional changes, and progressive intellectual loss.

People who have Huntington's disease have very unusual genetic changes. Parts of their Huntington, or HTT, gene are repeated over and over.

Some scientists study what causes these long repeats. If they could prevent the repeats from multiplying, they might find a way to help people with Huntington's.


Many scientists use yeast as a model organism. This yeast, called S. cerevisiae, has been used in baking and making beer and wine.

One way scientists use yeast is to study Friedriech's ataxia, an illness that results from the degeneration of nerve tissue in the spinal cord.

About 1 in 50,000 people in the United States have Friedriech's ataxia. The disease affects coordination, muscle movement, and some sensory functions.

Scientists now know that Friedriech's ataxia is caused by a "stutter" in the human FXN gene, located on chromosome 9 in humans.


The same striped zebrafish in home aquariums are model organisms for many studies.

Their large, transparent embryos grow quickly outside the mother, making their development easy to observe.

Some scientists use zebrafish to understand bone problems in I-cell disease.

I-cell disease causes a buildup of proteins and fats inside cells, affecting bone development.

People with this disease are short in stature and have stiff, painful joints.

I-cell disease is caused by changes in the GNPTAB gene, located on chromosome 12 in humans.

By studying bone growth in mutant zebrafish, scientists hope to better understand the abnormal bones in children affected by I-cell disease.

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